Vessel Painting Research Articles

Characterization of brain metabolism, volume, and vasculature of the 5xFAD mouse model of Alzheimer’s Disease across lifespan.

AbstractBackgroundThe MODEL‐AD Consortium seeks to develop the next generation of Alzheimer’s Disease models based on human data. A popular model of familial AD is the 5xFAD mouse, characterized by early amyloid‐β deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic features over its lifespan.MethodMale and female 5xFAD and WT littermates underwent in vivo 18F‐FDG‐PET imaging at 4, 6, and 12 months of age to evaluate regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent “vessel painting” that labels all cerebral vessels with a fluorescent dye. “Vessel painted” brains were analyzed for vascular characteristics such as vessel density, junction density, vessel length, network complexity, number of collaterals and vessel diameter.ResultsOur analyses revealed that vessel length, vessel and junction densities increased from 4 to 12 months on the cortical surface in both 5xFAD and WT mice. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but their diameters were significantly increased only in 5xFAD mice. MCA average vessel length was decreased in 5xFAD mice compared to WT. Analysis of 18F‐FDG cortical uptake found significant interactions between WT and 5xFAD mice spanning 4‐12 months of age in retrosplenial, somatosensory and visual cortices. Broadly, 5xFAD males had increased 18F‐FDG uptake at 12 months of age compared to WT mice. In most cortical regions, female 5xFAD mice had reduced FDG uptake compared to WT across the lifespan. In males these metabolic increases coincided with decreased vessel characteristics.ConclusionThe 5xFAD mouse exhibits AD‐like cognitive deficits with age that are associated with increasing amyloid‐β deposition. No significant differences were found in cortical vascular features although males and females exhibited opposite effects in 18F‐FDG uptake. The MCA supplies blood to large portions of the motor cortex and increased vessel lengths and decreased collaterals along with higher metabolic rates in 5xFAD mice may be related to increasing behavioral deficits via metabolic insufficiency or other mechanisms.

Characterization of brain metabolism, volume, and vasculature of the 5xFAD mouse model of Alzheimer’s Disease across lifespan

AbstractBackgroundThe MODEL‐AD Consortium seeks to develop the next generation of Alzheimer’s Disease models based on human data. A popular model of familial AD is the 5xFAD mouse, characterized by early amyloid‐ß deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic features over its lifespan.MethodMale and female 5xFAD and WT littermates underwent in vivo 18F‐FDG‐PET imaging at 4, 6, and 12 months of age to evaluate regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent “vessel painting” that labels all cerebral vessels with a fluorescent dye. “Vessel painted” brains were analyzed for vascular characteristics such as vessel density, junction density, vessel length, network complexity, number of collaterals and vessel diameter.ResultOur analyses revealed that vessel length, vessel and junction densities increased from 4 to 12 months on the cortical surface in both 5xFAD and WT mice. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but their diameters were significantly increased only in 5xFAD mice. MCA average vessel length was decreased in 5xFAD mice compared to WT. Analysis of 18F‐FDG cortical uptake found significant interactions between WT and 5xFAD mice spanning 4‐12 months of age in retrosplenial, somatosensory and visual cortices. Broadly, 5xFAD males had increased 18F‐FDG uptake at 12 months of age compared to WT mice. In most cortical regions, female 5xFAD mice had reduced FDG uptake compared to WT across the lifespan. In males these metabolic increases coincided with decreased vessel characteristics.ConclusionThe 5xFAD mouse exhibits AD‐like cognitive deficits with age that are associated with increasing amyloid‐ß deposition. No significant differences were found in cortical vascular features although males and females exhibited opposite effects in 18F‐FDG uptake. The MCA supplies blood to large portions of the motor cortex and increased vessel lengths and decreased collaterals along with higher metabolic rates in 5xFAD mice may be related to increasing behavioral deficits via metabolic insufficiency or other mechanisms.

