Recruiting activated endothellal progenitor cells to wounds by hyperoxia & SDF-1a

描述(申请人提供)：据估计，多达200万美国人患有无法愈合的腿部伤口，其中大多数是糖尿病的并发症。骨髓源性内皮祖细胞(BMD-EPC)是出生后血管生成的关键细胞效应器，对创面愈合有重要作用。糖尿病患者BMD、EPC缺乏。高压氧(HBO2)诱导的高氧是一种安全的、FDA批准的辅助疗法，用于刺激糖尿病患者的伤口愈合，但其作用机制尚不清楚，且HBO2并不是统一有效的，尤其是对糖尿病合并周围动脉病变(PAD)的糖尿病患者，原因是糖尿病/缺血性慢性无法愈合的下肢伤口仍然是一个未解决的临床问题。在初步研究中，我们已经确定，由临床相关的HBO2方案引起的高氧可以增加股骨骨髓中一氧化氮(.NO)的水平，加速手术诱导的后肢缺血的自发血运重建，并增加循环中的BMD EPC数量。更多的初步研究表明，基质细胞衍生生长因子11(SDF-1)是一种通过其受体CXCR4介导EPC归巢的趋化因子，在糖尿病创面中减少，SDF-1伤口注射部分修复了创面BMD EPC募集中的糖尿病缺陷，并(与高氧)协同促进糖尿病创面的愈合。我们的总体目标是开发治疗腿部慢性伤口患者的新策略。我们假设高氧诱导BMD-EPC的释放，然后这些细胞可能通过高氧诱导的激活和它们在血池中的数量增加而被招募到创面；然而，增强EPC归巢的局部伤口干预(如增加EPC归巢趋化因子水平，SDF-1)可能对于这些祖细胞在合并糖尿病和缺血的创面的最佳治疗性募集至关重要。我们进一步假设，描述导致高氧诱导的祖细胞/干细胞释放的机制将作为识别新的和潜在的协同靶点的基础，以进一步促进治疗性骨密度EPC的释放和它们在不可愈合伤口中的重新募集。这项研究计划的具体目标是：1.确定高氧(单独或联合SDF-1局部伤口治疗)诱导治疗性EPC释放和重新聚集到糖尿病/缺血创面的有效性，并确定血浆SDF-1水平是否可以预测糖尿病PAD患者和糖尿病遗传性小鼠模型的EPC计数和伤口愈合。2.为了阐明高氧动员祖细胞/干细胞的机制。在这项题为《向高氧和SDF-11的创伤中招募激活的内皮祖细胞》的拨款申请中，我们提议研究三个基本问题，如果回答这些问题，可能会给创伤修复领域带来革命性的变化：(1)系统中SDF-11的水平是否是糖尿病合并PAD患者伤口愈合的关键预测因素？(2)靶向最佳的高氧暴露和伤口趋化因子操作能否治愈糖尿病和缺血同时影响的伤口？以及(3)高氧诱导干细胞动员的下游机制是什么？

DESCRIPTION (provided by applicant): It has been estimated that up to 2 million Americans suffer from non-healing lower extremity wounds, most as a complication of Diabetes. Bone marrow-derived endothelial progenitor cells (BMD EPC) contribute to wound healing since these progenitor/stem cells are the key cellular effectors of post-natal vasculogenesis. BMD EPC are deficient in Diabetes. Hyperoxia induced by hyperbaric oxygen (HBO2) treatments is used as a safe, FDA- approved, adjunctive therapy to stimulate wound healing in diabetic patients, but the mechanisms of action are poorly understood and HBO2 is not uniformly effective, particularly in diabetic patients with associated peripheral arterial disease (PAD), accounting for the fact that diabetic/ischemic chronic non-healing lower extremity wounds continue to be an unsolved clinical problem. In preliminary studies, we have determined that hyperoxia, induced by a clinically relevant HBO2 protocol, increases nitric oxide (.NO) levels within femoral bone marrow, accelerates the spontaneous revascularization of surgically induced hindlimb ischemia, and increases the number of BMD EPC in circulation. Additional preliminary studies indicate that Stromal cell- derived growth factor 11 (SDF-1), a chemokine that mediates EPC homing via its receptor CXCR4, is decreased in diabetic wounds and SDF-1 wound-injections partially restores the diabetic defect in wound BMD EPC recruitment, and (together with hyperoxia) synergistically enhances diabetic wound healing. Our overall goal is to develop new strategies for treating patients with chronic wounds of the legs. We hypothesized that hyperoxia induces release of BMD EPC and that these cells may then be recruited into wounds in increased numbers by virtue of their hyperoxia-induced activation and their increased numbers within the blood pool; however, local wound interventions that enhance EPC homing (such as increasing level of EPC homing chemochine, SDF-1) may be crucial for optimal therapeutic recruitment of these progenitor cells to wounds complicated by diabetes and ischemia. We further hypothesized that the delineation of the mechanisms that result in hyperoxia-induced progenitor/stem cell release will serve as the foundation for identifying novel and potentially synergistic targets for further enhancing therapeutic BMD EPC release and their recruitment into non-healing wounds. The specific goals of this research proposal are: 1.To determine the efficacy of hyperoxia (alone and in combination with SDF-1 local wound treatment) for inducing therapeutic EPC release and recruitment into diabetic/ischemic wounds, and determine if that plasma SDF-1 levels are predictive of EPC counts and wound healing in diabetic patients with PAD and in genetic murine models of diabetes. 2. To elucidate the mechanism of progenitor/stem cell mobilization by hyperoxia.In this grant application entitled Recruiting Activated Endothelial Progenitor Cells to Wounds by Hyperoxia & SDF-11 , we propose to study three fundamental questions that if answered may revolutionize the field of wound healing: (1) Is the systemic level of SDF-11 a key predictor of wound healing in diabetic patients with PAD? (2) Can targeted optimal hyperoxia exposures and wound chemokine manipulations heal wounds affected by both diabetes and ischemia? And (3) what are the downstream mechanisms of hyperoxia-induced stem cell mobilization?