ObjectiveTo explore the effect of expression of miRNA-21 on bone marrow mesenchymal stem cells (BMSCs).MethodsIn this study, flow cytometry was used to identify the surface-associated antigens of BMSCs. The 10 μmol/L 5-azacytidine was used to induce BMSCs to differentiate to cardiomyocyte-like cells. Immunofluorescence was used to detect the expression of troponin I (cTnI). The samples were assigned to 3 groups: a blank group, a miRNA-21 mimic group, and a negative control (NC) group. The proliferation of BMSCs was detected by methyl thiazolylte-trazolium (MTT), the apoptosis of BMSCs was analyzed by flow cytometry. Western-blotting was used to identify the expression of cTnI and myod in the BMSCs.ResultsThe proliferation of BMSCs was increased, because of the over expression of miRNA-21. But the apoptotic rate of the BMSCs was slower in the miRNA-21 group, on account of the expression of miRNA-21 was higher than that in the NC group and the CK group. The expression of cTnI in the miRNA-21 group was higher than that in the NC group or the CK group.ConclusionThe results suggest that the up-regulation of miRNA-21 enhances proliferation of BMSCs, reduces the apoptosis of BMSCs. miRNA-21 promotes the differentiation of BMSCs, which may pave the way for the treatment directed toward restoring miRNA-21 function for myocardial ischemia.