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Specific in vivo detection of amyloid plaques in transgenic mice using bifunctional USPIO nanoparticles
P156
Poster Presentations: P1
Recent studies showed that synaptic Ab can further cause distal axonopathy and neurodegeneration leading to neuronal loss. We explored an in vivo setup to demonstrate the synaptic Ab to cause pre-synaptic axonal degeneration. Methods: Ab1-42 (4 n mole, N ¼ 6) or saline (N ¼ 6) were injected at the right optic tract axonal terminals in 12-week-old C57BL/6 mice. In 1 and 3 months after Ab injection, mice were placed in a Bruker 4.7T small animal MRI for Diffusion Tensor Imaging (DTI) with slice thickness 0.5 mm, field of view of 2cm x 2cm and matrix 128 x 128 (zero filling to 256 x 256) to cover the visual system from eyes to superior colliculus. Animals were then sacrificed. The optic tract and nerve were examined using a primary antibody against phosphorylated neurofilament (pNF, SMI-31) and myelin basic protein (MBP). Results: In optic tract, the Ab-injected side (right side) of the tracts showed a 12-16% decrease of axial diffusivity (P<0.05) in 1-3 months. As for optic nerves, DTI did not change until 3 months with a significant 13% reduction of Tr (P<0.05) in the left nerves. Immunohistochemistry showed a 30% loss of SMI-31 axonal counts in the right optic tract suggesting axonal damage. Conclusions: This is the first study demonstrated distal axonal damage in vivo induced by an exposure of axonal terminal to Ab. We used the unique anatomical feature of retinal ganglion cells with their cell bodies in the eye but the elongated axons reaching to the middle of the brain. Injecting Ab in the axonal terminals caused optic tract axonal damage in 1-3 months detected by DTI, confirmed by immunohistochemistry. This finding has significant clinical impact as to use DTI for diagnosis of AD and evaluation of the treatment.
P1-143
SPECIFIC IN VIVO DETECTION OF AMYLOID PLAQUES IN TRANSGENIC MICE USING BIFUNCTIONAL USPIO NANOPARTICLES
Thomas Wisniewski1, Jialin Li2, Dung Minh Hoang2, Hong Xu3, Yanjie Sun2, Andrew Wang3, Youssef Zaim Wadghiri2, 1New York University School of Medicine, New York, New York, United States; 2NYU School of Medicine, New York, New York, United States; 3Ocean NanoTech, Springdale, Arkansas, United States. Background: Amyloid plaques are a key pathological hallmark of Alzheimer’s disease (AD). Their visualization is important for the diagnosis of AD, monitoring disease progression and evaluation of the efficacy of therapeutic interventions. We were the first group to use ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles coupled to an amyloid targeting peptide to visualize amyloid plaques. USPIO’s have been widely used in animal and human imaging, and have been found to be very safe. However, our approach, so far, has required intra-carotid or intra-femoral injection, with mannitol to break the blood brain barrier (BBB). In the current study we sought to develop and test non-toxic, bifunctional USPIO particles which could be introduced via the femoral vein, without mannitol. Methods: 13 to 18 month old APP/PS1 transgenic mice and age-matched wild-type (C57Bl/6J) control mice were used. The USPIO nanoparticles were linked to Ab1-42 (targeting to amyloid plaques) and polyethyleneglycol (PEG, to increase BBB permeability), using EDC/NHS coupling methods. The potential neurotoxicity of USPIO-PEG-Ab42 was assessed in N2a cells using a MTS Assay. MRI scans were performed on a 7T micro-MRI system consisting of a 7-Telsa 200-mm horizontal bore magnet. All mice were scanned 6-hrs after iv injection (0.2 mmol Fe/kg body weight) of the USPIO-PEG-Ab42. Ex vivo imaging of mouse brains was also performed. Serial coronal sections were subject to anti-Ab immunohistochemistry and Perl staining to identify the USPIO. Results: The USPIO particles were non-toxic. Figure 1A shows m MRI and matching histology in an APP/ PS1 Tg mouse and wild type mouse injected with USPIO-PEG-Ab. Numerous dark spots are evident in 1A. To the right of 1A is a higher magnification of an area of the MRI which is matched to double Perl and Ab stain in figure 1B. A coronal section matching to 1A is seen in 1C. In 1D the blue areas point to Perl stain positive dots corresponding to USPIO particles while the red arrow points to the amyloid plaque. 1E shows a wild-type mouse injected with USPIO-PEG-Ab. 1F documents the lack of plaques in the WT
mouse. Conclusions: Our non-toxic, non-invasive m MRI method has great potential for the longitudinal assessment of amyloid burden.
