Assessing myofilament phenotype and contractile response to pharmacotherapies in a human induced pluripotent stem cell cardiomyocyte (hiPSC-CM) model of hypoplastic left heart syndrome (HLHS)

项目摘要 尽管在手术技术和术后护理方面取得了巨大的进步， 左心综合征（HLHS）仍然存在全身性右心室（RV）收缩衰竭的终身风险。在 对于HLHS患者，传统的成人心力衰竭药物在预防病理性心力衰竭方面总体无效。 心脏重塑或保持收缩功能。因此，一旦患有HLHS的儿童发展为心力衰竭， 心脏病继发心功能下降，心脏移植往往是唯一的长期 治疗选择 这一提议的中心假设是HLHS心肌细胞在心肌细胞中有固有的改变。 可能赋予心力衰竭倾向并改变对心肌收缩反应的肌丝水平 心力衰竭的治疗方法初步数据显示钙敏感性异常， 终末期心脏HLHS受试者心肌细胞中心肌肌钙蛋白I磷酸化降低 失败然而，有必要利用HLHS模型系统扩展这些研究， 评估这些肌丝变化的影响。因此，本提案的目标是开发一种 诱导的多能干细胞心肌细胞（hiPSC-CM）模型，其来源于HLHS受试者，以定义 肌丝对HLHS中存在的收缩异常的贡献，并评估 肌丝差异对HF治疗的收缩反应。患者特异性HLHS hiPSC-CM将 从3名患有终末期心力衰竭的HLHS受试者中产生，并且肌丝收缩表型将 通过对带皮hiPSC-CM的机械研究，肌丝蛋白同种型的定量， 和评估肌丝翻译后修饰。这些发现将与 肌丝表型在来自同一受试者的分离的HLHS心脏组织中得到证实。此外，本发明还 肌丝评估将在HLHS hiPSC-CM治疗后进行， HF药物治疗，以直接测量药物治疗对HLHS的影响 肌丝 最终，增加对HLHS中存在的收缩功能障碍的机械理解， 心肌细胞有可能通过告知准确的HF风险来改善HLHS患者的结局- 分层范式此外，优先对HLHS的收缩反应进行特定评估， 药物治疗可能会导致个性化的药理学策略，以保护系统RV功能。

Project Summary Despite tremendous advances in surgical technique and post-operative care, children with hypoplastic left heart syndrome (HLHS) remain at lifelong risk for systolic failure of the systemic right ventricle (RV). In HLHS patients, traditional adult heart failure medications have been overall ineffective in preventing pathologic cardiac remodeling or preserving contractile function. Thus, once children with HLHS develop heart failure symptomatology secondary to decreased cardiac function, heart transplantation is often the only long-term therapeutic option. The central hypothesis of this proposal is that HLHS cardiomyocytes have inherent alterations at the level of the myofilament that may confer a heart failure predisposition and alter the contractile response to medical heart failure therapies. Preliminary data demonstrates abnormalities in calcium sensitivity and decreased cardiac troponin I phosphorylation in cardiomyocytes from HLHS subjects with end-stage heart failure. Nevertheless, there is a need to expand upon these studies utilizing a HLHS model system to further evaluate the impact of these myofilament changes. Therefore, the goal of this proposal is to develop a human induced pluripotent stem cell cardiomyocytes (hiPSC-CM) model derived from HLHS subjects to define the myofilament contribution to the contractile abnormalities present in HLHS and assess the impact of myofilament differences on the contractile response to HF therapies. Patient-specific HLHS hiPSC-CM will be generated from 3 HLHS subjects with end-stage heart failure, and the myofilament contractile phenotype will be defined through mechanical studies of skinned hiPSC-CM, quantification of myofilament protein isoforms, and assessment of myofilament post-translational modifications. These findings will be paired with the myofilament phenotype demonstrated in the explanted, HLHS heart tissue from the same subject. Additionally, myofilament assessments will be performed following treatment of HLHS hiPSC-CM with current and emerging HF pharmacotherapies in order to directly measure the consequences of drug therapy on the HLHS myofilament. Ultimately, augmenting mechanistic understanding of the contractile dysfunction present in HLHS cardiomyocytes has the potential to improve outcomes for HLHS patients by informing an accurate HF risk- stratification paradigm. Furthermore, prioritizing an HLHS-specific appraisal of the contractile response to pharmacotherapies may result in personalized pharmacologic strategies to preserve systemic RV function.