Abstract: Objective After inducing and differentiating by different ways, we investigated the ability that mesenchymal stem cells( MSCs) differentiating into cardiomyocytes(CMs) and studied the differences that MSCs express cardiac cell-specific markers.Methods MSCs and CMs were isolated and cultivated, then MSCs were induced by 5-Aza-2'-deoxycytidine(5-aza), cocultured with CMs and cultured alone after labeled by 4 ,6-dimidino-2-phenylindone( DAPI) at the third passage. On the 1,2,3 and 4 weeks , DAPI-MSCs were observed the cell morphology and identified troponinT (cTnT) and connexin(Cx)43 by immunohistochemistry.Results DAPI-MSCs was't found shrinkage and the expression of cTnT and Cx43 in the control group. In the induction group and the co-culture group, the cells were found to be orientating with one accord, arranging into a muscular at 4 week. In the induction group ,the expression of cTnT and Cx43 was not observed at 1 week. In the co-culture group, the expressions of cTnT and Cx43 were detected at 5th day and increased with time .In the same weeks, the positive rate of cTnT and Cx43 in the co-culture group was higher than the rate of induction group（P＜0.01).Conclusion After induced by 5-aza and co-cultured with CMs,the MSCs could transformed into cardiomyocyte-like cells and expressed cTnT and Cx43. The ability of MSCs differentiated into CMs in the co-culture group was stronger than that of the induction group.

Key words: Bone marrow mesenchymal stem cells, cardiomyocytes, 5-Aza-2’-deoxycytidine, coculture