Neuroimaging of new and novel Alzheimer’s Disease (AD) mice from the MODEL AD Consortium

AbstractBackgroundThe ability of preclinical neuroimaging in rodent models of Alzheimer’s Disease and Related Dementia (ADRD) to assess the progression of disease is increasingly providing novel insights into AD, like human AD imaging. Preclinical studies have the advantage of being able to directly correlate findings to the observed neuropathology. Recently, University of California Irvine and Indiana University School of Medicine along with Jackson Laboratories were awarded funding to design and phenotype relevant mouse models of late onset AD (LOAD), forming the MODEL AD consortium (https://www.model‐ad.org/). Imaging cores from these will utilize existing state of the art translationally relevant medical imaging methodologies as well as ascertain feasibility of emerging imaging methods for increased diagnostic sensitivity.MethodsTwo primary imaging modalities will be utilized: high‐field MRI (9.4T and 17.6T) and PET/CT. Deep MRI phenotyping are based on the accepted human‐AD standards like ADNI (Structural T2W, FLAIR, diffusion, perfusion (PWI), susceptibility, and functional MRI and MR spectroscopy). Novel histological vessel painting combined with PWI will assess vascular modifications. PET imaging will evaluate brain metabolism (18F‐FDG), regional perfusion (64Cu‐PTSM), amyloid (18F‐AV45), tau (18F‐AV1451), neuroinflammation (18F‐CPPC and 18F‐GSK1482160), and astrogliosis (18F‐FEBU) markers in new mouse models.ResultsMODEL AD consortia will utilize platform mice (Table 1) across their lifespans and effects after being fed a high fat diet. Known and emerging GWAS risk variants for AD will be added to these platform mice to better replicate human AD. Neuroimaging data will be presented from PET/CT and MRI, focusing on exemplars from relevant AD mouse models including platform mice. A long‐term goal of the MODEL‐AD Imaging cores is to co‐register MRI, PET/CT and vascular measures to concordant histopathological and spatial RNA data. The cores have developed state‐of‐the‐art analytical pipelines to process imaging data to support spatial and temporal localization of ADRD.ConclusionsThe MODEL AD consortium (UCI/IUSM/Jax) will develop new and novel AD mouse models and the imaging cores will deeply phenotype these models using existing and emerging neuroimaging methods and analytic approaches, using MRI and PET/CT. All data will be made available to AD researchers via the Sage Knowledge Network (https://adknowledgeportal.synapse.org/).

Neuroimaging of new and novel Alzheimer’s Disease (AD) mice from the MODEL AD Consortium

AbstractBackgroundThe ability of preclinical neuroimaging in rodent models of Alzheimer’s Disease and Related Dementia (ADRD) to assess the progression of disease is increasingly providing novel insights into AD, like human AD imaging. Preclinical studies have the advantage of being able to directly correlate findings to the observed neuropathology. Recently, University of California Irvine and Indiana University School of Medicine along with Jackson Laboratories were awarded funding to design and phenotype relevant mouse models of late onset AD (LOAD), forming the MODEL AD consortium (https://www.model‐ad.org/). Imaging cores from these will utilize existing state of the art translationally relevant medical imaging methodologies as well as ascertain feasibility of emerging imaging methods for increased diagnostic sensitivity.MethodTwo primary imaging modalities will be utilized: high‐field MRI (9.4T and 17.6T) and PET/CT. Deep MRI phenotyping are based on the accepted human‐AD standards like ADNI (Structural T2W, FLAIR, diffusion, perfusion (PWI), susceptibility, and functional MRI and MR spectroscopy). Novel histological vessel painting combined with PWI will assess vascular modifications. PET imaging will evaluate brain metabolism (18F‐FDG), regional perfusion (64Cu‐PTSM), amyloid (18F‐AV45), tau (18F‐AV1451), neuroinflammation (18F‐CPPC and 18F‐GSK1482160), and astrogliosis (18F‐FEBU) markers in new mouse models.ResultMODEL AD consortia will utilize platform mice (Table 1) across their lifespans and effects after being fed a high fat diet. Known and emerging GWAS risk variants for AD will be added to these platform mice to better replicate human AD. Neuroimaging data will be presented from PET/CT and MRI, focusing on exemplars from relevant AD mouse models including platform mice. A long‐term goal of the MODEL‐AD Imaging cores is to co‐register MRI, PET/CT and vascular measures to concordant histopathological and spatial RNA data. The cores have developed state‐of‐the‐art analytical pipelines to process imaging data to support spatial and temporal localization of ADRD.ConclusionThe MODEL AD consortium (UCI/IUSM/Jax) will develop new and novel AD mouse models and the imaging cores will deeply phenotype these models using existing and emerging neuroimaging methods and analytic approaches, using MRI and PET/CT. All data will be made available to AD researchers via the Sage Knowledge Network (https://adknowledgeportal.synapse.org/).

