摘要Bone marrow-derived mesenchymal stem cells are multipotent stem cells,an attractive resource for regenerative medicine.Accumulating evidence suggests that all-trans retinoic acid plays a key role in the development and differentiation of smooth muscle cells.In the present study,we demonstrate,for the first time,that rabbit bone marrow-derived mesenchymal stem cells differentiate into smooth muscle cells upon the treatment with all-trans retinoic acid.All-trans retinoic acid increased the expression of myocardin,caldesmon,22-kDa smooth muscle cellspecific protein(SM22α),and SM-myosin heavy chains in rabbit bone marrow-derived mesenchymal stem cells,as detected by reverse transcription polymerase chain reaction(PCR).Immunostaining of SM22α and SM-myosin heavy chains using monoclonal antibodies also indicated smooth muscle cell differentiation of rabbit bone marrowderived mesenchymal stem cells following the treatment with all-trans retinoic acid.In addition,more than 47% of bone marrow-derived mesenchymal stem cells demonstrated the contractile phenotype of smooth muscle cells.Western blot results showed that SM-1 and SM-2 were highly expressed in the differentiated cells.These results suggest that all-trans retinoic acid may serve as a potent agent for functional smooth muscle cell differentiation in tissue engineering.