Chemokine Induced Hematopoietic Stem Cell Mobilization

描述(申请人提供)：动员的外周血干/祖细胞(HSPC)是造血移植的首选细胞来源；然而，我们对动员过程的了解还不完全。我们和其他人使用细胞和遗传模型的工作已经确定了G-CSF和GRObeta动员的一个反式作用成分，并证明了成熟的中性粒细胞(PMN)在动员中的作用。这些研究导致了一种假说，即蛋白水解酶的释放改变了导致HSPC外周化的黏附和细胞间相互作用。尽管没有得到证实，但正在出现的情况是，动员是一个复杂的过程，具有广泛的相互依存关系，可以通过多种机制加以刺激。我们假设，表面上看起来有多种机制，实际上可能反映了沿着中央动员轴的多个干预点，包括黏附辅助受体、趋化因子及其受体以及相互依赖的细胞间和细胞内信号成分。我们已经确定了一种新的动员策略，将CXCR2配体GRObeta与CXCR4拮抗剂AMD3100结合使用，可以意外地协同动员具有增强干细胞特性的HSPC，并在与G-CSF联合使用时产生额外的协同效应。我们推测，这些细胞可能是移植和基因治疗的更好的造血移植物。动员研究的机制将我们引向第二个假设，即协同动员是由于CXCR4和CXCR2受体之间意想不到的受体串扰导致的，导致PMN释放更多和持续的蛋白酶，特别是基质金属蛋白酶-9，从而促进细胞外流。在这项应用中，我们建议对GRObeta+AMD3100单独动员和联合G-CSF动员的HSPC群体进行鉴定，确定相对于PMN和MMP-9的动员作用机制，并评估GRObeta+AMD3100动员的HSPC作为一种改进的造血细胞移植物在造血移植和基因治疗中的应用。项目相关性：识别干细胞动员中涉及的调控途径将极大地增强我们对干细胞生态位的了解，并奖励我们收集具有增强特性的干细胞群体的优化程序，这将对干细胞移植和基因治疗产生积极影响。

DESCRIPTION (provided by applicant): Mobilized peripheral blood stem and progenitor cells (HSPC) are the preferred cell source for hematopoietic transplantation; however our understanding of the mobilization process is incomplete. Work by us and others using cellular and genetic models have identified a "trans" acting component to mobilization by G-CSF and GRObeta, and the demonstration of a role for mature polymorphonuclear neutrophils (PMN) in mobilization. These studies have led to the hypothesis that release of proteases alters adhesive and intercellular interactions that result in peripheralization of HSPC. Although not proven, what is emerging is that mobilization is a complex process with broad interdependencies that can be stimulated by multiple mechanisms. We hypothesize that what appears to be multiple mechanisms, may in fact reflect multiple points of intervention along a central mobilization axis that includes adhesion co-receptors, chemokines and their receptors and interdependent inter and intracellular signaling components. We have identified a novel mobilization strategy utilizing the CXCR2 ligand GRObeta in combination with the CXCR4 antagonist AMD3100 that results in unexpected synergistic mobilization of HSPC with enhanced stem cell properties, and additional synergy when used in combination with G-CSF. We hypothesize that these cells may represent better hematopoietic grafts for transplant and gene therapy. Mechanism of mobilization studies lead us to a second hypothesis that synergistic mobilization results from unexpected receptor crosstalk between the CXCR4 and CXCR2 receptors that results in elevated and sustained PMN release of proteases, particularly MMP-9, that facilitates cell egress. We propose in this application to characterize the HSPC populations mobilized by GRObeta plus AMD3100 alone and with G-CSF, determine the mechanism of action of mobilization relative to PMN and MMP-9, and evaluate the utility of GRObeta plus AMD3100 mobilized HSPC as an improved hematopoietic cellular graft for hematopoietic transplant and gene therapy application. Project Relevance: Identifying regulatory pathways involved in stem cell mobilization will greatly enhance our knowledge of the stem cell niche and reward us with optimized procedures to collect populations of stem cells with enhanced properties that will positively impact stem cell transplantation and gene therapy.