Analysis of Homing Receptors on Human Adult Stem Cells

描述(由申请人提供)： 尽管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，但还没有关于成体干细胞迁移到骨髓以外的部位的分子机制的信息(S)。为了离开血管隔室，所有循环细胞必须首先与靶组织处的内皮结合。血液中细胞与内皮细胞之间最初的关键黏附作用通常被描述为“滚动”，即流动中的快速移动的细胞开始在内皮表面“刹车”。这一过程是由白细胞的归巢受体介导的，归巢受体由专用于滚动相互作用的分子组成，如L-选择素、PSGL-1、CD44以及整合素VLA-4、LFA-1和α4β7。虽然这些分子在调节成熟的白细胞运输和人类CD34+造血祖细胞向骨髓迁移中的作用(S)已知很多，但几乎对这些分子的表达和活性知之甚少，因为它们与人类成年干细胞向非造血部位的迁移有关。我们推测，为了获得足够的输注的成体干细胞的组织输送以再生受损的器官，需要成体干细胞上的一个或多个归巢受体在功能上是完整的，而且这些分子的相对表达/活性将在一定程度上决定细胞向相关非造血组织迁移的能力。在这项建议中，我们将重点研究驻留在人类骨髓中的成体干细胞，因为这一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。我们的目标是确定已知的归巢受体在确定的人类骨髓来源的成体干细胞群体上的表达和功能能力，包括造血干细胞(HSCs)、间充质干细胞(MSC)和多潜能成体祖细胞(MAPC)。此外，为了确定干细胞是否表达新的归巢受体，我们将利用我们实验室最新开发的技术来检测在剪切条件下可以作为结合相互作用媒介的膜分子的全谱。基于来自这些研究的信息，我们将使用人皮肤移植到免疫缺陷小鼠的活体模型系统来分析人类成体干细胞与人内皮细胞的相互作用以及人类成体干细胞向非造血组织的迁移。预计这些研究结果将指导制定策略，实现将人类成体干细胞从血管系统高效输送到靶器官(S)，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.