Stroke is a leading cause of death and morbidity worldwide.In hypoxic lesions restricted to the striatum, type A pericytes remained associated to the vascular wall, contributing to revascularization of the ischemic lesion core, while no extensive fibrotic scar tissue was formed. In sharp contrast, type A pericytes and progeny detached from the vessel wall and contributed to widespread fibrotic scar tissue formation in cortical ischemic lesions . Preliminary results from our lab indicate that differences in fibrotic scarring between cortical and basal ganglia ischemic strokes exist in humans as well. The difference in the injury response of perivascular cells provides an opportunity to dissect the mechanisms of revascularization and fibrotic scarring by comparing the two ischemic lesions and forms the basis for this project. The overall aim of the project is to identify the mechanisms that mediate revascularization and fibrotic scarring in the CNS by using single cell RNA sequencing method.