- Email: [email protected]
Pushing the envelope in renal preservation
Pushing the Envelope in Renal Preservation: Improved Results With Novel Perfusate Modifications for Pulsatile Machine Perfusion of Cadaver Kidneys J.V. Guarrera, M.M.R. Polyak, B. Arrington, J. Boykin, T. Brown, M.A. Jean-Jacques, S. Kapur, W.T. Stubenbord, and M. Kinkhabwala ABSTRACT Introduction. Novel preservation techniques may diminish ischemia/reperfusion (I/R) injury. Our preservation laboratory has modified Belzer MPS (Trans-med, Elk River, Minn, USA) for machine perfusion (MP) with prostaglandin E1 (PGE 1), nitroglycerin (NTG), and polyethylene glycol-superoxide dismutase (PEG-SOD) to attenuate I/R injury. We reviewed our recent experience using this novel formulation (NF) compared with standard perfusates. Results. Between January 1998 and March 2000, 1060 consecutive kidneys were preserved in our laboratory. One hundred forty-eight kidneys (14%) were discarded. Fifty-eight percent of kidneys during this time period underwent MP (n ⫽ 532). En bloc kidney pairs were randomly assigned to pulsatile MP using Waters RM3 or MOX-100 perfusion systems using 1 of 3 perfusates; NF (NF; n ⫽ 119), Belzer MPS (MPS; n ⫽ 201), or Belzer II albumin gluconate (ALB; n ⫽ 212) Significant improvements in delayed graft function (DGF) rate were seen with NF versus other perfusates (8% vs 14% vs 19%, respectively; P ⫽ .03). At 6 months, graft survival was significantly improved with NF compared with MPS and ALB (96% vs 90% vs 87%, respectively; P ⫽ .03). NF also produced a significantly higher percentage of recipients with a serum creatinine level ⱕ1.5 mg/dL at 6 months posttransplant. Conclusions. Novel modifications of standard MP perfusate improved outcomes after renal transplantation. Preservation-based interventions targeted to ameliorate I/R injury can improve outcomes and may allow expansion of the donor pool.
A
LTHOUGH cadaver organ procurement rates have remained relatively constant during the past decade, the waiting list for kidney transplantation continues to grow,1 resulting in a significant disparity between organ availability and need. Expanding the criteria for donor suitability is one strategy to facilitate access to transplantation, but this strategy entails the need for innovation in organ preservation to optimize graft function. Early graft function is influenced by antigen- independent events, such as ischemia/reperfusion (I/R) injury, which is in turn affected by preservation techniques. Furthermore, early graft function represents an independent predictor of long-term renal graft survival.2,3 I/R injury might be attenuated or even reversed by interventions during preservation. Static cold storage (CS) remains the most common method of preservation worldwide. The benefits of this
technique include simplicity, cost, and reproducibility. Machine perfusion (MP) is an alternative preservation technique in which hypothermic solution is continuously circulated through the kidneys via the renal artery in pulsatile fashion, which mimics the in vivo arterial circulation. MP is believed to stabilize the endothelium and cellular orFrom the New York Presbyterian Hospital Organ Preservation Unit (J.V.G., M.M.R.P., B.A., J.B., T.B., M.A.J.-J., W.T.S.), the Department of Surgery, College of Physicians and Surgeons of Columbia University (J.V.G., M.K.), and Department of Surgery, Weill Medical College of Cornell University, (S.K., W.T.S.), New York, New York. Address reprint requests to James V. Guarrera, MD, New York Presbyterian Hospital, 525 East 68th Street, M507, Box 20, New York, NY 10021. E-mail: [email protected]
© 2004 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/04/$–see front matter doi:10.1016/j.transproceed.2004.04.083
Transplantation Proceedings, 36, 1257–1260 (2004)
1257
1258
GUARRERA, POLYAK, ARRINGTON ET AL Table 1. Novel Formulation (NF) Components
NF Added Component
Class
Mechanism
NTG
Vasodilator
PGE1
Vasodilator
PEG-SOD
Antioxidant
Nitric oxide donor, regulates vasodilatation Vasodilator, renal protective, inhibits neutrophil sequestration, platelet aggregation, membrane stabilizer Long-acting free radical scavenger
Note: NF base solution is identical to Belzer MPS.
