DECIPHERING INFLAMMATORY MECHANISMS TO IMPROVE THE EFFICACY OF STEM CELL THERAPY

Ischemic stroke is a leading cause of death and long-term disability worldwide, and current acute therapies benefit only a small subset of patients. To address this need, we model stem cell–based repair in the subacute phase of stroke, when transplantation of human induced pluripotent stem cell (hiPSC)–derived neuronal progenitors can promote tissue protection, neuronal replacement, and circuit reconstruction. However, successful clinical translation requires a mechanistic understanding of how the post-stroke inflammatory environment shapes neuronal graft survival and integration.
We induce focal cortical ischemic stroke in immunodeficient Rag1KO mice and transplant human long-term neuroepithelial stem (lt-NES) cell–derived neuronal progenitors into peri-infarct regions. Stroke triggers a robust sterile inflammatory response that critically influences graft outcomes. While microglial roles have been extensively studied, we specifically investigate border-associated macrophages, with a focus on perivascular macrophages (PVMs), which reside at the neurovascular interface and directly interact with both vascular and neuronal compartments.
Using selective PVM depletion via clodronate liposomes, we manipulate the inflammatory niche at the time of transplantation. This approach is combined with 3D tissue clearing, immunofluorescence, and functional MRI to quantify graft survival, neuronal maturation, synaptic connectivity, and local and brain-wide functional integration. In addition, monosynaptic rabies virus tracing enables circuit-level mapping of host–graft connectivity. By defining how PVM-driven inflammatory signaling regulates neuronal graft integration after stroke, this work identifies PVMs as modulators of regenerative success. These findings provide mechanistic insight into immune–neural interactions and highlight novel therapeutic targets to optimize stem cell–based strategies for post-stroke recovery.