Identification and Characterization of the Presomitic Mesoderm Progenitor

描述（由申请人提供）：身体中胚层组织的疾病，包括伤口愈合、关节炎、骨质疏松症和肌肉萎缩性疾病，影响着地球仪的数百万人。如果现有的障碍，有效地衍生中胚层组织从现成的，病人匹配的干细胞可以克服，这些疾病可以治疗干细胞为基础的再生医学。不幸的是，从胚胎干细胞（ESC）和诱导的多能干细胞（IPSC）稳健定向分化中胚层目前仅限于心血管和血液衍生物。用于分化肌肉、软骨和结缔组织，或更具体地说，仅由前体节中胚层（PSM）产生的那些中胚层衍生物的可再现方案尚未出现。虽然可以从人ESC获得后中胚层的一些细胞类型，但在这些组织的再生程序可行之前，必须大大提高这些效率（通常<1%）。 以前的研究表明，存在一个内源性PSM祖细胞（PSM-Pr）细胞位于原始条纹和亨森结（PSM-Pr龛）的边界。PSM-Pr的后代定殖于近轴中胚层并产生体节，体节又产生胚胎的骨骼肌、软骨和结缔组织。本文所述工作的主要重点是鉴定和彻底表征包含和维持内源性祖干细胞及其小生境的细胞类型。 在这个项目中，我们将（1）确定所有细胞类型位于边界 区域和（2）评估关键信号通路在维持PSM-Pr和PSM-Pr生态位中的作用。这些目标的成功完成将为体节中胚层的产生提供前所未有的洞察力，并使新的方法能够产生用于临床用途的治疗相关的中胚层细胞类型。 公共卫生相关性：这项探索性资助的目标是鉴定前体中胚层的长期祖细胞，并描述维持这种细胞类型及其生态位所需的功能。这些知识将提供重要的洞察力， 脊椎动物轴向中胚层的生成，因此也转化为肌肉骨骼先天缺陷和人类疾病。此外，PSM-Pr及其生态位的鉴定和表征将为用于治疗肌肉骨骼疾病（包括伤口愈合、关节炎、骨质疏松症和肌肉萎缩性疾病）的中胚层衍生物的引导分化提供基础。

DESCRIPTION (provided by applicant): Diseases of the mesodermal tissues of the body including wound healing, arthritis, osteoporosis and muscular wasting diseases, affect millions of people across the globe. If existing barriers to the efficient derivation of mesodermal tissues from readily-available, patient-matched stem cells could be overcome, these diseases could be treated with stem cell-based regenerative medicine. Unfortunately, robust directed differentiation of mesoderm from embryonic stem cells (ESC) and induced pluripotent stem cells (IPSC) is currently limited to cardiovascular and blood derivatives. Reproducible protocols for the differentiation of muscle, cartilage, and connective tissues, or more specifically, those mesodermal derivatives produced solely from pre-somitic mesoderm (PSM), have yet to emerge. While it is possible to obtain some cell types of the posterior mesoderm from human ESC, these efficiencies (commonly <1%) must be vastly improved before regenerative procedures for these tissues will be feasible. Previous studies have indicated the presence of an endogenous PSM-progenitor (PSM-Pr) cell located at the border of the primitive streak and Hensen's node (the PSM-Pr niche). Progeny of the PSM-Pr colonize the paraxial mesoderm and give rise to the somites, which in turn produce the skeletal muscle, cartilage, and connective tissue of the embryo. The primary focus of the work described here is to identify and exhaustively characterize the cell types that comprise and maintain the endogenous progenitor stem cell and its niche. In this project we will (1) identify all cell types located in the border region and (2) evaluate the role of key signaling pathways in the maintenance of the PSM-Pr and the PSM-Pr niche. Successful completion of these goals will provide unprecedented insight into the generation of somitic mesoderm and enable novel approaches to the generation of therapeutically relevant mesodermal cell types for clinical use. PUBLIC HEALTH RELEVANCE: The goals of this exploratory grant are to identify the long-term progenitor of the pre-somitic mesoderm and characterize functions required for the maintenance of this cell type and its niche. This knowledge will provide important insight into the generation of vertebrate axial mesoderm and, therefore, also into musculoskeletal birth defects and human disease. Moreover, identification and characterization of the PSM-Pr and its niche will provide a foundation for the guided differentiation of mesodermal derivatives for the treatment of musculoskeletal disorders including, wound healing, arthritis, osteoporosis, and muscle wasting diseases.