Exosomes Secreted By HUVECs Attenuate Hypoxia/reoxygenation-induced Apoptosis In Neural Cells By Suppressing MiR-21-3p

Cerebrovascular disease includes a variety of medical conditions which affect the blood vessels of the brain and the cerebral circulation.Arteries that supply oxygen and nutrients to the brain are often damaged or deformed in cerebrovascular disease,leading to ischemic stroke or small stroke.Cerebral injuries due to ischemia always result in the death of massive numbers of neurons in the central nerve system(CNS).These injuries are responsible for the most common type of acute cerebrovascular disease,and the damaged tissue recovers very little of it original function.Ischemia-induced cerebral injuries rank third among the leading causes of mortality and morbidity worldwide.A host of intrinsic and extrinsic factors are thought to regulate the survival of neurons during ischemia of the cerebrum,and these factors provide targets for new drugs and treatments that alleviate cerebral ischemia.However,most of the current interventions involve the transient stimulation of injured CNS tissues by exogenous means,making the beneficial effect of those interventions very tentative.Therefore,it is imperative to develop novel methods that have few side effects for treating cerebral ischemia.In recent years,scientists have proposed a theory that ischemic CNS tissue can be mobilized to develop endogenous protective mechanisms that combat injuries and promote the repair of damaged tissue,and this theory has been validated in other organs such as the heartExosomes are small-membrane vesicles with a size of 30-120 nm in diameter.They can be generated by several types of cells that contain not only surface membrane proteins but also mRNA and miR molecules.Many cells in the CNS release exosomes in the form of extracellular membrane vesicles,indicating that exosomes participate in the function,development,and pathologies of the nervous system.Studies have shown that the exosome-mediated delivery of miRNA could promote neurogenesis after ischemia.That finding partially supports our hypothesis that RIPostC might attenuate ischemia-induced cerebral injuries by facilitating the exosome-mediated remote transfer of miRNA.To validate that hypothesis,human umbilical vein endothelial cells(HUVECs)subjected to hypoxia/reoxygenation(H/R)were used as an in vitro model of remote cells receiving RIPostC.A profile of miRNA expression in the HUVECs was created by using data gathered from microarray assays.H/R-treated neural cells were incubated with exosomes from HUVECs and an inhibitor of miR-21-3p to determine the mechanism by which RIPostC exerts its anti-ischemia effect in the CNS.Our research shows that miR-21-3p was down-regulated in H/R-treated HUVCEs.miR-21-3p directly interacts with the 3 UTR of its target gene ATG12 and negatively regulates the expression of ATG12 mRNA and protein.Moreover,miR-21-3p inhibitor and HUCCE exosomes promoted H/R-induced autophagy in SH-SY5Y cells and inhibited apoptosis of SH-SY5Y cells.