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Understanding molecular upsets in diabetic nephropathy to identify novel targets and treatment opportunities
Drug Discovery Today Volume 00, Number 00 January 2020
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Teaser Growth of functional nanomedicines for diabetic nephropathy demands a perceptive understanding of pharmacological renal barriers and crosstalk with nanoparticulate engineering tactics to offer clinically adaptable solutions.
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Nidhi Raval1,z, Akshant Kumawat1,z, Dnyaneshwar Kalyane1, Kiran Kalia1 and Rakesh K. Tekade1,2
1 National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar 382355, Gujarat, India Q7 2 Indian Institute of Technology-Jammu, Jagti, PO Nagrota, Jammu 181 221, J&K, India
Diabetes and related complications are becoming a global encumbrance. Diabetic nephropathy (DN) is a major cause of end-stage renal disease (ESRD). The available therapeutic modalities related to DN do not treat DN at the molecular level, proposing further amendments in the management of DN based on the pathogenesis of DN. This manuscript discusses the concept and applications of nanomedicine for the treatment of DN that can improve renal targeting, retention and localization. This review also highlights the current issues related to targeting DN, challenges and allied opportunities toward the development of next-generation drugs and treatments for the management of DN.
Introduction Diabetes: a growing sweet demon Diabetes is a metabolic disorder characterized by hyperglycemia in a fasted or a fed state. The risk of diabetes increases when blood glucose is >130 mg/dl (80–140 mg/dl) [1]. The primary causes of diabetes include autoimmunity or destruction of insulin-secreting pancreatic b cells, insulin resistance, obesity, genetic polymorphism, ketoacidosis, sedentary lifestyle, improper diet and enzymatic defects such as incretin, dipeptidyl peptidase VI (DPP-VI), peroxisome proliferator activating receptors (PPARs), among others [2–4]. Diabetes is classified as either type I: autoimmune type of diabetes that involves b cell destruction, or type II: diabetes mellitus related to insulin deficiency or insulin resistance. Other types of diabetes that are less prevalent include gestational diabetes that occurs during pregnancy [5], diabetes caused by a genetic defect in the b cells and chemically induced diabetes caused by various drugs such as glucocorticoids, phenytoin, diazoxide, b-adrenergic blockers and nicotinic acid. Diabetes onset caused by other hormonal diseases such as Cushing’s syndrome, Down syndrome and Klinefelter syndrome have also been reported [6]. Type I and type II diabetes are more common and are responsible for various diabetes-related complications including diabetes retinopathy, diabetic nephropathy (DN), Corresponding author: Tekade, R.K. ([email protected]) z
Equal first author.
1359-6446/ã 2020 Published by Elsevier Ltd. https://doi.org/10.1016/j.drudis.2020.01.008
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Understanding molecular upsets in diabetic nephropathy to identify novel targets and treatment opportunities Nidhi Raval has completed her MS (Pharm) in pharmaceutics from NIPERAhmedabad and is now pursuing her doctoral degree from this institute under the guidance of Dr Rakesh K. Tekade. Her research in Dr Tekade’s lab involves the development of a novel renal-targeted platform for targeted siRNA/miRNA delivery and gene silencing. Kiran Kalia is Professor in Pharmacology and Director, NIPER, Ahmedabad, and is also a Professor in lien Department of Biosciences, Sardar Patel University. She has an extensive research experience of 35 years and has guided several masters and PhD students. She is an awardee of Indian National Science Academy (INSA) Research fellowship to work at NII, New Delhi; and has received CSIR Fellowships JRF, SRF, PDF and a research associateship. Professor Kiran is an Editorial Board and Review Committee member of several international journals. Her research interests encompass proteomic markers for diabetic nephropathy from urine, genomic markers for the susceptibility of diabetic retinopathy, genomic alterations in oral cancer, environmental biotechnology and toxicology studies. Rakesh K. Tekade is an academic researcher with >10 years of teaching and research experience. Dr. Tekade’s research group at the Department of Pharmaceutics at NIPERAhmedabad investigates the design, development and characterization of targeted nanotechnologybased products for the site-specific delivery of therapeutic drugs, siRNA, miRNA, among others, for the treatment of cancer, diabetes arthritis and neurological disorders. He has coauthored >100 peer-reviewed publications in international SCI cited journals (>4000 citations; H–index of 34), contributed >50 international reference book chapters, 5 invited editorial articles and 4 patent applications. Dr Tekade is an Editor-in-Chief of a Book Series entitled ‘Advances in Pharmaceutical Product Development and Research Series’ (https://www. elsevier.com/catalog/pharma/pharmaceutical-science/ drug-delivery/advances-in-pharmaceutical-productdevelopment-and-research).
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diabetic neuropathy and diabetic foot. DN is a major cause of chronic kidney disease that results in a progressive decrement in renal functioning [7].
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Around 25% of the population suffering from diabetes tends to develop DN. Among these DN affected individuals worldwide, 50% of them suffer from end-stage renal disease (ESRD), which requires costly and painful dialysis treatments. Of the population suffering from DN, 75% of has type I diabetes and the remaining are type II diabetic patients [8]. DN causes structural damage to the kidneys such as glomerular hyperfiltration, microalbuminuria, autophagy, glomerular basement membrane thickening, fibrosis caused by extracellular matrix protein and hypertrophy of mesangial cells. The effacement and apoptosis of the podocytes are also one of the hallmarks for DN [9]. In DN, the autophagy of podocytes was reduced resulting in leakiness of the filtration barrier. The delocalization of podocin and nephrin (a slit diaphragm protein) from the podocyte foot process is responsible for proteinuria or microalbuminuria. The proximal tubular part of the nephron is also affected in DN. The Q8 accumulation of fibronectin, AGE and various inflammatory mediators is responsible for fibrosis in renal tubules [10]. The early diagnosis of the diabetic nephropathic kidney (stage I DN) includes the identification of thickening events in the glomerular basement membrane and tubular basement. These are the most noticeable structural changes that can be observed along with proteinuria. After glomerular thickening, mesangium cells are expanded and considered as stage II DN. This expansion process in the mesangium further results in the leakiness of the glomerulus via the accumulation of fibronectin and collagen type IV, also causing nodular sclerosis (stage III DN) [11]. The prospective emergence of inflammation in the mesangium leads to the development of glomerular sclerosis and tubular apoptosis. At Q9 later stages of DN, glomerular filtration rate (GFR) drastically Q10 declines, the interstitium alters and the glomerulopathy coalesces into segmental and global sclerosis, resulting in end-stage renal damage (stage IV ESRD). Other structural changes occur in DN kidneys such as reduction in epithelial fenestration, loss of podocyte integrity with foot process effacement, mesangial expansion, tubular apoptosis and atrophy (Fig. 1a) [12]. Sometimes hyperglycemic conditions harden the arteries and eventually lead to an elevation in the blood pressure. This enhanced blood pressure of capillaries interacts with metabolic and hemodynamic factors in the kidneys, which are involved in progression of DN. Hyperglycemia adversely effects renal cells such as glomerular cells, mesangial cells, podocytes, proximal tubules cells and epithelial cells; and is responsible for activation of monocytes, macrophages, increased formation of advanced glycation end products and growth factors – for instance, transforming growth factor b1 (TGF-b1) and angiotensin II in renal cells (Fig. 1a) [13]. Diabetic factors can augment and alter the expression of the pathological gene involved in development of the DN. In context, bone morphogenetic protein 4 (BMP4) to Smad1 signaling has involvement in mesangial cell injury development in DN as well as in podocyte injury [14]. Overexpression of epidermal growth factor receptor (EGFR) and sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) augments the condition of the DN via the 2
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renal immune cell infiltration, fibrotic and pro-fibrotic markers and induction of oxidative stress. The suppression of these markers alleviates the DN and improves insulin resistance in type 2 diabetic mice through increments in autophagy of pancreatic b cells which helps to preserve b cells [15,16]. Similarly, overexpression of angiotensin II suppresses the expression of MYH9 and downregulation of Coro2b protein leading to podocyte damage and effacement [17,18]. Therefore, active potential therapeutic agents are needed that can target the kidneys and can localize in the kidney for a longer period of time and can suppress the genetic modulation without any notable adverse effects [19].
Therapeutics used in the treatment of diabetic nephropathy The hyperglycemic condition initiates multifactorial events that damage the kidney structurally and functionally such as glomerular hyperfiltration, epithelial hypertrophy, proteinuria, following thickening of the glomerular basement membrane, mesangial matrix accumulation, podocyte damage and sclerosis of glomerulus [9]. Hemodynamic and metabolic changes as well as structural damage also aid the progression of DN. Hyperglycemic response Q11 and metabolic and hemodynamic changes are proven mediators for diabetic kidney disease [9,20]. The high glucose induces the growth factors [TGF-b, nuclear factor (NF)-kB, vascular endothelial growth factor (VEGF)] and cytokines, leading to the production of reactive oxygen species (ROS) and the accumulation of advanced glycation end products. Renin–angiotensin system activation is mostly found in all stages of DN and suppressing angiotensin II showed an important role in reduction of the progression of DN. Angiotensin-converting enzyme (ACE) inhibitors are also involved in a renal protective effect, for example microalbuminuria reduction with valsartan. In earlier literature, it was reported that ACE inhibitors effectively decreased the proteinuria and showed a renal protective effect in normotensive and hypertensive patients [21]. Angiotensin receptor blockers (ARBs) also showed the renal protective effect and decreased proteinuria irrespective of its antihypertensive effect in type I and type II diabetic patients [22]. The idea of using ARBs and ACE inhibitors in combination has now been withdrawn owing to an increased risk of side effects, mainly of hyperkalemia which is responsible for metabolic acidosis. Also, because of a lack of efficacy compared with other novel therapeutics, ACE inhibitors and ARBs are not currently prescribed for DN. Hence, there is a need for delivery of therapeutics that can suppress the angiotensin receptor effectively, without any adverse events [23]. Peroxisome proliferator-activated receptor (PPAR) ligands have shown promising evidence in combating diabetes. Three subtypes of PPAR receptors were identified as alpha, beta/delta and gamma. Among them PPARa was involved in fatty acid uptake via the heart and liver. PPARbd contributes to fatty acid oxidation in muscles. PPARg is majorly expressed in fat and facilitates lipid and glucose uptake, glucose oxidation stimulation and suppresses the level of fatty acid and suppresses insulin resistance. However, PPARg agonists such as thiazolidinediones, rosiglitazone and pioglitazone gave symptomatic relief in DN via regulation of lipid and glucose metabolism, regulation of hypertension, insulin resistance as well as ameliorating proteinuria and preventing further renal damage observed in a rodent model. Along with a protective effect
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Damaged tubular epithelium
Tubular epithelium
Tubular atrophy
Slit diaphragm Disruption
Podocyte apoptosis
Detachment of pericyte
Inflammatory cells infiltration
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Leukocyte amassing
Leukocyte infiltration
Podocyte detachment
Myofibroblast Foot process effacement
Endothelial cells
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Albuminuria
Macrophage FibroblastInflammatory cells
Extracellular matrix deposition
Proximal tubule fibrosis Basement membrane thickening Podocyte effacement
Reduced recovery of albumin
Diabetic nephropathy
Normal kidney Tubular epithelial cells
Glomerular Podocytes basement Mesengial Albumin Foot process cells membrane Glomerular Parietal cells capillary
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Podocyte Targeted nanoparticles (size: 10–50 nm) Mesengial cells
Cationic nanoparticles (size: 50–100 nm)
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Nanoparticles (size: 70–130 nm) Mesoscale nanoparticles (350–500 nm)
Epithelial cells of proximal tubule
CNT (diameter: 3 nm and length: 500 nm) Peritubular capillary
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FIGURE 1
(a) Diagrammatic representation of healthy normal kidney and diabetic nephropathic kidney. Expanded portion shows podocyte dysfunction (loss of podocyte foot process, increased leakiness of filtration barrier leads to albuminuria) and proximal tubule fibrosis [caused by infiltration of inflammatory cytokines, transforming growth factor (TGF)-b, fibronectin and collagen], which occur in diabetic nephropathy. (b) Distribution of various-sized formulations for the treatment of diabetic nephropathy. Nanoparticles reach the specific area of the kidney based on size, charge or targeting molecules present. As shown, for example <10 nm nanoparticles could easily reach and become cleared through the proximal tubule region. Whereas a 10–50 nm targeted nanoparticle is able to reach the podocyte cells. Moreover, a 50–100 nm particle could be the desired size for glomerular deposition of nanoparticles and particles of 70–130 nm size for mesangial cell targeting in the kidney. The larger sized ( 350–500 nm ) nanoparticles could remain in blood circulation and reach the proximal tubule via the peritubular capillary. Further, a 3 nm diameter and 500 nm length carbon nanotube (CNT) becomes directly headed for proximal tubule cells owing to a greater aspect ratio [50].
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in DN, clinical application is hindered by common side effects such as cardiac complications, abnormal liver functions, malaise, myocardial infarction, weight gain and fluid retention [24]. In DN, the accumulation of AGE and receptor for binding of AGE (RAGE) was found to be caused by the hyperglycemic condition of the kidney leading to the development of glomerular lesions and endothelial dysfunction via activation of protein kinase C (PKC). RAGE and its interaction will scavenge the products formed as a result of glycation but activates various inflammatory mediators, namely NF-kb, TGF and interleukin (IL)-6. It also led to overexpression of endothelin-1-reduced nitric oxide generation and VEGF in DN. PKC and AGE were also responsible for developing oxidative stress in the kidney that further leads to inflammation. Moreover, pyridoxamine (an AGE inhibitor) was able to prevent the formation of reactive carbonyl species and reduce glycation and also aid in amelioration of DN [25]. However, the PKC antagonist ruboxistaurine could suppress vascular injury in DN, which caused activation of PKC. Hence, only PKC and AGE inhibitors do not improve the nephropathic condition. For that purpose, there was a need for antioxidants (quercetin and resveratrol) and anti-inflammatory agents (pentoxifylline and cilostazol) [26]. The reported investigation also suggested that endothelin 1 (ET1) causes renal injury owing to its fibrotic and inflammatory actions. Endothelin receptor inhibitors (i.e., atrasentan) were considered to reduce proteinuria but led to cardiovascular complications such as congestive heart failure and fluid accumulation [27]. DPP-VI inhibitors were also able to suppress the epithelial-tomesenchymal transition via suppression of crosstalk between caveolin-1 and integrin-b1 [28]. Whereas, low-dose sodium-glucose cotransporter 2 (SGLT2) inhibitors improved albuminuria and mesangial expansion in db/db mice same as high-dose but were not able to reduce glucose concentration in the blood. The main disadvantage of this class drugs is induction of genitourinary infections in a mild-to-moderate manner [29]. Vitamin D receptor (VDR) activators (e.g., paricalcitol) were reported to suppress renin receptor and angiotensinogen receptor as well as being able to improve glomerulus and tubular damage. However, sometimes it can cause vascular calcification in animal models and the dose of paricalcitol was not tolerated by patients and required reduction in dose [30]. Renal endothelin (ET) receptor activation in DN leads to mesangial cell proliferation, inflammation and fibrosis, whereas a selective ET-A receptor inhibitor suppresses the albuminuria in DN patients [21]. To date, no convincing data have been shown for reduction in renal endpoints. Specified therapeutic approaches mostly dealt with blood pressure as well as glucose control, it is manifest that DN progression still leads to ESRD in several patients. Hence, there is an urgent need for new therapeutic modalities that efficiently decrease the disease progression. The following section discusses novel therapeutic carriers for kidney targeting that could improve the effectiveness of therapeutic agents.
Approaches for targeted delivery of therapeutics in diabetic nephropathy DN is aggravated by hyperglycemia, fibrosis, inflammation, glomerular sclerosis, glomerular lesions and ROS generation. The conventional therapeutics that are available on the market were 4
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less effective because of a large amount of drug loss due to the firstpass metabolism effect, hepatic clearance, systemic absorption and distribution to other organs [31]. Therefore, nanomedicine is a better solution for the enhancement of targeting and improvement of the therapeutic effect in the kidney. The nanomedicine approach could help to target the above-mentioned therapeutics to the desired sites in treating DN [32]. These nanomedicines include liposomes, nanoparticles, microbubbles, prodrugs comprising nanoparticles and exosomes, providing the ability for peptide and gene therapy delivery for the treatment of DN.
Nanodrug-bearing particles During the past decade, DN has gained a lot more attention from pharmacological research, however few have shown promising results. Smaller diameter nanoparticles (10 nm) are cleared rapidly from kidney owing to inherent function of the kidney as a blood filter. The glomerular endothelium is the first component with 70–90 nm fenestrations and following 300–350 nm thick basal lamina of glomerular basement membrane (GBM) comprising heparin sulfate and proteoglycan with 3 nm pores, able to filter small molecules based on its size and charge. Besides GBM, podocytes are situated possessing a filtration slit of 32–40 nm. However, 10 nm nanoparticles easily enter the glomerular filtration unit and are cleared rapidly. Sometimes, prolonged retention of nanoparticles in the kidneys exhibited cellular shrinkage owing to more cellular uptake via renal cells. Therefore, retention, enhancing therapeutic index and activation of drug after reaching the target were found challenging for nanoparticles for effective delivery to the DN. The selective delivery of tailored nanoparticles to the target site enhanced therapeutic effect and reduced the toxic adverse effects. Several studies have been reported for the in vivo delivery of nanoparticles in tumors, resulting in accidental discovery of kidney-selective targeting and accumulation [33]. Nanoparticles can be engineered for delivery of drugs as well as imaging substances for enhancement of pharmacokinetic and pharmacodynamic effects that enable targeting delivery of the nanoparticles toward specific tissue cells at the site of the disease. A nanoparticle is a solid polymeric material that can be made efficient by slight modification with the help of PEGylation, conjugation, surface chemistry and ligand binding. Nanoparticles have proved to be a promising future theranostic for many diseases and disorders [34]. Wu et al. studied the receptor expressed by podocytes that is specific to glucocorticoids [i.e., neonatal Fc receptors (FcRn)]. Quantitative polymerase chain reaction (qPCR) confirmed the expression of FcRn in the podocytes. Albumin nanoparticles were fluorescently labeled and conjugated with methylprednisolone (BSA633-MP) for delivery to the podocytes. in vitro studies showed that uptake of nanoparticles was more (36-fold) in the human podocytes compared with HK-2 cells and other vascular smooth muscle cells. The results suggested that the albumin nanoparticles specifically reached kidney podocytes via interaction with FcRn receptors, indicating that the nanoparticles were specifically taken up by the podocytes [35]. Further, polylactic-co-glycolic acid (PLGA) nanoparticles comprising resveratrol were developed and evaluated for their antioxidant, anti-inflammatory and nephroprotective action effectiveness [36]. To enhance the targeting of the nanoparticle
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to the kidney, the nanoparticles were conjugated with KIM-1. The results suggested that there was a decrease in expression of NODlike receptor family pyrin-containing domain-3 (NLRP-3) – an inflammasome that is responsible for many diseases – compared with its expression in healthy kidneys [37]. There was also an increment in AMP-activated protein kinase (AMPK) and decrement in the phospho-mTOR level via PLGA nanoparticles that induced autophagy. In addition, the nanoparticles improved the renal condition of the adenine-induced CKD mouse model [38]. In another study, researchers used RGDfC (Arg-Gly-Asp-DPhe-Cys)-conjugated quantum dots for kidney targeting. The RGDfC binds to an avb3 integrin receptor of podocytes. in vitro data confirmed that RGDfC-conjugated quantum dots were selectively taken up by the podocytes that express avb3 integrin receptors. Upon incubation of the unconjugated formulation with podocytes, it was observed that the fluorescence intensity of the conjugated quantum dots was greater than unmodified quantum dots. When these formulations were incubated with glomeruli the targeted conjugate, with the help of avb3 receptors, became accumulated in the podocytes. These results give the idea that the conjugated quantum dots can be used for podocyte targeting [39]. Furthermore, rhein-loaded nanoparticles were developed to improve bioavailability and distribution in the kidney. Chen et al. synthesized the rhein-loaded nanoparticles by using a triblock copolymer of polyethyleneglycol-co-polycaprolactone-copolyethyleneimine to evaluate the targeting potential and therapeutic effect of the nanoparticle (size: 80 nm; z: 6–7 mV) in DN. The nanoparticles showed >90% cell viability to a concentration of 0.5 mM. The fasting blood glucose level was found to be decreased by <20 mmol/l along with a decrease in serum creatinine (<50 mmol/l) and serum urea nitrogen (<10 mmol/l). The proteinuria was also decreased in diabetes-induced mice to <2 mg/ 24 h. The in vivo imaging was helpful in understanding the localization of the nanoparticles in the kidney. Hence, the rhein-loaded nanoparticles proved to be beneficial in targeting for the treatment of DN [40]. The above-mentioned nanoparticles successfully delivered a drug to the kidneys. Numerous aspects that have been taken into consideration to improve targeting to the renal cells are discussed in the section below.
