Chemokine Induced Hematopoietic Stem Cell Mobilization

描述（由申请人提供）：动员的外周血干细胞和祖细胞（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并不完整。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GRO β动员的“反式”作用成分，并证明了成熟的多形核中性粒细胞（PMN）在动员中的作用。这些研究提出了这样的假设，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。尽管尚未得到证实，但正在出现的情况是，动员是一个复杂的进程，具有广泛的相互依存性，可以通过多种机制加以刺激。我们假设，似乎是多个机制，可能实际上反映了多个干预点沿着一个中央动员轴，包括粘附辅助受体，趋化因子及其受体和相互依赖的内部和细胞内信号传导组件。我们已经确定了一种利用CXCR 2配体GRO β与CXCR 4拮抗剂AMD 3100组合的新型动员策略，其导致HSPC的意外协同动员，具有增强的干细胞性质，并且当与G-CSF组合使用时具有额外的协同作用。我们假设这些细胞可能代表更好的造血移植和基因治疗。动员机制的研究导致我们的第二个假设，协同动员的结果从CXCR 4和CXCR 2受体之间的意想不到的受体串扰，导致升高和持续的PMN释放的蛋白酶，特别是MMP-9，促进细胞的出口。在本申请中，我们提出表征单独的GRO β + AMD 3100和G-CSF动员的HSPC群体，确定相对于PMN和MMP-9的动员作用机制，并评估GRO β + AMD 3100动员的HSPC作为用于造血移植和基因治疗应用的改进的造血细胞移植物的效用。项目相关性：识别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，并通过优化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.