Strategic activation of endogenous c-kit+ progenitor cells for cardiac regeneration

 描述（由申请人提供）：心力衰竭的患病率持续上升，发病率和死亡率不可接受。目前，超过600万美国人被诊断患有心力衰竭，相关的年度医疗费用估计为350亿美元，并且还在上升。心力衰竭的单一最重要原因是缺血性心肌病，其中由于缺血事件导致的心肌细胞损失是疾病的主要驱动因素。由于心脏再生的速率有限（估计在正常衰老期间每年有1%的新心肌细胞形成），剩余心肌细胞的工作量增加，导致心脏肥大并最终导致心力衰竭。由于心力衰竭最重要的驱动因素是心肌细胞的损失，因此在成人心脏中发现的心脏祖细胞（CPC）在培养时可以产生所有心脏谱系，从而发现了增强心脏再生的可能性。到目前为止，使用培养的CPC的细胞疗法一直是用于增强心脏再生的主要方法。然而，大多数注射的细胞在数周内死亡，心脏功能的最终改善可能是由内源性CPC介导的。目前的建议将确定刺激CPC以增强内源性再生的方法。我们的长期目标是了解内源性CPC如何响应心脏损伤而被激活，以及是什么决定了体内CPC的命运决定，最终目标是找到增强内源性心脏再生的策略。我们最近发表了遗传小鼠模型，允许内源性心脏祖细胞的谱系追踪，并将在整个提案中使用这些小鼠模型。在内源性CPC的遗传谱系追踪后，我们注意到产生了许多内皮细胞，但只有很少的心肌细胞。然而，我们假设内源性CPC可以被激活以增强其心源性潜力。所提出的遗传小鼠模型和特定信号通路的操纵将用于确定增强心脏再生的策略。我们的具体目标是1）确定不同的刺激是否以及如何激活内源性心脏c-kit+ CPC向心脏谱系，2）确定阻断内皮命运是否将激活内源性c-kit+ CPC成为心肌细胞，以及3）确定Notch 1信号传导对c-kit+祖细胞增殖和向内皮细胞和心肌细胞分化的重要程度。本研究的目的是确定可以刺激内源性心脏祖细胞产生更多心肌细胞的途径。未来的研究将采用增强eCPC增殖和分化的策略来改善心脏再生。

 DESCRIPTION (provided by applicant): The prevalence of heart failure continues to rise with unacceptable rates of morbidity and mortality. Currently, over 6 million Americans have been diagnosed with heart failure with an associated annual health care expense estimated at 35 billion US dollars and rising. The single most important cause for heart failure is ischemic cardiomyopathy, where loss of cardiomyocytes due to ischemic events is the main driver of disease. Due to limited rates of cardiac regeneration (estimated at 1% new cardiomyocyte formation per year during normal aging), the workload on remaining cardiomyocytes is increased, giving rise to cardiac hypertrophy and ultimately heart failure. Since the most important driver of heart failure is loss of cardiomyocytes, the discovery of cardiac progenitor cells (CPCs) in the adult heart that can give rise to all cardiac lineages when cultured uncovered the possibility of enhancing cardiac regeneration. Up until this point cell therapy using cultured CPCs has been the main method used to enhance cardiac regeneration. However, most injected cells die within weeks and the ultimate improvement in cardiac function is likely mediated by endogenous CPCs. The current proposal will identify ways of stimulating CPCs to enhance endogenous regeneration. Our long-term goal is to understand how endogenous CPCs are activated in response to cardiac injury and what determines CPC fate decisions in vivo with the ultimate objective of finding strategies that enhance endogenous cardiac regeneration. We recently published genetic mouse models that allow lineage tracing of endogenous cardiac progenitor cells and will use these mouse models throughout this proposal. Upon genetic lineage tracing of endogenous CPCs we noted many endothelial cells being generated, but only few cardiomyocytes. However, we hypothesize that endogenous CPCs can be activated to enhance their cardiogenic potential. The proposed genetic mouse models and manipulations of specific signaling pathways will be used to identify strategies to enhance cardiac regeneration. Our specific aims are to 1) Determine whether and how different stimuli activate endogenous cardiac c-kit+ CPCs toward cardiac lineage, 2) Determine whether blocking endothelial fates will activate endogenous c-kit+ CPCs to become cardiomyocytes, and 3) Establish to what extent Notch1 signaling is important for c-kit+ progenitor proliferation and differentiation toward both endothelial cells and cardiomyocytes. The goal of this study is to define pathways that can stimulate endogenous cardiac progenitor cells to produce more cardiomyocytes. Future studies will employ strategies to enhance the proliferation and differentiation of eCPCs to improve cardiac regeneration.