Murine Circulating Endothelial Precursors (CEPs) and Lung Capillary Repair

描述(由申请人提供)：这项拨款建议进行临床前研究，以提高对成人肺中血液来源细胞群体血管修复的细胞学基础的理解。我们已经确定了一种新的循环内皮细胞前体(CEP)群体，并发现它们通过一种以前未描述的血管生成过程修复小鼠肺中的毛细血管段。根据初步数据，这笔赠款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，并植入现有的毛细血管以修复其结构和功能；(Ii)动员到循环中并募集到受损肺的BMDCs对CEPs的毛细血管修复具有重要贡献；以及(Iii)CEPs介导BMDCs的动员和募集到受损肺和毛细血管修复。将使用最先进的高分辨率和荧光成像方法(使用免疫金标记物和量子点)以及其他定量方法，即流式细胞术分析。建议的研究将利用转基因小鼠和一种特征良好的毛细血管修复模型，该模型由CEPs修复因呼吸高氧而受损的肺中的毛细血管。急性肺损伤的修复和慢性损伤肺的修复--毛细血管网络丢失然后恢复--都将被研究。具体地说，我们的目标是描述小鼠CEPs恢复肺毛细血管时的动力学和表型(AIM 1)；在结构和功能研究中，包括骨髓抑制和BMDCs亚群的输注，BMDCs与CEPS修复毛细血管(AIM 2)之间的因果关系；以及证明选择性阻断VEGF/VEGF-R2和/或SDF-11/CXCR4信号损害了BMDCs在受损肺组织的动员和募集以及CEPS对毛细血管的修复(AIM 3)。通过了解CEPs在挽救现有毛细血管网络中的作用，拟议的研究应促进针对急性损伤的肺以及已确定的毛细血管丢失的肺的基于细胞的治疗策略的发展。 公共卫生相关性：在威胁生命的疾病中，如肺高压，或在急性肺损伤后导致严重形式的急性呼吸窘迫，血管损伤破坏整个肺的小血管。研究旨在提高对新发现的血液中循环细胞自发修复这些血管的过程的理解。进一步了解这种循环细胞如何挽救现有血管或引发新血管的生长，将促进基于细胞的治疗方法的发展，以恢复肺中受损的血管网络。

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.