Effect of different formulation aspects of nanoparticles on the kidney targeting The kidney is an excretory organ comprising 1–2.5 million nephrons, playing a part for homeostasis of fluid, osmotic regulation and the filtration of waste body material. A nephron consists of the glomerulus, proximal tubules, loop of Henle, distal tubule and a collecting duct. The glomerular consists of podocytes, mesangial cells and the glomerular basement membrane. In normal physiological conditions, blood is filtered via size and charge through the glomerular membrane, which allows passing of water and small molecules from plasma. Higher molecular weight substances and anionic charged components remain inside the blood (e.g., albumin). Anionic molecules easily pass through the filtration barrier of the glomerulus. This barrier is disturbed in DN and causes albuminuria. Therefore, nanoparticles must cross the glomerular filtration membrane. Hence, structural features of the nanoparticles are important in their role to reach kidney cells.
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Nanoparticle delivery to numerous kidney cells and their components are explained here [41]. The effect of zeta potential of nanoparticles is significant. Positively charged nanoparticles are quickly excreted from the kidney owing to increased potential to bind with the protein as well as more interaction with the mononuclear phagocytic system. Oppositely or negatively charged nanoparticles are taken up more Q12 by macrophages than neutrally charged nanoparticles. Nanoparticles with <15 mV charges are less prone to macrophage uptake and have improved circulation in the blood. However, anionic Q13 nanoparticles are not able to accumulate more in the liver and spleen compared with neutral nanoparticles [42]. Cationic nanoparticles are easily taken up by the cellular membrane and capable of endosomal escape. Therefore, positively charged to neutrally charged nanoparticles are easily taken up by the negatively charged glomerular basement membrane. This is because of the anionic nature of the basement membrane as a result of a large amount of heparin-sulfate-containing glycocalyx. Therefore, there could be a chance for positively charged nanoparticles to get accumulated in the GBM [43]. The selection of charged nanoparticles is also an important parameter for kidney targeting. In one research study, <5 nm (3.7 nm) and negatively charged ultra-small nanoparticles were administered via the intravenous route. It was found that most of the nanoparticles reached the glomerular capillaries, able to surpass glomerular endothelium and slowly accumulate in mesangial cells for 30 days. Hence, the anionic charged glomerular basement membrane prevents the excretion of <5 nm nanoparticles compared with positively charged nanoparticles [44]. This outcome suggests the charged principle of kidney barriers – majorly negatively charged nanoparticles also applied and utilized for the fluorescence imaging or biodistribution. This charge on the GBM could be useful for drug delivery purposes and, by taking it into consideration, Zuckerman et al. Q14 prepared cationic nanoparticles of cyclodextrin for delivering siRNA to the GBM. The nanoparticles were then coated with a conjugate of adamantane and PEG to improve the hydrophilicity and induce a positive charge on the nanoparticles. The charge on the siRNA nanoparticles was around +11 mV, which was attributed to the successful drug delivery to GBM and facilitated the accumulation in the glomeruli. By contrast, the free siRNA did not show any retention in the glomeruli. The PET images showed that siRNA accumulated in the kidney for a shorter amount of time <5 min. However, nanoparticles remained in the kidney for a long time. It was also observed that there was disassembly of nanoparticles. The researcher proved that it might be due to repulsive forces between siRNA and GBM. They further concluded that charge on the nanoparticles acted as an attractive force between the GBM and the nanoparticles. This led to the accumulation of the nanoparticles in the glomerular basement membrane. The effect of the hydrodynamic size of nanoparticles can also be considered. To develop an efficient nanomedicine, the particle size of nanoparticles has been vastly explored. The majority of nanoparticles (30–150 nm) are not subjected to filtration via the kidney, despite degradation to <10 nm particle size or a damaged membrane. Nanoparticles of 5–8 nm can easily cross the glomerular filtration barrier and are cleared through the kidney after 4 h of injection (Fig. 1b) [45]. However, cationic nanoparticles in the www.drugdiscoverytoday.com
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range 50–130 nm can accumulate in the glomerular basement membrane as well as the mesangium and enhance targeting to the kidney [43]. Recently, Williams et al. proposed that nanoparticles in the particle size range of 350–500 nm could be retained in the kidneys. PLGA nanoparticles were synthesized and then were PEGylated to improve hydrophilicity and circulation time. The nanoparticles were injected via the intravenous route and were found to increase the localization of nanoparticles in the kidney by 30-fold compared with localization in other organs [46]. Similarly, researchers have developed cationic (C-MNP; z: +18 mV) and anionically charged (A-MNP; z: 19 mV) mesoscale nanoparticles (400 nm) for renal proximal tubule targeting. Surprisingly, they found 25–30-times enhanced localization in the kidney compared with lungs (2–3.5 times). The A-MNP and C-MNP were 4.5-times and 3.7-times higher in the kidney at 7 days compared with the heart. From this, it can be said that mesoscale nanoparticles remained in the kidney for a longer period of time compared with other organs (Fig. 2a–c). From the results, it was inferred that Q15 targeting the nanoparticles toward the kidney was done mainly via mesoscale nanoparticles, despite surface charge. Investigators also reported that alteration in size of nanoparticles as well as opsonization potential was a new proposed mechanism for renal targeting and cellular uptake [47]. To check the effect of the size of nanoparticles on kidney retention and targeting, another research group prepared albumin nanoparticles (AN) of different sizes. They found that nanoparticles with a particle size 95 nm (AN-95) were retained in the kidney more. This was confirmed by fluorescence assay: nanoparticles with a size 95 nm showed greater fluorescence compared with albumin nanoparticles of different sizes (75 and 130 nm; AN75 and AN-130). Confocal images of kidney sections provided further evidence that there was a greater accumulation of nanoparticles with the size 95 nm in the mesangium of the kidneys (Fig. 2d,e). After 5 min of intravenous administration, the nanoparticles showed a significant amount of retention in the kidney and liver compared with other organs (Fig. 2f). The researchers believed that clathrin-mediated endocytosis was the major mechanism of uptake of nanoparticles in the mesangial cells. Another reason for the accumulation of nanoparticles in the cells was the systemic pressure of the blood flowing into the kidneys and the fenestration of 85–145 nm of the endothelium of glomerular capillaries that allowed the nanoparticles to enter into the mesangial cells. However, the cut-off for penetrating through the filtration barrier is 10 nm. Thus, nanoparticles were unable to penetrate the barrier and successfully localized in the mesangial cells and the targeted delivery was achieved by researchers [48]. The effect of nanoparticle shape is another consideration. The particle size and zeta potential of nanoparticles play a significant part in drug targeting to the kidney. Besides these key properties, the shape of nanoparticles also affects the drug targeting, even if the particle size might not be ideal given the key points made above. This holds true for carbon nanotubes owing to their larger aspect ratio. Because of the larger aspect ratio of nanotubes, carbon nanotubes with particle sizes in one dimension of >500 nm can pass through the glomerulus [49]. This happens because the diameter of the nanotubes is small (i.e., 3–4 nm). The smaller diameter and larger aspect ratio help them to pass through the 6
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glomerulus when its spatial orientation is perpendicular to the basement membrane. Therefore, even smaller diameters restricted Q16 the carbon nanotubes from kidney clearance [50]. In similar circumstances, Ruggiero et al. prepared nanotubes with a length of 500 nm and a diameter of 1 nm. The nanotubes had a negative zeta potential but a higher molecular weight and aspect ratio allowed them to pass through the glomerulus. Despite the higher molecular weight, >60% of the nanotubes were excreted through the urine and only 20% was reabsorbed, where the remaining nanotubes were excreted via hepatobiliary circulation. This was further confirmed via NIR – proximal tubule uptake occurred owing to the presence of brush borders. Because other parts of nephron do not have brush borders, investigators determined that most of the accumulation of nanotubes occurs in the proximal tubule based on the fluorescent intensity [51]. Thus, nanoparticle size, shape and charge played a vital part in kidney targeting. In addition, lipidic vesicles such as liposomes have also been explored by researchers for better kidney targeting to the different affected areas, which is explained in following section in detail.
Liposomes in diabetic nephropathy targeting Liposomes comprise lipids such as phospholipids, blended with other materials such as cholesterol to make a hollow sphere containing the phospholipid bilayer. The outer layer is hydrophilic and the inner layer is hydrophobic, and the liposomes are less stable than nanoparticles. However, liposomes can enhance solubility and permeability of BCS class II and class IV drugs. Liposomal formulations Q17 are studied to target different diseases, such as cancer, kidney disease, viral infections, fungal infections and pain [52]. In context, Morimoto and colleagues developed liposomes containing TRX-20 (3,5-dipentadecyloxy benzamidine hydrochloride) to check the renal targeting potential of liposomes. To improve the circulation time of the formulation, they formulated PEGylated liposomes. The results showed that TRX–liposomes were retained and became adhered to rat mesangial cells specifically. The normal PEGylated liposomes did not show any fluorescent absorbance or presence toward rat mesangial cells. The HPTS assay showed that the same amount (0.32 mg/kg) of Q18 injected PEG–liposomes and TRX–liposomes were localized in the renal cortex, whereas only TRX–liposomes were retained in the glomerular cells owing to the nephritic condition of rats. When a comparison between normal rats and nephritic rats injected with TRX–liposomes was performed, the nephritic rats showed greater fluorescence, indicating more localization of the liposomes. Hence, TRX-modified liposomes enhanced the tendency to become accumulated in the kidney compared with normal PEGylated liposomes [53]. Recently, various modifications in the liposomal formulation have been made to improve targeting potential. For example, Kowalski and colleagues developed modified SAINT-o-somes [liposomes made up of cationic lipid 1-methyl-4-(cis-9-dioleyl) methylpyridinium chloride] for improved targeting efficiency. The SAINT-o-some was found to have better serum stability as well as drug release properties compared with conventional therapeutics. It also showed better targeting effect toward podocytes when conjugated with specific antigen-targeting antibodies such as antiVCAM-1 [54].
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A-MNP day 3 C-MNP day 3 A-MNP day 7 C-MNP day 7 Dye day 3 PBS day 3 & 7
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FIGURE 2
(a) Localization and distribution of administered anionic mesoscale nanoparticles (A-MNPs) in kidney by fluorescence plus CT overlay. (b) Images of fluorescence plus CT transaxial section of a mouse treated with A-MNPs. (c) Images of ex vivo organ fluorescence from mice injected with mesoscale nanoparticles (MNPs), dye or PBS normalized by total organ weight; adapted, with permission, from [47]. (d) Ex vivo fluorescence image of excised kidneys after 5 min of administration of nanoparticles via ex vivo imaging system (Quick View 3000, Bio-Real, Austria). (e) Quantitative intensity of the excised kidney. (f) Confocal images of kidney sections taken after 5 min of administration of nanoparticles. Scale bar: 30 mm. D = peritubular interstitial space, * = glomeruli, AN = albumin nanoparticles with size in nm indicated by a number, AN-75: 75 nm contained albumin nanoparticle, AN-95: 95 nm-sized albumin nanoparticle and AN-130: 130 nm size contained Q1 albumin nanoparticle. Adapted, with permission, from [48].
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Another group prepared anti-VCAM-1-rapamycin-saint-osomes to evaluate targeting ability toward podocytes. However, podocytes are known to express mammalian target of rapamycin (mTOR) receptors. Hence, rapamycin was used as a carrier in this approach to target the podocytes. It was observed that in the presence of tumor necrosis factor (TNF)-a the VCAM-1 (vascular cell adhesion molecule-1) is expressed. Therefore, in the presence of TNF-a, the cellular uptake of targeted saint-o-somes was enhanced over nontargeted saint-o-somes. From the wound-healing assay, it was observed that there was no growth of cells in the wounded area of the cells treated with the targeted formulation as a result of VCAM-1 suppression [55]. Q19 Based on the previous study, Yuan et al. also prepared triptolideloaded PEGylated TRX-20-modified liposomes (TRX20–LP) to observe therapeutic potential in renal disease. The prepared liposomes had a particle size of 110 nm with a zeta potential of +14 mV. The in vitro data demonstrated that the liposomes underwent mesangial cell uptake, and the extent of this uptake was similar even after PEGylation. The modified liposomes showed successful anti-inflammatory action by decreasing the levels of nitric oxide by 70% and TNF-a by 50%. The TRX-20-modified liposomes showed greater accumulation in the mesangial cells compared with unmodified liposomes. The anti-inflammatory action of PEGylated and non-PEGylated TRX-20-modified liposomes was greater than unmodified liposomes and the plain drug itself. The in vivo data showed that the groups that were treated with PEGylated liposomes displayed a twofold decrement in proteinuria and simultaneous increment in the serum albumin levels when compared with control groups. These results proved the efficiency of the modified liposomes for renal targeting [56]. Owing to the high lipophilicity of liposomes, they can show some off-target effects. Although, owing to the ineffective biodistribution of liposomes, nanoparticles have been proven to be more efficient and promising compared with liposomal delivery [57]. There is a lack of well-defined factors affecting kidney targeting for liposomes in the same way as with nanoparticles owing to a lack of research in this field. Hence, there is a dire need to develop a more selective delivery system that can specifically target the kidney. These potential strategies include microbubble therapy, mesenchymal stem cells (MSCs), peptide drug delivery and prodrugs.
Ultrasound-targeted microbubble destruction Clinically, microbubbles are utilized as an ultrasound contrast agent and investigated as an ultrasound therapy mediator. To enhance the theranostic effect, the microbubble can be attached to the nanoparticles with the intention of targeting, skin permeation, imaging and enhancing the acoustic response under ultrasound waves. Currently available nanoparticle-loaded microbubbles necessitate polymers and an oil layer for conjugation with the nanoparticles, which might be responsible for less biocompatibility and includes several steps. However, nanoparticle-loaded phospholipid-coated microbubbles can reduce the stated limitations [58]. Recently, scientists have developed microbubbles that have a bubble-like structure with a gas core that is encapsulated by lipids, polymers or protein shells. The characteristic feature of this microbubble is the particle size of 1–8 mm in diameter and requires an ultrasound of 2–115 MHz for resonance. Similar to a nanoparticle, the particle size of micro8
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bubbles, as well as surface display targeting ligands, is an important feature for drug delivery toward the kidney [58]. These microbubbles could be used for diagnostics as well as for drug delivery to improve the targeting and efficacy of the drug. The microbubbles act by the mechanisms of cavitation and sonoporation. Sonoporation is the property of enhancing the permeability of a drug to the target site by the reaction between the ultrasound and microbubbles [59]. In line with this, Chen et al. used ultrasound-targeted microbubble destruction (UTMD) to target coenzyme Q10 (CoQ10)loaded liposomes to the kidney to evaluate the therapeutic efficacy of the CoQ10 in early DN. CoQ10 is an endogenously synthesized antioxidant that could control blood glucose and prevent the free radical formation in DN. After treatment, CoQ10 was entrapped in a liposome (CoQ10–LIP; 180 2.1 nm; z: 18.20 mV) and CoQ10– LIP with UTMD (CoQ10–LIP + UTMD), as a microvascular complication the renal blood flow and kidney volume were improved in diabetic rats compared with the free-CoQ10-treated group (Fig. 3a, b). In addition, renal targeting of CoQ10–LIP + UTMD improved the podocyte foot process effacement and showed a protective effect toward podocytes, whereas CoQ10–LIP combined with the UTMD (Fig. 3c). It also alleviated the expression of downregulated podocin/NPHS2 from DN podocytes as well as suppressing the mesangial cells and glomerulus fibrosis up to 60–70% compared with the control and free-CoQ10-treated groups. Therefore, it can be said that UTMD assisted CoQ10–LIP treatment method potential to decrease the incidence of DN [60]. Moreover, UTMD could be utilized for drug delivery to a specific organ and improved permeability. Based on the advantages of microbubble therapy, Sheng et al. used UTMD to improve the targeting potential of basic fibroblast growth factor (bFGF) – able to decrease the structural and functional damage of kidney in CKDloaded liposomes. The investigators found that intrarenal delivery of bFGF–liposomes with UTMD was successful in delivering a large amount of drug into the kidney compared with other treatment groups (bFGF, bFGF–liposomes, UTMD). The bFGF successfully decreased various inflammatory mediators of DN such as interleukins, NF-kb and TGF-a. The formulation was found to be successful in improving the overall condition of the DN rat model [61]. As an emerging delivery system, researchers are still working on the microbubble therapy technique for drug delivery to the kidney.
