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

描述（由申请人提供）：据估计，多达200万美国人患有无法愈合的下肢伤口，其中大多数是糖尿病的并发症。骨髓来源的内皮祖细胞（BMD EPC）有助于伤口愈合，因为这些祖细胞/干细胞是出生后血管生成的关键细胞效应器。糖尿病患者BMD EPC缺乏。高压氧（HBO2）治疗诱导的高氧是一种安全的、FDA批准的辅助治疗方法，用于刺激糖尿病患者的伤口愈合，但其作用机制尚不清楚，而且HBO2并不是统一有效，特别是在伴有外周动脉疾病（PAD）的糖尿病患者中，这说明糖尿病/缺血性慢性不愈合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方案诱导的高氧可增加股骨骨髓内一氧化氮（no）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BMD EPC的数量。另外的初步研究表明，基质细胞源性生长因子11 （SDF-1）是一种通过其受体CXCR4介导EPC归巢的趋化因子，在糖尿病伤口中减少，而SDF-1伤口注射部分恢复了糖尿病伤口BMD中EPC募集的缺陷，并（与高氧一起）协同促进糖尿病伤口愈合。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，这些细胞可能通过高氧诱导的激活和血液池中数量的增加而被招募到伤口中。然而，局部伤口干预增强EPC归巢（如增加EPC归巢化学机器，SDF-1的水平）可能对这些祖细胞在糖尿病和缺血并发伤口的最佳治疗募集至关重要。我们进一步假设，对高氧诱导的祖细胞/干细胞释放机制的描述将作为确定新的和潜在的协同靶点的基础，以进一步增强治疗性BMD EPC释放及其在未愈合伤口中的募集。本研究计划的具体目标是：1。确定高氧（单独和联合局部伤口处理）诱导治疗性EPC释放和募集到糖尿病/缺血性伤口的效果，并确定血浆SDF-1水平是否预测糖尿病伴PAD患者和糖尿病遗传小鼠模型中EPC计数和伤口愈合。2. 阐明高氧诱导祖细胞/干细胞动员的机制。在这项名为“通过高氧和SDF-11招募活化的内皮祖细胞到伤口”的资助申请中，我们提出研究三个基本问题，如果得到答案，可能会彻底改变伤口愈合领域：(1)全身SDF-11水平是否是糖尿病伴PAD患者伤口愈合的关键预测指标？(2)有针对性的最佳高氧暴露和伤口趋化因子操作是否可以治愈糖尿病和缺血影响的伤口？(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?