ganelles by removing waste products and continuously providing substrates for ATP synthesis.4 The New York local area adopted a multifaceted approach seeking to reducing the high rate of delayed graft function (DGF), including shortening allocation time and introduction of routine preservation by MP in 1993. DGF rates have decreased with these changes in regional practice. Our clinical preservation laboratory has been actively investigating how MP influences decision making in organ use.5 In addition, our efforts have focused on pretransplantation interventions to reverse poor perfusion characteristics, especially in extended criteria donor kidneys. MP has since been demonstrated to improve outcomes among extended criteria donor (ECD) kidneys.5–7 The aim of this study was to analyze the posttransplantation outcomes of kidneys preserved with a modified solution compared with conventional machine perfusates. METHODS All kidneys procured from heart-beating donors between January 1998 and March 2000 were eligible for inclusion after a standard in situ flush and procurement protocol, our regional protocol stipulated preservation of all grafts at a central site using MP as the first choice. Due to allocation or technical factors, some kidneys were not machine-perfused but underwent CS, most commonly due to the presence of an anomalous vasculature, severe atherosclerotic disease, or recovery-related surgical injury. Kidney pairs undergoing MP were randomized in an open label fashion to 1 of 3 perfusate groups. At times, the randomization was dependent on the availability of a given solution. The study groups were: (1) a Novel Formulation (NF): MPS base solution with the additives listed in Table 1; (2) Belzer MPS (MPS); or (3) Belzer II albumin gluconate (ALB).
MP Protocol The kidneys were perfused en bloc (4 – 6°C; 60 beats/min) with IL of assigned perfusate on Mox 100 or RM3 organ perfusion machines (Waters Medical Instruments, Rochester, Minn, United States). These machines provide a fixed pressure, which can be adjusted as needed. Perfusion pressure was kept ⬍60 mm Hg. Kidneys were perfused en bloc using the donor aortic segment whenever possible to minimize intimal damage associated with cannulation and perfusion of a solitary kidney.8
Donor and Recipient Data The data set includes donor age, gender, cause of death, intensive care unit (ICU) length of stay (LOS), final serum creatinine level (SCr), dopamine requirement, intraoperative urine output (U/O), and cold ischemia time (CIT), as well as recipient age, gender, and race. Outcome data were the incidence of DGF, defined as the need for dialysis within the first 7 days posttransplantation, 6-month graft survival, and SCr value. Recipients who were on dialysis were excluded from the 6-month SCr analysis.
Statistical Methods All data expressed as mean values ⫾ SD were analyzed using StatView 5.0.1. statistical software (SAS Inc., Cary, NC, United States) using chi-square, contingency tables, and unpaired Student t test as appropriate. A P value of ⬍ .05 was considered significant.
RESULTS
One thousand sixty kidneys were preserved and 148 kidneys (14%) were discarded during the study period. Reasons for discard included poor donor quality, surgical injury, or serologic data. Three hundred eighty kidneys (41.7%) preserved by CS were not analyzed leaving 532 kidneys (58.3%) that underwent MP and subsequent transplantation. No organs were lost due to MP techniques or equipment failure. Distribution of transplanted kidneys was as follows: NF (n ⫽ 119); MPS (n ⫽ 201); or ALB (n ⫽ 212). All groups were similar in terms of donor characteristics (Table 2) and recipient groups were alike in terms of age, gender, race, and CIT. Statistically significant improvements in both DGF rate and 6-month graft survival (6 mo-GS) were observed with the NF compared with both standard solutions (Table 2). Using Fisher’s Exact Test to compare NF with individual MPS revealed NF to yield a significantly better 6mo-GS (P ⫽ .05) and a trend toward a lower DGF rate (P ⫽ .14). Similarly, NF compared individually with the ALB group showed a significantly lower DGF rate (P ⫽ .01) and improved 6mo-GS (P ⫽ .009). There were no significant differences when control groups were compared with each other (MPS vs ALB). The NF group had significantly improved graft function at 6 months as indicated by a higher percentage of recipients with a SCr level ⱕ1.5 mg/dL compared with both MPS and ALB groups (Table 2). DISCUSSION
