Self-Renewing Presomitic Mesoderm Progenitor Lines Reprogrammed from human urine cells [xxx 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 Building library and sequencing process of producing cells that have been transplanted into mouse -- skeletal muscle cells Day 30 (overexpression of MYOD), Day 60 and urine cells

脊椎形成是所有脊椎动物的标志性特征1,2。不同脊椎动物物种沿脊柱形成体节的时序调控机制各具特色3-5。受限于技术与伦理层面的诸多约束，人类脊椎形成的相关研究仍较为匮乏。本研究通过重编程从人尿液中分离的上皮细胞，成功获得了具有典型节前体中胚层（presomitic mesoderm, PSM）特征的可自我更新干细胞。这类诱导扩增型节前体中胚层祖细胞（induced expandable presomitic mesoderm progenitor cells，UiPSM）可在化学成分明确的培养体系中广泛增殖，传代次数超过30次，可稳定扩增至10^40量级的细胞群体。该细胞群呈现典型的节前体中胚层转录谱，未检测到多能性、外胚层及内胚层相关基因的表达。UiPSM可在体内外分化为节前体中胚层谱系细胞，包括骨骼肌细胞（skeletal muscle cells, skm）、成骨细胞与软骨细胞。将UiPSM来源的人源骨骼肌细胞移植入肌肉损伤模型后，这些细胞可在体内存活长达1个月，并参与肌肉再生过程。综上，UiPSM是研究人类体节发育的高效研究体系，可为肌肉骨骼系统的再生医学研究提供全新策略。本研究同时完成了移植至小鼠体内的相关细胞的文库构建与测序流程，样本涵盖第30天（MYOD过表达）的骨骼肌细胞、第60天样本及尿液来源细胞。