Analysis of Homing Receptors on Human Adult Stem Cells

描述（由申请人提供）： 虽然许多人已经证明成体干细胞在各种非造血组织中具有广泛的再生能力，但关于成体干细胞迁移到骨髓以外的部位的分子机制还没有可用的信息。为了离开血管室，所有循环细胞必须首先结合到靶组织处的内皮。血液中的细胞与内皮之间的关键初始粘附相互作用通常被描述为“滚动”，由此流动中快速移动的细胞开始在内皮表面上“制动”。该过程由白细胞“归巢受体”介导，其由专门用于滚动相互作用的分子如L-选择蛋白、PSGL-1、CD 44和整合素VLA-4、LFA-1和α 4 β 7组成。虽然关于这些分子在调节成熟白细胞运输和人CD 34+造血祖细胞向骨髓中的迁移中的作用已知很多，但是关于这些分子的表达和活性几乎一无所知，因为它们涉及人成体干细胞向非造血位点的迁移。我们假设，为了实现用于受损器官再生的输注成体干细胞的充分组织递送，需要成体干细胞上的一种或多种归巢受体在功能上是完整的，此外，这些分子的相对表达/活性将部分决定细胞迁移到相关非造血组织的能力。在这项提案中，我们将研究重点放在人类骨髓中的成体干细胞上，因为这种来源为未来的临床应用提供了最容易获得和数量最多的成体干细胞。我们的目的是确定的人骨髓来源的成体干细胞，包括造血干细胞（HSC），间充质干细胞（MSC）和多能成体祖细胞（MAPC）的定义群体的表达和功能能力的已知归巢受体。此外，为了确定干细胞是否表达新的归巢受体，我们将利用实验室新开发的技术来检查在剪切条件下可以作为结合相互作用的介质的膜分子的全谱。基于来自这些研究的信息，我们将分析人成体干细胞-人内皮细胞的相互作用和人成体干细胞向非造血组织的迁移，使用人体皮肤移植到免疫缺陷小鼠的体内模型系统。预期这些研究的结果将指导策略的开发，以实现人成体干细胞从脉管系统到靶器官的高效递送，用于再生治疗的临床应用。

DESCRIPTION (provided by applicant): Though many have demonstrated that adult stem cells have broad regenerative capacity in a variety of non-hematopoietic tissues, there is no information available on the molecular mechanism(s) by which adult stem cells migrate to sites other than bone marrow. To exit the vascular compartment, all circulating cells must first bind to the endothelium at the target tissue. The key initial adhesive interactions between cells in blood and endothelium are generally described as "rolling", whereby the fast moving cells in flow begin to "brake" on the endothelial surface. This process is mediated by leukocyte "homing receptors" which consist of molecules specialized for rolling interactions such as L-selectin, PSGL-1, CD44, and the integrins VLA-4, LFA-1 and alpha4beta7. While much is known about the role(s) of these molecules in regulating mature leukocyte trafficking and the migration of human CD34+ hematopoietic progenitor cells into bone marrow, virtually nothing is known about the expression and activity of these molecules as they relate to migration of human adult stem cells to non-hematopoietic sites. We hypothesize that to achieve adequate tissue delivery of infused adult stem cells for regeneration of damaged organs requires that one or more of the homing receptors on adult stem cells be functionally intact and, moreover, that the relative expression/activity of these molecules will determine in part the capacity of the cells to emigrate to relevant non-hematopoietic tissues. In this proposal, we focus our studies on adult stem cells residing in human bone marrow, as this source provides the most accessible and quantitatively greatest amount of adult stem cells for future clinical applications. We aim to define the profile of expression and the functional capabilities of known homing receptors on defined populations of human bone marrow-derived adult stem cells including hematopoietic stem cells (HSCs), mesenchymal stem cells (MSC) and multipotential adult progenitor cells (MAPC). Moreover, to determine whether stem cells express novel homing receptors, we will utilize newly developed technology in our laboratory to examine the full spectrum of membrane molecules that can function as mediators of binding interactions under shear conditions. Based on information derived from these studies, we will analyze human adult stem cell-human endothelial interactions and the migration of human adult stem cells to non-hematopoietic tissue using an in vivo model system of human skin transplanted onto immunodeficient mice. It is anticipated that the results of these studies will guide the development of strategies to achieve high efficiency delivery of human adult stem ceils from the vasculature into target organ(s) for clinical applications of regeneration therapy.