Abstract: Objective To explore the effect of embryonic stem cells(ESCs) differentiating into cardiomyocytes(CM ) by cardiomyocytes. Methods The blastocytes of 3.5d from Kunming species mouse,cultured on mouse embryonic fibroblaste cell feeder layers for 4～5d, and the mouse ESCs were isolated and subsequently cultured in vitro. Day 2～3 embryoid bodies(EBs) were derived from ESCs of passage 3 to 5 and then cocultured with neonatal cardiomyocyte(CM) to induce into cardiomyocytes and the expression of cardiac specific cardiac troponin-T(TnT) and а-Actin were detected by immunofluoresence. Result The rhythmic beating embryoid bodies were observed on day 3and reached 93％ of rhythmic beating embryoid bodies on 12 day in group 2.All the beating cardiomyocytes derived from ESCs expressed cardiac-specific proteins for TnT and а-Actin, and the group induced by direct cell to cell contact acquired the highest differentiating ratio of 56.5%,and was the highest differentiating ratio compared with other groups (p<0.05).Conclusion Both cardiomyocyte coculturing system and cardiomyocyte-lysate system can induce mouse ESCs to differentiate into cardiomyocyte-like cells and the induced effect of direct cell-to-cell interaction with neonatal cardiomyocytes was higher than cardiomyocyte-lysate.

Key words: Embryonic stem cell, Coculture, Differentiation, Cardiomyocyte