Subtype Spec.& Arrhythmogenica Potential of Stem Cell Derived Cardiomyocytes

项目2：干细胞来源的心肌细胞的亚型鉴定和致心律失常的潜能。 人胚胎干细胞(HESCs)来源的心肌细胞具有巨大的心脏应用前景 修复，既用于替代心肌梗死后的心肌，又起到“生物起搏器”的作用 病态窦房结综合症之类的疾病。我们已经报告了产生大量高度放射性物质的方法 从hESCs中纯化的心肌细胞，但这些制剂包括具有不同结节/起搏器的细胞 和“工作”(即腔室状)表型。为了让这些细胞变得有用和安全，它们必须有 电生理特性与每种应用相匹配。因此，该项目将开发方法来 控制hESC衍生物的心脏亚型，然后将确定它们的电生理行为 在完整和梗死的心脏移植后。在目标1中，我们将开发一个遗传选择系统 追踪人类胚胎干细胞来源的心脏亚型的谱系关系。这项工作是建立在我们的 初步发现cGATA6基因的启动子元件识别hESC来源 结节表型的心肌细胞。在目标2中，我们将阐明通过哪些分子事件 NeuRegin/ErbB信号调节hESC来源的心肌细胞的心脏亚型。这项工作将使用来自AIM 1的遗传记者，但也将导致控制心脏亚型规范的补充药理学方法。在目标3中，我们将解决移植后hESC来源的心肌细胞电生理行为的两个不确定因素。首先，我们将测试这些细胞是否电耦合，并与宿主肌肉在正常和 梗塞的心脏。其次，我们将验证这样一种假设，即它们的移植将调节与梗塞相关的心律失常的发生率，而移植相关心律失常的发生率可以通过控制输入细胞准备的表型来“调节”。

Project 2: Subtype Specification and Arrhythmogenic Potential of Stem Cell Derived Cardiomyocytes. Cardiomyocytes derived from human embryonic stem cells (hESCs) have tremendous promise for cardiac repair, both for replacing ventricular myocardium after an infarct and serving as a "biologic pacemaker" in diseases like sick-sinus syndrome. We have reported methods to generate large quantities of highly purified cardiomyocytes from hESCs, but these preparations include cells with distinct nodal/pacemaker and "working" (i.e. chamber-like) phenotypes. For these cells to be useful and safe, they must have electrophysiological properties matched to each application. Hence, this project will develop approaches to control the cardiac subtype of hESC derivatives and then will determine their electrophysiological behavior following transplantation in intact and infarcted hearts. In Aim 1, we will develop a genetic selection system to follow the lineage relationships of cardiac subtypes derived from hESCs. This work builds on our preliminary findings that a promoter element from the cGATA6 gene identifies hESC-derived cardiomyocytes with the nodal phenotype. In Aim 2, we will elucidate the molecular events by which neuregulin/ErbB signaling regulates the cardiac subtype of hESC-derived cardion\yocytes. This work will employ the genetic reporters from Aim 1 but will also lead to complementary pharmacological approaches to control cardiac subtype specification. In Aim 3, we will address two uncertainties regarding the electrophysiological behavior of hESC-derived cardiomyocytes following transplantation. First, we will test whether these cells are electrically coupled and beat synchronously with host muscle in normal and infarcted hearts. Second, we will test the hypothesis that their transplantation will modulate the incidence of infarct-related arrhythmias, while the incidence of graft-associated arrhythmias can be "tuned" by controlling the phenotype of the input cell preparation.