Our data reflect a large experience with MP solutions. Our NF of vasodilatory and antioxidant additives significantly improved both DGF and 6mo-GS and function in MP kidneys. Components of our NF target several pathways that are mechanistically important in I/R injury. Prostaglandin E1 (PGE1) is a potent endogenous vasodilator efficacious under hypothermic ex vivo conditions. Reversal of brain death and organ recovery associated vasoconstriction may represent important mechanisms by which NF facilitates immediate posttransplantation graft function. In addition,
RENAL PRESERVATION
1259 Table 2. Donor and Recipient Characteristics of Machine-Perfused Kidneys
Donor variable Age (y) Gender (M:F) ICU LOS (d) Cause of death CVA/stroke (%) Trauma (%) Anoxia (%) Other (%) Donor creatinine (mg/dL) Dopamine (mcg/kg/min) Intraoperative U/O CIT (h) Recipient variable Age (y) Gender (M:F) DGF rate 6-mo creatinine ⱕ1.5 mg/dL ⬎1.5 mg/dL 6-mo graft survival
NF (n ⫽ 119)
MPS (n ⫽ 201)
ALB (n ⫽ 212)
P value
41.1 ⫾ 9.5 59%:41% 3.8 ⫾ 2.4
45.0 ⫾ 12.1 64%:36% 4.0 ⫾ 2.1
39.6 ⫾ 10.1 54%:46% 3.5 ⫾ 2.6
NS NS NS NS
41 28 25 6 0.9 ⫾ 7.8 ⫾ 308 ⫾ 26.1 ⫾
47 24 18 11 1.1 ⫾ 6.9 ⫾ 317 ⫾ 27.2 ⫾
39 36 17 8 1.0 ⫾ 8.2 ⫾ 288 ⫾ 25.4 ⫾
0.5 3.7 87 4.0
0.4 3.2 98 5.3
0.3 4.0 112 5.8
NS NS NS NS
47.0 ⫾ 11.3 52%:48% 8%
46.1 ⫾ 12.2 61%:39% 14%*
45.8 ⫾ 11.8 57%:43% 19%†
NS NS .03
85.7% 14.3% 96%
75.6%‡ 24.4% 90%㛳
72.2%§ 27.8% 87%¶
.02 .03
Abbreviations: M, male; F, female; NS, not significant. *NF vs MPS: P ⫽ .14. † NF vs ALB: P ⫽ .01. ‡ NF vs MPS: P ⫽ .031. § NF vs ALB: P ⫽ .005. 㛳 NF vs MPS: P ⫽ .05. ¶ NF vs ALB: P ⫽ .009.
PGE1-mediated reversal of intragraft vasoconstriction may improve uniform delivery of preservation solution into the microcirculation, reducing the potential for heterogeneous areas of ischemia and microcirculatory “no reflow,” which may be an important mediator of I/R injury. Other PGE1mediated cellular effects include stabilization of cell membranes, inhibition of platelet aggregation, and blockade of neutrophil chemotaxis after reperfusion.9 –12 We have previously reported that PGE1 in conjunction with MP markedly improves early graft function compared with CS. Endothelial-derived nitric oxide (NO) is an endogenous mediator of vasomotor tone. Endothelial cell (EC) injury and dysfunction are proximal events in the I/R cascade associated with hypothermic preservation. EC injury leads to cellular activation with expression of peptides, selectins, and adhesion molecules that initiate an inflammatory response, including platelet aggregation, neutrophil chemotaxis, and lymphocyte migration. Granulocyte degranulation generates locally toxic oxygen free radicals. EC injury produces a relative deficiency of endothelial-derived NO, which regulates microcirculatory vasomotor tone and determines microcirculatory failure (“no reflow”) with heterogeneous reperfusion, often leading to DGF. Pinsky et al13 demonstrated that NO levels decrease sharply after preservation and reperfusion. In our modified solution nitroglycerin (NTG) acts as an NO donor, which has been shown to be beneficial when added to CS solutions in experimental heart and lung preservation.14,15 The inclusion of NTG,
therefore, was designed to preserve microcirculatory tone during reperfusion. Reactive oxygen species (ROS) are produced in a “burst” after reperfusion. ROS may overwhelm endogenous defense mechanisms, initiate free radical chain reactions, and lead to membrane damage promoting programmed cell death. Standard MP and CS preservation solutions are relatively deficient in stable antioxidant capacity. In contrast, superoxide dismutase (SOD), a natural scavenger enzyme, is efficient and stable against oxidants. SOD conjugation to polyethylene glycol (PEG) results in a longeracting antioxidant (PEG-SOD).16 In a rabbit model of renal transplantation, Bennett et al17 demonstrated significant improvement in creatinine clearance when SOD was added to the perfusate, an effect that was enhanced with the PEGSOD form. PEG-SOD has been promising experimentally by improving reperfusion injury in a variety of organs and tissues including heart, liver, and kidney.16 –18 Addition of SOD-PEG to the preservation solution, therefore, may enhance the antioxidant capabilities, potentially combating the “free radical burst” of reperfusion. The NF produced significant improvements in the DGF rate and the 6mo-GS. At 6 months, the proportion of patients with a SCr level ⱕ1.5 mg/dL was significantly greater in the NF group, suggesting excellent quality renal function, as a metric of functional benefit, compared with the control groups. Indeed, Hariharan et al recently re-