Peptide and prodrug-based drug delivery Many low molecular weight proteins have been developed for targeting the kidneys. Among which, lysozymes have been found to undergo better retention in the kidney among the other molecules and could be a good carrier for targeting. However, their efficiency has suffered owing to adverse cardiotoxicity effects and complex synthesis methods. Also, any modification can lead to the synthesis of the immunogenic compound. To overcome the disadvantages of these compounds, other smaller carriers such as peptides can be used for targeting [62]. Yuan et al. demonstrated that a peptide fragment of albumin (PF-A299–585) became accumulated in the kidney (20–30% of administered nanoparticles) via endocytosis by megalin or cubulin receptors present on the inner lining of renal tubules [63]. In another study, the targeting potential of the peptide was evaluated
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(b)
Color doppler image
(c)
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Two-dimensional ultrasound image
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FIGURE 3
Q2 (a) 2D ultrasound image of kidney at 12 weeks. (b) Kidney blood flow imaged via color doppler flow at 12 weeks indicating impact of CoQ10-liposome on morphology of kidney as well as function of diabetic rat. (c) Transmission electron microscopy image of podocytes representing protection of renal podocytes in diabetic nephropathy (DN) rat model after treatment. Here, red arrow represents fusion of the podocytes. CoQ10: coenzyme Q10; CoQ10+UTMD: coenzyme Q10 + ultrasound-mediated microbubble destruction; CoQ10-LIP: coenzyme Q10 encapsulated in liposome and CoQ10-LIP + UTMD: coenzyme Q10 encapsulated in liposome combined with ultrasound-mediated microbubble destruction. Adapted, with permission, from [60].
via conjugating with triptolide, for anti-inflammatory and immunosuppressant activity. The in vitro and in vivo data showed less toxicity, improved anti-inflammatory action similar to a plain drug and the conjugated peptide rapidly accumulated in the kidney. Thus, this strategy improved the condition of the kidney in the rat model. The distribution of the conjugate in the kidneys compared with other organs was inferred by comparing the fluorescence intensity. The fluorescence was at a maximum after 1 h of administration of the conjugate and decreased afterwards, which confirms that the maximum conjugate reaches the kidney in 1 h and the uptake decreased after that [64]. In a recent investigation, Wischnjow et al. developed drugconjugated (ciprofloxacin as the model drug) low molecular
weight protein (KKEEE)3K comprising nanocarriers; and evaluated them for renal tubular uptake in C57BL/6 J mice. The immunohistochemistry staining and pharmacokinetics studies confirmed the accumulation of the ciprofloxacin–peptide conjugation in the renal tubule. The effect of the peptide conjugation is shown in Fig. 4a, which clearly indicates the renal targeting potential of the peptide when compared with the unconjugated drug. In Fig. 4b the PET images indicate that megalin is responsible for uptake of the conjugate in the renal tubules. In megalin-deficient mice, the conjugate was cleared quickly and a greater fluorescence was observed in the bladder than in the kidneys. Also, the free drug was observed in the abdominal area whereas on conjugation with peptide the intensity of the fluorescence was maximum in the Q20 www.drugdiscoverytoday.com
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|125 – labelled cipro-(KKEEE)3K
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|125 – labelled ciprofloxacin
(a)
10 min
30 min
60 min
(b)
Wildtype
K.O. mouse Drug Discovery Today
FIGURE 4
Q3 (a) Fluorescence study of localization of iodine-labeled free drug and iodine-labeled model drug (ciprofloxacin)–peptide conjugate. (b) Positron-emission tomography images of wild type (C57BL/6) and megalin-deficient (KO) mice 2 h after injection of iodine-labeled conjugate. Adapted, with permission, from [65].
kidneys. This proved the hypothesis of the investigator that (KKEEE)3K peptide could be used for targeting renal tubules [65]. Q21 Kim et al. conjugated PEA with a kidney-targeting peptide (LTCQVGRVH) and evaluated its transfection capability for gene delivery in treating renal fibrosis in a unilateral ureteral obstruction (UUO)-induced kidney fibrosis model. The results showed that PEA–peptide conjugate had higher transfection and low cytotoxicity compared with PEI. Successful delivery of hepatocyte Q22 growth fact or (HGH) gene to the tubules was achieved and the Q23 results showed that there was a decrease in fibrosis in the UUO kidney fibrosis model [66]. Conjugate drug delivery could be a promising drug delivery system but, at the same time, enzymes such as peptidases render the conjugate inactive. Hence, prodrugs could be the alternative that might be helpful to overcome this disadvantage. A prodrug is the inactive or active form of the drug that undergoes biotrans10
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formation and becomes activated. The prodrug approach is used by many medicinal chemists and researchers for changing various parameters of drug-related toxicology and biopharmaceutical studies. A drug can be modified to a prodrug by attaching an enzyme, gene or any easily removed functional group via biochemical reactions (i.e. esters, phosphates, etc.) [67]. Based on the advantages of prodrugs, Hu et al. synthesized hyaluronic-acid-conjugated curcumin (HA–CUR) prodrug linked by ester linkage where curcumin is a potent anti-inflammatory and antioxidant agent. CD-44-targeting hyaluronic acid was conjugated to localize the prodrug in the inflamed kidney. The in vitro data confirmed the anti-inflammatory and antioxidant effect of the HA–CUR prodrug by the observed decreased level of superoxide dismutase, glutathione and malondialdehyde. The in vivo imaging confirmed the localization of the prodrug into the renal cells via CD-44 receptor-mediated endocytosis. The results gave a clear
Formulation
Polymer/lipid used
Therapeutic molecule
Receptor involved
In vitro cells
In vivo model
Outcomes and characteristics
Refs
Podocytes
Nanoparticles
Albumin
Methylprednisolone
Semiconductor particles
RGDfC (arg-gly-D-phecys)
Female BALB/c mice Female adult C57BL/6 mice
SAINT-o-somes
1-Methyl-4-(cis-9dioleyl) methylpyridinium-chloride (SAINT-C18)
VCAM-1 antibody Rapamycin
Human podocytes cells U87-MG and MCF-7 breast cancer cells AB8/13 and MPC5 cell lines
36-fold nanoparticle uptake enhanced in podocytes Rod-shaped quantum dots successfully bind to receptors on the podocyte Size: 130 nm; zeta potential: 10 mV. The VCAM1 level was found to decrease in the assays performed
[30]
Quantum dots
Neonatal Fc receptors avb3 receptor
Nanoparticles
Gold and polyethylene glycol (PEG) cyclodextrin
Mesangial cells
Polymeric nanoparticles
Glomerular basement membrane
Mannose targeted EGFPsiRNA and transferrin targeted EGFP-siRNA
Mannose receptors
Male C57BL/6 mice
Female BALB/c mice SV40-MES (mouse mesangial) cells and CRL-2573 (rat mesangial) cells HBZY-1 rat glomerular mesangial cells Anti-thy1.1 IgG (OX7)synthesizing hybridoma cells mouse mesangial cells
C57BL/6-Tg and Balb/c mice
Nanoparticles
Albumin
Celastrol
Caveolae or clathrinmediated uptake
Immunoliposome
Hydrogenated soybean phosphatidylcholine
Mycophenolate mofetil
Size-dependent retention
siRNA/PEG-PLL (poly-L-lysine) conjugate siRNA/CDP nanoparticles
PLL
MAPK1 siRNA
Size-dependent uptake
Cyclodextrin
Electrostatic interaction
Murine lupus nephritis model (MRL/lpr) Female Balb/c mice
Cationic ironoxide nanoparticles
Iron oxide
Electrostatic interaction
Sprague Dawley rats
Chitosan/ AQP1siRNA nanoparticles (AQP-aquaporin)
Chitosan
AQP1 siRNA
Megalin
MDCK cells, megalin knockout mice (megalin lox/lox cre + )
anti-Thy1.1 nephritis rat model Anti-thy1.1 nephritis induced rats
BALB/cJBomTac female mice
Size: 80 nm and zeta potential: around 10 mV. Specifically taken up by mesangial cells Specific uptake of mannosetargeted nanoparticles was greater compared with others in the mesangium The albumin nanoparticles having size 90 nm accumulated in the mesangial cells Retained in the mesangium of the kidney. Proteinuria, extracellular matrix accumulation and mesangial cell expansion found to decrease The conjugate successfully targeted and retained in the mesangial cells Size: 80 nm; zeta potential: +10 mV. Negative charged GBM enables the positive charged nanoparticles to interact with them The small size of nanoparticles enabled them to reach GBM. The positive charge was responsible for retention of nanoparticles into GBM The formulation was specifically delivered to the kidney via megalin receptors and retained in tubular cells for about 48 h
[48,49]
[76]
[78]
[42]
[79]
[80]
[39]
[37]
[81]
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Proximal tubule
VCAM-1 (vascular cellular adhesion molecule 1) and mTOR (mammalian target of rapamycin) Diffusion
[34]
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Target
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TABLE 1
Q4 Targeting formulations on different parts of the nephron
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[84]
[83]
HK-1 adult human proximal tubule kidney epithelial cells, MDCK (MadinDarby canine kidney epithelial cells), HepG2
Rat nephrosis model
Renal ischemia/ reperfusion injury rat model
Aminoglycoside (gentamicin) PEI
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Megalin-mediated endocytosis
Captopril Lysozyme
Captopril lysozyme conjugate AminoglycosidecarboxyalkylatedPEI nanoplexes
14-succinyl triptolide
Therapeutic molecule
Megalin-mediated endocytosis
Megalin- or cubulinmediated endocytosis Lysozyme 14-succinyltriptolide– lysozyme conjugate
HK-2 cells Mechanism is unknown PLGA Mesoscale nanoparticles
Receptor involved Polymer/lipid used Formulation Target
TABLE 1 (Continued ) 12
[82]
Refs
[40]
Nanoparticles were localized in proximal tubules via peritubular capillaries. It was uptake via transcytosis followed by endocytosis The conjugate was smaller in size and was able to penetrate the filtration barrier. The lysozyme enhanced the uptake of conjugate into the proximal tubules The ACE level was decreased by >40% in <12 h after administration. The proteinuria was reduced Higher gene transfection ability. The megalin-mediated uptake found in the proximal cells Female SKH-1 elite hairless mice
In vitro cells
In vivo model
Reviews KEYNOTE REVIEW
Outcomes and characteristics
REVIEWS
indication that HA–CUR nanoparticles (400 mg/g in 24 h) were localized more in the kidney as compared with other organs and for a longer period [68].
Exosomes derived from mesenchymal stem cells MSCs are multipotent cells that can differentiate into various cells, while not producing an immune response, and are therefore considered to be safe in drug delivery to target sites. MSCs also induce some anti-inflammatory action by inhibiting cytokines and TGF-b. MSCs have the capability to generate and deliver therapeutics in situ, in a phenomenon that is also known as the trophic effect of MSCs. MSCs are capable of inducing angiogenesis and are recruited to the site of damage where they show their therapeutic effect [69]. MSCs are responsible for the secretion of extracellular vesicles as part of their therapeutic activity. The extracellular vesicles are of three types: exosomes, microvesicles and apoptotic bodies. Exosomes are the secretory vesicles or the product shed from the endosomes. The presence of such vesicles in the urine could be a sign of renal damage [70]. Therefore, exosomes can act as a biomarker for detecting early DN and can be used for therapeutic purposes. Nevertheless, isolation and purification of the exosomes is a highly challenging task and, hence, there is no standardized protocol to date. It was also investigated that extracellular vesicles of MSCs reverse the renal fibrosis in a streptozotocin-induced mouse DN model [71]. Further, Nagaishi et al. intravenously administered MSCs to DNinduced mice for the treatment of DN. This treatment strategy was able to decrease bone-marrow-derived cells (BMDCs) significantly, which is a major cause of renal fibrosis. MSC therapy was successful in preventing mesangium expansion. MSCs are reported to downregulate VEGF, which is responsible for abnormal mesangium expansion. The MSCs are considered to be large reserves of VEGF that could help in improving the glomerular pathology in DN. The MSCs also successfully downregulated p38/MAPK and TGF-b expression and, hence, decreased inflammation and fibrosis. The MSC-treated cells also showed no change in the zona occludes 1 (ZO-1) and lectin expression. The investigators thus concluded that the therapeutic effect of MSCs was observed as a result of the release of the exosomes [72]. Moreover, Wang et al. demonstrated the use of exosomal Q24 delivery in treating renal fibrosis. In this study, MSCs were genetically modified to release exosomes containing miR-let7c (micro RNA let7) that are expressed in the UUO mouse model. microRNA (miRNA) is noncoding single-stranded RNA containing 20–24 nucleotides [73]. The miR-let7 family of miRNA was observed to play a crucial part in renal fibrosis. Downregulation of this miRNA was assumed to be responsible for renal fibrosis. MSCs are considered a safe and reliable vehicle to deliver miRNA. In addition, MSCs have the property of secreting vesicles that contain the desired miRNA. The investigators found that MSCs successfully delivered miR-let7c to the target site, which led to an increased expression of miR-let7c. This observation was confirmed by repression of collagen type IVa-1 and TGF-bR1 levels, which are two genes that play a major part in renal fibrosis [74]. MSC exosomes could provide a major breakthrough in renal drug delivery but their use is controversial and treatment is very expensive at this time. Hence, conjugate or peptide drug delivery could be a better alternative in the context of renal drug delivery.
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TABLE 2
Patent
Application date
Granted on
Patent title
Outcome of Investigation
Refs
US9872840B2
18/08/2016
23/01/2018
Effect of garcinol in delaying the progression of DN
[85]
US20180143207A1
24/05/2018
US9803008B2
09/02/2017
200 mg/kg/day of garcinol was found effective that the glomerulosclerosis, albuminuria was reduced. The plasma protein, nephrin and erythropoietin levels increased The diabetes patient urine samples were screened. Glycated uromodulin a marker for DN was detected in the samples The treatment was successful in reducing hypertension, glomerular and tubular sclerosis, mesangial expansion and macroalbuminuria
US20170003299A1
05/01/2017
US20170153249A1
01/06/2017
Early prediction markers of DN
US20150275301A1
01/10/2015
Urine exosome mRNAs and methods of using same to detect DN
US9161930B2
01/03/2012
US20120164667A1
28/06/2012
US20110065598A1
17/03/2011
US20100216709A1
26/08/2010
US7396825B2
24/11/2005
31/10/2017
20/10/2015
Method for screening DN in a subject Method of treating DN by administering antibodies to vascular endothelial growth factor B (VEGF-B) Detecting podocyte injury in DN and glomerulonephritis
A pharmaceutical composition for DN and its preparation and application
Method for test on DN Methods and devices for detecting DN and associated disorders
08/07/2008
Systemic insulinlike growth factor-1 (IGF-1) therapy reduces diabetic peripheral neuropathy and improves renal function in DN Agonists of A2A adenosine receptors for treatment of DN
The method was found to detect markers such as nephrin, podocin, synaptopodin or podocalyxin, which are responsible for podocyte injury. The method was done via flow cytometry and enzyme-linked immunosorbent assay from urine samples The markers such as carbonic anhydrase 1, prothrombin, tetranectin, CD59 glycoprotein, plasma serine protease inhibitor and its isoforms are markers for DN. In DN patients that do not show albuminuria detection of any one of the above markers shows that the person is suffering from nephropathy The complementary DNA (cDNA) that are specific for PPARGC1A, SMAD1, NRF2 and CD24 were generated. It was observed that the amount of such cDNA was found to be greater than the healthy individual who does not have nephropathy A new pharmaceutical composition was prepared by using 4,40 -diphenylmethanebis(methyl)carbamates along with excipients such as lactose, magnesium stearate and amylum maydis. The pills were prepared using silicon oil and polyglycol 6000. The active ingredient was found to be active in decreasing blood sugar level The urinary podocalyxin level in DN patient was more than the reference value CTGF, VEGF, KIM-1, NGAL, calbindin and cystatin C are the markers for diabetic nephropathy. In diabetic nephropathic patient urine samples were found to contain at least three markers that are listed above. The samples were diagnosed by means of specified antibodies for a particular marker IGF-1 modulates serum albumin level with a reduction in urine column and protein levels thus improving the renal condition in diabetic glomerulosclerosis
A2A agonists were administered along with type IV phosphodiesterase inhibitor such as rolipram. Along with nephropathy they can also be used for reducing inflammation
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[86]
[87]
[88]
[89]
[90]
[77]
[91] [92]
[93]
[94]
13
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Patents related to diabetic nephropathy treatment and diagnosis
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TABLE 2 (Continued )
Reviews KEYNOTE REVIEW
Patent
Application date
US20080070862A1
20/03/2008
GAGs such as sulodexide were selected against HIVassociated nephropathy (HIVAN). The sulodexide was administered as salt, solvate, hydrate or clathrate. The GAGs were successful in inhibiting the symptoms or complications associated with HIVAN US20050214294A1
[95]
Granted on
29/09/2005
US6780603B1
24/08/2004
Targeting to different areas of the nephron involved in diabetic nephropathy The major parts of the kidney that are involved in nephropathy are the glomerular basement membrane, podocytes, mesangial cells and proximal tubules. The desirable site of action of the formulations is guarded by many factors, such as size, charge, protein conjugate and receptors involved. For instance, the cutoff for filtration of a molecule from the glomerular membrane is 8–10 nm. Hence, nanoparticle delivery systems with a particle size of <10 nm become excreted in the urine, whereas nanoparticles with a particle of more than that would be retained in the kidney. During nephropathy, albuminuria causes this filtration cut-off to increase to 12 nm [75]. Targeting the kidney is challenging because the different locations have different pore sizes. Various approaches such as peptide conjugation, nanoparticles and microbubbles have been used for targeting renal cells based on the localization in the different regions of the kidney [76]. Along with the physiology of the kidney, the formulation aspects also have key roles, as discussed in the section above. Table 1 provides detailed investigational evidence conducted to date for targeting different parts of the kidney, specifically the nephron.
Patents and clinical trials related to diabetic nephropathy Patents are considered to be the individual rights given to the investigators for the work that is novel, innovative and has an industrial application. The number of DN patients is increasing every year; and therefore there is a need for a potential delivery 14
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Patent title
Outcome of Investigation
Methods using
glycosaminoglycans (GAGs) for the treatment of nephropathy
DN therapies
A therapeutic dose of an agent that inhibits CTGF was administered to a subject. It was observed that the moiety successfully reduced creatinine clearance, glomerular hyperfiltration, urinary albumin excretion and improved the nephropathic condition of the subject The normal kidney and nephropathic kidney samples were compared for the study of levels of integrins a1 and a2. It was observed that in nephropathic kidney there was an increase in a2 whereas a1 level was found to decrease
Analysis of alpha integrins for diagnosis of DN
Refs
[96]
[97]
system and therapeutics that can eradicate diabetes-related complications such as DN. Interest regarding DN has led to an increase in a number of investigations as well as patents related to the diagnosis and treatment of DN. Table 2 summarizes the patents granted for intellectual rights related to DN. Numerous clinical trials are underway for safe and effective therapeutics for the treatment of the DN Q25 [77]. Table 3 provides the list of the therapeutics that are in clinical trials along with their trial status and sponsors.
Concluding remarks and future directions Targeting the kidneys in DN is a major hurdle owing to the ability of the kidney to excrete drugs out of the body. This area of nanomedicine is rapidly growing, as evidenced by the numerous nanoparticles already available on the market and the many more undergoing clinical trials. Nanomedicine-based approaches with tailored biophysical characteristics could yield greatly controlled nanocarriers for targeting to the kidney. Nanoparticles would be able to bind with renal cells for a prolonged duration, enhance retention, as well as improve cellular uptake within almost all cell types – for instance, glomerular basement epithelial cells, podocytes, mesangial cells and proximal tubule cells. During the past decade, different nanoparticles were proposed for the treatment of diseases with unanticipated responses to be retained and accumulate within kidney cells. These significantly elevated the correlation among the structure and nanoparticle activity based on their modification and physicochemical properties regarding kidney targeting function. Conjugation of drugs with different ligands that bind specifically to megalin or cubilin receptors can be synthesized for specific delivery of the drug to the kidney. The arena of nanomedicine
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TABLE 3
Therapeutic moiety
Clinical trial Phase
Status
Sponsor
Fulacimstat Aleglitazar Dulaglutide Alagebrium Berberine Finerenone Pyridoxamine dihydrochloride RTA 402 Nitroaspirin MT-3995 Canagliflozin Resveratrol Alfacalcidol Colchicine Spironolactone Atrasentan Sevelamer carbonate Sulodexide PH3 Pyridorin Benfotiamine Bindarit Pirfenidone Telmisartan Probucol Paricalcitol Bardoxolone Green tea extract XL784
Phase II Phase III Phase III Phase II Phase IV Phase III Phase II Phase II Phase II Phase II Phase III Early Phase I Phase IV Phase II Phase IV Phase III Phase I Phase IV Phase II Phase II Phase IV Phase II Phase III Phase IV Phase II Phase II Phase III Phase II Phase II
Recruiting Withdrawn Completed Terminated Recruiting Active, not recruiting Completed Completed Terminated Completed Completed Completed Recruiting Recruiting Completed Terminated Completed Terminated Completed Completed Completed Completed Active, not recruiting Completed Completed Completed Completed Completed Completed
Bayer Hoffmann-La Roche Eli Lilly Synvista Therapeutics Nanjing First Hospital, Nanjing Medical University Bayer NephroGenex Kyowa Hakko Kirin Mario Negri Institute for Pharmacological Research Mitsubishi Tanabe Mitsubishi Tanabe Shiraz University of Medical Sciences The Third Xiangya Hospital of Central South University Sheba Medical Center Steno Diabetes Center Abbvie Icahn School of Medicine at Mount Sinai Keryx Biopharmaceuticals PhytoHealth Corporation BioStratum University Medical Center Groningen Aziende Chimiche Riunite Angelini Francesco Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran Boehringer Ingelheim Korea Otsuka Pharmaceutical Abbott Kyowa Hakko Kirin University of Campinas, Brazil Symphony Evolution
Reviews KEYNOTE REVIEW
Clinical trials data for diabetic nephropathy
(Last accessed on 16 Sept 2019); data obtained from www.clinicaltrials.gov.
research still inflates with several nanoparticles, some of which have reached clinical trials. Current data provide detailed clinical records and next-level treatment modalities for renal targeting. To date, there are no such promising modalities available to directly deal with the proteinuria and DN complications. Based on physicochemical properties and design of the nanoparticle delivery systems, kidney retention has been shown to become enhanced. It is time that the nanotechnological research teams and nephrology experts collaborate to develop encouraging nanomedicine tactics for selective targeting and treatment of renal disorders.
