AUTHOR=Hao Lei , Yang Yongtao , Xu Xiaoli , Guo Xiuming , Zhan Qunling TITLE=Modulatory effects of mesenchymal stem cells on microglia in ischemic stroke JOURNAL=Frontiers in Neurology VOLUME=Volume 13 - 2022 YEAR=2023 URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.1073958 DOI=10.3389/fneur.2022.1073958 ISSN=1664-2295 ABSTRACT=Ischemic stroke accounts for 70%~80% of all stroke cases. Immunity plays an important role in the pathophysiology of ischemic stroke. Microglia are the first line of defense in the central nervous system. Microglial functions are largely dependent on their pro-inflammatory (M1-like) or anti-inflammatory (M2-like) phenotype. Modulating neuroinflammation via targeting microglia polarization toward anti-inflammatory phenotype might be novel therapeutic for ischemic stroke. Mesenchymal stem cells (MSC) and MSC derived extracellular vesicles (MSC-EVs) have been demonstrated to modulate microglia activation and phenotype polarization. In this review, we summarize physiological characteristics and functions of microglia in healthy brain, activation and polarization of microglia in stroke brain, the effects of MSC/MSC-EVs on the activation of MSC in vitro and in vivo and possible underlying mechanisms, providing evidence for a possible novel therapeutics for the treatment of ischemic stroke..