Extracellular vesicles derived from hypoxic human mesenchymal stem cells attenuate GSK3β expression via miRNA-26a in an ischemia-reperfusion injury model

Purpose: Bioactive molecules critical to intracellular signaling are contained in extracellular vesicles (EVs) and have cardioprotective effects in ischemia/reperfusion (IR) injured hearts. This study investigated the mechanism of the cardioprotective effects of EVs derived from hypoxia-preconditioned human mesenchymal stem cells (MSCs). Materials and Methods: EV solutions (0.4 μg/μL) derived from normoxia-preconditioned MSCs (EV_NM) and hypoxia-preconditioned MSCs (EV_HM) were delivered in a rat IR injury model. Successful EV delivery was confirmed by the detection of PKH26 staining in hearts from EV-treated rats. Results: EV_HM significantly reduced infarct size (24±2% vs. 8±1%, p<0.001), and diminished arrhythmias by recovering electrical conduction, I_Na current, and Cx43 expression. EV_HM also reversed reductions in Wnt1 and β-catenin levels and increases in GSK3β induced after IR injury. miRNA-26a was significantly increased in EV_HM, compared with EV_NM, in real-time PCR. Finally, in in vitro experiments, hypoxia-induced increases in GSK3β expression were significantly reduced by the overexpression of miRNA-26a. Conclusion: EV_HM reduced IR injury by suppressing GSK3β expression via miRNA-26a and increased Cx43 expression. These findings suggest that the beneficial effect of EV_HM is related with Wnt signaling pathway.