Conflicts of interest There are no conflicts of interest associated with this manuscript.
Uncited references
Q26
[98,99,100].
Q27
Acknowledgments R.K.T. would like to acknowledge the Science and Engineering Research Board (Statutory Body Established through an Act of Parliament: SERB Act 2008), Department of Science and Technology, Government of India for grant #ECR/2016/001964 and N-PDF funding (PDF/2016/003329) for work on targeted cancer therapy in Dr Tekade’s laboaratory. The authors would also like to acknowledge the Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, India, for supporting research on cancer and diabetes at NIPER-Ahmedabad.
References
Q28
Q29
1 Volpe, C.M.O. et al. (2018) Cellular death, reactive oxygen species (ROS) and diabetic complications. Cell Death Dis. 9 2 Harrison, L.C. (2019) Type 1 diabetes. In Clinical Immunology. pp. 957–966, Elsevier 3 Goedeke, L. et al. (2019) Emerging pharmacological targets for the treatment of nonalcoholic fatty liver disease, insulin resistance, and type 2 diabetes. Ann. Rev. Pharmacol. Toxicol. 59, 65–87 4 Chung, Y.-R. et al. (2019) Dipeptidyl peptidase-4 inhibitors versus other antidiabetic drugs added to metformin monotherapy in diabetic retinopathy progression: a real world-based cohort study. Diabetes Metab. J. 43, 640–648 5 Sperling, M.A., ed. (2014) Pediatric Endocrinology, Elsevier Health Sciences 6 Adi, S. and Gerard-Gonzalez, A. (2018) Type 1 diabetes mellitus: an overview. In Nutritional and Therapeutic Interventions for Diabetes and Metabolic Syndrome. (2nd edition), pp. 3–13, Elsevier
7 Chawla, A. et al. (2016) Microvasular and macrovascular complications in diabetes mellitus: distinct or continuum? Indian J. Endocrinol. Metab. 20, 546 8 Gheith, O. et al. (2016) Diabetic kidney disease: world wide difference of prevalence and risk factors. J. Nephropharmacol. 5, 49 9 Vinod, P. (2012) Pathophysiology of diabetic nephropathy. Clin. Queries Nephrol. 1, 121–126 10 Loeffler, I. and Wolf, G. (2019) Mechanisms of interstitial fibrosis in diabetic Q30 nephropathy. In Diabetic Nephropathy. pp. 227–251, Springer 11 Sulaiman, M.K. (2019) Diabetic nephropathy: recent advances in pathophysiology and challenges in dietary management. Diabetol. Metab. Syndr. 11, 7 12 Clemens, K.K. et al. (2019) Diabetes management in older adults with chronic kidney disease. Curr. Diabetes Rep. 19, 11
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13 Lai, X. et al. (2018) Amelioration of diabetic nephropathy in db/db mice treated with tibetan medicine formula Siwei Jianghuang Decoction Powder extract. Sci. Rep. 8, 16707 14 Fujita, Y. et al. (2018) An adjustment in BMP4 function represents a treatment for diabetic nephropathy and podocyte injury. Sci. Rep. 8, 13011 15 Li, Z. et al. (2018) Inhibition of epidermal growth factor receptor activation is associated with improved diabetic nephropathy and insulin resistance in type 2 diabetes. Diabetes 67, 1847–1857 16 Mitrofanova, A. et al. (2019) SMPDL3b modulates insulin receptor signaling in diabetic kidney disease. Nat. Commun. 10, 2692 17 Kang, J.S. et al. (2019) Angiotensin II-mediated MYH9 downregulation causes structural and functional podocyte injury in diabetic kidney disease. Sci. Rep. 9, 7679 18 Schwarz, A. et al. (2019) Coro2b, a podocyte protein downregulated in human diabetic nephropathy, is involved in the development of protamine sulphateinduced foot process effacement. Sci. Rep. 9, 8888 19 Rossing, P. et al. (2018) Prognosis and treatment of diabetic nephropathy: recent advances and perspectives. Nephrol. Ther. 14, S31–S37 20 Lim, A.K. (2014) Diabetic nephropathy – complications and treatment. Int. J. Nephrol. Renovasc. Dis. 7, 361 21 Chan, G.C. and Tang, S.C. (2015) Diabetic nephropathy: landmark clinical trials and tribulations. Nephrol. Dialysis Transpl. 31, 359–368 22 Coleman, C. et al. (2020) Impact of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers on renal and mortality outcomes in people with type 2 diabetes and proteinuria. Diabet. Med. 37, 44–52 23 Kim, Y. and Park, C.W. (2017) New therapeutic agents in diabetic nephropathy. Korean J. Int. Med. 32, 11 24 Jia, Z. et al. (2014) New insights into the PPARg agonists for the treatment of diabetic nephropathy. PPAR Res. 2014, 818530 25 Shahbazian, H. et al. (2019) Increased level of advanced glycation end-products in renal transplant patients is associated with decreased measured GFR and grafted kidney function. J. Nephropathol. 8, e3 26 Sun, Y.-M. et al. (2013) Recent advances in understanding the biochemical and molecular mechanism of diabetic nephropathy. Biochem. Biophys. Res. Commun. 433, 359–361 27 Kohan, D.E. et al. (2011) Addition of atrasentan to renin-angiotensin system blockade reduces albuminuria in diabetic nephropathy. J. Am. Soc. Nephrol. 22, 763–772 28 Takagaki, Y. et al. (2019) Dipeptidyl peptidase-4 plays a pathogenic role in BSAinduced kidney injury in diabetic mice. Sci. Rep. 9, 7519 29 Maki, T. et al. (2019) Amelioration of diabetic nephropathy by SGLT2 inhibitors independent of its glucose-lowering effect: a possible role of SGLT2 in mesangial cells. Sci. Rep. 9, 4703 30 Ahmed, O.M. et al. (2019) Effects of enalapril and paricalcitol treatment on diabetic nephropathy and renal expressions of TNF-a, P53, Caspase-3 and Bcl-2 in STZ-induced diabetic rats. PLoS One 14, e0214349 31 Devarajan, P.V. and Jain, S. (2015) Targeted Drug Delivery: Concepts and Design. Springer 32 Kim, S.S. et al. (2016) Current challenges in diabetic nephropathy: early diagnosis and ways to improve outcomes. Endocrinol. Metab. 31, 245–253 33 Pelaz, B. et al. (2017) Diverse applications of nanomedicine. ACS Nano 11, 2313– 2381 34 Cerna, T. et al. (2016) Targeted nanoparticles – a promising opportunity in cancer therapy – review. J. Metallomics Nanotechnol. 4, 6–11 35 Wu, L. et al. (2017) Albumin-based nanoparticles as methylprednisolone carriers for targeted delivery towards the neonatal Fc receptor in glomerular podocytes. Int. J. Mol. Med. 39, 851–860 36 Malhotra, A. et al. (2015) An organ system approach to explore the antioxidative, anti-inflammatory, and cytoprotective actions of resveratrol. Oxid. Med. Cell. Longev. 2015, 803971 37 Anders, H.-J. and Muruve, D.A. (2011) The inflammasomes in kidney disease. J. Am. Soc. Nephrol. ASN.2010080798 38 Lin, Y.-F. et al. (2017) Resveratrol-loaded nanoparticles conjugated with kidney injury molecule-1 as a drug delivery system for potential use in chronic kidney disease. Nanomedicine 12, 2741–2756 39 Pollinger, K. et al. (2012) Kidney podocytes as specific targets for cyclo (RGDfC)modified nanoparticles. Small 8, 3368–3375 40 Chen, D. et al. (2018) Kidney-targeted drug delivery via rhein-loaded polyethyleneglycol-co-polycaprolactone-co-polyethylenimine nanoparticles for diabetic nephropathy therapy. Int. J. Nanomed. 13, 3507 41 Kamaly, N. et al. (2016) Nanomedicines for renal disease: current status and future applications. Nat. Rev. Nephrol. 12, 738
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42 He, C. et al. (2010) Effects of particle size and surface charge on cellular uptake and biodistribution of polymeric nanoparticles. Biomaterials 31, 3657–3666 43 Zuckerman, J.E. et al. (2012) Polycation-siRNA nanoparticles can disassemble at the kidney glomerular basement membrane. Proc. Natl. Acad. Sci. U. S. A. 109, 3137–3142 44 Liang, X. et al. (2016) Short-and long-term tracking of anionic ultrasmall nanoparticles in kidney. ACS Nano 10, 387–395 45 Choi, H.S. et al. (2007) Renal clearance of quantum dots. Nat. Biotechnol. 25, 1165 46 Williams, R.M. et al. (2018) Selective nanoparticle targeting of the renal tubules. Hypertension 71, 87–94 47 Williams, R.M. et al. (2015) Mesoscale nanoparticles selectively target the renal proximal tubule epithelium. Nano Lett. 15, 2358–2364 48 Guo, L. et al. (2017) Targeted delivery of celastrol to mesangial cells is effective against mesangioproliferative glomerulonephritis. Nat. Commun. 8, 878 49 Im, H.-J. (2018) Excretion and clearance. In Radionanomedicine. pp. 347–368, Q32 Springer 50 Lacerda, L. et al. (2008) Carbon-nanotube shape and individualization critical for renal excretion. Small 4, 1130–1132 51 Ruggiero, A. et al. (2010) Paradoxical glomerular filtration of carbon nanotubes. Proc. Natl. Acad. Sci. U. S. A. 107, 12369–12374 52 Bulbake, U. et al. (2017) Liposomal formulations in clinical use: an updated review. Pharmaceutics 9, 12 53 Morimoto, K. et al. (2007) Advances in targeting drug delivery to glomerular mesangial cells by long circulating cationic liposomes for the treatment of glomerulonephritis. Pharm. Res. 24, 946–954 54 Kowalski, P.S. et al. (2013) Anti-VCAM-1 and anti-E-selectin SAINT-O-Somes for selective delivery of siRNA into inflammation-activated primary endothelial cells. Mol. Pharm. 10, 3033–3044 55 Visweswaran, G.R.R. et al. (2015) Targeting rapamycin to podocytes using a vascular cell adhesion molecule-1 (VCAM-1)-harnessed SAINT-based lipid carrier system. PLoS One 10, e0138870 56 Fan, D. et al. (2018) The effect of triptolide in rheumatoid arthritis: from basic research towards clinical translation. Int. J. Mol. Sci. 19, 376 57 Sarko, D. and Georges, R. (2016) Kidney-specific drug delivery: review of opportunities, achievements, and challenges. J. Anal. Pharm. Res. 2, 00033 58 Schuh, S. et al. (2015) Properties of serial ultrasound clinical diagnostic pathway in suspected appendicitis and related computed tomography use. Acad. Emerg. Med. 22, 406–414 59 Sirsi, S.R. and Borden, M.A. (2012) Advances in ultrasound mediated gene therapy using microbubble contrast agents. Theranostics 2, 1208 60 Chen, P.-P. et al. (2018) CoQ10-loaded liposomes combined with UTMD prevented early nephropathy of diabetic rats. Oncotarget 9, 11767 61 Sheng, W.-S. et al. (2018) Intrarenal delivery of bFGF-loaded liposome under guiding of ultrasound-targeted microbubble destruction prevent diabetic nephropathy through inhibition of inflammation. Artif. Cells Nanomed. Biotechnol. 46 (suppl. 2), 373–385 62 De Groot, A.S. and Scott, D.W. (2007) Immunogenicity of protein therapeutics. Trends Immunol. 28, 482–490 63 Yuan, Z.-X. et al. (2014) Peptide fragments of human serum albumin as novel renal targeting carriers. Int. J. Pharm. 460, 196–204 64 Yuan, Z.-X. et al. (2015) Renal targeted delivery of triptolide by conjugation to the fragment peptide of human serum albumin. Eur. J. Pharm. Biopharm. 94, 363–371 65 Wischnjow, A. et al. (2016) Renal targeting: peptide-based drug delivery to proximal tubule cells. Bioconj. Chem. 27, 1050–1057 66 Kim, Y.-K. et al. (2012) Kidney-specific peptide-conjugated poly (ester amine) for the treatment of kidney fibrosis. J. Nanosci. Nanotechnol. 12, 5149–5154 67 Zhang, X. et al. (2017) Prodrug strategy for cancer cell-specific targeting: a recent overview. Eur. J. Med. Chem. 139, 542–563 68 Hu, J.-B. et al. (2018) CD44-targeted hyaluronic acid-curcumin prodrug protects renal tubular epithelial cell survival from oxidative stress damage. Carbohydr. Polym. 193, 268–280 69 Park, S.-R. et al. (2018) A novel endogenous damage signal, glycyl tRNA synthetase, activates multiple beneficial functions of mesenchymal stem cells. Cell Death Differ. 25, 2023–2036 70 Xu, W.-C. et al. (2018) Urinary extracellular vesicle: a potential source of early diagnostic and therapeutic biomarker in diabetic kidney disease. Chin. Med. J. 131, 1357 71 Grange, C. et al. (2019) Stem cell-derived extracellular vesicles inhibit and revert fibrosis progression in a mouse model of diabetic nephropathy. Sci. Rep. 9, 4468 72 Nagaishi, K. et al. (2016) Mesenchymal stem cell therapy ameliorates diabetic nephropathy via the paracrine effect of renal trophic factors including exosomes. Sci. Rep. 6, 34842
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73 Kawahara, Y. (2014) Human diseases caused by germline and somatic abnormalities in microRNA and microRNA-related genes. Congenit. Anom. 54, 12– 21 74 Wang, B. et al. (2016) Mesenchymal stem cells deliver exogenous microRNA-let7c via exosomes to attenuate renal fibrosis. Mol. Ther. 24, 1290–1301 75 Scindia, Y.M. et al. (2010) Mesangial pathology in glomerular disease: targets for therapeutic intervention. Adv. Drug Deliv. Rev. 62, 1337–1343 76 Zhou, P. et al. (2014) Kidney – targeted drug delivery systems. Acta Pharm. Sin. B 4, 37–42 77 Garovic, V.D. and Jayachandran, M. (2017) Detecting podocyte injury in diabetic nephropathy and glomerulonephritis. Google Patents2017 78 Choi, C.H.J. et al. (2011) Targeting kidney mesangium by nanoparticles of defined size. Proc. Natl. Acad. Sci. U. S. A. 108, 6656–6661 79 Zuckerman, J.E. et al. (2015) siRNA delivery to the glomerular mesangium using polycationic cyclodextrin nanoparticles containing siRNA. Nucleic Acid Ther. 25, 53–64 80 Mo, Y. et al. (2017) Morphological switching of unimolecular micelles of ternary graft copolymers in different solvents. J. Polym. Sci. A Polym. Chem. 55, 1021–1030 81 Suana, A. et al. (2011) Single application of low-dose mycophenolate mofetil-OX7immunoliposomes ameliorates experimental mesangial proliferative glomerulonephritis. J. Pharmacol. Exp. Ther. 337, 411–422 82 Shimizu, H. et al. (2010) siRNA-based therapy ameliorates glomerulonephritis. J. Am. Soc. Nephrol. 21, 622–633 83 Bennett, K.M. et al. (2008) MRI of the basement membrane using charged nanoparticles as contrast agents. Magn. Res. Med. 60, 564–574 84 Gao, S. et al. (2014) Megalin-mediated specific uptake of chitosan/siRNA nanoparticles in mouse kidney proximal tubule epithelial cells enables AQP1 gene silencing. Theranostics 4, 1039 85 Zhang, Z. et al. (2009) The targeting of 14-succinate triptolide-lysozyme conjugate to proximal renal tubular epithelial cells. Biomaterials 30, 1372–1381
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86 Prakash, J. et al. (2005) Renal-selective delivery and ACE inhibition by subcutaneously administered captopril-lysozyme. Drug Metab. Dispos. 33, 683–688 87 Oroojalian, F. et al. (2017) Megalin-targeted enhanced transfection efficiency in cultured human HK-2 renal tubular proximal cells using aminoglycosidecarboxyalkyl-polyethylenimine-containing nanoplexes. Int. J. Pharm. 523, 102–120 88 Gandhi, S. and Srinivasan, B. (2018) Effect of garcinol in delaying the progression of diabetic nephropathy. Google Patents2018 89 Chang, C.H. and Chang, C.C. (2018) Method for screening diabetic nephropathy in a subject. Google Patents2018 90 Eriksson, U. et al. (2017) Method of treating diabetic nephropathy by administering antibodies to vascular endothelial growth factor B (VEGF-B). Google Patents2017 91 Granier, C. et al. (2017) Early prediction markers of diabetic nephropathy. Google Patents2017 92 Mitsuhashi, M. and Sharma, K. (2015) Urine exosome mRNAS and methods of using the same to detect diabetic nephropathy. Google Patents2015 93 Zhu, Q. et al. (2015) Pharmaceutical composition for diabetic nephropathy and its preparation and application. Google Patents2015 94 Hara, M. et al. (2012) Method for test on diabetic nephropathy. Google Patents2012 95 Labrie, S.T. et al. (2011) Methods and devices for detecting diabetic nephropathy and associated disorders. Google Patents2011 96 Scheule, R.K. and Chu, Q. (2010) Systemic insulin-like growth factor-1 therapy reduces diabetic peripheral neuropathy and improves renal function in diabetic nephropathy. Google Patents2010 97 Okusa, M.D. et al. (2008) Agonists of A2A adenosine receptors for treatment of diabetic nephropathy. Google Patents2008 98 Laster, M. and Shelach, N. (2008) Methods using glycosaminoglycans for the treatment Q33 of nephropathy. Google Patents2008 99 Flyvbjerg, A. et al. (2005) Diabetic nephropathy therapies. Google Patents2005 100 Tsilibary, P.-E. et al. (2004) Analysis of alpha integrins for the diagnosis of diabetic nephropathy. Google Patents2004
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Teaser Growth of functional nanomedicines for diabetic nephropathy demands a perceptive understanding of pharmacological renal barriers and crosstalk with nanoparticulate engineering tactics to offer clinically adaptable solutions.