P1-144
DOSE-DEPENDENT EFFECTS OF SMALL-VESSEL DISEASE MRI MARKERS ON REGIONAL CORTICAL THINNING AND STRUCTURAL CONNECTIVITY
Byoung Seok Ye1, Geon Ha Kim1, Hanna Cho2, Young Noh1, Duk L. Na3, Sang Won Seo3, 1Samsung Medical Center, Seoul, South Korea; 2Samsung Medical Center, Seoul, South Korea; 3Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea. Background: MRI markers of cerebral small vessel disease including white matter hyperintensities (WMH), lacunes, and microbleeds are related to cognitive dysfunction in subjects with vascular cognitive impairment (VCI). Previous studies have usually focused on the location of these vascular markers and did not consider the concomitant effect by Alzheimer’s disease (AD) pathology. In this study, we aimed to find dose-dependent effects of these MRI markers on regional cortical thinning and white matter tract damage in VCI patients, considering the effect by concomitant AD pathology. Methods: Participants consisted of 65 patients with mild cognitive impairment associated with small-vessel disease (svMCI) and 69 with subcortical vascular dementia (SVaD). Conventional brain MRI scans, diffusion tensor imaging (DTI), and PIB PET were performed. WMH, lacunes, microbleeds, and PIB retention amount were measured. Multiple regression analyses were used to elucidate the relationship between regional cortical thickness, DTI abnormalities, and each small vessel vascular marker, adjusting the effects by demographic factors and PIB retention amount. Results: Higher WMH volume was associated with cortical thinning in bilateral cingulate cortices, right insular cortex, and left lingual gyrus. More lacunes were associated with cortical thinning in the right medial and superior frontal gyrus, and left superior temporal gyrus. Microbleeds were not related with regional cortical thinning. Higher PIB retention was associated with cortical thinning in left medial temporal lobe. Independent of other vascular markers and PIB retention amount, larger WMH volume was associated with decreased fractional anisotropy (FA) in widespread periventricular white matter
Poster Presentations: P1
Recent studies showed that synaptic Ab can further cause distal axonopathy and neurodegeneration leading to neuronal loss. We explored an in vivo setup to demonstrate the synaptic Ab to cause pre-synaptic axonal degeneration. Methods: Ab1-42 (4 n mole, N ¼ 6) or saline (N ¼ 6) were injected at the right optic tract axonal terminals in 12-week-old C57BL/6 mice. In 1 and 3 months after Ab injection, mice were placed in a Bruker 4.7T small animal MRI for Diffusion Tensor Imaging (DTI) with slice thickness 0.5 mm, field of view of 2cm x 2cm and matrix 128 x 128 (zero filling to 256 x 256) to cover the visual system from eyes to superior colliculus. Animals were then sacrificed. The optic tract and nerve were examined using a primary antibody against phosphorylated neurofilament (pNF, SMI-31) and myelin basic protein (MBP). Results: In optic tract, the Ab-injected side (right side) of the tracts showed a 12-16% decrease of axial diffusivity (P<0.05) in 1-3 months. As for optic nerves, DTI did not change until 3 months with a significant 13% reduction of Tr (P<0.05) in the left nerves. Immunohistochemistry showed a 30% loss of SMI-31 axonal counts in the right optic tract suggesting axonal damage. Conclusions: This is the first study demonstrated distal axonal damage in vivo induced by an exposure of axonal terminal to Ab. We used the unique anatomical feature of retinal ganglion cells with their cell bodies in the eye but the elongated axons reaching to the middle of the brain. Injecting Ab in the axonal terminals caused optic tract axonal damage in 1-3 months detected by DTI, confirmed by immunohistochemistry. This finding has significant clinical impact as to use DTI for diagnosis of AD and evaluation of the treatment.
