Protective paracrine effect of mesenchymal stem cells on cardiomyocytes

Objective:The aim of this study was to test the protective effect of mesenchymal stem cells(MSCs) on cardiomyocytes in vitro and to investigate the anti-apoptotic signaling pathway.Methods:MSCs from Sprague-Dawley(SD) rats were separated and cultured.MSC medium was collected from MSCs cultured in serum-free Dulbecco's modified eagle medium(DMEM) under hypoxia.Cultured cardiomyocytes from neonatal SD rats were exposed to hypoxia/reoxygenation(H/R) and treated with MSC medium.The apoptotic cardiomyocytes were stained with Annexin-V-fluorescein isothiocyanate(FITC),Hoechst 33342 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL).The mitochondrial transmembrane potential of cardiomyocytes was assessed using a fluorescence microscope.The expression of Bcl-2,Bax,cytochrome C,apoptosis-induced factor(AIF),and caspase-3 was tested by Western blot analysis.Results:Our data demonstrated that MSC medium reduced H/R-induced cardiomyocyte apoptosis,increased the Bcl-2/Bax ratio,and reduced the release of cyto-chrome C and AIF from mitochondria into the cytosol.Conclusion:MSCs protected the cardiomyocytes from H/R-induced apoptosis through a mitochondrial pathway in a paracrine manner.