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Nidhi Raval1,z, Akshant Kumawat1,z, Dnyaneshwar Kalyane1, Kiran Kalia1 and Rakesh K. Tekade1,2
1 National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar 382355, Gujarat, India Q7 2 Indian Institute of Technology-Jammu, Jagti, PO Nagrota, Jammu 181 221, J&K, India
Diabetes and related complications are becoming a global encumbrance. Diabetic nephropathy (DN) is a major cause of end-stage renal disease (ESRD). The available therapeutic modalities related to DN do not treat DN at the molecular level, proposing further amendments in the management of DN based on the pathogenesis of DN. This manuscript discusses the concept and applications of nanomedicine for the treatment of DN that can improve renal targeting, retention and localization. This review also highlights the current issues related to targeting DN, challenges and allied opportunities toward the development of next-generation drugs and treatments for the management of DN.
Introduction Diabetes: a growing sweet demon Diabetes is a metabolic disorder characterized by hyperglycemia in a fasted or a fed state. The risk of diabetes increases when blood glucose is >130 mg/dl (80–140 mg/dl) [1]. The primary causes of diabetes include autoimmunity or destruction of insulin-secreting pancreatic b cells, insulin resistance, obesity, genetic polymorphism, ketoacidosis, sedentary lifestyle, improper diet and enzymatic defects such as incretin, dipeptidyl peptidase VI (DPP-VI), peroxisome proliferator activating receptors (PPARs), among others [2–4]. Diabetes is classified as either type I: autoimmune type of diabetes that involves b cell destruction, or type II: diabetes mellitus related to insulin deficiency or insulin resistance. Other types of diabetes that are less prevalent include gestational diabetes that occurs during pregnancy [5], diabetes caused by a genetic defect in the b cells and chemically induced diabetes caused by various drugs such as glucocorticoids, phenytoin, diazoxide, b-adrenergic blockers and nicotinic acid. Diabetes onset caused by other hormonal diseases such as Cushing’s syndrome, Down syndrome and Klinefelter syndrome have also been reported [6]. Type I and type II diabetes are more common and are responsible for various diabetes-related complications including diabetes retinopathy, diabetic nephropathy (DN), Corresponding author: Tekade, R.K. ([email protected]) z
Equal first author.
1359-6446/ã 2020 Published by Elsevier Ltd. https://doi.org/10.1016/j.drudis.2020.01.008
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Understanding molecular upsets in diabetic nephropathy to identify novel targets and treatment opportunities Nidhi Raval has completed her MS (Pharm) in pharmaceutics from NIPERAhmedabad and is now pursuing her doctoral degree from this institute under the guidance of Dr Rakesh K. Tekade. Her research in Dr Tekade’s lab involves the development of a novel renal-targeted platform for targeted siRNA/miRNA delivery and gene silencing. Kiran Kalia is Professor in Pharmacology and Director, NIPER, Ahmedabad, and is also a Professor in lien Department of Biosciences, Sardar Patel University. She has an extensive research experience of 35 years and has guided several masters and PhD students. She is an awardee of Indian National Science Academy (INSA) Research fellowship to work at NII, New Delhi; and has received CSIR Fellowships JRF, SRF, PDF and a research associateship. Professor Kiran is an Editorial Board and Review Committee member of several international journals. Her research interests encompass proteomic markers for diabetic nephropathy from urine, genomic markers for the susceptibility of diabetic retinopathy, genomic alterations in oral cancer, environmental biotechnology and toxicology studies. Rakesh K. Tekade is an academic researcher with >10 years of teaching and research experience. Dr. Tekade’s research group at the Department of Pharmaceutics at NIPERAhmedabad investigates the design, development and characterization of targeted nanotechnologybased products for the site-specific delivery of therapeutic drugs, siRNA, miRNA, among others, for the treatment of cancer, diabetes arthritis and neurological disorders. He has coauthored >100 peer-reviewed publications in international SCI cited journals (>4000 citations; H–index of 34), contributed >50 international reference book chapters, 5 invited editorial articles and 4 patent applications. Dr Tekade is an Editor-in-Chief of a Book Series entitled ‘Advances in Pharmaceutical Product Development and Research Series’ (https://www. elsevier.com/catalog/pharma/pharmaceutical-science/ drug-delivery/advances-in-pharmaceutical-productdevelopment-and-research).
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diabetic neuropathy and diabetic foot. DN is a major cause of chronic kidney disease that results in a progressive decrement in renal functioning [7].
Diabetic nephropathy Reviews KEYNOTE REVIEW
Around 25% of the population suffering from diabetes tends to develop DN. Among these DN affected individuals worldwide, 50% of them suffer from end-stage renal disease (ESRD), which requires costly and painful dialysis treatments. Of the population suffering from DN, 75% of has type I diabetes and the remaining are type II diabetic patients [8]. DN causes structural damage to the kidneys such as glomerular hyperfiltration, microalbuminuria, autophagy, glomerular basement membrane thickening, fibrosis caused by extracellular matrix protein and hypertrophy of mesangial cells. The effacement and apoptosis of the podocytes are also one of the hallmarks for DN [9]. In DN, the autophagy of podocytes was reduced resulting in leakiness of the filtration barrier. The delocalization of podocin and nephrin (a slit diaphragm protein) from the podocyte foot process is responsible for proteinuria or microalbuminuria. The proximal tubular part of the nephron is also affected in DN. The Q8 accumulation of fibronectin, AGE and various inflammatory mediators is responsible for fibrosis in renal tubules [10]. The early diagnosis of the diabetic nephropathic kidney (stage I DN) includes the identification of thickening events in the glomerular basement membrane and tubular basement. These are the most noticeable structural changes that can be observed along with proteinuria. After glomerular thickening, mesangium cells are expanded and considered as stage II DN. This expansion process in the mesangium further results in the leakiness of the glomerulus via the accumulation of fibronectin and collagen type IV, also causing nodular sclerosis (stage III DN) [11]. The prospective emergence of inflammation in the mesangium leads to the development of glomerular sclerosis and tubular apoptosis. At Q9 later stages of DN, glomerular filtration rate (GFR) drastically Q10 declines, the interstitium alters and the glomerulopathy coalesces into segmental and global sclerosis, resulting in end-stage renal damage (stage IV ESRD). Other structural changes occur in DN kidneys such as reduction in epithelial fenestration, loss of podocyte integrity with foot process effacement, mesangial expansion, tubular apoptosis and atrophy (Fig. 1a) [12]. Sometimes hyperglycemic conditions harden the arteries and eventually lead to an elevation in the blood pressure. This enhanced blood pressure of capillaries interacts with metabolic and hemodynamic factors in the kidneys, which are involved in progression of DN. Hyperglycemia adversely effects renal cells such as glomerular cells, mesangial cells, podocytes, proximal tubules cells and epithelial cells; and is responsible for activation of monocytes, macrophages, increased formation of advanced glycation end products and growth factors – for instance, transforming growth factor b1 (TGF-b1) and angiotensin II in renal cells (Fig. 1a) [13]. Diabetic factors can augment and alter the expression of the pathological gene involved in development of the DN. In context, bone morphogenetic protein 4 (BMP4) to Smad1 signaling has involvement in mesangial cell injury development in DN as well as in podocyte injury [14]. Overexpression of epidermal growth factor receptor (EGFR) and sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) augments the condition of the DN via the 2
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renal immune cell infiltration, fibrotic and pro-fibrotic markers and induction of oxidative stress. The suppression of these markers alleviates the DN and improves insulin resistance in type 2 diabetic mice through increments in autophagy of pancreatic b cells which helps to preserve b cells [15,16]. Similarly, overexpression of angiotensin II suppresses the expression of MYH9 and downregulation of Coro2b protein leading to podocyte damage and effacement [17,18]. Therefore, active potential therapeutic agents are needed that can target the kidneys and can localize in the kidney for a longer period of time and can suppress the genetic modulation without any notable adverse effects [19].
Therapeutics used in the treatment of diabetic nephropathy The hyperglycemic condition initiates multifactorial events that damage the kidney structurally and functionally such as glomerular hyperfiltration, epithelial hypertrophy, proteinuria, following thickening of the glomerular basement membrane, mesangial matrix accumulation, podocyte damage and sclerosis of glomerulus [9]. Hemodynamic and metabolic changes as well as structural damage also aid the progression of DN. Hyperglycemic response Q11 and metabolic and hemodynamic changes are proven mediators for diabetic kidney disease [9,20]. The high glucose induces the growth factors [TGF-b, nuclear factor (NF)-kB, vascular endothelial growth factor (VEGF)] and cytokines, leading to the production of reactive oxygen species (ROS) and the accumulation of advanced glycation end products. Renin–angiotensin system activation is mostly found in all stages of DN and suppressing angiotensin II showed an important role in reduction of the progression of DN. Angiotensin-converting enzyme (ACE) inhibitors are also involved in a renal protective effect, for example microalbuminuria reduction with valsartan. In earlier literature, it was reported that ACE inhibitors effectively decreased the proteinuria and showed a renal protective effect in normotensive and hypertensive patients [21]. Angiotensin receptor blockers (ARBs) also showed the renal protective effect and decreased proteinuria irrespective of its antihypertensive effect in type I and type II diabetic patients [22]. The idea of using ARBs and ACE inhibitors in combination has now been withdrawn owing to an increased risk of side effects, mainly of hyperkalemia which is responsible for metabolic acidosis. Also, because of a lack of efficacy compared with other novel therapeutics, ACE inhibitors and ARBs are not currently prescribed for DN. Hence, there is a need for delivery of therapeutics that can suppress the angiotensin receptor effectively, without any adverse events [23]. Peroxisome proliferator-activated receptor (PPAR) ligands have shown promising evidence in combating diabetes. Three subtypes of PPAR receptors were identified as alpha, beta/delta and gamma. Among them PPARa was involved in fatty acid uptake via the heart and liver. PPARbd contributes to fatty acid oxidation in muscles. PPARg is majorly expressed in fat and facilitates lipid and glucose uptake, glucose oxidation stimulation and suppresses the level of fatty acid and suppresses insulin resistance. However, PPARg agonists such as thiazolidinediones, rosiglitazone and pioglitazone gave symptomatic relief in DN via regulation of lipid and glucose metabolism, regulation of hypertension, insulin resistance as well as ameliorating proteinuria and preventing further renal damage observed in a rodent model. Along with a protective effect
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(a)
Damaged tubular epithelium
Tubular epithelium
Tubular atrophy
Slit diaphragm Disruption
Podocyte apoptosis
Detachment of pericyte
Inflammatory cells infiltration
Peritubular capillary
Leukocyte amassing
Leukocyte infiltration
Podocyte detachment
Myofibroblast Foot process effacement
Endothelial cells
Mesangial hypertrophy
Tubular apoptosis
Reviews KEYNOTE REVIEW
Albuminuria
Macrophage FibroblastInflammatory cells
Extracellular matrix deposition
Proximal tubule fibrosis Basement membrane thickening Podocyte effacement
Reduced recovery of albumin
Diabetic nephropathy
Normal kidney Tubular epithelial cells
Glomerular Podocytes basement Mesengial Albumin Foot process cells membrane Glomerular Parietal cells capillary
Blood flow
(b)
Glomerular capillary
Nanoparticles (size: <10 nm)
Podocyte Targeted nanoparticles (size: 10–50 nm) Mesengial cells
Cationic nanoparticles (size: 50–100 nm)
Glomerular basement membrane
Nanoparticles (size: 70–130 nm) Mesoscale nanoparticles (350–500 nm)
Epithelial cells of proximal tubule
CNT (diameter: 3 nm and length: 500 nm) Peritubular capillary
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FIGURE 1
(a) Diagrammatic representation of healthy normal kidney and diabetic nephropathic kidney. Expanded portion shows podocyte dysfunction (loss of podocyte foot process, increased leakiness of filtration barrier leads to albuminuria) and proximal tubule fibrosis [caused by infiltration of inflammatory cytokines, transforming growth factor (TGF)-b, fibronectin and collagen], which occur in diabetic nephropathy. (b) Distribution of various-sized formulations for the treatment of diabetic nephropathy. Nanoparticles reach the specific area of the kidney based on size, charge or targeting molecules present. As shown, for example <10 nm nanoparticles could easily reach and become cleared through the proximal tubule region. Whereas a 10–50 nm targeted nanoparticle is able to reach the podocyte cells. Moreover, a 50–100 nm particle could be the desired size for glomerular deposition of nanoparticles and particles of 70–130 nm size for mesangial cell targeting in the kidney. The larger sized ( 350–500 nm ) nanoparticles could remain in blood circulation and reach the proximal tubule via the peritubular capillary. Further, a 3 nm diameter and 500 nm length carbon nanotube (CNT) becomes directly headed for proximal tubule cells owing to a greater aspect ratio [50].
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in DN, clinical application is hindered by common side effects such as cardiac complications, abnormal liver functions, malaise, myocardial infarction, weight gain and fluid retention [24]. In DN, the accumulation of AGE and receptor for binding of AGE (RAGE) was found to be caused by the hyperglycemic condition of the kidney leading to the development of glomerular lesions and endothelial dysfunction via activation of protein kinase C (PKC). RAGE and its interaction will scavenge the products formed as a result of glycation but activates various inflammatory mediators, namely NF-kb, TGF and interleukin (IL)-6. It also led to overexpression of endothelin-1-reduced nitric oxide generation and VEGF in DN. PKC and AGE were also responsible for developing oxidative stress in the kidney that further leads to inflammation. Moreover, pyridoxamine (an AGE inhibitor) was able to prevent the formation of reactive carbonyl species and reduce glycation and also aid in amelioration of DN [25]. However, the PKC antagonist ruboxistaurine could suppress vascular injury in DN, which caused activation of PKC. Hence, only PKC and AGE inhibitors do not improve the nephropathic condition. For that purpose, there was a need for antioxidants (quercetin and resveratrol) and anti-inflammatory agents (pentoxifylline and cilostazol) [26]. The reported investigation also suggested that endothelin 1 (ET1) causes renal injury owing to its fibrotic and inflammatory actions. Endothelin receptor inhibitors (i.e., atrasentan) were considered to reduce proteinuria but led to cardiovascular complications such as congestive heart failure and fluid accumulation [27]. DPP-VI inhibitors were also able to suppress the epithelial-tomesenchymal transition via suppression of crosstalk between caveolin-1 and integrin-b1 [28]. Whereas, low-dose sodium-glucose cotransporter 2 (SGLT2) inhibitors improved albuminuria and mesangial expansion in db/db mice same as high-dose but were not able to reduce glucose concentration in the blood. The main disadvantage of this class drugs is induction of genitourinary infections in a mild-to-moderate manner [29]. Vitamin D receptor (VDR) activators (e.g., paricalcitol) were reported to suppress renin receptor and angiotensinogen receptor as well as being able to improve glomerulus and tubular damage. However, sometimes it can cause vascular calcification in animal models and the dose of paricalcitol was not tolerated by patients and required reduction in dose [30]. Renal endothelin (ET) receptor activation in DN leads to mesangial cell proliferation, inflammation and fibrosis, whereas a selective ET-A receptor inhibitor suppresses the albuminuria in DN patients [21]. To date, no convincing data have been shown for reduction in renal endpoints. Specified therapeutic approaches mostly dealt with blood pressure as well as glucose control, it is manifest that DN progression still leads to ESRD in several patients. Hence, there is an urgent need for new therapeutic modalities that efficiently decrease the disease progression. The following section discusses novel therapeutic carriers for kidney targeting that could improve the effectiveness of therapeutic agents.
Approaches for targeted delivery of therapeutics in diabetic nephropathy DN is aggravated by hyperglycemia, fibrosis, inflammation, glomerular sclerosis, glomerular lesions and ROS generation. The conventional therapeutics that are available on the market were 4
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less effective because of a large amount of drug loss due to the firstpass metabolism effect, hepatic clearance, systemic absorption and distribution to other organs [31]. Therefore, nanomedicine is a better solution for the enhancement of targeting and improvement of the therapeutic effect in the kidney. The nanomedicine approach could help to target the above-mentioned therapeutics to the desired sites in treating DN [32]. These nanomedicines include liposomes, nanoparticles, microbubbles, prodrugs comprising nanoparticles and exosomes, providing the ability for peptide and gene therapy delivery for the treatment of DN.
Nanodrug-bearing particles During the past decade, DN has gained a lot more attention from pharmacological research, however few have shown promising results. Smaller diameter nanoparticles (10 nm) are cleared rapidly from kidney owing to inherent function of the kidney as a blood filter. The glomerular endothelium is the first component with 70–90 nm fenestrations and following 300–350 nm thick basal lamina of glomerular basement membrane (GBM) comprising heparin sulfate and proteoglycan with 3 nm pores, able to filter small molecules based on its size and charge. Besides GBM, podocytes are situated possessing a filtration slit of 32–40 nm. However, 10 nm nanoparticles easily enter the glomerular filtration unit and are cleared rapidly. Sometimes, prolonged retention of nanoparticles in the kidneys exhibited cellular shrinkage owing to more cellular uptake via renal cells. Therefore, retention, enhancing therapeutic index and activation of drug after reaching the target were found challenging for nanoparticles for effective delivery to the DN. The selective delivery of tailored nanoparticles to the target site enhanced therapeutic effect and reduced the toxic adverse effects. Several studies have been reported for the in vivo delivery of nanoparticles in tumors, resulting in accidental discovery of kidney-selective targeting and accumulation [33]. Nanoparticles can be engineered for delivery of drugs as well as imaging substances for enhancement of pharmacokinetic and pharmacodynamic effects that enable targeting delivery of the nanoparticles toward specific tissue cells at the site of the disease. A nanoparticle is a solid polymeric material that can be made efficient by slight modification with the help of PEGylation, conjugation, surface chemistry and ligand binding. Nanoparticles have proved to be a promising future theranostic for many diseases and disorders [34]. Wu et al. studied the receptor expressed by podocytes that is specific to glucocorticoids [i.e., neonatal Fc receptors (FcRn)]. Quantitative polymerase chain reaction (qPCR) confirmed the expression of FcRn in the podocytes. Albumin nanoparticles were fluorescently labeled and conjugated with methylprednisolone (BSA633-MP) for delivery to the podocytes. in vitro studies showed that uptake of nanoparticles was more (36-fold) in the human podocytes compared with HK-2 cells and other vascular smooth muscle cells. The results suggested that the albumin nanoparticles specifically reached kidney podocytes via interaction with FcRn receptors, indicating that the nanoparticles were specifically taken up by the podocytes [35]. Further, polylactic-co-glycolic acid (PLGA) nanoparticles comprising resveratrol were developed and evaluated for their antioxidant, anti-inflammatory and nephroprotective action effectiveness [36]. To enhance the targeting of the nanoparticle
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to the kidney, the nanoparticles were conjugated with KIM-1. The results suggested that there was a decrease in expression of NODlike receptor family pyrin-containing domain-3 (NLRP-3) – an inflammasome that is responsible for many diseases – compared with its expression in healthy kidneys [37]. There was also an increment in AMP-activated protein kinase (AMPK) and decrement in the phospho-mTOR level via PLGA nanoparticles that induced autophagy. In addition, the nanoparticles improved the renal condition of the adenine-induced CKD mouse model [38]. In another study, researchers used RGDfC (Arg-Gly-Asp-DPhe-Cys)-conjugated quantum dots for kidney targeting. The RGDfC binds to an avb3 integrin receptor of podocytes. in vitro data confirmed that RGDfC-conjugated quantum dots were selectively taken up by the podocytes that express avb3 integrin receptors. Upon incubation of the unconjugated formulation with podocytes, it was observed that the fluorescence intensity of the conjugated quantum dots was greater than unmodified quantum dots. When these formulations were incubated with glomeruli the targeted conjugate, with the help of avb3 receptors, became accumulated in the podocytes. These results give the idea that the conjugated quantum dots can be used for podocyte targeting [39]. Furthermore, rhein-loaded nanoparticles were developed to improve bioavailability and distribution in the kidney. Chen et al. synthesized the rhein-loaded nanoparticles by using a triblock copolymer of polyethyleneglycol-co-polycaprolactone-copolyethyleneimine to evaluate the targeting potential and therapeutic effect of the nanoparticle (size: 80 nm; z: 6–7 mV) in DN. The nanoparticles showed >90% cell viability to a concentration of 0.5 mM. The fasting blood glucose level was found to be decreased by <20 mmol/l along with a decrease in serum creatinine (<50 mmol/l) and serum urea nitrogen (<10 mmol/l). The proteinuria was also decreased in diabetes-induced mice to <2 mg/ 24 h. The in vivo imaging was helpful in understanding the localization of the nanoparticles in the kidney. Hence, the rhein-loaded nanoparticles proved to be beneficial in targeting for the treatment of DN [40]. The above-mentioned nanoparticles successfully delivered a drug to the kidneys. Numerous aspects that have been taken into consideration to improve targeting to the renal cells are discussed in the section below.
