Molecular and Cellular Mechanisms of Neonatal Cardiac Development and Repair

 描述(由申请人提供)：本提案描述了一项为期五年的职业发展计划，为候选人Vahid Serposhan博士作为独立调查员的职业生涯做好准备。该项目将在Serposhan博士作为生物工程科学家的多学科背景的基础上，通过提供心脏发育的细胞和分子生物学方面的专业知识，接受心脏细胞生物学方面的培训。这项拟议研究的主要目标是确定新生儿心脏发育的关键机制，这些机制可以通过一种工程补丁来调节哺乳动物心脏的发育和修复，在缺血性心脏损伤后。这位少年派将在斯坦福医学院由肖恩·吴博士和丹尼尔·伯恩斯坦博士指导。吴博士在研究胚胎发育期间心脏谱系承诺的调节机制以及心脏前体细胞在发育和疾病中的生物学方面拥有丰富的专业知识。伯恩斯坦博士是斯坦福大学小动物外科和成像设施的负责人，他的研究重点是在正常生理状态和疾病状态下心血管功能的调节。我们等人的最新发现表明，新生哺乳动物心脏具有几种进化上保守的心肌再生机制，包括激活承诺的祖细胞和/或心肌细胞增殖。然而，这些过程背后的细胞/分子机制以及它们是否可以用于修复新生儿心脏仍不清楚。我们的初步数据表明，新生小鼠体内存在一组受转化生长因子β和MEK信号调控的NKX2.5成心肌细胞，具有增殖和分化为心肌细胞的潜力。在这项拟议的研究中，我将测试假设，即新生儿心脏中存在基于细胞的再生反应，可以通过生物工程心脏贴片输送小分子来招募，用于治疗心肌损伤。这项研究的结果有望产生积极的翻译影响，因为它们将为成年哺乳动物心脏的治疗干预引入一种新的无细胞递送方法。我的具体目标是：目标1：鉴定NKX2.5成心肌细胞及其在新生小鼠心脏中的功能。NKX2.5 ENH-Cre/EGFP报告基因小鼠模型将用于鉴定NKX2.5心肌祖细胞在新生大鼠心脏中的活性。目的2：研究NKX2.5心肌成肌细胞增殖分化过程中的信号和通路。转化生长因子β信号通路的小分子调控将被用来诱导新生NKX2.5成心肌细胞的扩增和向心肌细胞分化。目的3：研究NKX2.5成肌细胞和发育信号在缺血性心脏损伤后心脏修复中的作用。我将评估缺血损伤后成心肌细胞数量的变化及其对信号通路刺激的反应。

 DESCRIPTION (provided by applicant): This proposal describes a five-year career development program to prepare the candidate, Dr. Vahid Serpooshan, for a career as an independent investigator. This program will build upon Dr. Serpooshan's multidisciplinary background as a bioengineer scientist, trained in cardiac cellular biology, by providing expertise in cellular and molecular biology underlying heart development. The main goal of the proposed research is to identify the key mechanisms underlying neonatal heart development that could be exploited - via an engineered patch - to regulate mammalian heart development and repair, following ischemic heart injury. The PI will be mentored at Stanford Medical School by Drs. Sean Wu and Daniel Bernstein. Dr. Wu has extensive expertise in investigating the mechanisms regulating cardiac lineage commitment during embryonic development and the biology of cardiac progenitor cells in development and disease. Dr. Bernstein is the director of the small animal surgery and imaging facilities at the Stanford, and his research focuses on regulation of cardiovascular function in both normal physiologic states as well as in disease states. Recent findings by our group and others have demonstrated that neonatal mammalian hearts possess several evolutionarily conserved mechanisms for myocardial regeneration, including activation of committed progenitors and/or cardiomyocytes proliferation. However, the cellular/molecular mechanisms underlying these processes and whether they can be employed to repair neonatal heart remains elusive. Our preliminary data demonstrates the existence of a population of TGFβ and MEK signaling-regulated Nkx2.5+ cardiomyoblasts in neonatal mice with the potential to proliferate and differentiate into cardiomyocytes. In the proposed study, I will test the hypothesi that a cell-based regenerative response is present in the neonatal heart that can be recruited, via a bioengineered cardiac patch delivery of small molecules, for the treatment of myocardium injury. Results from this research are expected to have positive translational impact as they will introduce a novel cell-free delivery approach for therapeutic interventions in the adult mammalian heart. My specific aims are: Aim 1: Identify an Nkx2.5+ cardiomyoblast population and their function in the neonatal mouse heart. An Nkx2.5 enh-Cre/eGFP reporter mouse model will be used to identify the activated Nkx2.5 cardiomyogenic progenitors in neonatal heart. Aim 2: Determine the signal and pathways involved in Nkx2.5+ cardiomyoblasts proliferation and differentiation. Small molecule regulation of TGFβ and MEK signaling pathways will be used to induce the expansion and cardiomyogenic differentiation of the neonatal Nkx2.5+ cardiomyoblasts. Aim 3: Examine the role of Nkx2.5 cardiomyoblasts and developmental signals to mediate cardiac repair following ischemic heart injury. I will assess the changes to the cardiomyoblast population size and their response to signaling pathway stimulation following ischemic injury.