Adult Hemangioblast/HSC Recruitment and Maintenance

描述（由申请人提供）：我们已经证明成体造血干细胞（HSC）能够发挥成血管细胞的功能。使用成人视网膜新生血管形成的独特模型，我们进行了一系列实验，以询问成人HSC是否通过促进血液和血管修复来响应缺血性损伤而表现出成血管细胞活性。骨髓移植受者持久重建与一个单一的供体HSC从同源小鼠表达GFP。在每只动物的一个视网膜中诱导缺血。通过共聚焦显微镜观察由GFP+内皮细胞组成的新分化的血管簇，检测骨髓衍生的后代在视网膜上的生理定位。流式细胞术和荧光显微镜检查证实了移植受者的完全多系造血重建。这项研究首次证明了成体干细胞在移植环境中可以表现出功能可塑性。在本提案中，我们试图利用这一独特的模型来解决以下假设：目标1。假设：通过成血管细胞活性重塑内皮生态位是骨髓移植后骨髓重塑的第一步。目标二。假设：HSC成血管细胞活性产生具有分化为内皮细胞潜能的细胞的发育层次。利用我们的模型，我们可以定义这种新的造血活性的谱系关系和表型。目标3。假设：HSC是循环内皮祖细胞的来源。因此，影响HSC或白细胞迁移的因素将影响EPC的产生和募集。

DESCRIPTION (provided by applicant): We have proven that the adult hematopoietic stem cell (HSC) is able to function as a hemangioblast. Using a unique model of adult retinal neovascularization, we performed a series of experiments to ask if adult HSC exhibit hemangioblast activity by contributing to both blood and blood vessel repair in response to ischemic injury. Bone marrow transplant recipients were durably reconstituted with a single donor HSC from congenic mice expressing Gfp. Ischemia was induced in one retina per animal. Physiological localization of marrow-derived progeny to retina was detected by confocal microscopy of newly differentiated vascular tufts composed of Gfp+ endothelial cells. Both FACS and fluorescent microscopy confirmed full multilineage hematopoietic reconstitution of the transplant recipients. This study is the first to prove that an adult stem cell can exhibit functional plasticity in a transplant setting. In this proposal we seek to utilize this unique model to address the following hypotheses: Aim 1. Hypothesis: Remodeling of the endothelial niche by hemangioblast activity is the initial step in bone marrow remodeling following bone marrow transplant. Aim 2. Hypothesis: HSC hemangioblast activity produces a developmental hierarchy of cells with the potential to differentiate into endothelial cells. With our model we can define the lineage relationships and phenotypes of this new hematopoietic activity. Aim 3. Hypothesis: HSC are the source of circulating endothelial progenitors. Therefore, factors that affect HSC or leukocyte migration will affect EPC production and recruitment.