Effect of different formulation aspects of nanoparticles on the kidney targeting The kidney is an excretory organ comprising 1–2.5 million nephrons, playing a part for homeostasis of fluid, osmotic regulation and the filtration of waste body material. A nephron consists of the glomerulus, proximal tubules, loop of Henle, distal tubule and a collecting duct. The glomerular consists of podocytes, mesangial cells and the glomerular basement membrane. In normal physiological conditions, blood is filtered via size and charge through the glomerular membrane, which allows passing of water and small molecules from plasma. Higher molecular weight substances and anionic charged components remain inside the blood (e.g., albumin). Anionic molecules easily pass through the filtration barrier of the glomerulus. This barrier is disturbed in DN and causes albuminuria. Therefore, nanoparticles must cross the glomerular filtration membrane. Hence, structural features of the nanoparticles are important in their role to reach kidney cells.
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Nanoparticle delivery to numerous kidney cells and their components are explained here [41]. The effect of zeta potential of nanoparticles is significant. Positively charged nanoparticles are quickly excreted from the kidney owing to increased potential to bind with the protein as well as more interaction with the mononuclear phagocytic system. Oppositely or negatively charged nanoparticles are taken up more Q12 by macrophages than neutrally charged nanoparticles. Nanoparticles with <15 mV charges are less prone to macrophage uptake and have improved circulation in the blood. However, anionic Q13 nanoparticles are not able to accumulate more in the liver and spleen compared with neutral nanoparticles [42]. Cationic nanoparticles are easily taken up by the cellular membrane and capable of endosomal escape. Therefore, positively charged to neutrally charged nanoparticles are easily taken up by the negatively charged glomerular basement membrane. This is because of the anionic nature of the basement membrane as a result of a large amount of heparin-sulfate-containing glycocalyx. Therefore, there could be a chance for positively charged nanoparticles to get accumulated in the GBM [43]. The selection of charged nanoparticles is also an important parameter for kidney targeting. In one research study, <5 nm (3.7 nm) and negatively charged ultra-small nanoparticles were administered via the intravenous route. It was found that most of the nanoparticles reached the glomerular capillaries, able to surpass glomerular endothelium and slowly accumulate in mesangial cells for 30 days. Hence, the anionic charged glomerular basement membrane prevents the excretion of <5 nm nanoparticles compared with positively charged nanoparticles [44]. This outcome suggests the charged principle of kidney barriers – majorly negatively charged nanoparticles also applied and utilized for the fluorescence imaging or biodistribution. This charge on the GBM could be useful for drug delivery purposes and, by taking it into consideration, Zuckerman et al. Q14 prepared cationic nanoparticles of cyclodextrin for delivering siRNA to the GBM. The nanoparticles were then coated with a conjugate of adamantane and PEG to improve the hydrophilicity and induce a positive charge on the nanoparticles. The charge on the siRNA nanoparticles was around +11 mV, which was attributed to the successful drug delivery to GBM and facilitated the accumulation in the glomeruli. By contrast, the free siRNA did not show any retention in the glomeruli. The PET images showed that siRNA accumulated in the kidney for a shorter amount of time <5 min. However, nanoparticles remained in the kidney for a long time. It was also observed that there was disassembly of nanoparticles. The researcher proved that it might be due to repulsive forces between siRNA and GBM. They further concluded that charge on the nanoparticles acted as an attractive force between the GBM and the nanoparticles. This led to the accumulation of the nanoparticles in the glomerular basement membrane. The effect of the hydrodynamic size of nanoparticles can also be considered. To develop an efficient nanomedicine, the particle size of nanoparticles has been vastly explored. The majority of nanoparticles (30–150 nm) are not subjected to filtration via the kidney, despite degradation to <10 nm particle size or a damaged membrane. Nanoparticles of 5–8 nm can easily cross the glomerular filtration barrier and are cleared through the kidney after 4 h of injection (Fig. 1b) [45]. However, cationic nanoparticles in the www.drugdiscoverytoday.com
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range 50–130 nm can accumulate in the glomerular basement membrane as well as the mesangium and enhance targeting to the kidney [43]. Recently, Williams et al. proposed that nanoparticles in the particle size range of 350–500 nm could be retained in the kidneys. PLGA nanoparticles were synthesized and then were PEGylated to improve hydrophilicity and circulation time. The nanoparticles were injected via the intravenous route and were found to increase the localization of nanoparticles in the kidney by 30-fold compared with localization in other organs [46]. Similarly, researchers have developed cationic (C-MNP; z: +18 mV) and anionically charged (A-MNP; z: 19 mV) mesoscale nanoparticles (400 nm) for renal proximal tubule targeting. Surprisingly, they found 25–30-times enhanced localization in the kidney compared with lungs (2–3.5 times). The A-MNP and C-MNP were 4.5-times and 3.7-times higher in the kidney at 7 days compared with the heart. From this, it can be said that mesoscale nanoparticles remained in the kidney for a longer period of time compared with other organs (Fig. 2a–c). From the results, it was inferred that Q15 targeting the nanoparticles toward the kidney was done mainly via mesoscale nanoparticles, despite surface charge. Investigators also reported that alteration in size of nanoparticles as well as opsonization potential was a new proposed mechanism for renal targeting and cellular uptake [47]. To check the effect of the size of nanoparticles on kidney retention and targeting, another research group prepared albumin nanoparticles (AN) of different sizes. They found that nanoparticles with a particle size 95 nm (AN-95) were retained in the kidney more. This was confirmed by fluorescence assay: nanoparticles with a size 95 nm showed greater fluorescence compared with albumin nanoparticles of different sizes (75 and 130 nm; AN75 and AN-130). Confocal images of kidney sections provided further evidence that there was a greater accumulation of nanoparticles with the size 95 nm in the mesangium of the kidneys (Fig. 2d,e). After 5 min of intravenous administration, the nanoparticles showed a significant amount of retention in the kidney and liver compared with other organs (Fig. 2f). The researchers believed that clathrin-mediated endocytosis was the major mechanism of uptake of nanoparticles in the mesangial cells. Another reason for the accumulation of nanoparticles in the cells was the systemic pressure of the blood flowing into the kidneys and the fenestration of 85–145 nm of the endothelium of glomerular capillaries that allowed the nanoparticles to enter into the mesangial cells. However, the cut-off for penetrating through the filtration barrier is 10 nm. Thus, nanoparticles were unable to penetrate the barrier and successfully localized in the mesangial cells and the targeted delivery was achieved by researchers [48]. The effect of nanoparticle shape is another consideration. The particle size and zeta potential of nanoparticles play a significant part in drug targeting to the kidney. Besides these key properties, the shape of nanoparticles also affects the drug targeting, even if the particle size might not be ideal given the key points made above. This holds true for carbon nanotubes owing to their larger aspect ratio. Because of the larger aspect ratio of nanotubes, carbon nanotubes with particle sizes in one dimension of >500 nm can pass through the glomerulus [49]. This happens because the diameter of the nanotubes is small (i.e., 3–4 nm). The smaller diameter and larger aspect ratio help them to pass through the 6
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glomerulus when its spatial orientation is perpendicular to the basement membrane. Therefore, even smaller diameters restricted Q16 the carbon nanotubes from kidney clearance [50]. In similar circumstances, Ruggiero et al. prepared nanotubes with a length of 500 nm and a diameter of 1 nm. The nanotubes had a negative zeta potential but a higher molecular weight and aspect ratio allowed them to pass through the glomerulus. Despite the higher molecular weight, >60% of the nanotubes were excreted through the urine and only 20% was reabsorbed, where the remaining nanotubes were excreted via hepatobiliary circulation. This was further confirmed via NIR – proximal tubule uptake occurred owing to the presence of brush borders. Because other parts of nephron do not have brush borders, investigators determined that most of the accumulation of nanotubes occurs in the proximal tubule based on the fluorescent intensity [51]. Thus, nanoparticle size, shape and charge played a vital part in kidney targeting. In addition, lipidic vesicles such as liposomes have also been explored by researchers for better kidney targeting to the different affected areas, which is explained in following section in detail.
Liposomes in diabetic nephropathy targeting Liposomes comprise lipids such as phospholipids, blended with other materials such as cholesterol to make a hollow sphere containing the phospholipid bilayer. The outer layer is hydrophilic and the inner layer is hydrophobic, and the liposomes are less stable than nanoparticles. However, liposomes can enhance solubility and permeability of BCS class II and class IV drugs. Liposomal formulations Q17 are studied to target different diseases, such as cancer, kidney disease, viral infections, fungal infections and pain [52]. In context, Morimoto and colleagues developed liposomes containing TRX-20 (3,5-dipentadecyloxy benzamidine hydrochloride) to check the renal targeting potential of liposomes. To improve the circulation time of the formulation, they formulated PEGylated liposomes. The results showed that TRX–liposomes were retained and became adhered to rat mesangial cells specifically. The normal PEGylated liposomes did not show any fluorescent absorbance or presence toward rat mesangial cells. The HPTS assay showed that the same amount (0.32 mg/kg) of Q18 injected PEG–liposomes and TRX–liposomes were localized in the renal cortex, whereas only TRX–liposomes were retained in the glomerular cells owing to the nephritic condition of rats. When a comparison between normal rats and nephritic rats injected with TRX–liposomes was performed, the nephritic rats showed greater fluorescence, indicating more localization of the liposomes. Hence, TRX-modified liposomes enhanced the tendency to become accumulated in the kidney compared with normal PEGylated liposomes [53]. Recently, various modifications in the liposomal formulation have been made to improve targeting potential. For example, Kowalski and colleagues developed modified SAINT-o-somes [liposomes made up of cationic lipid 1-methyl-4-(cis-9-dioleyl) methylpyridinium chloride] for improved targeting efficiency. The SAINT-o-some was found to have better serum stability as well as drug release properties compared with conventional therapeutics. It also showed better targeting effect toward podocytes when conjugated with specific antigen-targeting antibodies such as antiVCAM-1 [54].
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A-MNP day 3 C-MNP day 3 A-MNP day 7 C-MNP day 7 Dye day 3 PBS day 3 & 7
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FIGURE 2
(a) Localization and distribution of administered anionic mesoscale nanoparticles (A-MNPs) in kidney by fluorescence plus CT overlay. (b) Images of fluorescence plus CT transaxial section of a mouse treated with A-MNPs. (c) Images of ex vivo organ fluorescence from mice injected with mesoscale nanoparticles (MNPs), dye or PBS normalized by total organ weight; adapted, with permission, from [47]. (d) Ex vivo fluorescence image of excised kidneys after 5 min of administration of nanoparticles via ex vivo imaging system (Quick View 3000, Bio-Real, Austria). (e) Quantitative intensity of the excised kidney. (f) Confocal images of kidney sections taken after 5 min of administration of nanoparticles. Scale bar: 30 mm. D = peritubular interstitial space, * = glomeruli, AN = albumin nanoparticles with size in nm indicated by a number, AN-75: 75 nm contained albumin nanoparticle, AN-95: 95 nm-sized albumin nanoparticle and AN-130: 130 nm size contained Q1 albumin nanoparticle. Adapted, with permission, from [48].
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Another group prepared anti-VCAM-1-rapamycin-saint-osomes to evaluate targeting ability toward podocytes. However, podocytes are known to express mammalian target of rapamycin (mTOR) receptors. Hence, rapamycin was used as a carrier in this approach to target the podocytes. It was observed that in the presence of tumor necrosis factor (TNF)-a the VCAM-1 (vascular cell adhesion molecule-1) is expressed. Therefore, in the presence of TNF-a, the cellular uptake of targeted saint-o-somes was enhanced over nontargeted saint-o-somes. From the wound-healing assay, it was observed that there was no growth of cells in the wounded area of the cells treated with the targeted formulation as a result of VCAM-1 suppression [55]. Q19 Based on the previous study, Yuan et al. also prepared triptolideloaded PEGylated TRX-20-modified liposomes (TRX20–LP) to observe therapeutic potential in renal disease. The prepared liposomes had a particle size of 110 nm with a zeta potential of +14 mV. The in vitro data demonstrated that the liposomes underwent mesangial cell uptake, and the extent of this uptake was similar even after PEGylation. The modified liposomes showed successful anti-inflammatory action by decreasing the levels of nitric oxide by 70% and TNF-a by 50%. The TRX-20-modified liposomes showed greater accumulation in the mesangial cells compared with unmodified liposomes. The anti-inflammatory action of PEGylated and non-PEGylated TRX-20-modified liposomes was greater than unmodified liposomes and the plain drug itself. The in vivo data showed that the groups that were treated with PEGylated liposomes displayed a twofold decrement in proteinuria and simultaneous increment in the serum albumin levels when compared with control groups. These results proved the efficiency of the modified liposomes for renal targeting [56]. Owing to the high lipophilicity of liposomes, they can show some off-target effects. Although, owing to the ineffective biodistribution of liposomes, nanoparticles have been proven to be more efficient and promising compared with liposomal delivery [57]. There is a lack of well-defined factors affecting kidney targeting for liposomes in the same way as with nanoparticles owing to a lack of research in this field. Hence, there is a dire need to develop a more selective delivery system that can specifically target the kidney. These potential strategies include microbubble therapy, mesenchymal stem cells (MSCs), peptide drug delivery and prodrugs.
Ultrasound-targeted microbubble destruction Clinically, microbubbles are utilized as an ultrasound contrast agent and investigated as an ultrasound therapy mediator. To enhance the theranostic effect, the microbubble can be attached to the nanoparticles with the intention of targeting, skin permeation, imaging and enhancing the acoustic response under ultrasound waves. Currently available nanoparticle-loaded microbubbles necessitate polymers and an oil layer for conjugation with the nanoparticles, which might be responsible for less biocompatibility and includes several steps. However, nanoparticle-loaded phospholipid-coated microbubbles can reduce the stated limitations [58]. Recently, scientists have developed microbubbles that have a bubble-like structure with a gas core that is encapsulated by lipids, polymers or protein shells. The characteristic feature of this microbubble is the particle size of 1–8 mm in diameter and requires an ultrasound of 2–115 MHz for resonance. Similar to a nanoparticle, the particle size of micro8
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bubbles, as well as surface display targeting ligands, is an important feature for drug delivery toward the kidney [58]. These microbubbles could be used for diagnostics as well as for drug delivery to improve the targeting and efficacy of the drug. The microbubbles act by the mechanisms of cavitation and sonoporation. Sonoporation is the property of enhancing the permeability of a drug to the target site by the reaction between the ultrasound and microbubbles [59]. In line with this, Chen et al. used ultrasound-targeted microbubble destruction (UTMD) to target coenzyme Q10 (CoQ10)loaded liposomes to the kidney to evaluate the therapeutic efficacy of the CoQ10 in early DN. CoQ10 is an endogenously synthesized antioxidant that could control blood glucose and prevent the free radical formation in DN. After treatment, CoQ10 was entrapped in a liposome (CoQ10–LIP; 180 2.1 nm; z: 18.20 mV) and CoQ10– LIP with UTMD (CoQ10–LIP + UTMD), as a microvascular complication the renal blood flow and kidney volume were improved in diabetic rats compared with the free-CoQ10-treated group (Fig. 3a, b). In addition, renal targeting of CoQ10–LIP + UTMD improved the podocyte foot process effacement and showed a protective effect toward podocytes, whereas CoQ10–LIP combined with the UTMD (Fig. 3c). It also alleviated the expression of downregulated podocin/NPHS2 from DN podocytes as well as suppressing the mesangial cells and glomerulus fibrosis up to 60–70% compared with the control and free-CoQ10-treated groups. Therefore, it can be said that UTMD assisted CoQ10–LIP treatment method potential to decrease the incidence of DN [60]. Moreover, UTMD could be utilized for drug delivery to a specific organ and improved permeability. Based on the advantages of microbubble therapy, Sheng et al. used UTMD to improve the targeting potential of basic fibroblast growth factor (bFGF) – able to decrease the structural and functional damage of kidney in CKDloaded liposomes. The investigators found that intrarenal delivery of bFGF–liposomes with UTMD was successful in delivering a large amount of drug into the kidney compared with other treatment groups (bFGF, bFGF–liposomes, UTMD). The bFGF successfully decreased various inflammatory mediators of DN such as interleukins, NF-kb and TGF-a. The formulation was found to be successful in improving the overall condition of the DN rat model [61]. As an emerging delivery system, researchers are still working on the microbubble therapy technique for drug delivery to the kidney.
