American Heart Association, Stroke, Suppl_1(50), 2019
DOI: 10.1161/str.50.suppl_1.wp149
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The time course, mode, regulation, and relevance to functional recovery of post-stroke vascular remodeling are poorly defined. We tracked peri-infarct vascular remodeling in mice with repeated in vivo two-photon imaging of vascular structure (labeled with transgenic expression of green fluorescent protein) and multi-exposure speckle imaging of cortical blood flow over months after photothrombotic cortical lesions. Vascular structure in the intact brain is remarkably stable. In contrast, we found that peri-infarct vasculature (micro- and macrovessels) underwent long-term structural changes, including formation and elimination of vessel segments, beginning within days of infarction. Remodeling continued after peri-infarct blood flow was restored and was most pronounced in superficial vessels. Histological methods indicated that vascular density was rapidly (within days of ischemia) and persistently (at least one month) increased surrounding the infarct. Past findings suggest that neural precursor cells (NPCs) originating in the subventricular zone associate closely with remodeling blood vessels in peri-infarct cortex. To evaluate the role of NPCs in vascular remodeling, we used a pharmacogenetic method to ablate NPCs. NPC ablation prior to infarct altered the pattern of vascular remodeling: the neovascularization response was exaggerated and the orientation of peri-infarct vessels was disordered compared to the normal pattern of vessels oriented towards the lesion. As well, NPC ablation worsened recovery of behavioral function after ischemia. Collectively, these results suggest that vascular remodeling is a chronic process instigated by stroke and that proper vascular patterning is directed by NPCs. NPCs likely contribute to behavioral recovery after brain injury at least in part through their influence on neovascularization.