Molecular determinants of the fate of human heart mesenchymal progenitor cells

基于细胞和生物学的疗法，旨在促进损伤后心肌恢复或预防进展 心力衰竭的治疗方法正在临床试验中进行开发和测试。然而，在这一领域工作的一个主要限制 是对人类心肌细胞生物学的了解相对较少。提高我们的理解 心脏祖细胞功能的生物学研究是本提案的重点。分离出一小部分细胞 来自成人心室心肌的培养物具有高度增殖性，并表达关键的多能性 转录因子，并可被刺激分化为内皮细胞、心肌细胞和 间充质谱系。这些细胞表达 CD105（又名内皮糖蛋白），其功能在于传递 转化生长因子β（TGFβ）和骨形态发生蛋白（BMP）信号传导。这些细胞还 表达不同水平的 ERBB1-4 受体酪氨酸激酶，介导表皮细胞的作用 生长因子 (EGF) 家族，包括 Neuregulin-1β (NRG)。 NRG 和 ERBB1-4 对于心脏至关重要 成人心脏的发育和维护。 ERBB1-4在新鲜分离祖细胞中的表达 细胞在个体之间存在差异，并且与可被高度增殖的克隆的数量相关。 来自心肌活检。 ERBB2 表达决定了这些祖细胞是否可以 响应重组 EGF 或 NRG-1 的刺激而诱导内皮表型。该共同 BMP 家族辅助受体 CD105 的表达及其在血管生成和心脏发育中的作用， 表明该配体家族对这些细胞进行共同调节。该提案的中心假设是 ERBB1-4 受体表达由 BMP9/CD105 决定，并调节细胞的活力、数量和能力 祖细胞分化为内皮细胞和其他谱系。早期传代祖细胞的集合 缅因州医疗中心已在同意受试者的心室心肌中分离出克隆 过去3年。这些细胞中可变 ERBB2 表达的功能意义是 在 AIM 1 心肌梗死后早期和晚期将细胞移植到小鼠心脏的情况下进行了检查。 BMP9/CD105/Alk1调控ERBB表达的机制及其功能意义 在 AIM 2 中进行检查。可以从骨骼肌中分离出具有相似特征的高度增殖克隆 还有心房心肌。从心房心肌中分离出祖细胞的程度 骨骼肌与心室肌相似，将在 AIM 3 中进行检查。最终这些发现 将提高我们对 ERBB 和 CD105 如何调节心血管健康以及恢复的理解 免受损伤，并将为临床策略的设计提供信息，以增强心脏的恢复潜力。

Cell and biology-based therapies designed to promote myocardial recovery after injury or prevent progression of heart failure are being developed and tested in clinical trials. However a major limitation to work in this area is the relatively poor understanding of the cell biology of the human myocardium. Improving our understanding of the biology of cardiac progenitor cells function is the focus of this proposal. A small fraction of cells isolated from the adult human ventricular myocardium are highly proliferative in culture, and express key pluripotency transcription factors, and can be stimulated to differentiate into endothelial, cardiac myocyte, and mesenchymal lineages. These cells express CD105 (a.k.a. endoglin), which functions in the transmission of transforming growth factor beta (TGFβ) and bone morphogenetic protein (BMP) signaling. These cells also express variable levels of ERBB1-4 receptor tyrosine kinases which mediate the effects of the epidermal growth factor (EGF) family including Neuregulin-1β (NRG). NRG and ERBB1-4 are critical for cardiac development and maintenance of the adult heart. The expression of ERBB1-4 in freshly isolated progenitor cells varies amongst individuals and is correlated to the quantity of highly proliferative clones that can be derived from myocardial biopsies. ERBB2 expression determines whether these progenitor cells can be induced toward an endothelial phenotype in response to stimulation with recombinant EGF or NRG-1. The co- expression of the BMP family co-receptor CD105, and its roles in angiogenesis and heart development, suggest co-regulation of these cells by this family of ligands. The central hypothesis of this proposal is that ERBB1-4 receptor expression is determined by BMP9/CD105 and regulates the viability, number, and ability of progenitor cells to differentiate to endothelial and other lineages. A collection of early passage progenitor cell clones isolated from ventricular myocardium in consenting subjects at Maine Medical Center has been created over the past 3 years. The functional significance of variable ERBB2 expression in these cells will be examined in the setting of cell transplant into mouse heart early and late after myocardial infarction in AIM 1. The mechanism by which BMP9/CD105/Alk1 regulates ERBB expression and its functional significance will be examined in AIM 2. Highly proliferative clones with similar characteristics can be isolated from skeletal muscle as well as atrial myocardium. The extent to which progenitor cells isolated from atrial myocardium and skeletal muscle are similar to the ventricular myocardium will be examined in AIM 3. Ultimately these findings will improve our understanding of how ERBB and CD105 regulate cardiovascular health as well as recovery from injury, and will inform the design of clinical strategies to enhance the restorative potential of the heart.