Peptide and prodrug-based drug delivery Many low molecular weight proteins have been developed for targeting the kidneys. Among which, lysozymes have been found to undergo better retention in the kidney among the other molecules and could be a good carrier for targeting. However, their efficiency has suffered owing to adverse cardiotoxicity effects and complex synthesis methods. Also, any modification can lead to the synthesis of the immunogenic compound. To overcome the disadvantages of these compounds, other smaller carriers such as peptides can be used for targeting [62]. Yuan et al. demonstrated that a peptide fragment of albumin (PF-A299–585) became accumulated in the kidney (20–30% of administered nanoparticles) via endocytosis by megalin or cubulin receptors present on the inner lining of renal tubules [63]. In another study, the targeting potential of the peptide was evaluated
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FIGURE 3
Q2 (a) 2D ultrasound image of kidney at 12 weeks. (b) Kidney blood flow imaged via color doppler flow at 12 weeks indicating impact of CoQ10-liposome on morphology of kidney as well as function of diabetic rat. (c) Transmission electron microscopy image of podocytes representing protection of renal podocytes in diabetic nephropathy (DN) rat model after treatment. Here, red arrow represents fusion of the podocytes. CoQ10: coenzyme Q10; CoQ10+UTMD: coenzyme Q10 + ultrasound-mediated microbubble destruction; CoQ10-LIP: coenzyme Q10 encapsulated in liposome and CoQ10-LIP + UTMD: coenzyme Q10 encapsulated in liposome combined with ultrasound-mediated microbubble destruction. Adapted, with permission, from [60].
via conjugating with triptolide, for anti-inflammatory and immunosuppressant activity. The in vitro and in vivo data showed less toxicity, improved anti-inflammatory action similar to a plain drug and the conjugated peptide rapidly accumulated in the kidney. Thus, this strategy improved the condition of the kidney in the rat model. The distribution of the conjugate in the kidneys compared with other organs was inferred by comparing the fluorescence intensity. The fluorescence was at a maximum after 1 h of administration of the conjugate and decreased afterwards, which confirms that the maximum conjugate reaches the kidney in 1 h and the uptake decreased after that [64]. In a recent investigation, Wischnjow et al. developed drugconjugated (ciprofloxacin as the model drug) low molecular
weight protein (KKEEE)3K comprising nanocarriers; and evaluated them for renal tubular uptake in C57BL/6 J mice. The immunohistochemistry staining and pharmacokinetics studies confirmed the accumulation of the ciprofloxacin–peptide conjugation in the renal tubule. The effect of the peptide conjugation is shown in Fig. 4a, which clearly indicates the renal targeting potential of the peptide when compared with the unconjugated drug. In Fig. 4b the PET images indicate that megalin is responsible for uptake of the conjugate in the renal tubules. In megalin-deficient mice, the conjugate was cleared quickly and a greater fluorescence was observed in the bladder than in the kidneys. Also, the free drug was observed in the abdominal area whereas on conjugation with peptide the intensity of the fluorescence was maximum in the Q20 www.drugdiscoverytoday.com
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FIGURE 4
Q3 (a) Fluorescence study of localization of iodine-labeled free drug and iodine-labeled model drug (ciprofloxacin)–peptide conjugate. (b) Positron-emission tomography images of wild type (C57BL/6) and megalin-deficient (KO) mice 2 h after injection of iodine-labeled conjugate. Adapted, with permission, from [65].
kidneys. This proved the hypothesis of the investigator that (KKEEE)3K peptide could be used for targeting renal tubules [65]. Q21 Kim et al. conjugated PEA with a kidney-targeting peptide (LTCQVGRVH) and evaluated its transfection capability for gene delivery in treating renal fibrosis in a unilateral ureteral obstruction (UUO)-induced kidney fibrosis model. The results showed that PEA–peptide conjugate had higher transfection and low cytotoxicity compared with PEI. Successful delivery of hepatocyte Q22 growth fact or (HGH) gene to the tubules was achieved and the Q23 results showed that there was a decrease in fibrosis in the UUO kidney fibrosis model [66]. Conjugate drug delivery could be a promising drug delivery system but, at the same time, enzymes such as peptidases render the conjugate inactive. Hence, prodrugs could be the alternative that might be helpful to overcome this disadvantage. A prodrug is the inactive or active form of the drug that undergoes biotrans10
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formation and becomes activated. The prodrug approach is used by many medicinal chemists and researchers for changing various parameters of drug-related toxicology and biopharmaceutical studies. A drug can be modified to a prodrug by attaching an enzyme, gene or any easily removed functional group via biochemical reactions (i.e. esters, phosphates, etc.) [67]. Based on the advantages of prodrugs, Hu et al. synthesized hyaluronic-acid-conjugated curcumin (HA–CUR) prodrug linked by ester linkage where curcumin is a potent anti-inflammatory and antioxidant agent. CD-44-targeting hyaluronic acid was conjugated to localize the prodrug in the inflamed kidney. The in vitro data confirmed the anti-inflammatory and antioxidant effect of the HA–CUR prodrug by the observed decreased level of superoxide dismutase, glutathione and malondialdehyde. The in vivo imaging confirmed the localization of the prodrug into the renal cells via CD-44 receptor-mediated endocytosis. The results gave a clear
Formulation
Polymer/lipid used
Therapeutic molecule
Receptor involved
In vitro cells
In vivo model
Outcomes and characteristics
Refs
Podocytes
Nanoparticles
Albumin
Methylprednisolone
Semiconductor particles
RGDfC (arg-gly-D-phecys)
Female BALB/c mice Female adult C57BL/6 mice
SAINT-o-somes
1-Methyl-4-(cis-9dioleyl) methylpyridinium-chloride (SAINT-C18)
VCAM-1 antibody Rapamycin
Human podocytes cells U87-MG and MCF-7 breast cancer cells AB8/13 and MPC5 cell lines
36-fold nanoparticle uptake enhanced in podocytes Rod-shaped quantum dots successfully bind to receptors on the podocyte Size: 130 nm; zeta potential: 10 mV. The VCAM1 level was found to decrease in the assays performed
[30]
Quantum dots
Neonatal Fc receptors avb3 receptor
Nanoparticles
Gold and polyethylene glycol (PEG) cyclodextrin
Mesangial cells
Polymeric nanoparticles
Glomerular basement membrane
Mannose targeted EGFPsiRNA and transferrin targeted EGFP-siRNA
Mannose receptors
Male C57BL/6 mice
Female BALB/c mice SV40-MES (mouse mesangial) cells and CRL-2573 (rat mesangial) cells HBZY-1 rat glomerular mesangial cells Anti-thy1.1 IgG (OX7)synthesizing hybridoma cells mouse mesangial cells
C57BL/6-Tg and Balb/c mice
Nanoparticles
Albumin
Celastrol
Caveolae or clathrinmediated uptake
Immunoliposome
Hydrogenated soybean phosphatidylcholine
Mycophenolate mofetil
Size-dependent retention
siRNA/PEG-PLL (poly-L-lysine) conjugate siRNA/CDP nanoparticles
PLL
MAPK1 siRNA
Size-dependent uptake
Cyclodextrin
Electrostatic interaction
Murine lupus nephritis model (MRL/lpr) Female Balb/c mice
Cationic ironoxide nanoparticles
Iron oxide
Electrostatic interaction
Sprague Dawley rats
Chitosan/ AQP1siRNA nanoparticles (AQP-aquaporin)
Chitosan
AQP1 siRNA
Megalin
MDCK cells, megalin knockout mice (megalin lox/lox cre + )
anti-Thy1.1 nephritis rat model Anti-thy1.1 nephritis induced rats
BALB/cJBomTac female mice
Size: 80 nm and zeta potential: around 10 mV. Specifically taken up by mesangial cells Specific uptake of mannosetargeted nanoparticles was greater compared with others in the mesangium The albumin nanoparticles having size 90 nm accumulated in the mesangial cells Retained in the mesangium of the kidney. Proteinuria, extracellular matrix accumulation and mesangial cell expansion found to decrease The conjugate successfully targeted and retained in the mesangial cells Size: 80 nm; zeta potential: +10 mV. Negative charged GBM enables the positive charged nanoparticles to interact with them The small size of nanoparticles enabled them to reach GBM. The positive charge was responsible for retention of nanoparticles into GBM The formulation was specifically delivered to the kidney via megalin receptors and retained in tubular cells for about 48 h
[48,49]
[76]
[78]
[42]
[79]
[80]
[39]
[37]
[81]
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Proximal tubule
VCAM-1 (vascular cellular adhesion molecule 1) and mTOR (mammalian target of rapamycin) Diffusion
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TABLE 1
Q4 Targeting formulations on different parts of the nephron
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[84]
[83]
HK-1 adult human proximal tubule kidney epithelial cells, MDCK (MadinDarby canine kidney epithelial cells), HepG2
Rat nephrosis model
Renal ischemia/ reperfusion injury rat model
Aminoglycoside (gentamicin) PEI
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Megalin-mediated endocytosis
Captopril Lysozyme
Captopril lysozyme conjugate AminoglycosidecarboxyalkylatedPEI nanoplexes
14-succinyl triptolide
Therapeutic molecule
Megalin-mediated endocytosis
Megalin- or cubulinmediated endocytosis Lysozyme 14-succinyltriptolide– lysozyme conjugate
HK-2 cells Mechanism is unknown PLGA Mesoscale nanoparticles
Receptor involved Polymer/lipid used Formulation Target
TABLE 1 (Continued ) 12
[82]
Refs
[40]
Nanoparticles were localized in proximal tubules via peritubular capillaries. It was uptake via transcytosis followed by endocytosis The conjugate was smaller in size and was able to penetrate the filtration barrier. The lysozyme enhanced the uptake of conjugate into the proximal tubules The ACE level was decreased by >40% in <12 h after administration. The proteinuria was reduced Higher gene transfection ability. The megalin-mediated uptake found in the proximal cells Female SKH-1 elite hairless mice
In vitro cells
In vivo model
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Outcomes and characteristics
REVIEWS
indication that HA–CUR nanoparticles (400 mg/g in 24 h) were localized more in the kidney as compared with other organs and for a longer period [68].
Exosomes derived from mesenchymal stem cells MSCs are multipotent cells that can differentiate into various cells, while not producing an immune response, and are therefore considered to be safe in drug delivery to target sites. MSCs also induce some anti-inflammatory action by inhibiting cytokines and TGF-b. MSCs have the capability to generate and deliver therapeutics in situ, in a phenomenon that is also known as the trophic effect of MSCs. MSCs are capable of inducing angiogenesis and are recruited to the site of damage where they show their therapeutic effect [69]. MSCs are responsible for the secretion of extracellular vesicles as part of their therapeutic activity. The extracellular vesicles are of three types: exosomes, microvesicles and apoptotic bodies. Exosomes are the secretory vesicles or the product shed from the endosomes. The presence of such vesicles in the urine could be a sign of renal damage [70]. Therefore, exosomes can act as a biomarker for detecting early DN and can be used for therapeutic purposes. Nevertheless, isolation and purification of the exosomes is a highly challenging task and, hence, there is no standardized protocol to date. It was also investigated that extracellular vesicles of MSCs reverse the renal fibrosis in a streptozotocin-induced mouse DN model [71]. Further, Nagaishi et al. intravenously administered MSCs to DNinduced mice for the treatment of DN. This treatment strategy was able to decrease bone-marrow-derived cells (BMDCs) significantly, which is a major cause of renal fibrosis. MSC therapy was successful in preventing mesangium expansion. MSCs are reported to downregulate VEGF, which is responsible for abnormal mesangium expansion. The MSCs are considered to be large reserves of VEGF that could help in improving the glomerular pathology in DN. The MSCs also successfully downregulated p38/MAPK and TGF-b expression and, hence, decreased inflammation and fibrosis. The MSC-treated cells also showed no change in the zona occludes 1 (ZO-1) and lectin expression. The investigators thus concluded that the therapeutic effect of MSCs was observed as a result of the release of the exosomes [72]. Moreover, Wang et al. demonstrated the use of exosomal Q24 delivery in treating renal fibrosis. In this study, MSCs were genetically modified to release exosomes containing miR-let7c (micro RNA let7) that are expressed in the UUO mouse model. microRNA (miRNA) is noncoding single-stranded RNA containing 20–24 nucleotides [73]. The miR-let7 family of miRNA was observed to play a crucial part in renal fibrosis. Downregulation of this miRNA was assumed to be responsible for renal fibrosis. MSCs are considered a safe and reliable vehicle to deliver miRNA. In addition, MSCs have the property of secreting vesicles that contain the desired miRNA. The investigators found that MSCs successfully delivered miR-let7c to the target site, which led to an increased expression of miR-let7c. This observation was confirmed by repression of collagen type IVa-1 and TGF-bR1 levels, which are two genes that play a major part in renal fibrosis [74]. MSC exosomes could provide a major breakthrough in renal drug delivery but their use is controversial and treatment is very expensive at this time. Hence, conjugate or peptide drug delivery could be a better alternative in the context of renal drug delivery.
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TABLE 2
Patent
Application date
Granted on
Patent title
Outcome of Investigation
Refs
US9872840B2
18/08/2016
23/01/2018
Effect of garcinol in delaying the progression of DN
[85]
US20180143207A1
24/05/2018
US9803008B2
09/02/2017
200 mg/kg/day of garcinol was found effective that the glomerulosclerosis, albuminuria was reduced. The plasma protein, nephrin and erythropoietin levels increased The diabetes patient urine samples were screened. Glycated uromodulin a marker for DN was detected in the samples The treatment was successful in reducing hypertension, glomerular and tubular sclerosis, mesangial expansion and macroalbuminuria
US20170003299A1
05/01/2017
US20170153249A1
01/06/2017
Early prediction markers of DN
US20150275301A1
01/10/2015
Urine exosome mRNAs and methods of using same to detect DN
US9161930B2
01/03/2012
US20120164667A1
28/06/2012
US20110065598A1
17/03/2011
US20100216709A1
26/08/2010
US7396825B2
24/11/2005
31/10/2017
20/10/2015
Method for screening DN in a subject Method of treating DN by administering antibodies to vascular endothelial growth factor B (VEGF-B) Detecting podocyte injury in DN and glomerulonephritis
A pharmaceutical composition for DN and its preparation and application
Method for test on DN Methods and devices for detecting DN and associated disorders
08/07/2008
Systemic insulinlike growth factor-1 (IGF-1) therapy reduces diabetic peripheral neuropathy and improves renal function in DN Agonists of A2A adenosine receptors for treatment of DN
The method was found to detect markers such as nephrin, podocin, synaptopodin or podocalyxin, which are responsible for podocyte injury. The method was done via flow cytometry and enzyme-linked immunosorbent assay from urine samples The markers such as carbonic anhydrase 1, prothrombin, tetranectin, CD59 glycoprotein, plasma serine protease inhibitor and its isoforms are markers for DN. In DN patients that do not show albuminuria detection of any one of the above markers shows that the person is suffering from nephropathy The complementary DNA (cDNA) that are specific for PPARGC1A, SMAD1, NRF2 and CD24 were generated. It was observed that the amount of such cDNA was found to be greater than the healthy individual who does not have nephropathy A new pharmaceutical composition was prepared by using 4,40 -diphenylmethanebis(methyl)carbamates along with excipients such as lactose, magnesium stearate and amylum maydis. The pills were prepared using silicon oil and polyglycol 6000. The active ingredient was found to be active in decreasing blood sugar level The urinary podocalyxin level in DN patient was more than the reference value CTGF, VEGF, KIM-1, NGAL, calbindin and cystatin C are the markers for diabetic nephropathy. In diabetic nephropathic patient urine samples were found to contain at least three markers that are listed above. The samples were diagnosed by means of specified antibodies for a particular marker IGF-1 modulates serum albumin level with a reduction in urine column and protein levels thus improving the renal condition in diabetic glomerulosclerosis
A2A agonists were administered along with type IV phosphodiesterase inhibitor such as rolipram. Along with nephropathy they can also be used for reducing inflammation
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[86]
[87]
[88]
[89]
[90]
[77]
[91] [92]
[93]
[94]
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Patents related to diabetic nephropathy treatment and diagnosis
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TABLE 2 (Continued )
Reviews KEYNOTE REVIEW
Patent
Application date
US20080070862A1
20/03/2008
GAGs such as sulodexide were selected against HIVassociated nephropathy (HIVAN). The sulodexide was administered as salt, solvate, hydrate or clathrate. The GAGs were successful in inhibiting the symptoms or complications associated with HIVAN US20050214294A1
[95]
Granted on
29/09/2005
US6780603B1
24/08/2004
Targeting to different areas of the nephron involved in diabetic nephropathy The major parts of the kidney that are involved in nephropathy are the glomerular basement membrane, podocytes, mesangial cells and proximal tubules. The desirable site of action of the formulations is guarded by many factors, such as size, charge, protein conjugate and receptors involved. For instance, the cutoff for filtration of a molecule from the glomerular membrane is 8–10 nm. Hence, nanoparticle delivery systems with a particle size of <10 nm become excreted in the urine, whereas nanoparticles with a particle of more than that would be retained in the kidney. During nephropathy, albuminuria causes this filtration cut-off to increase to 12 nm [75]. Targeting the kidney is challenging because the different locations have different pore sizes. Various approaches such as peptide conjugation, nanoparticles and microbubbles have been used for targeting renal cells based on the localization in the different regions of the kidney [76]. Along with the physiology of the kidney, the formulation aspects also have key roles, as discussed in the section above. Table 1 provides detailed investigational evidence conducted to date for targeting different parts of the kidney, specifically the nephron.
Patents and clinical trials related to diabetic nephropathy Patents are considered to be the individual rights given to the investigators for the work that is novel, innovative and has an industrial application. The number of DN patients is increasing every year; and therefore there is a need for a potential delivery 14
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Patent title
Outcome of Investigation
Methods using
glycosaminoglycans (GAGs) for the treatment of nephropathy
DN therapies
A therapeutic dose of an agent that inhibits CTGF was administered to a subject. It was observed that the moiety successfully reduced creatinine clearance, glomerular hyperfiltration, urinary albumin excretion and improved the nephropathic condition of the subject The normal kidney and nephropathic kidney samples were compared for the study of levels of integrins a1 and a2. It was observed that in nephropathic kidney there was an increase in a2 whereas a1 level was found to decrease
Analysis of alpha integrins for diagnosis of DN
Refs
[96]
[97]
system and therapeutics that can eradicate diabetes-related complications such as DN. Interest regarding DN has led to an increase in a number of investigations as well as patents related to the diagnosis and treatment of DN. Table 2 summarizes the patents granted for intellectual rights related to DN. Numerous clinical trials are underway for safe and effective therapeutics for the treatment of the DN Q25 [77]. Table 3 provides the list of the therapeutics that are in clinical trials along with their trial status and sponsors.
Concluding remarks and future directions Targeting the kidneys in DN is a major hurdle owing to the ability of the kidney to excrete drugs out of the body. This area of nanomedicine is rapidly growing, as evidenced by the numerous nanoparticles already available on the market and the many more undergoing clinical trials. Nanomedicine-based approaches with tailored biophysical characteristics could yield greatly controlled nanocarriers for targeting to the kidney. Nanoparticles would be able to bind with renal cells for a prolonged duration, enhance retention, as well as improve cellular uptake within almost all cell types – for instance, glomerular basement epithelial cells, podocytes, mesangial cells and proximal tubule cells. During the past decade, different nanoparticles were proposed for the treatment of diseases with unanticipated responses to be retained and accumulate within kidney cells. These significantly elevated the correlation among the structure and nanoparticle activity based on their modification and physicochemical properties regarding kidney targeting function. Conjugation of drugs with different ligands that bind specifically to megalin or cubilin receptors can be synthesized for specific delivery of the drug to the kidney. The arena of nanomedicine
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TABLE 3
Therapeutic moiety
Clinical trial Phase
Status
Sponsor
Fulacimstat Aleglitazar Dulaglutide Alagebrium Berberine Finerenone Pyridoxamine dihydrochloride RTA 402 Nitroaspirin MT-3995 Canagliflozin Resveratrol Alfacalcidol Colchicine Spironolactone Atrasentan Sevelamer carbonate Sulodexide PH3 Pyridorin Benfotiamine Bindarit Pirfenidone Telmisartan Probucol Paricalcitol Bardoxolone Green tea extract XL784
Phase II Phase III Phase III Phase II Phase IV Phase III Phase II Phase II Phase II Phase II Phase III Early Phase I Phase IV Phase II Phase IV Phase III Phase I Phase IV Phase II Phase II Phase IV Phase II Phase III Phase IV Phase II Phase II Phase III Phase II Phase II
Recruiting Withdrawn Completed Terminated Recruiting Active, not recruiting Completed Completed Terminated Completed Completed Completed Recruiting Recruiting Completed Terminated Completed Terminated Completed Completed Completed Completed Active, not recruiting Completed Completed Completed Completed Completed Completed
Bayer Hoffmann-La Roche Eli Lilly Synvista Therapeutics Nanjing First Hospital, Nanjing Medical University Bayer NephroGenex Kyowa Hakko Kirin Mario Negri Institute for Pharmacological Research Mitsubishi Tanabe Mitsubishi Tanabe Shiraz University of Medical Sciences The Third Xiangya Hospital of Central South University Sheba Medical Center Steno Diabetes Center Abbvie Icahn School of Medicine at Mount Sinai Keryx Biopharmaceuticals PhytoHealth Corporation BioStratum University Medical Center Groningen Aziende Chimiche Riunite Angelini Francesco Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran Boehringer Ingelheim Korea Otsuka Pharmaceutical Abbott Kyowa Hakko Kirin University of Campinas, Brazil Symphony Evolution
Reviews KEYNOTE REVIEW
Clinical trials data for diabetic nephropathy
(Last accessed on 16 Sept 2019); data obtained from www.clinicaltrials.gov.
research still inflates with several nanoparticles, some of which have reached clinical trials. Current data provide detailed clinical records and next-level treatment modalities for renal targeting. To date, there are no such promising modalities available to directly deal with the proteinuria and DN complications. Based on physicochemical properties and design of the nanoparticle delivery systems, kidney retention has been shown to become enhanced. It is time that the nanotechnological research teams and nephrology experts collaborate to develop encouraging nanomedicine tactics for selective targeting and treatment of renal disorders.
