Delineating the mechanisms underlying heart valve endothelial repair

项目摘要 瓣膜性主动脉瓣狭窄(VAS)约占所有先天性心脏病的3%-6%，1如果是左心 如果不进行治疗，可能会导致新生儿和幼儿充血性心力衰竭。非侵入性，经皮 球囊瓣膜成形术(BVP)是儿科首选的第一步治疗，目的是推迟 彻底的手术。结果显示，虽然BVP显著降低了主动脉瓣(AOV)的峰值梯度 在大多数患者的前24小时内，经过2-3年的随访，一半以上的患者再狭窄并需要 手术干预修复或替换畸形和衰竭的瓣膜2，3因此，在BVP有利的情况下 在一些患者中，另一些患者被诊断为临床结果较差，原因尚不清楚。 研究报道，BVP可损伤甚至断裂AOV、4、5，对兔的研究表明， 6，7此外，我们在小鼠身上的研究有力地表明 瓣膜内皮的直接损伤或靶向性功能障碍会导致结构和功能的恶化 AOV受损，与人类组织学研究报告的内皮完整性差一致 病变的瓣膜组织。8-11综合起来，这些研究表明内皮损伤是一个重要的 瓣膜病变的因素，这可能是BVP后VAS患者观察到不良结果的原因。 这就提出了一个问题：恢复内皮功能是否是治疗结构性肝炎的有效治疗策略？ 易感人群的AOV功能恶化？为了探索这一点，我们开发了一种外科手术 AOV内皮损伤的小鼠模型，导致结构和功能恶化。使用这个模型，我们 研究表明，在对损伤做出反应时，年轻健康的小鼠会激活一种有益的内在修复反应，从而导致 内皮修复，而这种反应在已知内皮功能障碍的老年小鼠中受损。 此外，我们提出了一种支持这些不同反应的机制。这项提议将考验整体 假设：受损的瓣膜内皮的有益的内在修复反应需要转化生长因子1- Ctrc1信号在瓣膜内皮细胞和瓣膜间质细胞之间促进增殖和 邻近未受损伤的细胞迁移，导致内皮修复。 为了验证这一点，我们提出了三个具体目标：1)确定细胞和分子机制 参与AOV血管内皮损伤后有益的内源性反应；2)确定 内皮-转化生长因子-1对受损血管内皮细胞有益的内源性修复反应；3)鉴定 间质-Ctrc1是AOV损伤后有益内源性修复反应的关键因子 内皮细胞。成功的完成将把内在修复性反应的创新机制定义为 AOV内皮损伤的结果可用于机械性化合物的治疗设计 促进内皮修复，防止结构和功能恶化，特别是在易感人群 个人。

PROJECT ABSTRACT Valvular aortic stenosis (VAS) accounts for approximately 3-6% of all congenital heart defects,1 and if left untreated can lead to congestive heart failure in neonates and young infants. Non-invasive, percutaneous balloon valvuloplasty (BVP) is the preferred first step of treatment in pediatrics with the intent to postpone definitive surgery. Outcomes show that while BVP significantly reduces aortic valve (AoV) peak gradient within the first 24 hours in the majority of patients, by the 2-3 year follow up more than half re-stenose and require surgical intervention to repair or replace the dysmorphic and failing valve.2, 3 Therefore, while BVP is favorable in some patients, others are diagnosed with poor clinical outcomes and it is not clear why. Studies report that BVP can injure or even rupture the AoV,4, 5 and studies in rabbits have shown that balloon inflation specifically injures the endothelium.6, 7 Furthermore, our work in mice strongly suggests that direct injury to, or targeted dysfunction of the valve endothelium causes structural deterioration and functional impairment of the AoV, consistent with histological studies in humans reporting poor endothelial integrity in diseased valve tissue.8-11 Taken together, these studies suggest that endothelial damage is a significant contributor of valve pathology, and this may underlie poor outcomes observed in VAS patients following BVP. This raises the question: Can restoring endothelial function be an effective therapeutic strategy to treat structural and functional deterioration of the AoV in susceptible individuals? To explore this, we developed a surgical mouse model of AoV endothelial injury that causes structural and functional deterioration. Using this model, we show that in response to injury, young healthy mice activate a beneficial intrinsic reparative response that leads to endothelial restoration, while this response is impaired in aging mice with known endothelial dysfunction.12 In addition, we propose a mechanism underlying these diverse responses. This proposal will test the overall hypothesis that: The beneficial intrinsic reparative response of the injured valve endothelium requires Tgf1- Cthrc1 signaling between valve endothelial, and underlying valve interstitial cells to promote proliferation and migration of neighboring uninjured cells, leading to endothelial restoration. To test this, we propose three specific aims: 1) Determine the cellular and molecular mechanisms involved in the beneficial intrinsic response following AoV endothelial injury; 2) Determine the requirement of endothelial-Tgf1 for the beneficial intrinsic reparative response of the injured AoV endothelium; and 3) Identify interstitial-Cthrc1 as a critical factor for the beneficial intrinsic reparative response of the injured AoV endothelium. Successful completion will define innovative mechanisms of the intrinsic reparative response as a result of AoV endothelial injury that can be applied to the therapeutic design of mechanistic-based compounds to promote endothelial restoration and prevent structural and functional deterioration, particularly in susceptible individuals.