Endothelial Cell Growth and Differentiation in Semilunar Heart Valves

描述（由申请人提供）：正确成形的心脏瓣膜瓣叶对于实现单向血流至关重要，因此对生命至关重要。精致的小叶随着每次心跳打开和关闭，通过防止反流促进最佳心脏功能，从而将氧气输送到全身组织。先天性心脏缺陷，其中许多影响心脏瓣膜，发生在约1/100的婴儿。一些先天性瓣膜缺陷从出生的那一刻起就威胁生命;其他问题较小，但最终瓣膜置换在成年后成为必要。尽管瓣膜在心脏功能中起着关键作用，但人们对瓣膜的发育知之甚少，对维持瓣膜功能的细胞和分子过程知之甚少。我们已经表明，从成人肺动脉瓣和主动脉瓣叶的内皮细胞表现出瓣膜特异性的性能，这是在瓣膜发生的关键步骤，这表明，从成人小叶的内皮细胞保留重演胚胎发育过程的能力。我们已经表明，在人类瓣膜内皮细胞中，转录因子NFATc 1的激活和核转位是VEGF诱导的增殖和迁移所必需的，我们还表明，成年瓣膜内皮细胞的克隆群体可以被诱导经历内皮细胞向间充质细胞的转分化（EMT），这是从内皮细胞垫形成瓣膜小叶的关键事件。我们建立的瓣膜内皮细胞培养模型为鉴定控制内皮细胞增殖和分化的基因以及了解心脏瓣膜增殖和分化之间的相互作用提供了有力的工具。将追求三个具体目标。第一个将是确定和功能特性的目标血管内皮细胞生长因子/NFATc 1信号通路在瓣膜内皮。第二个将是识别和功能特性的基因参与TGF-β介导的EMT。第三个目的是研究心脏瓣膜内皮细胞增殖和分化之间的交叉调节。基于新的初步数据，我们假设骨形态发生蛋白-2（BMP-2）连接这两个途径。目的3在本修订申请中进行了扩展，以专门测试BMP-2在心脏瓣膜内皮细胞增殖、迁移和EMT中的作用。本文提出的研究将提供以下方面的见解：1）瓣膜内皮的正常功能和能力，2）心脏瓣膜疾病和潜在的修复机制，以及3）为患有瓣膜特异性缺陷的患者创建改进的瓣膜置换术的策略。

DESCRIPTION (provided by applicant): Properly formed heart valve leaflets are essential to achieve unidirectional blood flow and thus, are critical for life. The delicate leaflets open and close with each heart beat, promoting optimal heart function by preventing regurgitation and thus, oxygen delivery to tissues throughout the body. Congenital heart defects, many of which affect the heart valves, occur in about 1 in 100 infants. Some congenital valve defects are life threatening from the moment of birth; others are less problematic, but eventually valve replacement becomes necessary in adult life. Despite the critical role of the valves in heart function, relatively little is known about the development of the valves and even less about the cellular and molecular processes that sustain valve function through adult life. We have shown that endothelial cells from adult pulmonary and aortic valve leaflets exhibit valve specific properties that are reminiscent of critical steps in valvulogenesis, indicating that endothelial cells from adult leaflets retain the ability to recapitulate embryonic developmental processes. We have shown that in human valvular endothelial cells, activation and nuclear translocation of the transcription factor NFATc1 is required for VEGF-induced proliferation and migration, we have also shown that clonal populations of adult valvular endothelial cells can be induced to undergo an endothelial to mesenchymal transdifferentiation (EMT), a critical event in formation of valve leaflets from the endocardial cushions. The valvular endothelial cell culture models we have established provide powerful tools for identifying genes that control endothelial proliferation and differentiation and for understanding the interplay between proliferation and differentiation in cardiac valves. Three specific aims will be pursued. The first will be to identify and functionally characterize targets of the VEGF/NFATc1 signaling pathway in valve endothelium. The second will be to identify and functionally characterize genes involved in TGF-beta mediated EMT. The third aim will be to examine the cross-regulation between proliferation and differentiation in cardiac valve endothelial cells. Based on new preliminary data, we hypothesize the bone morphogenetic protein-2 (BMP-2) links these two pathways. Aim 3 has been expanded in this revised application to specifically test the role of BMP-2 in proliferation, migration and EMT in cardiac valve endothelium. The studies proposed here will provide insights on 1) normal functions and capabilities of valvular endothelium, 2) heart valve diseases and potential mechanisms for repair, and 3) strategies to create improved valve replacements for patients suffering from valve-specific defects.