Cerebral perfusion is elevated in a novel model of aged hAβKI APOE4 mice

AbstractBackgroundThe Model Organism Development and Evaluation for Late‐Onset Alzheimer’s Disease (MODEL‐AD) Consortium is developing the next generation of Alzheimer’s disease (AD) models based on human genomic and imaging data. Recently, MODEL‐AD has generated a new human Aβ Knock‐In (hAβKI) mouse carrying the APOE4 allele. APOE4 carriers are at increased risk for AD. Previous studies have demonstrated altered cerebrovascular integrity and function. We examined the cerebrovascular function in the hAβKI APOE4 mice at 18mo of age using perfusion‐weighted magnetic resonance imaging (PWI). We investigated brain‐wide perfusion alterations in conjunction with histopathological vessel painting.MethodsContrast‐enhanced PWI MRI (9.4T) was undertaken from hAβKI APOE4 (n = 6) and WT (n = 5) mice at 18mo of age following tail vein cannulation for Gadolinium infusion. Imaging sequences included: T1‐pre and post‐infusion, PWI (10min) and susceptibility‐weighted imaging (SWI) for blood extravasation and iron content. All data were processed using JIM v9 software for maps of cerebral blood flow (CBF), volumes (CBV), time to peak, mean transit time and dynamic susceptibility measures for blood‐brain barrier dysfunction. Manual regions of interest (ROI) were performed for cortex, temporal lobe cortex, dorsal hippocampus and thalamus, and semi‐automatic 30+ regions based on the Allen mouse brain atlas. At the end of the in vivo experiments all mice underwent vessel painting followed by microscopic analyses.ResultsCompared to WT mice at 18mo of age, hAβKI APOE4 mice exhibited elevated CBF in virtually all regions examined. CBF was elevated approx. 16%, 11%, 4% and 23% in the cortex, hippocampus, thalamus and temporal lobe cortex, respectively. CBF was significantly elevated in the retrosplenial and temporal lobe cortices (p<0.05). CBV was also significantly increased in temporal lobe. Ongoing analyses will correlate vascular network measures (density, junctions, length) to PWI metrics as well as to hAβKI only mice.ConclusionsThe 18mo hAβKI APOE4 mouse compared to WT exhibited consistent brain‐wide elevations in cerebrovascular measures. This increase may represent a compensatory mechanism to maintain decreased metabolism that occurs with aging. The MODEL‐AD consortium (UCI/IUSM/JAX) continues to develop new and novel AD mouse models. All data will be made available to AD researchers via the Sage Knowledge Network (https://adknowledgeportal.synapse.org/).

Cerebral perfusion is elevated in a novel model of aged hAβKI APOE4 mice

AbstractBackgroundThe Model Organism Development and Evaluation for Late‐Onset Alzheimer’s Disease (MODEL‐AD) Consortium is developing the next generation of Alzheimer’s disease (AD) models based on human genomic and imaging data. Recently, MODEL‐AD has generated a new human Aß Knock‐In (hAßKI) mouse carrying the APOE4 allele. APOE4 carriers are at increased risk for AD. Previous studies have demonstrated altered cerebrovascular integrity and function. We examined the cerebrovascular function in the hAßKI APOE4 mice at 18mo of age using perfusion‐weighted magnetic resonance imaging (PWI). We investigated brain‐wide perfusion alterations in conjunction with histopathological vessel painting.MethodContrast‐enhanced PWI MRI (9.4T) was undertaken from hAßKI APOE4 (n = 6) and WT (n = 5) mice at 18mo of age following tail vein cannulation for Gadolinium infusion. Imaging sequences included: T1‐pre and post‐infusion, PWI (10min) and susceptibility‐weighted imaging (SWI) for blood extravasation and iron content. All data were processed using JIM v9 software for maps of cerebral blood flow (CBF), volumes (CBV), time to peak, mean transit time and dynamic susceptibility measures for blood‐brain barrier dysfunction. Manual regions of interest (ROI) were performed for cortex, temporal lobe cortex, dorsal hippocampus and thalamus, and semi‐automatic 30+ regions based on the Allen mouse brain atlas. At the end of the in vivo experiments all mice underwent vessel painting followed by microscopic analyses.ResultCompared to WT mice at 18mo of age, hAßKI APOE4 mice exhibited elevated CBF in virtually all regions examined. CBF was elevated approx. 16%, 11%, 4% and 23% in the cortex, hippocampus, thalamus and temporal lobe cortex, respectively. CBF was significantly elevated in the retrosplenial and temporal lobe cortices (p<0.05). CBV was also significantly increased in temporal lobe. Ongoing analyses will correlate vascular network measures (density, junctions, length) to PWI metrics as well as to hAßKI only mice.ConclusionThe 18mo hAßKI APOE4 mouse compared to WT exhibited consistent brain‐wide elevations in cerebrovascular measures. This increase may represent a compensatory mechanism to maintain decreased metabolism that occurs with aging. The MODEL‐AD consortium (UCI/IUSM/JAX) continues to develop new and novel AD mouse models. All data will be made available to AD researchers via the Sage Knowledge Network (https://adknowledgeportal.synapse.org/).

