Murine Circulating Endothelial Precursors (CEPs) and Lung Capillary Repair

描述（由申请人提供）：该资助提出临床前研究，以提高对成人肺血管修复的细胞基础的理解。我们已经确定了一种新的循环内皮前体（cep）群体，并发现它们通过先前未描述的血管生成过程修复小鼠肺部毛细血管段的潜力。基于初步数据，该基金支持的研究将以三个主要假设为指导：(i)在肺血管损伤中，cep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） BMDCs被动员到循环中并被招募到受伤的肺部，对cep的毛细血管修复做出了重大贡献；（iii） VEGF和SDF-11信号介导cep对损伤肺和毛细血管修复的BMDCs的动员和募集。将使用最先进的高分辨率和荧光成像方法（使用免疫金标记和量子点）以及其他定量方法，即流式细胞术分析。提出的研究将利用转基因小鼠和具有良好特征的cep在高氧呼吸损伤肺中的毛细血管修复模型。急性肺损伤和慢性肺损伤（毛细血管网络丢失然后恢复）的修复都将被研究。具体来说，我们的目标是描述小鼠cep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，证明BMDCs与cep的毛细血管修复之间的因果关系（AIM 2）；并证明选择性阻断VEGF/VEGF- r2和/或SDF-11/CXCR4信号通路会损害BMDCs对受损肺和cep修复的动员和募集（AIM 3）。通过了解cep在挽救现有毛细血管网络中的作用，拟议的研究应该促进基于细胞的治疗策略的发展，以治疗急性损伤的肺以及已经建立毛细血管损失的肺。

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.