Endothelial progenitor cell transplantation alleviated ischemic brain injury via inhibiting C3/C3aR pathway in mice

Abstract

Endothelial progenitor cell transplantation is a potential therapeutic approach in brain ischemia. However, whether the therapeutic effect of endothelial progenitor cells is via affecting complement activation is unknown. We established a mouse focal ischemia model (<i>n</i> = 111) and transplanted endothelial progenitor cells into the peri-infarct region immediately after brain ischemia. Neurological outcomes and brain infarct/atrophy volume were examined after ischemia. Expression of C3, C3aR and pro-inflammatory factors were further examined to explore the role of endothelial progenitor cells in ischemic brain. We found that endothelial progenitor cells improved neurological outcomes and reduced brain infarct/atrophy volume after 1 to 14 days of ischemia compared to the control (<i>p </i><<i> </i>0.05). C3 and C3aR expression in the brain was up-regulated at 1 day up to 14 days (<i>p </i><<i> </i>0.05). Endothelial progenitor cells reduced astrocyte-derived C3 (<i>p </i><<i> </i>0.05) and C3aR expression (<i>p </i><<i> </i>0.05) after ischemia. Endothelial progenitor cells also reduced inflammatory response after ischemia (<i>p </i><<i> </i>0.05). Endothelial progenitor cell transplantation reduced astrocyte-derived C3 expression in the brain after ischemic stroke, together with decreased C3aR and inflammatory response contributing to neurological function recovery. Our results indicate that modulating complement C3/C3aR pathway is a novel therapeutic target for the ischemic stroke.