Chemokine Induced Hematopoietic Stem Cell Mobilization

描述（由申请人提供）：动员外周血干和祖细胞（HSPC）是造血移植的首选细胞来源；然而，我们对动员过程的理解是不完整的。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“反式”作用成分，并证明了成熟多形核中性粒细胞（PMN）在动员中的作用。这些研究提出了一种假设，即蛋白酶的释放改变了导致HSPC外周化的粘附和细胞间相互作用。虽然没有得到证实，但正在出现的是，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，这似乎是多种机制，实际上可能反映了中央动员轴上的多个干预点，包括粘附共受体、趋化因子及其受体以及相互依赖的细胞间和细胞内信号传导成分。我们已经确定了一种新的动员策略，利用CXCR2配体GRObeta与CXCR4拮抗剂AMD3100联合使用，可产生意想不到的协同动员HSPC，增强干细胞特性，并在与G-CSF联合使用时产生额外的协同作用。我们假设这些细胞可能代表更好的移植和基因治疗的造血移植物。动员机制的研究使我们提出了第二个假设，即协同动员是由CXCR4和CXCR2受体之间意想不到的受体串扰引起的，该串扰导致蛋白酶，特别是促进细胞出口的MMP-9的PMN释放升高和持续。本研究拟对GRObeta + AMD3100单独和与G-CSF联合动员的HSPC群体进行表征，确定动员相对于PMN和MMP-9的作用机制，并评估GRObeta + AMD3100动员的HSPC作为造血移植和基因治疗应用的改良造血细胞移植物的效用。项目相关性：确定参与干细胞动员的调控途径将极大地增强我们对干细胞生态位的了解，并奖励我们优化的程序来收集具有增强特性的干细胞群体，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.