Intravital imaging of transplant evoked glia repair in stroke

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Ischemic stroke is a major healthcare burden and there is an important unmet need for new treatments that can be applied beyond the narrow acute phase of injury after which ischemic tissue becomes infarcted. A hallmark of natural wound responses after stroke is the formation of compartmentalized lesions that contain non-neural cell cores that lack specialized glia cells that are fundamental to supporting neural circuits and barrier functions. In organisms capable of neural regeneration such as zebrafish and the mammalian neonate, immature glia cells readily repopulate lesion cores to effectively drive neural repair, but this competency is lost in adult mammals. With the overall goal of promoting scar-free glia repair in stroke to transform lesion cores into neural regeneration permissive environments, this project’s main objective is to use cutting-edge intravital imaging methods to longitudinally track cell graft evoked changes in wound repair outcomes following cortical strokes to identify critical graft parameters that lead to effective glia-repair. Our hypothesis is that multiple intravital imaging modalities can be used to effectively track temporal changes in grafted cell number and phenotype as well as quantify graft induced alterations to microvasculature density, perfusion, and permeability in lesion cores. Grafting cells during the sub-acute injury phase to alter the nature of adult central nervous system (CNS) wound healing and drive glia repair represents a novel and potentially transformative strategy that would have broad impact for treatment of stroke and other CNS injuries. In the first aim, we will longitudinally track differences in glia repair in cortical strokes directed by neural progenitor cells (NPC) and immature astroglia grafts. Priming grafts into proliferating immature astrocytes prior to transplantation may accelerate and better guide glia repair processes. Using two-photon microscopy (2PM) we will evaluate graft cell number, density, and morphology and optical coherence tomography (OCT) to quantify graft induced changes in vascular density and quantitative blood flow in and around stroke lesion cores. To evaluate return of CNS barrier functions we will quantify the leakage of intravenous contrast agents using 2PM. In the second aim, we evaluate the effect of post stroke grafting timepoint on glia repair outcomes. This project will provide mechanistically validated, proof-of-principle evidence into how cell grafts, including immature astrocyte grafts, can remodel lesion cores by directing angiogenesis and restoration of glia barriers. This project will advance our understanding of cell transplantation and certify a toolkit for evaluating transplant functions in vivo that will position us to pursue advanced stroke functional recovery studies in future work.