A Multiscale Modeling Approach to Hypoplastic Left Heart Syndrome

 描述(申请人提供)：左心发育不全综合征(HLHS)是一种先天性缺陷，其特征是左心室(LV)发育不全，无法为身体提供足够的血液流动。目前，HLHS患者的治疗标准是手术姑息或心脏移植，两者都有严重的并发症。胎儿超声心动图显示发育过程中LV充盈减少导致LV发育不良，从而提示HLHS的生物力学机制。我们这个项目的基本原理是，了解生物力学反应通路在HLHS发病机制中的作用将改变目前HLHS患者的管理模式，使这一缺陷能够得到药物治疗。我们的首要目标是：1)发现新的分子调节剂，以增加HLHS患者的左室大小；2)建立和验证多尺度计算模型，以评估这些调节剂在细胞和整个器官水平上的疗效。我们假设，增加拉伸激活的生长途径的活性将促进子宫内发育不良的LV的生长。这一假设是基于我们的数据，即拉伸刺激心肌细胞的增殖、生长和心室生长。此外，利用miRNA-Seq，我们已经确定了一个microRNA，miR-486，即1)在体外/HLHS患者中对拉伸反应，2)在体内促进心脏生长。为了验证我们的假设并实现我们的首要目标，我们将执行两个具体目标：目标1.预测和验证miR-486治疗对发育成HLHS的小鼠和人类胚胎心脏的影响。我们推测miR-486可以促进胚胎心脏的生长。因此，这一目标将检验miR-486在LV生长中的作用，无论是在小鼠还是在人类HLHS胚胎中。MIR-486对细胞增殖、大小和收缩功能的影响也将在小鼠和 人iPS心肌细胞。这些体外数据将被合并到一个新的胚胎心脏生长的3D有限元(FE)模型中。最后，将使用miR-486在子宫内处理HLHS小鼠胚胎，以验证有限元建模模拟。目的2.基于改善胚胎心室生长的miRNAʼS潜能的计算模型，确定体内测试的候选miRNA的优先顺序。我们推测，miRNA靶标预测、心肌细胞的数学分子模型和HLHS FE模型可以结合起来测试候选拉伸反应miRNAs是否有可能增加HLHS心脏的左室大小。在模拟小鼠HLHS胚胎的情况下，增加LV的候选miRNA将在体内进行测试。这一miRNA将在子宫中进行测试，以1)检查对LV生长的影响，2)验证耦合模型。拟议中的研究将使用体外(小鼠和人类iPS细胞)、体内和硅胶中的互补方法来阐明关键途径。 生物力学压力通过这种方式刺激心脏生长。这种独特的综合方法是由一个多学科团队实现的，该团队整合了儿科心脏病学、心脏生物力学、分子生物学和计算建模方面的专业知识。

 DESCRIPTION (provided by applicant): Hypoplastic Left Heart Syndrome (HLHS) is a congenital defect marked by an underdeveloped left ventricle (LV) that is unable to provide adequate blood flow to the body. Currently, the standard of care for HLHS patients is surgical palliation or cardiac transplantation, both of which have serious complications. Fetal echocardiograms demonstrate that decreased LV filling during development results in a hypoplastic LV, thereby indicating a biomechanical mechanism for HLHS. Our rationale for this project is that understanding the role of biomechanical responsive pathways in the pathogenesis of HLHS will shift the current management paradigm of HLHS patients by enabling pharmacological treatment of this defect. Our overarching goals are 1) to discover novel molecular modulators that increase LV size in HLHS patients, and 2) to build and validate multi-scale computational models to evaluate the efficacy of these modulators at the cellular and whole-organ level. We hypothesize that increasing the activity of stretch-activated growth pathways will improve the growth of hypoplastic LVs in utero. This hypothesis is based on our data that stretch stimulates cardiomyocyte proliferation, growth, and ventricular growth. Furthermore, utilizing miRNA-Seq, we have identified a microRNA, miR-486, that is 1) stretch responsive in vitro/HLHS patients and 2) promotes cardiac growth in vivo. To test our hypothesis and to achieve our overarching goals, we will perform two specific aims: Aim 1. Predict and validate the effects of miR-486 treatment on mouse and human embryonic hearts developing HLHS. We postulate that miR-486 increases embryonic cardiac growth. Thus this aim will examine miR-486 role in LV growth, both in murine and human HLHS embryos. miR-486 effects on cell proliferation, size, and contractile function will also be studied in mouse and human iPS cardiomyocytes. These in vitro data will be incorporated into a novel 3D finite element (FE) model of embryonic cardiac growth. Finally, treatment of HLHS mouse embryos with miR-486 in utero will be used to validate FE modeling simulations. Aim 2. Prioritization of candidate miRNAs for in vivo testing based upon computational modeling of the miRNAʼs potential to improve embryonic ventricular growth. We postulate that miRNA target predictions, mathematic molecular model of cardiomyocytes, and HLHS FE modeling can be coupled to test candidate stretch-responsive miRNAs for potential to increase LV size in HLHS hearts. The candidate miRNA that increases LV the most growth within simulations of mouse HLHS embryos will be tested in vivo. This miRNA will be tested in utero, to 1) examine the effects on LV growth and 2) validate the coupled model. The proposed studies using complementary in vitro (murine and human iPS cells), in vivo, and in silico methods will elucidate critical pathways by which biomechanical stress stimulates cardiac growth. Such a unique comprehensive approach is made possible by a multidisciplinary team that incorporates expertise in pediatric cardiology, cardiac biomechanics, molecular biology, and computational modeling.