Comparison of differentiation of bone marrow mesenchymal stem cells treated with 5-azacytidine on different moments

Objective To compare the effects of 5-azacytidine aclministered at different moments on differentiation of bone marrow mesenchymal stem cells(MSCs).Methods MSCs were isolated from female Wistar rats. The cells were divided randomly into 6 groups(groups A to F of 12 each).MSCs were exposed to 5-aza cytidine(10 μmol·L-1) for 24 hours in each induction.Group A were induced on hour 72 of primary culture,group B on 72 hour of passage 5,group C on 72 hour of passage 10,group D on 72 hour of passage 15,group E on hour 72 of primary culture and 72 hour of passage 5,whereas group F was used as control.Twenty-one days after treatment,MSCs were identified by immunocytochemistry technique.The positive rates of each group were compared.Results MSCs treated with 5-aza cytidine could be identified by the positive staining for myosin heavy chains(MHC) and cardiac specific troponin-T.Groups A,B and E did not differ significantly between them(P0.05);however,they had more positive rates than groups C and D(P0.05).Conclusions MSCs treated with 5-azacytidine can differentiate into cardiac-like muscle cells.With increasing number of passages,the directional differentiation of MSCs is decreased.As donor cells,MSCs of passage 3～5 are recommended.