Abstract: AIM: To observe the effect of cardiotrophin-1 on cardiac differentiation of mouse-induced pluripotent stem cells(miPSCs).METHODS: Differentiation of miPS cells was initiated by embryoid body formation with the hanging drop method.In the experimental group,CT-1 application started at day 3 of the differentiation process(1 μmol/ml,CT-1 group) and normal medium was used in control group.Real-time PCR analysis,immunofluorescence staining,flow cytometry analysis and transmission electron microscope were used to examine the expression of embryonic and cardiac-specific cell markers and the cellular ultramicrostructure at days 4,7,10 and 14.RESULTS: Compared with the control group,expression of cardiac-specific marker cTnT in CT-1 group at day 10 increased 1.75 times(P<0.05).Immunofluorescence staining showed cTnI positive cells in both groups and flow cytometry analysis showed that the rates of cTnI positive cells were 28.5% and 56.4%,respectively(P<0.05).Compared with those in control group,more organized myofibril,mitochondria and cell junction formation were observed in CT-1 group.CONCULSION: CT-1 significantly promotes cardiac differentiation of miPS cells.