1260
ported that a SCr level ⱕ1.5 mg/dL at 1 year posttransplantation predicted improved long-term graft survival.19 Our study is limited by the lack of information on human leukocyte antigen matching, etiology of the recipient renal disease, and variations in immunosuppressive protocols, factors that may have contributed to differences between groups. Although solution groups were randomized, there was a lower number of kidneys in the NF group, due to the lack of availability of necessary additives at various times, a circumstance that was beyond our control. The rate of discarded kidneys was similar in all groups, suggesting that it did not produce a selection bias. DGF substantially increases hospital resource use compared with kidneys that function immediately,20 suggesting the reduction in DGF has substantial implications beyond patient morbidity alone. In summary, novel modifications to Belzer MPS improved outcomes after cadaver renal transplantation. Continued investigations have the potential to further improve results, effectively expanding the donor pool.12 REFERENCES 1. The Organ Procurement and Transplantation Network: Available at: http://www.optn.org. Accessed October 1, 2003 2. Troppmann C, Gillingham KJ, Benedetti E, et al: Delayed graft function, acute rejection and outcome after cadaver renal transplantation. Transplantation 59:962, 1995 3. Cole E, Naimark D, Aprile M, et al: An analysis of predictors of long-term cadaveric renal allograft survival. Clin Transplant 9:282, 1995 4. St. Peter SD, Imber CJ, Friend PJ: Liver and kidney preservation by perfusion. Lancet 359:604,, 2002 5. Polyak MM, Arrington BO, Stubenbord WT, et al: The influence of pulsatile preservation on renal transplantation in the 1990s. Transplantation 69:249, 2000 6. Sellers MT, Gallichio MH, Hudson SL, et al: Improved outcomes in cadaveric renal allografts with pulsatile preservation. Clin Transplant 14:543, 2000
GUARRERA, POLYAK, ARRINGTON ET AL 7. Barber WH, Deierhoi MH, Phillips MG, et al: Preservation by pulsatile perfusion improves early renal allograft function. Transplant Proc 20:865, 1988 8. Oakes DD, Spees EK, Light JA, et al: Renal perfusion preservation without cannulation. Prevention of posttransplant renal artery stenosis. Arch Surg 113:654, 1978 9. Polyak MMR, Arrington B, Stubenbord WT, et al: Prostaglandin E1 influences pulsatile preservation characteristics and early graft function in expanded criteria donor kidneys. J Surg Res 85:17, 1999 10. Schlondorff D, Yoo P, Alpert BE: Stimulation of adenylate cyclase in isolated rat glomeruli by prostaglandins. Am J Physiol 235:F458, 1978 11. Oltoff K, Evette W, Seu P, et al: PGE1 reduces injury to hepatic allografts following preservation. J Surg Res 50:595, 1991 12. Fantone JC, Kimes DA: Prostaglandin E1 and prostaglandin 12 modulation of superoxide production by human neutrophils. Biochem Biophys Res Comm 113:506, 1983 13. Pinsky DJ, Naka Y, Chowdhury NC, et al: The nitric oxide/cyclic GMP pathway in organ transplantation: critical role in successful lung preservation. Proc Natl Acad Sci U S A 91:12086, 1994 14. Bhabra MS, Hopkinson DN, Shaw TE, et al: Relative importance of prostaglandin/cyclic adenosine monophosphate and nitric oxide/cyclic guanosine monophosphate pathways in lung preservation. Ann Thorac Surg 62:1494, 1996 15. Baxter K, Howden BO, Jablonski P: Heart preservation with celsior solution improved by the addition of nitroglycerine. Transplantation 71:1380, 2001 16. Veronese FM, Caliceti P, Schiavon O, et al: Polyethylene glycol-superoxide dismutase, a conjugate in search of exploitation. Adv Drug Deliv Rev 54:587, 2002 17. Bennett JF, Bry WI, Collins GM, et al: The effects of oxygen free radicals on the preserved kidney. Cryobiology 24:264, 1987 18. Kanamasa K, Ishida N, Ishikawa K: Protective effect of PEG-SOD against early coronary reperfusion injury assessed in reperfused and non-reperfused ischemic areas of the same heart. Acta Cardiol 56:181, 2001 19. Hariharan S, McBride MA, Cherikh WS, et al: Post-transplant renal function in the first year predicts long-term kidney transplant survival. Kidney Int 62:311, 2002 20. Rosenthal JT, Danovitch GM, Wilkinson A, et al: The high cost of delayed graft function in cadaveric renal transplantation. Transplantation 51:1115, 1991
