Self-Renewing Presomitic Mesoderm Progenitor Lines Reprogrammed from human urine cells [UiPSC and UiPSM scRNA-seq]. Self-Renewing Presomitic Mesoderm Progenitor Lines Reprogrammed from human urine cells [UiPSC and UiPSM scRNA-seq]

Vertebrae formation is the defining feature of all vertebrates1,2. Yet, each vertebrate species appears to have a unique timing mechanism for forming somites along the vertebral column3-5. Human vertebrate formation remains poorly studied due to technical and ethical limitations. Here we report the generation of self-renewing stem cells with characteristic presomitic mesoderm (PSM) features by reprogramming epithelial cells isolated from human urine. These induced expandable presomitic mesoderm progenitor cells (UiPSM) proliferated extensively for more than 30 passages in chemically defined conditions, robustly producing 1040 UiPSM cells. UiPSM established presomitic mesodermal transcription profile, not detected pluripotency, ectoderm and endoderm related genes. UiPSM developed into presomitic mesodermal lineage cells, such as skeletal muscle cells(skm), osteoblast and chrondroblast cells in vivo and vitro, when transplanted UiPSM derived human skm cells in muscle injury model, the skm cells can survive in vivo and contribute to muscle regeneration up to one month. Thus, UiPSM is a powerful system to study human somite development and provide strategies for regenerative medicine in musculoskeletal system Overall design: Building library and sequencing process of producing teratoma cells of UiPSC and UiPSM

脊椎形成是所有脊椎动物（vertebrate）的标志性特征[1,2]。然而，不同脊椎动物物种沿脊柱形成体节（somite）的时序调控机制各具特色[3-5]。受限于技术与伦理双重因素，目前人类脊椎形成的相关研究仍较为薄弱。本研究通过重编程从人类尿液中分离得到的上皮细胞，成功构建了具备典型前体节中胚层（presomitic mesoderm, PSM）特征的自我更新干细胞系。该诱导得到的可扩增前体节中胚层祖细胞（UiPSM）可在化学成分明确的培养体系中大量增殖，传代次数超过30次，最终可稳定生成1040个UiPSM细胞。UiPSM细胞呈现出典型的前体节中胚层转录组特征，未检测到多能性、外胚层及内胚层相关基因的表达。UiPSM可在体内外定向分化为前体节中胚层谱系细胞，包括骨骼肌细胞（skm）、成骨细胞与成软骨细胞；将UiPSM来源的人类骨骼肌细胞移植至肌肉损伤模型后，该细胞可在宿主体内存活，并在长达1个月的时间内参与肌肉再生过程。综上，UiPSM是研究人类体节发育的高效研究体系，同时可为肌肉骨骼系统的再生医学研究提供全新策略。整体实验设计：UiPSC与UiPSM的畸胎瘤细胞建库及测序流程