Generation of Hematopoietic Stem and Progenitor Cells from Multiple Source-Derived Endothelial Cells

造血干细胞(HSCs)是一个人一生中整个血液系统的中心组织者。最近的发现有力地支持了这样的概念，即HSCs是由妊娠中期的小鼠胚胎中的血源性内皮细胞(HECs)通过一种称为内皮向造血转化(EHT)的过程形成的。因此，深入了解胚胎发育中控制EHT和随后的HSCs成熟的潜在过程可能是从非造血细胞来源高效生成HSCs的关键先决条件，例如诱导多能干细胞(iPS-)。通过消除与异基因干细胞移植相关的危及生命的移植物抗宿主病的风险，IPSC来源的HSCs可能在未来为患者量身定做、基于自体HSC的细胞治疗带来巨大的希望。这个中德联合项目的目标是从胚胎、出生后和多潜能干细胞(PSC)来源的内皮细胞中培养HSC，基于对其个体发育调控机制的洞察。在一种协调的循序渐进的方法中，我们将首先从胚胎和分化的PSCs中纯化血源性内皮细胞亚群，通过转录组分析确定它们的分子特性，并确定它们的发育潜力。由于外源性生态位细胞在不同的解剖部位和不同的发育阶段控制着HSC的发育，我们将研究一组基质细胞是否适合支持小鼠和人类EHT/前HSCs的完全成熟。已发现在体外和体内系统中特异和一致表达的基因，包括最近发现的两个候选基因，将通过在内皮细胞和造血细胞中的异位表达和组织特异性敲除来询问它们在造血干细胞的出现、成熟和扩张中的作用。

Hematopoietic stem cells (HSCs) are the central organizers of the entire blood system throughout the lifetime of an individual. Recent findings strongly support the concept that HSCs are formed from hemogenic endothelial cells (HECs) in mid-gestation mouse embryos by a process termed endothelial-to-hematopoietic transition (EHT). Therefore, a deeper understanding of the underlying processes controlling EHT and the subsequent maturation of HSCs during embryonic development presumably is a key prerequisite for the efficient generation of HSCs from non-hematopoietic cell sources, such as induced pluripotent stem (iPS-) cells. iPSC-derived HSCs may hold great promise for patient-tailored, autologous HSC-based cell therapies in future by eliminating the risk of a life-threatening graft-versus-host disease associated with allogeneic stem cell transplantation.The aim of this joint Chinese-German project is to generate HSCs from endothelial cells of embryonic, postnatal and pluripotent stem cell (PSC) - derived sources, based on insights into the regulatory mechanisms of their ontogeny. In a coordinated step-by-step approach, we will first purify hemogenic endothelium subpopulations both from embryos and differentiating PSCs, define their molecular identity by transcriptome analysis and determine their developmental potencies. Because extrinsic niche cells are known to control HSC development at different anatomical sites and during different developmental stages, we will investigate the suitability of a set of stroma cells to support a full maturation of the post-EHT/pre-HSCs of mice and humans. Genes found to be specifically and concordantly expressed both in the in vitro and in vivo systems, including two recently identified candidates, will be interrogated for their role in the emergence, maturation and expansion of HSCs by ectopic expression and tissue-specific knockouts in endothelial and hematopoietic cells.