BACKGROUND: Several studies have demonstrated that sphingosine-l-phosphate(S1P)can induce the differentiation of adipose-derived stem cells differentiation into smooth muscle cells.Whether S1P,rather than 5-azacytidine,can be used as an inducer of mesenchymal stem cells differentiation into cardiomyocytes remains unclear.OBJECTIVE: To investigate the possibility that S1P promotes human umbilical cord mesenchymal stem cells(HUMSCs)differentiation into cardiomyocytes in the presence of different culture media.METHODS: HUMSCs were cultured with cardiomyocyte conditional medium(CMCM)and/or SIP media.At 1,5,and 10 days of culture,morphological changes of HUMSCs were observed.After culture for 10 days,the induced cells were confirmed by immunocytochemical analysis and patch clamp in terms of cell phenotype and function.RESULTS AND CONCLUSION: During the induction,some cells gradually enlarged,elongated,connected with adjacent cells,and formed myotube-like structures,and some cells congregated into cell clusters in the CMCM and CMCM+S1P groups.In the CMCM+S1P group,cells exhibited special perpendicular terrace-shaped,intercalated disc-like arrangement.Immunohistochemistry results revealed that some cells strongly express specific antibodies against sarcomeric myosin andα-actinin in the CMCM and CMCM+S1P groups.These findings suggest that HUMSCs can be induced to differentiate into cardiomyocytes.Through the use of patch clamp technique,a rapid ascending,but without plateau phase,action potential,a voltage dependent inward current,and a voltage dependent outward current were recorded in some cells from the CMCM+S1P group.These findings indicate that S1P plays a key role in promoting cardiomyogenic differentiation of HUMSCs and functional integration.