Directed In Vitro Myogenesis of Human Embryonic Stem Cells and Their In Vivo Engraftment

Development of human embryonic stem cell (hESC)-based therapy requires derivation of in vitro expandable cell populations that can readily differentiate to specified cell types and engraft upon transplantation. Here, we report that hESCs can differentiate into skeletal muscle cells without genetic manipulation. This is achieved through the isolation of cells expressing a mesodermal marker, platelet-derived growth factor receptor-α (PDGFRA), following embryoid body (EB) formation. The ESC-derived cells differentiated into myoblasts in vitro as evident by upregulation of various myogenic genes, irrespective of the presence of serum in the medium. This result is further corroborated by the presence of sarcomeric myosin and desmin, markers for terminally differentiated cells. When transplanted in vivo, these pre-myogenically committed cells were viable in tibialis anterior muscles 14 days post-implantation. These hESC-derived cells, which readily undergo myogenic differentiation in culture medium containing serum, could be a viable cell source for skeletal muscle repair and tissue engineering to ameliorate various muscle wasting diseases.基于人类胚胎干细胞（human embryonic stem cell, hESC）的治疗技术开发，需要获取可在体外扩增、能够定向分化为特定细胞类型且移植后可成功定植的细胞群。本研究证实，人类胚胎干细胞可无需遗传操作即可分化为骨骼肌细胞：具体方法为在拟胚体（embryoid body, EB）形成后，分离表达中胚层标志物血小板衍生生长因子受体-α（platelet-derived growth factor receptor-α, PDGFRA）的细胞。该胚胎干细胞来源的细胞可在体外分化为肌母细胞，无论培养基是否含血清，多种肌源性基因的表达上调均可证明这一点。终末分化细胞标志物肌节肌球蛋白与结蛋白的存在进一步验证了该实验结果。体内移植实验显示，这些成肌前定向细胞在植入后14天仍可在胫骨前肌中存活。这类可在含血清的培养基中高效发生肌源性分化的人类胚胎干细胞来源细胞，有望成为骨骼肌修复与组织工程的理想细胞源，用于改善各类肌肉萎缩性疾病。