Optical pacing of the embryonic heart

描述（由申请人提供）：我们的长期目标是确定生物物理力对心脏发育的影响，以及这些力在发育早期的改变如何导致先天性心脏缺陷（CHD）。CHD非常普遍，每年影响美国近36，000名新生儿，或每1，000名活产婴儿中有9名。为了梳理出哪些分子通路受到生物力学的调节，我们将开发能够以精确的方式扰乱心脏动力学的新技术（光学起搏）。以前的扰动技术涉及大体操作（血管结扎，圆锥动脉束等）。这并不能提供必要的控制来确定生物力学对发育的确切影响。我们已经证明，光学起搏能够在一系列发育阶段以精确的方式在体内持续起搏早期胚胎鹌鹑心脏，而不会对组织造成损伤。最近的数据表明，我们可以修改流出道中的反流水平，从而改变振荡剪切 应力（OSS）。有人认为，流出道中的剪切力是瓣膜和隔正常发育所必需的。流出道缺损占CHD的15-20%，非常严重，需要手术干预。为了证明OP的潜力，我们将在流出道中创建异常反流模型，并研究其影响。 心脏发育过程中剪切力对分子表达和形态发生的影响。将进行实验以确定光学起搏的最佳能量要求，这些最佳设置将用于开发光学起搏协议， 一致地将流出道中的OSS水平改变到精确的程度。光学相干断层扫描将用于优化光学起搏方法，并在光学起搏期间和之后测量血流动力学和形态学。完成后，我们将优化和表征OP作为一种新的实验工具，使用该工具创建流出道中异常湍流的模型，并研究剪切力变化对 心脏发育过程中的基因表达和形态发生。这个实验工具将是有价值的更广泛地揭示机制的机械转导信号在早期发育的心脏，这将使我们能够开发一个更好地了解先天性缺陷的病因。OP具有以多种方式操纵心脏功能的潜力，并且可能能够产生其他心脏不规则模型（例如心律失常、房室交界处血流异常水平等）。 公共卫生相关性：先天性心脏病（CHD）背后的机制在很大程度上尚不清楚，生物力学力量可能在CHD的发展过程中发挥作用。该项目旨在开发能够扰乱心脏生物力学力的新技术（光学起搏），以阐明体内发育中心脏结构和功能之间的复杂相互作用。更好地了解先天性心脏病的起源和进展可能会导致更好的预测结果，以及更早，更有效的治疗。

DESCRIPTION (provided by applicant): Our long-term objective is to determine the influence biophysical forces have on heart development and how alterations of these forces early in development can lead to congenital heart defects (CHDs). CHDs are extremely prevalent affecting almost 36,000 newborns in the US each year, or 9 out of 1,000 live births. In order to tease apart what molecular pathways are being regulated by biomechanics, we will be developing new technology (optical pacing) capable of perturbing cardiac dynamics in precise ways. Previous perturbation techniques have involved gross manipulations (vessel ligation, conotruncal banding, etc.) that do not offer the necessary control to determine the exact influences of biomechanics on development. We have demonstrated that optical pacing is capable of consistently pacing early embryonic quail hearts in vivo in a precise manner over a range of developmental stages without causing damage to the tissue. Recent data shows that we can modify the level of regurgitant flow in the outflow tract thereby altering oscillatory shear stress (OSS). It has been suggested that shear forces in the outflow tract are needed for normal development of valves and septa. Outflow tract defects which make up 15-20% of CHDs are very serious requiring surgical intervention. As a demonstration of the potential of OP, we will create a model of abnormal regurgitant flow in the outflow tract and investigate the impact of this change in shear force on molecular expression and morphogenesis during cardiac development. Experiments will be conducted to determine the optimal energy requirements for optical pacing and these optimal settings will be utilized to develop optical pacing protocols that consistently change the levels OSS in the outflow tract to precise degrees. Optical coherence tomography will be employed to refine optical pacing methods and to measure hemodynamics and morphology both during and after optical pacing. Upon completion, we will have optimized and characterized OP as a new experimental tool, used that tool to create a model of abnormal regurgitant flow in the outflow tract, and investigated the impact of this change in shear force on gene expression and morphogenesis during cardiac development. This experimental tool will be valuable more broadly for uncovering the mechanisms of mechanically transduced signaling in the early developing heart, which will enable us to develop a better understanding of the etiology of congenital defects. OP has the potential to manipulate cardiac function in multiple ways and may be capable of producing other models of cardiac irregularities (e.g. arrhythmias, abnormal levels of regurgitant flow in the atrioventricular junction, etc.). PUBLIC HEALTH RELEVANCE: The mechanisms behind congenital heart defects (CHDs) are largely unclear, and biomechanical forces likely play a role during the development of CHDs. This project aims to develop new technology (optical pacing) capable of perturbing biomechanical forces in the heart in order to elucidate the complex interplay between structure and function in the developing heart in vivo. Better understanding of the origins and progression of congenital heart defects can potentially lead to better prediction of outcomes, and earlier, more effective treatments.