Cortical cerebrovascular and metabolic perturbations in the 5xFAD mouse model of Alzheimer's disease.

The 5xFAD mouse is a popular model of familial Alzheimer's disease (AD) that is characterized by early beta-amyloid (Aβ) deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic perturbations over its lifespan. Male and female 5xFAD and wild type (WT) littermates underwent in vivo 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging at 4, 6, and 12 months of age to assess regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent "vessel painting" which labels all cerebral vessels and were analyzed for vascular characteristics such as vessel density, junction density, vessel length, network complexity, number of collaterals, and vessel diameter. With increasing age, vessels on the cortical surface in both 5xFAD and WT mice showed increased vessel length, vessel and junction densities. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but collateral diameters were significantly increased only in 5xFAD mice. MCA total vessel length and junction density were decreased in 5xFAD mice compared to WT at 4 months. Analysis of 18F-FDG cortical uptake revealed significant differences between WT and 5xFAD mice spanning 4-12 months. Broadly, 5xFAD males had significantly increased 18F-FDG uptake at 12 months compared to WT mice. In most cortical regions, female 5xFAD mice had reduced 18F-FDG uptake compared to WT across their lifespan. While the 5xFAD mouse exhibits AD-like cognitive deficits as early as 4 months of age that are associated with increasing Aβ deposition, we only found significant differences in cortical vascular features in males, not in females. Interestingly, 5xFAD male and female mice exhibited opposite effects in 18F-FDG uptake. The MCA supplies blood to large portions of the somatosensory cortex and portions of motor and visual cortex and increased vessel length alongside decreased collaterals which coincided with higher metabolic rates in 5xFAD mice. Thus, a potential mismatch between metabolic demand and vascular delivery of nutrients in the face of increasing Aβ deposition could contribute to the progressive cognitive deficits seen in the 5xFAD mouse model.

Hypoxia-Preconditioned Bone Marrow Mesenchymal Stem Cells Improved Cerebral Collateral Circulation and Stroke Outcome in Mice.

Adequate collateral circulation can remarkably improve patient prognoses for patients experiencing ischemic stroke. Hypoxic preconditioning enhances the regenerative properties of bone marrow mesenchymal stem cells (BMSCs). Rabep2 (RAB GTPase binding effector protein 2) is a key protein in collateral remodeling. We investigated whether BMSCs and hypoxia-preconditioned BMSCs (H-BMSCs) augment collateral circulation poststroke, particularly through Rabep2 regulation. BMSCs or H-BMSCs (1×106) were delivered intranasally in ischemic mice with distal middle cerebral artery occlusion at 6 hours poststroke. Two-photon microscopic imaging and vessel painting methods were used to analyze collateral remodeling. Blood flow, vascular density, infarct volume, and gait analysis were assessed to evaluate poststroke outcomes. Expressions of proangiogenic marker VEGF (vascular endothelial growth factor) and Rabep2 were determined by Western blotting. Western blot, EdU (5-ethynyl-2'-deoxyuridine) incorporation, and tube formation assays were conducted on cultured endothelial cells treated with BMSCs. BMSCs were more effectively transplanted in the ischemic brain after hypoxic preconditioning. The ipsilateral collateral diameter was increased by BMSCs and strengthened by H-BMSCs (P<0.05). BMSCs increased peri-infarct blood flow and vascular density and reduced infarct volume, gait deficits (P<0.05), and furthermore by H-BMSCs (P<0.05). VEGF and Rabep2 protein expression was increased by BMSCs (P<0.05), which was enhanced by preconditioning (P<0.01). Additionally, BMSCs increased Rabep2 expression, proliferation, and tube formation of endothelial cells in vitro (P<0.05). H-BMSCs enhanced these effects (P<0.05), which were annulled by Rabep2 knockdown. BMSCs increased collateral circulation and improved poststroke outcomes, through the upregulation of Rabep2. These effects were enhanced by hypoxic preconditioning.

