CELLULAR & MOLECULAR PHENOTYPE OF MYOCARDIUM STEM CELLS

这项建议的总体目标是更好地了解哺乳动物细胞的起源、身份和生物学特性，这些细胞在适当的刺激下能够再生成年和衰老的心肌。这一目标是基于这样一个前提，即成年和衰老的心肌含有少量具有心脏干细胞(CSCs)特征和行为的细胞：它们具有克隆性、自我更新和多潜能。从老化的心肌中分离出单个CSC的后代可以分化为肌细胞、平滑肌细胞和内皮细胞。当在缺血后心肌中注射或激活这些细胞时，它们会重建功能性室壁。它们的数量和/或功能的减少可能是老年和衰老心脏功能改变的原因之一。关于CSC的起源，我们一无所知。来自动物和人类的数据显示，这些细胞在心肌和心肌外组织之间持续运输。骨髓包含一群具有相似特征的细胞，其他几种心脏外细胞类型已被证明能够分化为心肌细胞。我们将验证这一假设，即CSCs出现在发育较晚的阶段，通过循环到达心肌，并不断补充，以允许正常和病理心脏的持续周转。一旦我们确定了CSCs的起源并确定了它们的生心潜能，我们就开始剖析它们分化的遗传调节因素，首先确定“干细胞标记基因”在产生生心表型中的作用。我们将继续检验假设，CSCs的分化在很大程度上 总结心脏早期个体发育，需要下调规范的Wnt途径以及上调TGFbeta家族的成员，即某些骨形态发生蛋白(BMPs)基因。将追求三个具体目标：1.确定能够产生心源性谱系的不同成体细胞之间的起源和关系，并比较它们在缺血后心肌再生的潜力 心。2.阐明干细胞标记物基因在CSCs心肌再生能力中的作用。3.-开始解剖负责维持CSCs分化状态的信号通路及其在正常条件下、衰老和缺血反应中的分化。从这些实验中获得的信息将被用来设计更有效的方法，通过对CSCs的指导来促进心肌再生。

The general goal of this proposal is to gain a better understanding of the origin, identity, and biological properties of mammalian cells that when properly stimulated are capable of regenerating the adult and senescent myocardium. This objective is based on the premise that adult and senescent myocardium contains a small population of cells with the characteristics and behavior of cardiac stem cells (CSCs): they are clonogenic, self-renewing and multipotent. The progeny of a single CSC isolated from an aging myocardium can differentiate into myocytes, smooth muscle and endothelial cells. When injected or activated in a post-ischemic myocardium, these cells reconstitute a functional ventricular wall. A decrease in their number and/or function might be one of the causal factors in the altered performance of the old and senescent heart. Nothing is known about the origin of the CSCs. Data from animals and humans show a continuous trafficking of these cells between myocardium and extra-myocardial tissues. The bone marrow contains a population of cells with similar characteristics and a several other extra-cardiac cell types have been shown able to differentiate into cardiocytes. We will test the hypothesis that CSCs appear late in development, reach the myocardium through the circulation, and are constantly replenished to allow a continuous turnover of the normal and pathological heart. Once we have established the origin of the CSCs and determined their cardiogenic potential, we initiate the dissection of the genetic regulators of their differentiation, starting by identifying the role of "stem cell marker genes" in the production of the cardiogenic phenotype. We will continue by testing the hypothesis that differentiation of CSCs in large measure recapitulates early cardiac ontogeny and requires the down regulation of the canonical Wnt pathway as well as the upregulation of members of the TGFbeta family of regulators, namely certain bone morphogenetic protein (BMPs) genes. Three Specific Aims will be pursued: 1.- To ascertain the origin and relationship among the different adult cells capable of producing the cardiogenic lineages and to compare their myocardial regenerating potential in the post-ischemic heart. 2.- To elucidate the role of "stem cell marker genes" on the myocardial regenerating capability of the CSCs. 3.- To initiate the dissection of the signaling pathways responsible for the maintenance of the differentiated state of the CSCs and their differentiation under normal conditions, in aging and in response to ischemia. The information obtained from these experiments will be used to devise more effective ways of fostering myocardial regeneration through the coaching of the CSCs.