Murine Circulating Endothelial Precursors (CEPs) and Lung Capillary Repair

描述（由申请人提供）：该基金提出了临床前研究，以提高对血液来源的细胞群在成人肺血管修复的细胞基础的理解。我们已经确定了一个新的人口循环内皮前体（CEP），并发现他们的潜力，以修复毛细血管节段在小鼠肺血管生成过程中以前未描述的。基于初步数据，该基金支持的研究将遵循三个主要假设：（i）在肺血管损伤中，CEPs与内皮细胞融合，获得内皮样表型，并植入现有毛细血管以修复其结构和功能;（ii）动员进入循环并募集到损伤肺的BMDC对CEPs修复毛细血管做出重要贡献;和（iii）VEGF和SDF-11信号传导介导BMDC向受损肺的动员和募集以及CEP对毛细血管的修复。最先进的高分辨率和荧光成像方法（使用免疫金标记和量子点），以及其他定量方法，即，将使用流式细胞术分析。这项研究将利用转基因小鼠和一个充分表征的毛细血管修复模型，该模型通过呼吸高氧损伤的肺中的CEP进行。急性肺损伤和慢性肺损伤的修复-其中毛细血管网络丢失，然后恢复-都将被研究。具体而言，我们的目标是表征小鼠CEP恢复肺毛细血管的动力学和表型（AIM 1）;在结构和功能研究中，包括骨髓抑制和BMDC亚群的输注，证明BMDC和CEP的毛细血管修复之间的因果关系（AIM 2）;并证明VEGF/VEGF-R2和/或SDF-11/CXCR 4信号传导的选择性阻断损害了BMDC向受损肺的动员和募集以及CEP对毛细血管的修复（AIM 3）。通过了解CEP在挽救现有毛细血管网络中的作用，拟议的研究应促进急性损伤肺以及已建立毛细血管损失的肺的基于细胞的治疗策略的发展。 公共卫生相关性：在危及生命的疾病中，如肺动脉高压，或急性肺损伤导致严重形式的急性呼吸窘迫的发展，血管损伤破坏整个肺的小血管。研究旨在提高对新发现的通过血液中循环的细胞自发修复这些血管的过程的理解。进一步了解这些循环细胞如何挽救现有的血管或触发新血管的生长，将促进基于细胞的治疗方法的发展，以恢复肺部受损的血管网络。

DESCRIPTION (provided by applicant): This grant proposes preclinical studies to improve understanding of the cellular basis of vascular repair in the adult lung by a blood-derived cell population. We have identified a novel population of circulating endothelial precursors (CEPs) and discovered their potential to repair capillary segments in the murine lung by a previously undescribed angiogenic process. Based on preliminary data, the studies supported by this grant will be guided by three principal hypotheses: (i) in lung vascular injury CEPs fuse to endothelial cells, acquire an endothelial-like phenotype, and engraft into existing capillaries to repair their structure and function; (ii) BMDCs mobilized into the circulation and recruited to the injured lung make a major contribution to capillary repair by CEPs; and (iii) VEGF and SDF-11 signaling mediate the mobilization and recruitment of BMDCs to the injured lung and capillary repair by CEPs. State-of-the-art high resolution and fluorescence imaging approaches (using immunogold labels and quantum dots), and other quantitative approaches, i.e., flow cytometry analyses, will be used. The studies proposed will take advantage of genetically modified mice and a well-characterized model of capillary repair by CEPs in the lung injured by breathing high oxygen. Repair in acute lung injury and in the chronically injured lung - in which capillary networks are lost and then restored - will both be studied. Specifically, we aim to characterize the kinetics and phenotype of murine CEPs as they restore pulmonary capillaries (AIM 1); demonstrate in structural and functional studies, that include myelo-suppression and infusion of BMDCs sub-sets, a causal relationship between BMDCs and capillary repair by CEPs (AIM 2); and demonstrate that selective blockade of VEGF/VEGF-R2 and/or of SDF-11/CXCR4 signaling impair the mobilization and recruitment of BMDCs to the injured lung and capillary repair by CEPs (AIM 3). By understanding the role of CEPs in the salvage of existing capillary networks, the proposed studies should promote the development of cell-based treatment strategies for the acutely injured lung as well as the lung with established capillary loss. PUBLIC HEALTH RELEVANCE: In life-threatening diseases such as the Pulmonary Hypertensions, or following acute lung injury leading to the development of a severe form of Acute Respiratory Distress, vascular injury destroys small blood vessels throughout the lung. Studies are designed to improve understanding of a newly identified process of spontaneous repair of these blood vessels by cells circulating in blood. Further understanding of how such circulating cells salvage existing blood vessels, or trigger growth of new ones, will promote the development of cell-based therapies to restore damaged vascular networks in the lung.