A
LTHOUGH cadaver organ procurement rates have remained relatively constant during the past decade, the waiting list for kidney transplantation continues to grow,1 resulting in a significant disparity between organ availability and need. Expanding the criteria for donor suitability is one strategy to facilitate access to transplantation, but this strategy entails the need for innovation in organ preservation to optimize graft function. Early graft function is influenced by antigen- independent events, such as ischemia/reperfusion (I/R) injury, which is in turn affected by preservation techniques. Furthermore, early graft function represents an independent predictor of long-term renal graft survival.2,3 I/R injury might be attenuated or even reversed by interventions during preservation. Static cold storage (CS) remains the most common method of preservation worldwide. The benefits of this
technique include simplicity, cost, and reproducibility. Machine perfusion (MP) is an alternative preservation technique in which hypothermic solution is continuously circulated through the kidneys via the renal artery in pulsatile fashion, which mimics the in vivo arterial circulation. MP is believed to stabilize the endothelium and cellular orFrom the New York Presbyterian Hospital Organ Preservation Unit (J.V.G., M.M.R.P., B.A., J.B., T.B., M.A.J.-J., W.T.S.), the Department of Surgery, College of Physicians and Surgeons of Columbia University (J.V.G., M.K.), and Department of Surgery, Weill Medical College of Cornell University, (S.K., W.T.S.), New York, New York. Address reprint requests to James V. Guarrera, MD, New York Presbyterian Hospital, 525 East 68th Street, M507, Box 20, New York, NY 10021. E-mail: [email protected]
© 2004 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/04/$–see front matter doi:10.1016/j.transproceed.2004.04.083
Transplantation Proceedings, 36, 1257–1260 (2004)
1257
1258
GUARRERA, POLYAK, ARRINGTON ET AL Table 1. Novel Formulation (NF) Components
NF Added Component
Class
Mechanism
NTG
Vasodilator
PGE1
Vasodilator
PEG-SOD
Antioxidant
Nitric oxide donor, regulates vasodilatation Vasodilator, renal protective, inhibits neutrophil sequestration, platelet aggregation, membrane stabilizer Long-acting free radical scavenger
Note: NF base solution is identical to Belzer MPS.
ganelles by removing waste products and continuously providing substrates for ATP synthesis.4 The New York local area adopted a multifaceted approach seeking to reducing the high rate of delayed graft function (DGF), including shortening allocation time and introduction of routine preservation by MP in 1993. DGF rates have decreased with these changes in regional practice. Our clinical preservation laboratory has been actively investigating how MP influences decision making in organ use.5 In addition, our efforts have focused on pretransplantation interventions to reverse poor perfusion characteristics, especially in extended criteria donor kidneys. MP has since been demonstrated to improve outcomes among extended criteria donor (ECD) kidneys.5–7 The aim of this study was to analyze the posttransplantation outcomes of kidneys preserved with a modified solution compared with conventional machine perfusates. METHODS All kidneys procured from heart-beating donors between January 1998 and March 2000 were eligible for inclusion after a standard in situ flush and procurement protocol, our regional protocol stipulated preservation of all grafts at a central site using MP as the first choice. Due to allocation or technical factors, some kidneys were not machine-perfused but underwent CS, most commonly due to the presence of an anomalous vasculature, severe atherosclerotic disease, or recovery-related surgical injury. Kidney pairs undergoing MP were randomized in an open label fashion to 1 of 3 perfusate groups. At times, the randomization was dependent on the availability of a given solution. The study groups were: (1) a Novel Formulation (NF): MPS base solution with the additives listed in Table 1; (2) Belzer MPS (MPS); or (3) Belzer II albumin gluconate (ALB).
