P5397Mesenchymal stem cells derived from bone marrow promotes cardiomyocytes survival under hypoxia through exosomal miR-210

Abstract Mesenchymal stem cells derived from bone marrow promotes cardiomyocytes survival under hypoxia through exosomal miR-210 Background A paracrine effect was regarded as the key mechanism involved in the MSC (mesenchymal stem cell)-based treatment for myocardial infarction. In our pilot experiments, hypoxia remarkably promotes MSC to paracrine exosomal miR-210, which could significantly enhance the cardiomyocytes survival in hypoxic incubation, suggesting that exosomal miR-210 played critical roles in the favorable paracrine effect of MSC on cardiomyocytes. Purpose The aim of this study was to investigate the important mechanism by which MSCs promote the tolerance of cardiomyocytes to hypoxia by secreting exosomal miR-210. Methods and results The exosomes were isolated from MSCs conditioned medium through ultracentrifugation, and we detected that miR-210 was the most abundant in MSC-exosome and increased most prominently in the hypoxia. The extracted exosomes were prepared for conditioned medium and the effect on myocardial protection was examined. The viability of control group was much better than the cardiomyocytes treated with hypoxia, but it was further increased in the presence of MSC-exosome, however, measurement was significantly lower in cardiomyocytes in hypoxia with exosomes derived from MSCs treated with GW4869. Subsequently, the co-localization of miR-210 with exosome-specific surface markers CD81 and CD63 were observed by immunofluorescence technique. Continuous magnetic live cell imaging was used to observe the uptake of exosome by cardiomyocytes, and fluorescence localization was used to observe the localization of miR-210 with Cy3 fluorescence in cardiomyocytes. Then, we demonstrated that MSCs exosomal miR-210 exerts the cardioprotective effect by regulating the AIFM3 (apoptosis-inducing factor mitochondria-associated protein 3), and we directly overexpressed miRNA-210 in cardiomyocytes and the results showed that the regulatory activity of the intake of exosomal miR-210 was consistent with that of the biological exosomal miR-210. Finally, we verified the protective effect on the ischemic myocardium by constructing rat myocardial infarction models. The level of apoptosis was detected at 1 week after myocardial infarction. The left ventricular ejection fraction and ventricular remodeling were measured at 4 weeks. In vivo, we demonstrated that explanted miR-210 from transplanted MSCs significantly reduced myocardial necrosis and apoptosis induced by ischemia and improved cardiac function and myocardial remodeling. Conclusion Here, we show that the exosomal miR-210 secreted by MSCs significantly increase the viability of cardiomyocytes and cardiac function. These findings suggest that exosomal miR-210 is a key effector that mediates the protection against hypoxia. Acknowledgement/Funding National Natural Science Foundation of China (Grant Nos. 81470467)