Five transcriptional factors reprogram fibroblast into myogenic lineage cells via paraxial mesoderm stage

It is hard to supply satellite cells as a cell source for therapy of muscle degenerative disease since the sampling of muscle tissue is very invasive to a patient with muscular disease. Direct conversion allows us to get specific cell types by transduction of defined transcriptional factors. To induce myogenic direct conversion, we transduced five transcriptional factors including Pax3, Sox2, Klf4, c-Myc, and Esrrb into mouse embryonic fibroblasts. We found that the transduction of the five transcriptional factors induced myogenic direct conversion of fibroblast. We revealed that the transduced cells with the five transcriptional factors were converted to myogenic lineage cells through a paraxial mesoderm-like stage. The expression level of myogenic-related genes of the transduced cells gradually increased as the passage increased. The induced myogenic lineage cells differentiated into muscle fibers <i>in virto</i> and <i>in vivo</i>. The current study revealed that the five transcription factors generated myogenic lineage cells from fibroblast via a paraxial mesoderm stage. The induced myogenic lineage cells may have a potential being applied as cell source for degenerative muscle disease.

由于肌肉组织活检对肌肉疾病患者具有极强侵入性，因此难以获取肌卫星细胞（satellite cells）作为肌肉退行性疾病治疗的细胞来源。直接重编程（direct conversion）技术可通过向细胞转导特定转录因子（transcriptional factors），从而获得目标特异性细胞类型。为诱导肌源性直接重编程，我们将Pax3、Sox2、Klf4、c-Myc及Esrrb五种转录因子转导至小鼠胚胎成纤维细胞（mouse embryonic fibroblasts）中。实验发现，该五种转录因子的转导可诱导成纤维细胞发生肌源性直接重编程。我们进一步揭示，经五种转录因子转导的细胞会通过类轴旁中胚层（paraxial mesoderm-like）阶段，最终分化为肌源性谱系细胞（myogenic lineage cells）。随着传代次数增加，转导细胞中肌源性相关基因的表达水平逐渐升高。所诱导获得的肌源性谱系细胞可在体外（in vitro）与体内（in vivo）环境中分化为肌纤维。本研究证实，这五种转录因子可通过轴旁中胚层阶段，将成纤维细胞重编程为肌源性谱系细胞。所诱导的肌源性谱系细胞具备作为细胞来源应用于肌肉退行性疾病治疗的潜力。