Mechanisms of Cell-Based Heart Regeneration

项目摘要 本课题组最近的研究表明，人胚胎干细胞来源的心肌细胞(hESC- Cm)可改善猕猴脑梗塞心脏功能。这些改进高达 20个射血分数点与强健的肌肉化有关，通常会产生厘米级的移植物。 通过核磁共振可以看到。然而，随着临床试验的进展，仍然存在几个悬而未决的问题。 无人接听。HESC-CM的作用机制是什么？相对较低的心脏效率如何才能 植入率会提高吗？如果我们增加关键的心肌细胞类型，我们是否会获得更完全的再生 除了心肌细胞？在目标1中，我们讨论了hESC-CM的作用机制是否与 直接细胞替代，或者如果有重要的旁分泌成分。为了测试这一点，我们使用了CRISPR- Cas9在HiPSCs中删除心脏和骨骼TNNI基因，产生完整的非收缩心肌细胞 肌原纤维、动作电位和钙瞬变。这些只有旁分泌的心肌细胞将被比较 野生型细胞修复大鼠梗死心脏的能力。在目标2中，我们将检验假设 “智能水凝胶”旨在通过Notch途径发出信号，可以通过HiPSC促进心脏再生- 不育系CMS。这种Notch凝胶在植入后刺激HiPSC-CM的增殖并促进血管生长 从周围的宿主微循环。我们将测试这些结构性好处是否伴随着 增强了心功能。最后，目标3对最近在老鼠身上完成的研究进行了跟进，在那里我们 观察到hESC来源的心外膜细胞(hESC-Epi)与hESC-CMS在促进 增强心肌梗死后的肌化和功能恢复。我们将利用我们的猕猴 猴子模型测试hESC-Epi是否增强基于hESC-CM的心脏再生，假设为 这些细胞将促进hESC-CM成熟并促进其增殖，从而减少心律失常的发生 能更彻底地使梗塞重新肌肉化的移植物。这项建议中的研究将直接影响我们的 即将进行的心脏修复临床试验。

Project Summary Recent studies from our group demonstrate that human embryonic stem cell-derived cardiomyocytes (hESC- CM) can improve the function of infarcted hearts of macaque monkeys. These improvements of as much as 20 ejection fraction points are associated with robust remuscularization, often giving centimeter-scale grafts that are visible by MRI. As we progress toward clinical trials, however, several outstanding questions remain unanswered. What is the mechanism of hESC-CM action? How can the relatively low efficiency of cardiac engraftment be improved? Will we get more complete regeneration if we add key myocardial cell types in addition to cardiomyocytes? In Aim 1 we address whether the mechanism of hESC-CM action is related to direct cell replacement, or if there is a significant paracrine component. To test this, we have used CRISPR- Cas9 to delete cardiac and skeletal TNNI genes in hiPSCs, yielding non-contractile cardiomyocytes with intact myofibrils, action potentials and calcium transients. These “paracrine-only” cardiomyocytes will be compared to wild type cells for their ability to repair the infarcted rat heart. In Aim 2 we will test the hypothesis that a “smart hydrogel”, designed to signal through the Notch pathway, can improve cardiac regeneration with hiPSC- CMs. This Notch gel stimulates hiPSC-CM proliferation after engraftment and promotes vascular ingrowth from the surrounding host microcirculation. We will test if these structural benefits are accompanied by enhanced ventricular function. Finally, Aim 3 follows up on recently completed studies in the rat, where we observed that hESC-derived epicardial cells (hESC-Epi) are synergistic with hESC-CMs in terms of promoting enhanced remuscularization and functional recovery of the infarcted heart. We will utilize our macaque monkey model to test whether hESC-Epi augment hESC-CM-based heart regeneration, with the hypothesis that these cells will promote hESC-CM maturation and enhance their proliferation, resulting in less arrhythmogenic grafts that more completely remuscularize the infarct. Studies in this proposal will impact directly on our upcoming clinical trials of cardiac repair.