Objective To investigate the differentiation of rat bone marrow mesenchymal stem cells (MSCs) into myocytes and their expression of dystrophin/utrophin after transplantation in mdx mice. Methods BrdU-labeled fifth-passage rat MSCs were transplanted in mdx mice with previous total body γ irradiation (7 Gy). At 4,8,12 and 16 weeks after the transplantation,the mice were sacrificed to detect dystrophin/BrdU and utrophin expressions in the gastrocnemius muscle using immunofluorescence assay,RT-PCR and Western b...