Metabolic and Cerebrovascular Perturbations in the 5xFAD Mouse Model of Alzheimer’s Disease

AbstractBackgroundThe Model Organism Development and Evaluation for Late‐Onset Alzheimer’s Disease (MODEL‐AD) Consortium seeks to develop the next generation of AD models based on human data. A popular model of familial AD is the 5xFAD mouse. It is characterized by early amyloid‐β deposition and cognitive decrements. Despite numerous studies, the 5xFAD mouse has not been comprehensively phenotyped for vascular and metabolic aspects over its lifespan.MethodMales and females 5xFAD and WT littermates underwent in vivo 18F‐FDG‐PET imaging at 4, 6, and 12 months to evaluate regional glucose metabolism. A separate cohort of mice (4, 8, 12 months) underwent “vessel painting” that labels all cerebral vessels with a fluorescent dye. Brains were analyzed for vascular characteristics such as vessel and junction density, vessel length, network complexity, number and diameter of collaterals.ResultOur analyses revealed that vessel length, vessel and junction densities increased from 4 to 12 months on the cortical surface in both 5xFAD and WT mice. The number of collateral vessels between the middle cerebral artery (MCA) and the anterior and posterior cerebral arteries decreased with age but interestingly their diameters were significantly increased only in 5xFAD mice. MCA average vessel length was significantly decreased at 8 and 12 months in 5xFAD mice compared to WT; primarily driven by males. Analysis of 18F‐FDG cortical uptake found significant interactions between WT and 5xFAD mice spanning 4‐12 months of age in retrosplenial somatosensory and visual cortices. Broadly, 5xFAD males had increased 18F‐FDG uptake at 12 months of age compared to WT mice. In most cortical regions, female 5xFAD mice had reduced FDG uptake compared to WT across the lifespan. In males these metabolic increases coincided with decreased vessel characteristics.ConclusionThe 5xFAD mouse exhibits AD‐like cognitive deficits with age that are associated with increasing amyloid‐β deposition. No significant differences were found in cortical vascular features although males and females exhibited opposite effects in 18F‐FDG uptake. The MCA supplies blood to large portions of the motor cortex and increased vessel lengths and decreased collaterals along with higher metabolic rates in 5xFAD mice may be related to increasing behavioral deficits via metabolic insufficiency or other mechanisms.

Progressive Vascular Abnormalities in the Aging 3xTg-AD Mouse Model of Alzheimer's Disease.

Vascular dysfunction and structural abnormalities in Alzheimer’s disease (AD) are known to contribute to the progression of the pathology, and studies have tended to ignore the role of the vasculature in AD progression. We utilized the 3xTg-AD mouse model of AD to examine individual cerebral vessels and the cortical vascular network across the lifespan. Our vessel painting approach was used to label the entire cortical vasculature, followed by epifluorescence microscopy. The middle cerebral artery (MCA) tree was assessed with confocal microscopy, and a new method was developed to assess branching patterns as a measure of aging-related changes. We found that vascular remodeling was profoundly altered at 4–6 months of age, when the 3xTg-AD mouse is known to transition to cognitive impairment and Aβ deposition in both sexes. Analysis of vascular features (density, junctions, length) of the MCA territory highlighted sex-dependent differences across the 3xTg-AD mouse lifespan, with no alterations in branching patterns. Our current cerebrovascular angioarchitectural analyses demonstrate progressive alterations in individual cortical vessels, as well as in the vascular network of the cortex. These new findings advance our understanding of brain anatomy and physiology in the 3xTg-AD mouse, while potentially identifying unique diagnostic signatures of AD progression.

