Engineered Human Heart Slice for Testing Drug-Induced Arrhythmia

最终，针对心律失常风险的药物的心脏安全性测试的新标准正在制定中。 临床前目标是预测尖端扭矩(TDP)的风险。美国的体外综合技术 心律失常分析(CIPA)倡议一直由政府监管机构倡导，公私合营 合作伙伴关系、工业界和学术界。该倡议的一个组成部分依赖于人类诱导的使用 多能干细胞来源的心肌细胞(hiPSC-CMS)作为药物反应的验证平台 取代停留在单个离子通道(HERG)阻断上的异源表达系统。如果被 FDA，CIPA代表着使用包含主要离子通道和 在人类心脏中发现的信号通路。HiPSC-CMS的这一应用是一个活跃的研究领域和 开发，并建立了许多合同研究机构和大多数制药公司 实验室使用这些细胞对测试化合物进行高通量筛选。然而，目前的HiPSC-CM 筛查往往在单个或少量显示不成熟和异质性的细胞上。此外, 心律失常事件仅限于早期后除极(EAD)或不规则搏动。TDP归根结底是一个 由折返性或多灶性异位活动引起的多细胞组织现象，要求最低限度 尺寸待定。 该项目的目标是开发一种适合于测试药理化合物和 评估组织水平心律失常的风险。霍普金斯大学的三个研究实验室将为 项目。用于支持HiPSC-CMS的组织平台将是董建华开发的工程心脏切片 心脏电生理实验室。将实现具有改进的生理功能的切片的2.0版 使用已证实的和假定的成熟刺激剂，然后用于测试药物诱导的折返性或多灶性 心律不齐。为此，将通过波赫勒实验室的专业知识来追求细胞的新陈代谢成熟， 它已经确定CD36是一个细胞表面标记，区分代谢上更成熟的细胞。一个 在权氏心脏发育生物学实验室开发的生物信息学方法将用于跟踪 心肌细胞的成熟轨迹。这些技术的融合将导致先进的 体外组织模型将用于独立和机械地评估阿司匹林的致心律失常作用 已在临床上确定为低、中和高风险的选定化合物，并确定 心肌细胞的成熟状态是否影响其药物反应。这种方法代表了一种新的 心脏安全性测试的范例-这是一种更接近于预测TDP样心律失常事件的范例 心肌--并可能为HiPSC-CMS的实用性、有效性和成熟性依赖建立新的标准 作为评估心律失常风险的实验模型。

New standards are under development for cardiac safety testing of drugs for risk of arrhythmia, ultimately with the preclinical goal of predicting risk for Torsade de Pointes (TdP). In the U.S. the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative has been advocated by government regulatory agencies, public-private partnerships, industry and academia. One component of the initiative rests on the usage of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) as a validation platform of drug responses that can replace heterologous expression systems which dwell on block of a single ion channel (HERG). If adopted by the FDA, CiPA represents a major step forward for drug testing using cells that contain the major ion channels and signaling pathways found in human heart. This application of hiPSC-CMs is an area of active research and development, and numerous contract research organizations and most pharmaceutical companies have founded labs to perform high throughput screening of test compounds using these cells. However, current hiPSC-CM screens tend to be on single or small numbers of cells that exhibit immaturity and heterogeneity. In addition, arrhythmic events are limited to early afterdepolarizations (EADs) or irregular beating. TdP is ultimately a multicellular tissue phenomenon that results from reentrant or multifocal ectopic activity that require a minimum size to be revealed. The goal of this project is to develop an in vitro model suitable for testing pharmacological compounds and assessing risk for tissue-level arrhythmia. Three research labs at Hopkins will contribute their expertise for the project. The tissue platform used to support the hiPSC-CMs will be the Engineered Heart Slice developed in Tung’s cardiac electrophysiology lab. Version 2.0 of the slice with improved physiological function will be implemented using proven and putative maturation stimulants, and then used to test for drug-induced reentrant or multifocal arrhythmia. To this end, metabolic maturation of the cells will be pursued via the expertise of the Boheler lab, which has identified CD36 as a cell surface marker distinguishing cells that are metabolically more mature. A bioinformatics approach developed in Kwon’s cardiac developmental biology lab will be used to follow the maturation trajectory of the cardiomyocytes. The convergence of these technologies will result in an advanced in vitro tissue model that will be used to independently and mechanistically assess the proarrhythmic effects of selected compounds which have been identified clinically as low, intermediate, and high risk, and to determine whether the maturation state of the cardiomyocytes affects their drug responses. This approach represents a new paradigm for cardiac safety testing – one that is a step closer to predicting TdP-like arrhythmic events in the myocardium – and may establish new standards for the utility, validity, and maturation-dependence of hiPSC-CMs as an experimental model to assess arrhythmia risk.