P1-143
SPECIFIC IN VIVO DETECTION OF AMYLOID PLAQUES IN TRANSGENIC MICE USING BIFUNCTIONAL USPIO NANOPARTICLES
Thomas Wisniewski1, Jialin Li2, Dung Minh Hoang2, Hong Xu3, Yanjie Sun2, Andrew Wang3, Youssef Zaim Wadghiri2, 1New York University School of Medicine, New York, New York, United States; 2NYU School of Medicine, New York, New York, United States; 3Ocean NanoTech, Springdale, Arkansas, United States. Background: Amyloid plaques are a key pathological hallmark of Alzheimer’s disease (AD). Their visualization is important for the diagnosis of AD, monitoring disease progression and evaluation of the efficacy of therapeutic interventions. We were the first group to use ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles coupled to an amyloid targeting peptide to visualize amyloid plaques. USPIO’s have been widely used in animal and human imaging, and have been found to be very safe. However, our approach, so far, has required intra-carotid or intra-femoral injection, with mannitol to break the blood brain barrier (BBB). In the current study we sought to develop and test non-toxic, bifunctional USPIO particles which could be introduced via the femoral vein, without mannitol. Methods: 13 to 18 month old APP/PS1 transgenic mice and age-matched wild-type (C57Bl/6J) control mice were used. The USPIO nanoparticles were linked to Ab1-42 (targeting to amyloid plaques) and polyethyleneglycol (PEG, to increase BBB permeability), using EDC/NHS coupling methods. The potential neurotoxicity of USPIO-PEG-Ab42 was assessed in N2a cells using a MTS Assay. MRI scans were performed on a 7T micro-MRI system consisting of a 7-Telsa 200-mm horizontal bore magnet. All mice were scanned 6-hrs after iv injection (0.2 mmol Fe/kg body weight) of the USPIO-PEG-Ab42. Ex vivo imaging of mouse brains was also performed. Serial coronal sections were subject to anti-Ab immunohistochemistry and Perl staining to identify the USPIO. Results: The USPIO particles were non-toxic. Figure 1A shows m MRI and matching histology in an APP/ PS1 Tg mouse and wild type mouse injected with USPIO-PEG-Ab. Numerous dark spots are evident in 1A. To the right of 1A is a higher magnification of an area of the MRI which is matched to double Perl and Ab stain in figure 1B. A coronal section matching to 1A is seen in 1C. In 1D the blue areas point to Perl stain positive dots corresponding to USPIO particles while the red arrow points to the amyloid plaque. 1E shows a wild-type mouse injected with USPIO-PEG-Ab. 1F documents the lack of plaques in the WT
mouse. Conclusions: Our non-toxic, non-invasive m MRI method has great potential for the longitudinal assessment of amyloid burden.
P1-144
DOSE-DEPENDENT EFFECTS OF SMALL-VESSEL DISEASE MRI MARKERS ON REGIONAL CORTICAL THINNING AND STRUCTURAL CONNECTIVITY
Byoung Seok Ye1, Geon Ha Kim1, Hanna Cho2, Young Noh1, Duk L. Na3, Sang Won Seo3, 1Samsung Medical Center, Seoul, South Korea; 2Samsung Medical Center, Seoul, South Korea; 3Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea. Background: MRI markers of cerebral small vessel disease including white matter hyperintensities (WMH), lacunes, and microbleeds are related to cognitive dysfunction in subjects with vascular cognitive impairment (VCI). Previous studies have usually focused on the location of these vascular markers and did not consider the concomitant effect by Alzheimer’s disease (AD) pathology. In this study, we aimed to find dose-dependent effects of these MRI markers on regional cortical thinning and white matter tract damage in VCI patients, considering the effect by concomitant AD pathology. Methods: Participants consisted of 65 patients with mild cognitive impairment associated with small-vessel disease (svMCI) and 69 with subcortical vascular dementia (SVaD). Conventional brain MRI scans, diffusion tensor imaging (DTI), and PIB PET were performed. WMH, lacunes, microbleeds, and PIB retention amount were measured. Multiple regression analyses were used to elucidate the relationship between regional cortical thickness, DTI abnormalities, and each small vessel vascular marker, adjusting the effects by demographic factors and PIB retention amount. Results: Higher WMH volume was associated with cortical thinning in bilateral cingulate cortices, right insular cortex, and left lingual gyrus. More lacunes were associated with cortical thinning in the right medial and superior frontal gyrus, and left superior temporal gyrus. Microbleeds were not related with regional cortical thinning. Higher PIB retention was associated with cortical thinning in left medial temporal lobe. Independent of other vascular markers and PIB retention amount, larger WMH volume was associated with decreased fractional anisotropy (FA) in widespread periventricular white matter