MP Protocol The kidneys were perfused en bloc (4 – 6°C; 60 beats/min) with IL of assigned perfusate on Mox 100 or RM3 organ perfusion machines (Waters Medical Instruments, Rochester, Minn, United States). These machines provide a fixed pressure, which can be adjusted as needed. Perfusion pressure was kept ⬍60 mm Hg. Kidneys were perfused en bloc using the donor aortic segment whenever possible to minimize intimal damage associated with cannulation and perfusion of a solitary kidney.8
Donor and Recipient Data The data set includes donor age, gender, cause of death, intensive care unit (ICU) length of stay (LOS), final serum creatinine level (SCr), dopamine requirement, intraoperative urine output (U/O), and cold ischemia time (CIT), as well as recipient age, gender, and race. Outcome data were the incidence of DGF, defined as the need for dialysis within the first 7 days posttransplantation, 6-month graft survival, and SCr value. Recipients who were on dialysis were excluded from the 6-month SCr analysis.
Statistical Methods All data expressed as mean values ⫾ SD were analyzed using StatView 5.0.1. statistical software (SAS Inc., Cary, NC, United States) using chi-square, contingency tables, and unpaired Student t test as appropriate. A P value of ⬍ .05 was considered significant.
RESULTS
One thousand sixty kidneys were preserved and 148 kidneys (14%) were discarded during the study period. Reasons for discard included poor donor quality, surgical injury, or serologic data. Three hundred eighty kidneys (41.7%) preserved by CS were not analyzed leaving 532 kidneys (58.3%) that underwent MP and subsequent transplantation. No organs were lost due to MP techniques or equipment failure. Distribution of transplanted kidneys was as follows: NF (n ⫽ 119); MPS (n ⫽ 201); or ALB (n ⫽ 212). All groups were similar in terms of donor characteristics (Table 2) and recipient groups were alike in terms of age, gender, race, and CIT. Statistically significant improvements in both DGF rate and 6-month graft survival (6 mo-GS) were observed with the NF compared with both standard solutions (Table 2). Using Fisher’s Exact Test to compare NF with individual MPS revealed NF to yield a significantly better 6mo-GS (P ⫽ .05) and a trend toward a lower DGF rate (P ⫽ .14). Similarly, NF compared individually with the ALB group showed a significantly lower DGF rate (P ⫽ .01) and improved 6mo-GS (P ⫽ .009). There were no significant differences when control groups were compared with each other (MPS vs ALB). The NF group had significantly improved graft function at 6 months as indicated by a higher percentage of recipients with a SCr level ⱕ1.5 mg/dL compared with both MPS and ALB groups (Table 2). DISCUSSION
Our data reflect a large experience with MP solutions. Our NF of vasodilatory and antioxidant additives significantly improved both DGF and 6mo-GS and function in MP kidneys. Components of our NF target several pathways that are mechanistically important in I/R injury. Prostaglandin E1 (PGE1) is a potent endogenous vasodilator efficacious under hypothermic ex vivo conditions. Reversal of brain death and organ recovery associated vasoconstriction may represent important mechanisms by which NF facilitates immediate posttransplantation graft function. In addition,
RENAL PRESERVATION
1259 Table 2. Donor and Recipient Characteristics of Machine-Perfused Kidneys
Donor variable Age (y) Gender (M:F) ICU LOS (d) Cause of death CVA/stroke (%) Trauma (%) Anoxia (%) Other (%) Donor creatinine (mg/dL) Dopamine (mcg/kg/min) Intraoperative U/O CIT (h) Recipient variable Age (y) Gender (M:F) DGF rate 6-mo creatinine ⱕ1.5 mg/dL ⬎1.5 mg/dL 6-mo graft survival
NF (n ⫽ 119)
MPS (n ⫽ 201)
ALB (n ⫽ 212)
P value
41.1 ⫾ 9.5 59%:41% 3.8 ⫾ 2.4
45.0 ⫾ 12.1 64%:36% 4.0 ⫾ 2.1
39.6 ⫾ 10.1 54%:46% 3.5 ⫾ 2.6
NS NS NS NS
41 28 25 6 0.9 ⫾ 7.8 ⫾ 308 ⫾ 26.1 ⫾
47 24 18 11 1.1 ⫾ 6.9 ⫾ 317 ⫾ 27.2 ⫾
