Modulatory effects of mesenchymal stem cells on microglia in ischemic stroke

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 a novel treatment 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 the physiological characteristics and functions of microglia in the healthy brain, the 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.

Automated summary

Ischemic stroke is the most common type of stroke and the immune system plays a crucial role in its development. Microglia, the first responders in the central nervous system, can switch between pro- and anti-inflammatory states. Modulating microglia polarization towards an anti-inflammatory phenotype could be a potential treatment for ischemic stroke. This review explores the impact of mesenchymal stem cells and their extracellular vesicles on microglia activation and phenotype polarization, providing evidence for novel therapeutics.