Conflicts of interest There are no conflicts of interest associated with this manuscript.
Uncited references
Q26
[98,99,100].
Q27
Acknowledgments R.K.T. would like to acknowledge the Science and Engineering Research Board (Statutory Body Established through an Act of Parliament: SERB Act 2008), Department of Science and Technology, Government of India for grant #ECR/2016/001964 and N-PDF funding (PDF/2016/003329) for work on targeted cancer therapy in Dr Tekade’s laboaratory. The authors would also like to acknowledge the Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, India, for supporting research on cancer and diabetes at NIPER-Ahmedabad.
References
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1 Volpe, C.M.O. et al. (2018) Cellular death, reactive oxygen species (ROS) and diabetic complications. Cell Death Dis. 9 2 Harrison, L.C. (2019) Type 1 diabetes. In Clinical Immunology. pp. 957–966, Elsevier 3 Goedeke, L. et al. (2019) Emerging pharmacological targets for the treatment of nonalcoholic fatty liver disease, insulin resistance, and type 2 diabetes. Ann. Rev. Pharmacol. Toxicol. 59, 65–87 4 Chung, Y.-R. et al. (2019) Dipeptidyl peptidase-4 inhibitors versus other antidiabetic drugs added to metformin monotherapy in diabetic retinopathy progression: a real world-based cohort study. Diabetes Metab. J. 43, 640–648 5 Sperling, M.A., ed. (2014) Pediatric Endocrinology, Elsevier Health Sciences 6 Adi, S. and Gerard-Gonzalez, A. (2018) Type 1 diabetes mellitus: an overview. In Nutritional and Therapeutic Interventions for Diabetes and Metabolic Syndrome. (2nd edition), pp. 3–13, Elsevier
7 Chawla, A. et al. (2016) Microvasular and macrovascular complications in diabetes mellitus: distinct or continuum? Indian J. Endocrinol. Metab. 20, 546 8 Gheith, O. et al. (2016) Diabetic kidney disease: world wide difference of prevalence and risk factors. J. Nephropharmacol. 5, 49 9 Vinod, P. (2012) Pathophysiology of diabetic nephropathy. Clin. Queries Nephrol. 1, 121–126 10 Loeffler, I. and Wolf, G. (2019) Mechanisms of interstitial fibrosis in diabetic Q30 nephropathy. In Diabetic Nephropathy. pp. 227–251, Springer 11 Sulaiman, M.K. (2019) Diabetic nephropathy: recent advances in pathophysiology and challenges in dietary management. Diabetol. Metab. Syndr. 11, 7 12 Clemens, K.K. et al. (2019) Diabetes management in older adults with chronic kidney disease. Curr. Diabetes Rep. 19, 11
www.drugdiscoverytoday.com Please cite this article in press as: Raval, N. et al.
15
DRUDIS 2617 1–17 REVIEWS
Reviews KEYNOTE REVIEW Q31
13 Lai, X. et al. (2018) Amelioration of diabetic nephropathy in db/db mice treated with tibetan medicine formula Siwei Jianghuang Decoction Powder extract. Sci. Rep. 8, 16707 14 Fujita, Y. et al. (2018) An adjustment in BMP4 function represents a treatment for diabetic nephropathy and podocyte injury. Sci. Rep. 8, 13011 15 Li, Z. et al. (2018) Inhibition of epidermal growth factor receptor activation is associated with improved diabetic nephropathy and insulin resistance in type 2 diabetes. Diabetes 67, 1847–1857 16 Mitrofanova, A. et al. (2019) SMPDL3b modulates insulin receptor signaling in diabetic kidney disease. Nat. Commun. 10, 2692 17 Kang, J.S. et al. (2019) Angiotensin II-mediated MYH9 downregulation causes structural and functional podocyte injury in diabetic kidney disease. Sci. Rep. 9, 7679 18 Schwarz, A. et al. (2019) Coro2b, a podocyte protein downregulated in human diabetic nephropathy, is involved in the development of protamine sulphateinduced foot process effacement. Sci. Rep. 9, 8888 19 Rossing, P. et al. (2018) Prognosis and treatment of diabetic nephropathy: recent advances and perspectives. Nephrol. Ther. 14, S31–S37 20 Lim, A.K. (2014) Diabetic nephropathy – complications and treatment. Int. J. Nephrol. Renovasc. Dis. 7, 361 21 Chan, G.C. and Tang, S.C. (2015) Diabetic nephropathy: landmark clinical trials and tribulations. Nephrol. Dialysis Transpl. 31, 359–368 22 Coleman, C. et al. (2020) Impact of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers on renal and mortality outcomes in people with type 2 diabetes and proteinuria. Diabet. Med. 37, 44–52 23 Kim, Y. and Park, C.W. (2017) New therapeutic agents in diabetic nephropathy. Korean J. Int. Med. 32, 11 24 Jia, Z. et al. (2014) New insights into the PPARg agonists for the treatment of diabetic nephropathy. PPAR Res. 2014, 818530 25 Shahbazian, H. et al. (2019) Increased level of advanced glycation end-products in renal transplant patients is associated with decreased measured GFR and grafted kidney function. J. Nephropathol. 8, e3 26 Sun, Y.-M. et al. (2013) Recent advances in understanding the biochemical and molecular mechanism of diabetic nephropathy. Biochem. Biophys. Res. Commun. 433, 359–361 27 Kohan, D.E. et al. (2011) Addition of atrasentan to renin-angiotensin system blockade reduces albuminuria in diabetic nephropathy. J. Am. Soc. Nephrol. 22, 763–772 28 Takagaki, Y. et al. (2019) Dipeptidyl peptidase-4 plays a pathogenic role in BSAinduced kidney injury in diabetic mice. Sci. Rep. 9, 7519 29 Maki, T. et al. (2019) Amelioration of diabetic nephropathy by SGLT2 inhibitors independent of its glucose-lowering effect: a possible role of SGLT2 in mesangial cells. Sci. Rep. 9, 4703 30 Ahmed, O.M. et al. (2019) Effects of enalapril and paricalcitol treatment on diabetic nephropathy and renal expressions of TNF-a, P53, Caspase-3 and Bcl-2 in STZ-induced diabetic rats. PLoS One 14, e0214349 31 Devarajan, P.V. and Jain, S. (2015) Targeted Drug Delivery: Concepts and Design. Springer 32 Kim, S.S. et al. (2016) Current challenges in diabetic nephropathy: early diagnosis and ways to improve outcomes. Endocrinol. Metab. 31, 245–253 33 Pelaz, B. et al. (2017) Diverse applications of nanomedicine. ACS Nano 11, 2313– 2381 34 Cerna, T. et al. (2016) Targeted nanoparticles – a promising opportunity in cancer therapy – review. J. Metallomics Nanotechnol. 4, 6–11 35 Wu, L. et al. (2017) Albumin-based nanoparticles as methylprednisolone carriers for targeted delivery towards the neonatal Fc receptor in glomerular podocytes. Int. J. Mol. Med. 39, 851–860 36 Malhotra, A. et al. (2015) An organ system approach to explore the antioxidative, anti-inflammatory, and cytoprotective actions of resveratrol. Oxid. Med. Cell. Longev. 2015, 803971 37 Anders, H.-J. and Muruve, D.A. (2011) The inflammasomes in kidney disease. J. Am. Soc. Nephrol. ASN.2010080798 38 Lin, Y.-F. et al. (2017) Resveratrol-loaded nanoparticles conjugated with kidney injury molecule-1 as a drug delivery system for potential use in chronic kidney disease. Nanomedicine 12, 2741–2756 39 Pollinger, K. et al. (2012) Kidney podocytes as specific targets for cyclo (RGDfC)modified nanoparticles. Small 8, 3368–3375 40 Chen, D. et al. (2018) Kidney-targeted drug delivery via rhein-loaded polyethyleneglycol-co-polycaprolactone-co-polyethylenimine nanoparticles for diabetic nephropathy therapy. Int. J. Nanomed. 13, 3507 41 Kamaly, N. et al. (2016) Nanomedicines for renal disease: current status and future applications. Nat. Rev. Nephrol. 12, 738
16
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42 He, C. et al. (2010) Effects of particle size and surface charge on cellular uptake and biodistribution of polymeric nanoparticles. Biomaterials 31, 3657–3666 43 Zuckerman, J.E. et al. (2012) Polycation-siRNA nanoparticles can disassemble at the kidney glomerular basement membrane. Proc. Natl. Acad. Sci. U. S. A. 109, 3137–3142 44 Liang, X. et al. (2016) Short-and long-term tracking of anionic ultrasmall nanoparticles in kidney. ACS Nano 10, 387–395 45 Choi, H.S. et al. (2007) Renal clearance of quantum dots. Nat. Biotechnol. 25, 1165 46 Williams, R.M. et al. (2018) Selective nanoparticle targeting of the renal tubules. Hypertension 71, 87–94 47 Williams, R.M. et al. (2015) Mesoscale nanoparticles selectively target the renal proximal tubule epithelium. Nano Lett. 15, 2358–2364 48 Guo, L. et al. (2017) Targeted delivery of celastrol to mesangial cells is effective against mesangioproliferative glomerulonephritis. Nat. Commun. 8, 878 49 Im, H.-J. (2018) Excretion and clearance. In Radionanomedicine. pp. 347–368, Q32 Springer 50 Lacerda, L. et al. (2008) Carbon-nanotube shape and individualization critical for renal excretion. Small 4, 1130–1132 51 Ruggiero, A. et al. (2010) Paradoxical glomerular filtration of carbon nanotubes. Proc. Natl. Acad. Sci. U. S. A. 107, 12369–12374 52 Bulbake, U. et al. (2017) Liposomal formulations in clinical use: an updated review. Pharmaceutics 9, 12 53 Morimoto, K. et al. (2007) Advances in targeting drug delivery to glomerular mesangial cells by long circulating cationic liposomes for the treatment of glomerulonephritis. Pharm. Res. 24, 946–954 54 Kowalski, P.S. et al. (2013) Anti-VCAM-1 and anti-E-selectin SAINT-O-Somes for selective delivery of siRNA into inflammation-activated primary endothelial cells. Mol. Pharm. 10, 3033–3044 55 Visweswaran, G.R.R. et al. (2015) Targeting rapamycin to podocytes using a vascular cell adhesion molecule-1 (VCAM-1)-harnessed SAINT-based lipid carrier system. PLoS One 10, e0138870 56 Fan, D. et al. (2018) The effect of triptolide in rheumatoid arthritis: from basic research towards clinical translation. Int. J. Mol. Sci. 19, 376 57 Sarko, D. and Georges, R. (2016) Kidney-specific drug delivery: review of opportunities, achievements, and challenges. J. Anal. Pharm. Res. 2, 00033 58 Schuh, S. et al. (2015) Properties of serial ultrasound clinical diagnostic pathway in suspected appendicitis and related computed tomography use. Acad. Emerg. Med. 22, 406–414 59 Sirsi, S.R. and Borden, M.A. (2012) Advances in ultrasound mediated gene therapy using microbubble contrast agents. Theranostics 2, 1208 60 Chen, P.-P. et al. (2018) CoQ10-loaded liposomes combined with UTMD prevented early nephropathy of diabetic rats. Oncotarget 9, 11767 61 Sheng, W.-S. et al. (2018) Intrarenal delivery of bFGF-loaded liposome under guiding of ultrasound-targeted microbubble destruction prevent diabetic nephropathy through inhibition of inflammation. Artif. Cells Nanomed. Biotechnol. 46 (suppl. 2), 373–385 62 De Groot, A.S. and Scott, D.W. (2007) Immunogenicity of protein therapeutics. Trends Immunol. 28, 482–490 63 Yuan, Z.-X. et al. (2014) Peptide fragments of human serum albumin as novel renal targeting carriers. Int. J. Pharm. 460, 196–204 64 Yuan, Z.-X. et al. (2015) Renal targeted delivery of triptolide by conjugation to the fragment peptide of human serum albumin. Eur. J. Pharm. Biopharm. 94, 363–371 65 Wischnjow, A. et al. (2016) Renal targeting: peptide-based drug delivery to proximal tubule cells. Bioconj. Chem. 27, 1050–1057 66 Kim, Y.-K. et al. (2012) Kidney-specific peptide-conjugated poly (ester amine) for the treatment of kidney fibrosis. J. Nanosci. Nanotechnol. 12, 5149–5154 67 Zhang, X. et al. (2017) Prodrug strategy for cancer cell-specific targeting: a recent overview. Eur. J. Med. Chem. 139, 542–563 68 Hu, J.-B. et al. (2018) CD44-targeted hyaluronic acid-curcumin prodrug protects renal tubular epithelial cell survival from oxidative stress damage. Carbohydr. Polym. 193, 268–280 69 Park, S.-R. et al. (2018) A novel endogenous damage signal, glycyl tRNA synthetase, activates multiple beneficial functions of mesenchymal stem cells. Cell Death Differ. 25, 2023–2036 70 Xu, W.-C. et al. (2018) Urinary extracellular vesicle: a potential source of early diagnostic and therapeutic biomarker in diabetic kidney disease. Chin. Med. J. 131, 1357 71 Grange, C. et al. (2019) Stem cell-derived extracellular vesicles inhibit and revert fibrosis progression in a mouse model of diabetic nephropathy. Sci. Rep. 9, 4468 72 Nagaishi, K. et al. (2016) Mesenchymal stem cell therapy ameliorates diabetic nephropathy via the paracrine effect of renal trophic factors including exosomes. Sci. Rep. 6, 34842
DRUDIS 2617 1–17
73 Kawahara, Y. (2014) Human diseases caused by germline and somatic abnormalities in microRNA and microRNA-related genes. Congenit. Anom. 54, 12– 21 74 Wang, B. et al. (2016) Mesenchymal stem cells deliver exogenous microRNA-let7c via exosomes to attenuate renal fibrosis. Mol. Ther. 24, 1290–1301 75 Scindia, Y.M. et al. (2010) Mesangial pathology in glomerular disease: targets for therapeutic intervention. Adv. Drug Deliv. Rev. 62, 1337–1343 76 Zhou, P. et al. (2014) Kidney – targeted drug delivery systems. Acta Pharm. Sin. B 4, 37–42 77 Garovic, V.D. and Jayachandran, M. (2017) Detecting podocyte injury in diabetic nephropathy and glomerulonephritis. Google Patents2017 78 Choi, C.H.J. et al. (2011) Targeting kidney mesangium by nanoparticles of defined size. Proc. Natl. Acad. Sci. U. S. A. 108, 6656–6661 79 Zuckerman, J.E. et al. (2015) siRNA delivery to the glomerular mesangium using polycationic cyclodextrin nanoparticles containing siRNA. Nucleic Acid Ther. 25, 53–64 80 Mo, Y. et al. (2017) Morphological switching of unimolecular micelles of ternary graft copolymers in different solvents. J. Polym. Sci. A Polym. Chem. 55, 1021–1030 81 Suana, A. et al. (2011) Single application of low-dose mycophenolate mofetil-OX7immunoliposomes ameliorates experimental mesangial proliferative glomerulonephritis. J. Pharmacol. Exp. Ther. 337, 411–422 82 Shimizu, H. et al. (2010) siRNA-based therapy ameliorates glomerulonephritis. J. Am. Soc. Nephrol. 21, 622–633 83 Bennett, K.M. et al. (2008) MRI of the basement membrane using charged nanoparticles as contrast agents. Magn. Res. Med. 60, 564–574 84 Gao, S. et al. (2014) Megalin-mediated specific uptake of chitosan/siRNA nanoparticles in mouse kidney proximal tubule epithelial cells enables AQP1 gene silencing. Theranostics 4, 1039 85 Zhang, Z. et al. (2009) The targeting of 14-succinate triptolide-lysozyme conjugate to proximal renal tubular epithelial cells. Biomaterials 30, 1372–1381
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86 Prakash, J. et al. (2005) Renal-selective delivery and ACE inhibition by subcutaneously administered captopril-lysozyme. Drug Metab. Dispos. 33, 683–688 87 Oroojalian, F. et al. (2017) Megalin-targeted enhanced transfection efficiency in cultured human HK-2 renal tubular proximal cells using aminoglycosidecarboxyalkyl-polyethylenimine-containing nanoplexes. Int. J. Pharm. 523, 102–120 88 Gandhi, S. and Srinivasan, B. (2018) Effect of garcinol in delaying the progression of diabetic nephropathy. Google Patents2018 89 Chang, C.H. and Chang, C.C. (2018) Method for screening diabetic nephropathy in a subject. Google Patents2018 90 Eriksson, U. et al. (2017) Method of treating diabetic nephropathy by administering antibodies to vascular endothelial growth factor B (VEGF-B). Google Patents2017 91 Granier, C. et al. (2017) Early prediction markers of diabetic nephropathy. Google Patents2017 92 Mitsuhashi, M. and Sharma, K. (2015) Urine exosome mRNAS and methods of using the same to detect diabetic nephropathy. Google Patents2015 93 Zhu, Q. et al. (2015) Pharmaceutical composition for diabetic nephropathy and its preparation and application. Google Patents2015 94 Hara, M. et al. (2012) Method for test on diabetic nephropathy. Google Patents2012 95 Labrie, S.T. et al. (2011) Methods and devices for detecting diabetic nephropathy and associated disorders. Google Patents2011 96 Scheule, R.K. and Chu, Q. (2010) Systemic insulin-like growth factor-1 therapy reduces diabetic peripheral neuropathy and improves renal function in diabetic nephropathy. Google Patents2010 97 Okusa, M.D. et al. (2008) Agonists of A2A adenosine receptors for treatment of diabetic nephropathy. Google Patents2008 98 Laster, M. and Shelach, N. (2008) Methods using glycosaminoglycans for the treatment Q33 of nephropathy. Google Patents2008 99 Flyvbjerg, A. et al. (2005) Diabetic nephropathy therapies. Google Patents2005 100 Tsilibary, P.-E. et al. (2004) Analysis of alpha integrins for the diagnosis of diabetic nephropathy. Google Patents2004
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