Longitudinal dynamics of microvascular recovery after acquired cortical injury

Acquired brain injuries due to trauma damage the cortical vasculature, which in turn impairs blood flow to injured tissues. There are reports of vascular morphological recovery following traumatic brain injury, but the remodeling process has not been examined longitudinally in detail after injury in vivo. Understanding the dynamic processes that influence recovery is thus critically important. We evaluated the longitudinal and dynamic microvascular recovery and remodeling up to 2 months post injury using live brain miniscope and 2-photon microscopic imaging. The new imaging approaches captured dynamic morphological and functional recovery processes at high spatial and temporal resolution in vivo. Vessel painting documented the initial loss and subsequent temporal morphological vascular recovery at the injury site. Miniscopes were used to longitudinally image the temporal dynamics of vascular repair in vivo after brain injury in individual mice across each cohort. We observe near-immediate nascent growth of new vessels in and adjacent to the injury site that peaks between 14 and 21 days post injury. 2-photon microscopy confirms new vascular growth and further demonstrates differences between cortical layers after cortical injury: large vessels persist in deeper cortical layers (> 200 μm), while superficial layers exhibit a dense plexus of fine (and often non-perfused) vessels displaying regrowth. Functionally, blood flow increases mirror increasing vascular density. Filopodia development and endothelial sprouting is measurable within 3 days post injury that rapidly transforms regions devoid of vessels to dense vascular plexus in which new vessels become increasingly perfused. Within 7 days post injury, blood flow is observed in these nascent vessels. Behavioral analysis reveals improved vascular modulation after 9 days post injury, consistent with vascular regrowth. We conclude that morphological recovery events are closely linked to functional recovery of blood flow to the compromised tissues, which subsequently leads to improved behavioral outcomes.

Lifespan neuroimaging of the 5xFAD mouse model of Alzheimer’s disease: Evolution of metabolic and vascular perturbations

AbstractBackgroundThe Model Organism Development and Evaluation for Late‐Onset Alzheimer’s Disease (MODEL‐AD) consortium seeks to develop the next generation of Alzheimer’s disease models guided by human data. As new mice models become available, they are extensively phenotyped and compared to existing models, such as the 5xFAD. The 5xFAD models familial AD onset, which results in amyloid β (Aβ) deposition and cognitive decrements early in life; however, no studies have comprehensively phenotyped the vascular and metabolic aspects of this mouse over its lifespan (∼15mo). Here we report lifespan perturbations in male and female 5xFAD mice compared to healthy aging C57BL/6J (WT) mice using multi‐modal neuroimaging with assessment of vascular networks.MethodAge (4, 8, 12mo) and sex‐matched 5xFAD and healthy aging WT (C57BL/6J) mice underwent ex vivo MRI and in vivo PET evaluation for regional brain volumes (T2‐weighted imaging), Aβ load (susceptibility weighted imaging and 18F‐AV45 PET) and brain metabolism (18F‐FDG PET). After neuroimaging, selected mice underwent novel vessel painting (VP) to label whole brain vascular networks. Histology and immunohistochemical analyses verified neuroimaging findings.ResultWhole brain volumes were significantly decreased (∼6%) in 8mo female 5xFAD compared to WT, as were hippocampal volumes in both sexes. SWI and AV45‐PET were able to detect elevated Aβ plaques with age in 8‐12mo old 5xFAD mice when compared to WT. 18F‐FDG showed a reduction in glycolysis with age when compared to WT. Whole brain vascular networks in 8mo 5xFAD mice had vessel numbers and complexity compared to 4mo 5xFAD, with males having larger reductions than females. The middle cerebral artery vessel density in 5xFAD was also decreased. Immunohistochemistry confirmed Aβ deposition and microglia activation with genotype and age.ConclusionThis is the first report of vascular and metabolic disturbances during the lifespan in the 5xFAD model of AD. Our findings suggest that vascular and metabolic ageing are correlated to temporal cumulative Aβ deposition. Early decrements in vascularity in the 5xFAD may precede the development of pathology. Further, the 5XFAD mice exhibit age and region‐specific neuroimaging alterations coincident with metabolic disturbances.

Survey of imposex in Nucella lapillus as an indicator of tributyltin pollution in Northern Irish coastal waters, 2004 to 2017

Tributyltin (TBT) was a commonly used biocide in anti-fouling paints for marine vessels, however, it had negative impacts on non-target species, including causing imposex in dogwhelks (Nucella lapillus). Since the 1980s, legislation has been introduced to curtail its usage, culminating in a ban by the International Maritime Organisation (IMO) in 2008. In 2004 a national imposex monitoring network was established in Northern Ireland to determine the level and extent of TBT pollution. The level of imposex in N. lapillus was assessed according to the degree of male sexual development in the female using three measures: percentage of imposex-affected females (%I), the relative penis size index (RPSI), and the vas deferens sequence index (VDSI). All sites showed improvement since the initial survey with a reduction in imposex and an improvement in ecological quality under the classification of the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR).

