PS-B10-10: MRI CEREBROVASCULAR CHARACTERIZATION IN A MOUSE MODEL OF HYPERTENSION-INDUCED BRAIN INJURY

Hypertension has been recognized as the main modifiable risk factor for vascular cognitive impairment (VCI), dementias and neurodegenerative pathologies as Alzheimer Disease (AD). As we previously demonstrated, Transverse aortic constriction (TAC) is a relevant mouse model of cerebral injury and cognitive impairment induced by vascular factors. In this work we characterize the effect of TAC procedure on cerebral injury leveraging Magnetic Resonance Imaging (MRI), and investigate the relationship between the alterations found by MRI and histological, cognitive and cardiac parameters of injury, to establish a framework of translational imaging biomarkers to be applied in human. We subjected C57Bl/6J to TAC procedure, inducing severe cerebral hypertension. Thereafter, the brain injury was characterized by macro and microstructural MRI; cerebral blood flow (CBF) was analyzed by perfusion MRI. All neuroimaging scans were performed on a small-animal dedicated 7 Tesla MRI. The cognitive phenotype was characterized by Morris Water Maze (MWM) and Novel Object Recognition (NOR), while cardiac and carotid remodeling was assessed by ultrasound imaging. Finally, brains were analyzed for histological alterations in terms of microvascular density and integrity. Structural MRI showed white matter microstructural degradation in the left Fimbria of TAC mice, evidenced by a reduction of Fractional Anisotropy, Mean Diffusivity and Radial Diffusiity, coupled with bilateral hypothalamic enlargement (Figure A). Hemodynamic alterations resulted in reduced global, cortical and hypothalamic CBF (Figure B). The histological microvascular analysis evidenced capillary rarefaction, reduced capillary-pericyte coverage and Blood-Brain Barrier leakiness in the neocortex (Figure C). Finally, we evaluated whether cerebral MRI parameters of injury were correlated with cardiac, carotid and cognitive alterations: CBF was significantly correlated with mouse performance at Probe trial of MWM test and correlated to cardiac remodeling and diastolic dysfunction. Diastolic disfunction was correlated also to hypothalamic swelling, and cardiac remodeling was significantly correlated to microstructural alterations in the fimbria. Finally, CBF was correlated to bilateral carotid remodeling. In conclusion we have developed a mouse model of hypertension-induced brain damage that recapitulates typical traits of the human pathology and a pipeline of analysis that will ease allow to appreciate findings resulting from novel molecular targeting of the brain and translate them from bench to bedside. JOURNAL/jhype/04.03/00004872-202301001-01152/figure1/v/2023-10-24T163949Z/r/image-jpeg