39 36 17 8 1.0 ⫾ 8.2 ⫾ 288 ⫾ 25.4 ⫾
0.5 3.7 87 4.0
0.4 3.2 98 5.3
0.3 4.0 112 5.8
NS NS NS NS
47.0 ⫾ 11.3 52%:48% 8%
46.1 ⫾ 12.2 61%:39% 14%*
45.8 ⫾ 11.8 57%:43% 19%†
NS NS .03
85.7% 14.3% 96%
75.6%‡ 24.4% 90%㛳
72.2%§ 27.8% 87%¶
.02 .03
Abbreviations: M, male; F, female; NS, not significant. *NF vs MPS: P ⫽ .14. † NF vs ALB: P ⫽ .01. ‡ NF vs MPS: P ⫽ .031. § NF vs ALB: P ⫽ .005. 㛳 NF vs MPS: P ⫽ .05. ¶ NF vs ALB: P ⫽ .009.
PGE1-mediated reversal of intragraft vasoconstriction may improve uniform delivery of preservation solution into the microcirculation, reducing the potential for heterogeneous areas of ischemia and microcirculatory “no reflow,” which may be an important mediator of I/R injury. Other PGE1mediated cellular effects include stabilization of cell membranes, inhibition of platelet aggregation, and blockade of neutrophil chemotaxis after reperfusion.9 –12 We have previously reported that PGE1 in conjunction with MP markedly improves early graft function compared with CS. Endothelial-derived nitric oxide (NO) is an endogenous mediator of vasomotor tone. Endothelial cell (EC) injury and dysfunction are proximal events in the I/R cascade associated with hypothermic preservation. EC injury leads to cellular activation with expression of peptides, selectins, and adhesion molecules that initiate an inflammatory response, including platelet aggregation, neutrophil chemotaxis, and lymphocyte migration. Granulocyte degranulation generates locally toxic oxygen free radicals. EC injury produces a relative deficiency of endothelial-derived NO, which regulates microcirculatory vasomotor tone and determines microcirculatory failure (“no reflow”) with heterogeneous reperfusion, often leading to DGF. Pinsky et al13 demonstrated that NO levels decrease sharply after preservation and reperfusion. In our modified solution nitroglycerin (NTG) acts as an NO donor, which has been shown to be beneficial when added to CS solutions in experimental heart and lung preservation.14,15 The inclusion of NTG,
therefore, was designed to preserve microcirculatory tone during reperfusion. Reactive oxygen species (ROS) are produced in a “burst” after reperfusion. ROS may overwhelm endogenous defense mechanisms, initiate free radical chain reactions, and lead to membrane damage promoting programmed cell death. Standard MP and CS preservation solutions are relatively deficient in stable antioxidant capacity. In contrast, superoxide dismutase (SOD), a natural scavenger enzyme, is efficient and stable against oxidants. SOD conjugation to polyethylene glycol (PEG) results in a longeracting antioxidant (PEG-SOD).16 In a rabbit model of renal transplantation, Bennett et al17 demonstrated significant improvement in creatinine clearance when SOD was added to the perfusate, an effect that was enhanced with the PEGSOD form. PEG-SOD has been promising experimentally by improving reperfusion injury in a variety of organs and tissues including heart, liver, and kidney.16 –18 Addition of SOD-PEG to the preservation solution, therefore, may enhance the antioxidant capabilities, potentially combating the “free radical burst” of reperfusion. The NF produced significant improvements in the DGF rate and the 6mo-GS. At 6 months, the proportion of patients with a SCr level ⱕ1.5 mg/dL was significantly greater in the NF group, suggesting excellent quality renal function, as a metric of functional benefit, compared with the control groups. Indeed, Hariharan et al recently re-
1260
