Induced Bone Marrow-derived Human Mesenchymal Stem Cells Into Cardiomyocytes In Vitro

Objective Our goals were the isolation, characterization of bone marrow-derived human mesenchymal stem cells, and study their potential differentiation "in vitro" into cardiomyocytes. Methods In present studies, MSCs from human BM were isolated by Ficoll density centrifugation and cultured expanded in L-DMEM containing FBS, then these cells were treated with 5-azacytidine for 24 hour. After cultured for additional 2 weeks, these cells were identified by means of immunochemistry and transmission electron microscopy. Result hMSCs are adherent and fibroblastic, and maintained similar morphology with passaging. Flow cytometry analysis indicated that hMSCs were universally negative for CD34, CD45, CD31, and weakly positive for CD90. hMSCs showed a fibroblast- like morphology before treated with 5-azacytidine, but the morphology changed after 5-azacytidine treatment in most of the cells; they connected with adjoining cells after 1 week, formed myotube-like structures.2 weeks after induction, immunohistochemistry show that the induced cells were positive for desmin, connexin-43 and atrial natriuretic peptide. Electron microscopy revealed typical sarcomeres, a centrally positioned nucleus, and atrial granules-like ultra-structure. Conclusion 1) Ficoll separating medium is a well medium for density gradient centrifugation of hMSCs; 2) hMSCs have a capacity for extensive self-renewal, and apparently maintain themselves throughout the long-term culture.3) hMSCs are multipotential stem cells, they were able to differentiate "ex vivo" into cardiac-like muscle cells.