Pathological application of carbocyanine dye-based multicolour imaging of vasculature and associated structures

Simultaneous visualisation of vasculature and surrounding tissue structures is essential for a better understanding of vascular pathologies. In this work, we describe a histochemical strategy for three-dimensional, multicolour imaging of vasculature and associated structures, using a carbocyanine dye-based technique, vessel painting. We developed a series of applications to allow the combination of vessel painting with other histochemical methods, including immunostaining and tissue clearing for confocal and two-photon microscopies. We also introduced a two-photon microscopy setup that incorporates an aberration correction system to correct aberrations caused by the mismatch of refractive indices between samples and immersion mediums, for higher-quality images of intact tissue structures. Finally, we demonstrate the practical utility of our approach by visualising fine pathological alterations to the renal glomeruli of IgA nephropathy model mice in unprecedented detail. The technical advancements should enhance the versatility of vessel painting, offering rapid and cost-effective methods for vascular pathologies.

Acute Treatment With Gleevec Does Not Promote Early Vascular Recovery Following Intracerebral Hemorrhage in Adult Male Rats.

Intracerebral hemorrhage (ICH) remains one of the most debilitating types of stroke and is characterized by a sudden bleeding from a ruptured blood vessel. ICH often results in high mortality and in survivors, permanent disability. Most studies have focused on neuroprotective strategies designed to minimize secondary consequences and prevent further pathology. Lacking is an understanding of how ICH acutely affects cerebrovascular components and their response to therapeutic interventions. We hypothesized that ICH alters cortical vessel complexity in the parenchyma adjacent to site of the initial vascular disruption and that vascular abnormalities would be mitigated by administration of the PDGFR inhibitor, Imatinib mesylate (Gleevec). Briefly, ICH was induced in male adult rats by injection of collagenase into basal ganglia, followed by Gleevec administration (60 mg/kg) 1 h after injury. Rats were then perfused using vessel painting methodology (Salehi et al., 2018b) to stain whole brain vascular networks at 1 day post-ICH. Axial and coronal wide field fluorescence microscopy was performed. Analyses for vascular features were undertaken and fractal analysis for vascular complexity. Data were collected from four groups of rats: Sham + Vehicle; Sham + Gleevec; ICH + Vehicle; ICH + Gleevec. Microscopy revealed that cortical vessels in both ipsi- and contralateral hemispheres exhibited significantly reduced density and branching by 22 and 34%, respectively. Fractal measures confirmed reduced complexity as well. Gleevec treatment further reduced vascular parameters, including reductions in vessel density in tissues adjacent to the ICH. The reductions in brain wide vascular networks after Gleevec in the current study after ICH is contrasted by previous reports of improved behavioral outcomes and decreased lCH lesion volumes Reductions in the vascular network after Gleevec may be involved in long-term repair mechanisms by pruning injured vessels to ultimately promote new vessel growth.

EphA4/Tie2 crosstalk regulates leptomeningeal collateral remodeling following ischemic stroke.

Leptomeningeal anastomoses or pial collateral vessels play a critical role in cerebral blood flow (CBF) restoration following ischemic stroke. The magnitude of this adaptive response is postulated to be controlled by the endothelium, although the underlying molecular mechanisms remain under investigation. Here we demonstrated that endothelial genetic deletion, using EphA4fl/fl/Tie2-Cre and EphA4fl/fl/VeCahderin-CreERT2 mice and vessel painting strategies, implicated EphA4 receptor tyrosine kinase as a major suppressor of pial collateral remodeling, CBF, and functional recovery following permanent middle cerebral artery occlusion. Pial collateral remodeling is limited by the crosstalk between EphA4-Tie2 signaling in vascular endothelial cells, which is mediated through p-Akt regulation. Furthermore, peptide inhibition of EphA4 resulted in acceleration of the pial arteriogenic response. Our findings demonstrate that EphA4 is a negative regulator of Tie2 receptor signaling, which limits pial collateral arteriogenesis following cerebrovascular occlusion. Therapeutic targeting of EphA4 and/or Tie2 represents an attractive new strategy for improving collateral function, neural tissue health, and functional recovery following ischemic stroke.

Evolution of cerebral perfusion in the peri-contusional cortex in mice revealed by in vivo laser speckle imaging after traumatic brain injury