ported that a SCr level ⱕ1.5 mg/dL at 1 year posttransplantation predicted improved long-term graft survival.19 Our study is limited by the lack of information on human leukocyte antigen matching, etiology of the recipient renal disease, and variations in immunosuppressive protocols, factors that may have contributed to differences between groups. Although solution groups were randomized, there was a lower number of kidneys in the NF group, due to the lack of availability of necessary additives at various times, a circumstance that was beyond our control. The rate of discarded kidneys was similar in all groups, suggesting that it did not produce a selection bias. DGF substantially increases hospital resource use compared with kidneys that function immediately,20 suggesting the reduction in DGF has substantial implications beyond patient morbidity alone. In summary, novel modifications to Belzer MPS improved outcomes after cadaver renal transplantation. Continued investigations have the potential to further improve results, effectively expanding the donor pool.12 REFERENCES 1. The Organ Procurement and Transplantation Network: Available at: http://www.optn.org. Accessed October 1, 2003 2. Troppmann C, Gillingham KJ, Benedetti E, et al: Delayed graft function, acute rejection and outcome after cadaver renal transplantation. Transplantation 59:962, 1995 3. Cole E, Naimark D, Aprile M, et al: An analysis of predictors of long-term cadaveric renal allograft survival. Clin Transplant 9:282, 1995 4. St. Peter SD, Imber CJ, Friend PJ: Liver and kidney preservation by perfusion. Lancet 359:604,, 2002 5. Polyak MM, Arrington BO, Stubenbord WT, et al: The influence of pulsatile preservation on renal transplantation in the 1990s. Transplantation 69:249, 2000 6. Sellers MT, Gallichio MH, Hudson SL, et al: Improved outcomes in cadaveric renal allografts with pulsatile preservation. Clin Transplant 14:543, 2000
GUARRERA, POLYAK, ARRINGTON ET AL 7. Barber WH, Deierhoi MH, Phillips MG, et al: Preservation by pulsatile perfusion improves early renal allograft function. Transplant Proc 20:865, 1988 8. Oakes DD, Spees EK, Light JA, et al: Renal perfusion preservation without cannulation. Prevention of posttransplant renal artery stenosis. Arch Surg 113:654, 1978 9. Polyak MMR, Arrington B, Stubenbord WT, et al: Prostaglandin E1 influences pulsatile preservation characteristics and early graft function in expanded criteria donor kidneys. J Surg Res 85:17, 1999 10. Schlondorff D, Yoo P, Alpert BE: Stimulation of adenylate cyclase in isolated rat glomeruli by prostaglandins. Am J Physiol 235:F458, 1978 11. Oltoff K, Evette W, Seu P, et al: PGE1 reduces injury to hepatic allografts following preservation. J Surg Res 50:595, 1991 12. Fantone JC, Kimes DA: Prostaglandin E1 and prostaglandin 12 modulation of superoxide production by human neutrophils. Biochem Biophys Res Comm 113:506, 1983 13. Pinsky DJ, Naka Y, Chowdhury NC, et al: The nitric oxide/cyclic GMP pathway in organ transplantation: critical role in successful lung preservation. Proc Natl Acad Sci U S A 91:12086, 1994 14. Bhabra MS, Hopkinson DN, Shaw TE, et al: Relative importance of prostaglandin/cyclic adenosine monophosphate and nitric oxide/cyclic guanosine monophosphate pathways in lung preservation. Ann Thorac Surg 62:1494, 1996 15. Baxter K, Howden BO, Jablonski P: Heart preservation with celsior solution improved by the addition of nitroglycerine. Transplantation 71:1380, 2001 16. Veronese FM, Caliceti P, Schiavon O, et al: Polyethylene glycol-superoxide dismutase, a conjugate in search of exploitation. Adv Drug Deliv Rev 54:587, 2002 17. Bennett JF, Bry WI, Collins GM, et al: The effects of oxygen free radicals on the preserved kidney. Cryobiology 24:264, 1987 18. Kanamasa K, Ishida N, Ishikawa K: Protective effect of PEG-SOD against early coronary reperfusion injury assessed in reperfused and non-reperfused ischemic areas of the same heart. Acta Cardiol 56:181, 2001 19. Hariharan S, McBride MA, Cherikh WS, et al: Post-transplant renal function in the first year predicts long-term kidney transplant survival. Kidney Int 62:311, 2002 20. Rosenthal JT, Danovitch GM, Wilkinson A, et al: The high cost of delayed graft function in cadaveric renal transplantation. Transplantation 51:1115, 1991