[ ABSTRACT] AIM:In order to observe the myocardial differentiation capacity of the dedifferentiated fat ( DFAT) cells treated with vitamin C in vitro.METHODS: DFAT cells were dedifferentiated from the mature rat adipocytes with ceiling adherent culture.The DFAT cells of passage 3 were used in the study.Vitamin C and/or neonatal rat heart tissue lysate were added into the culture medium to induce myocardial differentiation for 3 weeks.The cell morphology was ob-served under microscope.The myocardial-specific markers, such as cTnT, GATA-4 and NKx2.5, were examined by the methods of immunofluorescence, PCR and Western blot.RESULTS:Mature rat adipocytes dedifferentiated into fibroblast-like DFAT cells after ceiling adherent culture.The DFAT cells spontaneously differentiated into cardiomyocyte-like cells under normal culture condition with a low incidence.After treated with neonatal rat heart cell lysate, the DFAT cells be-came cardiomyocyte-like cells that had bigger size, longer shape and myotubule-structure.The expression of cTnT, GATA-4 and NKx2.5 was remarkably increased at both mRNA and protein levels as compared with the normal cultured DFAT cells.The expression of cTnT, GATA-4 and NKx2.5 was further increased in DFAT cells after treating with vitamin C.No spontaneous beating cell was observed.CONCLUSION:Vitamin C enhances the differentiation of DFAT cells into cardio-myocyte-like cells.