Exosomal microRNA-22-3p alleviates cerebral ischemic injury by modulating KDM6B/BMP2/BMF axis

BACKGROUND: Cerebral ischemia-reperfusion (I/R) injury, the most common form of stroke, has high mortality and often brings persistent and serious brain dysfunction among survivors. Administration of adipose-derived mesenchymal stem cells (ASCs) has been suggested to alleviate the I/R brain injury, but the mechanism remains uncharacterized. Here, we aimed at investigating the mechanism of ASCs and their extracellular vesicles (EVs) in the repair of or protection from I/R injury. METHODS: We established the middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation/reperfusion (OGD/RP) neuron model. ASCs or ASC-derived EVs (ASC-EVs) were co-cultured with neurons. RT-qPCR and Western blot analyses determined microRNA (miRNA)-22-3p, BMP2, BMF, and KDM6B expression in neurons upon treatment with ASC-EVs. Bioinformatics analysis predicted the binding between miR-22-3p and KDM6B. Using gain- and loss-of-function methods, we tested the impact of these molecules on I/R injury in vivo and in vitro. RESULTS: Treatment with ASCs and ASC-derived EVs significantly alleviated the I/R brain injury in vivo, elevated neuron viability in vitro, and decreased apoptosis. Interestingly, miR-22-3p was upregulated in ASC-EVs, and treatment with EV-miR-22-3p inhibitor led to increased apoptosis and decreased neuronal. Of note, miR-22-3p bound to and inhibited KDM6B, as demonstrated by dual-luciferase reporter gene assay and Western blot assay. Overexpression of KDM6B enhanced apoptosis of neurons in the OGD/RP model, and KDM6B bound to BMB2 and promoted its expression by binding to BMP2. Silencing of BMF reduced infarct volume and apoptosis in the stroke model. CONCLUSION: Results support a conclusion that ASC-EV-derived miR-22-3p could alleviate brain ischemic injury by inhibiting KDM6B-mediated effects on the BMP2/BMF axis. These findings compelling indicate a novel treatment strategy for cerebral ischemic injury.