Evaluation of Stem Cell Plasticity In Vivo

描述（由申请人提供）：干细胞的能力， 造血系统不仅参与正常的替换和修复 也能重新编程，分化成不相关的细胞， 与多能干细胞相似的知识相结合 存在于多个器官系统中，开辟了干细胞研究的新领域。 需要解决的一个关键问题是这些干细胞是否 构成一个混合的人口，其中每个成员都致力于自己的 胚胎的命运，或一个真正的多能干细胞池存在于各种 组织中为了解决这个问题，在临床相关模型中进行的研究 需要使用单细胞或克隆衍生群体的系统。的 早期妊娠的胎儿代表了一个独特的环境，在其中测定干细胞 分化潜力和可塑性，因为这两个需要多个 细胞类型，由发育中的胎儿的指数生长率产生， 大量感应环境信号的存在。因此，将使用 我们认为羊胎模型是独一无二的，非常适合研究 高度纯化的人类干细胞的分化潜力，以测试 干细胞可塑性存在于各种器官中， 单细胞水平。为此，我们将实现以下具体目标： 确定人骨髓源性的分化潜能/可塑性 干细胞在体内通过检查高度纯化， 逆转录病毒标记的造血干细胞（HSC）群体和克隆 来源的骨髓基质细胞（MSC）不仅分化成细胞， 其他胚胎学衍生物，而且MSC和HSC之间的相互转化 表型，和2）测试的假设，基质祖细胞的各种表型， 胚胎学衍生物在抗原性上与BM中发现的衍生物相当， 表现出类似的可塑性，通过评估克隆种群的能力， 来自内胚层、外胚层和中胚层衍生组织的基质细胞， 在体内分化成不相关的胚胎来源的细胞，和 进行表型分析以鉴定这些基因中常见的标记物， 细胞通过这些研究，我们希望提供新的见解， 潜在的干细胞池在体内，并定义行为， 这些细胞的能力具有潜在的巨大临床价值。

DESCRIPTION (provided by applicant): The ability of stem cells within the hematopoietic system to not only participate in normal replacement and repair but also to reprogram themselves to differentiate into unrelated cell populations combined with the knowledge that similarly pluripotent stem cells reside in multiple organ systems, has opened new fields in stem cell research. A critical question that needs to be addressed is whether these stem cells constitute a mixed population each member of which is committed to its own embryonic fate, or a pooi of truly multipotent stem cells exists within various tissues. To address this question, studies in a clinically relevant model system using single cells or clonally derived populations are required. The early gestational fetus represents a unique setting in which to assay stem cell differentiation potential and plasticity because of both the need for multiple cell types, created by the exponential growth rate of a developing fetus and the presence of a wide array of inductive environmental signals. Thus, will use the fetal sheep model that we feel is unique and ideally suited for studying the differentiative potential of highly purified human stem cells to test the underlying hypothesis that stem cell plasticity exists in various organs at a single cell level. To this end, we will address the following specific aims: I) Determine the differentiative potential/plasticity of human bone marrow derived stem cells in vivo by examining the ability of both highly purified, retrovirally marked populations of hematopoietic stem cells (HSC) and clonally derived marrow stromal cells (MSC) to not only differentiate into cells of other embryologic derivations but also to interconvert between MSC and HSC phenotypes, and 2) Test the hypothesis that stromal progenitor cells of various embryologic derivations are antigenically comparable to those found in BM and exhibit similar plasticity, by evaluating the ability of clonal population of stromal cells from endodermic, ectodermic and mesodermic derived tissues to differentiate in vivo into cells of an unrelated embryologic derivation, and performing phenotypic analysis to identify markers that are common among these cells. With these studies we hope to provide novel insights into the location of latent stem cell poois within the body and define the behavior and capabilities of these cells that are potentially of great clinical value.