Biomechanical regulation of valvulogenesis

描述（由申请人提供）：瓣膜相关先天性心脏病（CHD）是早产和婴儿死亡的主要原因。尽管相当大的研究进展揭示了心脏形态发生的重要遗传调节因子，但由于缺乏对这些途径如何协调驱动瓣膜形成和重塑的理解，导致临床获益的转化受到阻碍。胚胎瓣膜在生长和成熟过程中暴露于越来越苛刻的机械环境中，但这些力的功能后果远未被理解。瓣膜发生也可以被认为是一个工程过程，而不是一个纯粹的遗传程序。因此，揭示这些新的管理关系是必不可少的，但一直具有挑战性，因为缺乏分析工具和实验方法，可以隔离和量化活胚胎瓣膜中的机械效应。首先，我们开发了独特的生物力学测试设备，可以量化胚胎垫和瓣膜的生物力学。其次，我们已经创建了一种新的斑点跟踪算法，结合高频超声，可以非侵入性地量化胚胎瓣膜内的动态组织应变。第三，我们开发了一种独特的有限元模拟策略，通过体内测量进行迭代，以在解剖学上精确的几何形状中映射局部生物力学参数。第四，我们已经创建了第一个实验策略，通过飞秒激光光消融（FLP）非侵入性地在活禽胚胎中创建局部孤立的心内缺陷。使用这些使能技术，我们的目标是确定和表征指导胚胎瓣膜形成的机械遗传关系。我们的总体假设是，机械信号通过同时调节多个瓣膜发生信号通路来协调胚胎瓣膜的塑造和强化。我们将首先量化瓣膜周围的体内机械环境变化及其生物力学适应性（目标1）。我们接下来将确定瓣膜发生的已知分子调节剂网络如何通过体外机械刺激进行调节（目的2）。然后，我们测试的机械遗传机制，建议在体内使用局部控制的光消融禽胚胎瓣膜（目的3）。这一建议将产生显着的定量详细的体内生物力学环境在胚胎瓣膜形成和如何调节局部基因表达，以促进瓣膜的形成和成熟。这些新的信息将补充遗传操作研究的现有数据集，并指导对这些结果的新解释。更好地理解指导瓣膜形成和重塑的机械生物学关系，显著拓宽了解释CHD发病机制的机制阵列，并拓宽了预防或修复CHD的新临床策略的工具。

DESCRIPTION (provided by applicant): Valve related congenital heart defects (CHD) are a major cause of preterm and infant death. Despite considerable research progress uncovering important genetic regulators of cardiac morphogenesis, translation to clinical benefit has been hampered by a lack of understanding of how these pathways coordinate to drive valve formation and remodeling. The embryonic valves are exposed to an increasingly demanding mechanical environment as they grow and mature, but the functional consequences of these forces are far less understood. Valvulogenesis can alternatively be considered an engineering process rather than a purely genetic program. Uncovering these new governing relationships is therefore essential but has been challenging because of the lack of analytical tools and experimental approaches that can isolate and quantify mechanical effects in live embryonic valves. First, we have developed unique biomechanical testing devices that can quantify embryonic cushion and valve biomechanics. Second, we have created a novel speckle tracking algorithm in conjunction with high frequency ultrasound that can non-invasively quantify dynamic tissue strains within the embryonic valves. Third, we developed a unique finite element simulation strategy that iterates with in vivo measurements to map local biomechanical parameters in anatomically precise geometries. Fourth, we have created the first experimental strategy to create locally isolated intracardiac defects in live avian embryos non-invasively through femtosecond laser photoablation (FLP). Using these enabling technologies, our objective for this proposal is to identify and characterize mechano-genetic relationships that guide the formation of the embryonic valves. Our overall hypothesis is that mechanical signaling orchestrates the sculpting and strengthening of the embryonic valves through simultaneous regulation of multiple valvulogenic signaling pathways. We will first quantify the changing in vivo mechanical environments surrounding the valves and their biomechanical adaptation (Aim 1). We will next determine how the network of known molecular regulators of valvulogenesis is modulated by mechanical stimulation in vitro (Aim 2). Then we test the mechano-genetic mechanisms suggested by the previous experiments in vivo using locally controlled photoablations to avian embryonic valves (Aim 3). This proposal will generate significant quantitative detail of the in vivo biomechanical environment during embryonic valvulogenesis and how this regulates local gene expression to promote valve formation and maturation. This novel information will complement existing datasets from genetic manipulation studies and guide new interpretations of these results. A better understanding of the mechanobiological relationships guiding valve formation and remodeling significantly broadens the array of mechanisms to explain the pathogenesis of CHD and tools to enable new clinical strategies to prevent or repair CHD.