The role of the cerebrovascular network during the acute and chronic phases after traumatic brain injury (TBI) is poorly defined and emerging evidence suggests that cerebral perfusion is altered. The purpose of this study is to explore how the cortical blood flow is pathologically altered following TBI using a newly developed technique, laser speckle imaging. The controlled cortical impact (CCI) model was established in mice. Then, cerebral blood flow was monitored in vivo laser speckle imaging and vessel painting was labeled by Lectin in the peri-contusional cortex. Lastly, mice were assessed for lesion size and neurological functions. Our results indicated that: 1) In the acute phase of TBI, cerebral blood flow and microvessel counts decreased significantly (P < 0.05) 2) In the chronic phase of TBI, cerebral blood flow and microvessel counts recovered gradually (P < 0.05) 3) Cortical lesion volume reduced significantly in the chronic phase of TBI (P < 0.05) 4) Spontaneous neurocognitive recovery occurred following CCI in mice (P < 0.05). In the acute phase of TBI, there is a reduction in cerebral perfusion at the lesion site. However, this reduction recovers in the chronic phase of TBI ultimately, followed by an improvement of ameliorated neurobehavioral functions and a decrease in the lesion size. The novel approach for cerebral blood flow monitoring by laser speckle imaging can be extended from bench to bedside and provide potential therapeutic strategies for TBI patients.

Male and Female Mice Exhibit Divergent Responses of the Cortical Vasculature to Traumatic Brain Injury.

We previously reported that traumatic brain injuries (TBI) alter the cerebrovasculature near the injury site in rats, followed by revascularization over a 2-week period. Here, we tested our hypothesis that male and female adult mice have differential cerebrovascular responses following a moderate controlled cortical impact (CCI). Using in vivo magnetic resonance imaging (MRI), a new technique called vessel painting, and immunohistochemistry, we found no differences between males and females in lesion volume, neurodegeneration, blood-brain barrier (BBB) alteration, and microglia activation. However, females exhibited more astrocytic hypertrophy and heme-oxygenase-1 (HO-1) induction at 1 day post-injury (dpi), whereas males presented with increased endothelial activation and expression of β-catenin, shown to be involved in angiogenesis. At 7 dpi, we observed an increase in the number of vessels and an enhancement in vessel complexity in the injured cortex of males compared with females. Cerebrovasculature recovers differently after CCI, suggesting biological sex should be considered when designing new therapeutic agents.

Stability studies of endocrine disrupting tributyltin and triphenyltin compounds in an artificial sea water model.

Triorganotins belong to toxic components present predominantly in antifouling paints for marine vessels. Tributyltin/triphenyltin at pico- or nanomolar concentrations in sea water are known to induce an irreversible sexual abnormality in females of over 190 marine species, an "imposex" phenomenon - the superimposition of male genitalia on a female. Moreover, trialkyltins and triaryltins function as potent nuclear retinoid X receptors (RXR) agonists. In mammals, triorganotin compounds induce immunosuppressive, metabolic, reproductive or developmental effects. Toxic effects of triorganotins warrant the need for monitoring of their long-lasting presence in the environment. This study brings novel data on the stability of two triorganotin compounds in artificial sea water model obtained by applying ultra-pressure liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS) methods. Stability of tributyltin and triphenyltin chlorides was studied for 180 days and the degradation kinetic parameters were obtained. Tributyltin chloride was the less stable with the degradation kinetic parameters Kdeg = 0.00014 day-1 and t1/2 = 4950 days (13.6 years). Kdeg of the more stable triphenyltin chloride was determined to be Kdeg = 0.00006 day-1 with t1/2 = 11550 days (31.6 years). Since similar stability data of triorganotin compounds were not published previously, we report high stability for both tested compounds, which indicates a significant environmental problem when these substances enter sea water and later coastal sediments.

Up-regulation of Wnt/β-catenin expression is accompanied with vascular repair after traumatic brain injury

Recent data suggest that repairing the cerebral vasculature after traumatic brain injury (TBI) may help to improve functional recovery. The Wnt/β-catenin signaling pathway promotes blood vessel formation during vascular development, but its role in vascular repair after TBI remains elusive. In this study, we examined how the cerebral vasculature responds to TBI and the role of Wnt/β-catenin signaling in vascular repair. We induced a moderate controlled cortical impact in adult mice and performed vessel painting to visualize the vascular alterations in the brain. Brain tissue around the injury site was assessed for β-catenin and vascular markers. A Wnt transgenic mouse line was utilized to evaluate Wnt gene expression. We report that TBI results in vascular loss followed by increases in vascular structure at seven days post injury (dpi). Immature, non-perfusing vessels were evident in the tissue around the injury site. β-catenin protein expression was significantly reduced in the injury site at 7 dpi. However, there was an increase in β-catenin expression in perilesional vessels at 1 and 7 dpi. Similarly, we found increased number of Wnt-GFP-positive vessels after TBI. Our findings suggest that Wnt/β-catenin expression contributes to the vascular repair process after TBI.