Mesenchymal stem cells transfer mitochondria into cerebral microvasculature and promote recovery from ischemic stroke.

Mesenchymal stem cells can be used as a novel treatment of ischemic stroke, but their therapeutic effect and mechanism of action require further evaluation. Mitochondrial dysfunction has core functions in ischemia-reperfusion stroke injury. Our recent research has demonstrated that mesenchymal stem cells can transfer their functional mitochondria to injured endothelial cells via tunneling nanotubes in vitro, resulting in the rescue of aerobic respiration and protection of endothelial cells from apoptosis. Therefore, we presume that the mechanisms of mitochondrial protection may be involved in stem cell-mediated rescue of injured cerebral microvasculature and recovery from ischemic stroke. In this study, the middle cerebral artery occlusion and reperfusion surgery were conducted on rats, and mesenchymal stem cells were then engrafted into the injured cerebrovascular system. Our results showed that the host cells of injured cerebral microvasculature accepted the mitochondria transferred from the transplanted stem cells, thereby resulting in significantly improving in mitochondrial activity of injured microvasculature, enhancing angiogenesis, reducing infarct volume, and improving functional recovery. Our data provided the evidence that stem cells can rescue damaged cerebrovascular system in stroke through a mechanism not yet identified.