Functional Analysis of Hematopoietic Stem Cell Origin

描述(由申请人提供)：这份R21申请结合了 两个独立实验室的专业知识来解决一个关键问题 关于我们对造血个体发育--发育起源的理解 造血干细胞(HSC)。 在小鼠胚胎中，原始造血祖细胞出现在卵黄囊中。 原肠发育期间(E7.0-E8.5)。而最终的血细胞在体内分化 从E.9.5开始的胎肝，HSC具有移植成人的能力 受者只有在胚胎10岁时才会在胚胎内部首先出现。最近的一次 “胚胎”造血干细胞提供新生儿的长期植入，但不是成人， 受体在卵黄囊和胚胎中均已确定为E9.0。它 目前尚不清楚这些HSC是起源于胚胎内还是胚胎外 (卵黄囊)部位。在初步实验中，J.Palis已经发现 具有高增殖能力的造血细胞仅在 循环前小鼠胚胎的卵黄囊(E8.25)。我们假设 胚胎HSC在原肠发育过程中也产生于胚外部位。在 这项提议的第一个目的是，我们将使用宫内移植模型来 确定哺乳动物造血干细胞的发育来源 精确分期的小鼠胚胎的囊状细胞和胚胎固有细胞 E9.5将被直接移植到E14.5 W42胎儿的肝脏中。这 独特的移植系统将最大限度地提高我们鉴定造血干细胞的能力 植入后早期胚胎内的活动。在此的第二个目标中 建议，我们将研究嫁接的时间和空间动力学。 造血器官由胚胎和胎儿的造血干细胞组成。这些 实验将利用表型定义的E9.5卵黄囊和 E14.5表达增强型绿色荧光的肝脏供体干细胞群 蛋白 更好地了解哺乳动物造血的启动将 提供对HSC的个体发育、调节和扩展的见解，以及 白血病和骨髓衰竭综合征的起源。这一知识将会 最终提高骨髓移植的治愈率 治疗先天性贫血、遗传性疾病以及许多儿童和成人 癌症。

DESCRIPTION (provided by applicant): This R21 application combines the expertise of two independent laboratories to address a pivotal question regarding our understanding of hematopoietic ontogeny- the developmental origin of hematopoietic stem cells (HSC). In the mouse embryo, primitive hematopoietic progenitors arise in the yolk sac during gastrulation (E7.0-E8.5). While definitive blood cells differentiate in the fetal liver beginning at E.9.5, HSC with the ability to engraft adult recipientsfirst arise within the embryo proper only at E10. Recently an "embryonic" HSC that provides long-term engraftment of newborn, but not adult, recipients has been identified at E9.0 in both yolk sac and embryo proper. It is not known if these HSC arise from intraembryonic (AGM) or extraembryonic (yolk sac) sites. In preliminary experiments, J. Palis has identified hematopoietic cells with high proliferative potential exclusively within the yolk sac of the pre-circulation mouse embryo (E8.25). We hypothesize that embryonic HSC also arise from extraembryonic sites during gastrulation. In the First Aim of this proposal, we will use an in utero transplantation model to determine the developmental origin of mammalian hematopoietic stem cells.Yolk sac and embryo proper cells from accurately staged mouse embryos between E7.5 - E9.5 will be transplanted directly into the livers of E14.5 W42 fetuses. This unique transplantation system will maximize our ability to identify HSC activity within the early post-implantation embryo. In the Second Aim of this proposal, we will study the temporal and spatial kinetics of engraftment of hematopoietic organs by embryonic and fetal hematopoietic stem cells. These experiments will take advantage of phenotypically defined E9.5 yolk sac and E14.5 liver donor stem cell populations expressing enhanced green fluorescent protein A better understanding of the initiation of mammalian hematopoiesis will provide insights into the ontogeny, regulation and expansion of HSC, as well as the origin of leukemias and bone marrow failure syndromes. This knowledge will ultimately lead to improvements in bone marrow transplantation for the curative treatment of congenital anemias, genetic diseases and many childhood and adult cancers.