Division of Systems Biology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas.
Department of Structural Heart Disease, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China.
Toxicol Sci. 2020 Apr 1;174(2):254-265. doi: 10.1093/toxsci/kfaa010.
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold great potential for personalized cardiac safety prediction, particularly for that of drug-induced proarrhythmia. However, hiPSC-CMs fire spontaneously and the variable beat rates of cardiomyocytes can be a confounding factor that interferes with data interpretation. Controlling beat rates with pacing may reduce batch and assay variations, enable evaluation of rate-dependent drug effects, and facilitate the comparison of results obtained from hiPSC-CMs with those from adult human cardiomyocytes. As electrical stimulation (E-pacing) of hiPSC-CMs has not been validated with high-throughput assays, herein, we compared the responses of hiPSC-CMs exposed with classic cardiac ion channel blockers under spontaneous beating and E-pacing conditions utilizing microelectrode array technology. We found that compared with spontaneously beating hiPSC-CMs, E-pacing: (1) reduced overall assay variabilities, (2) showed limited changes of field potential duration to pacemaker channel block, (3) revealed reverse rate dependence of multiple ion channel blockers on field potential duration, and (4) eliminated the effects of sodium channel block on depolarization spike amplitude and spike slope due to a software error in acquiring depolarization spike at cardiac pacing mode. Microelectrode array optogenetic pacing and current clamp recordings at various stimulation frequencies demonstrated rate-dependent block of sodium channels in hiPSC-CMs as reported in adult cardiomyocytes. In conclusion, pacing enabled more accurate rate- and concentration-dependent drug effect evaluations. Analyzing responses of hiPSC-CMs under both spontaneously beating and rate-controlled conditions may help better assess the effects of test compounds on cardiac electrophysiology and evaluate the value of the hiPSC-CM model.
人诱导多能干细胞衍生的心肌细胞（hiPSC-CMs）在个性化心脏安全性预测方面具有巨大潜力，特别是在药物诱导的致心律失常方面。然而，hiPSC-CMs 会自发搏动，并且心肌细胞的可变搏动率可能是干扰数据解释的一个混杂因素。起搏控制搏动率可以减少批次和测定变异性，能够评估与搏动率相关的药物作用，并促进从 hiPSC-CMs 获得的结果与成人人心肌细胞的结果进行比较。由于尚未通过高通量测定验证 hiPSC-CMs 的电刺激（E-pacing），在此，我们利用微电极阵列技术比较了在自发搏动和 E-pacing 条件下暴露于经典心脏离子通道阻滞剂的 hiPSC-CMs 的反应。我们发现，与自发搏动的 hiPSC-CMs 相比，E-pacing：（1）降低了整体测定变异性，（2）显示出对起搏通道阻滞的场电位持续时间的变化有限，（3）揭示了多个离子通道阻滞剂对场电位持续时间的反向搏动率依赖性，以及（4）消除了由于在心脏起搏模式下获取去极化尖峰时的软件错误而导致钠通道阻滞对去极化尖峰幅度和尖峰斜率的影响。在各种刺激频率下，微电极阵列光遗传学起搏和电流钳记录显示 hiPSC-CMs 中的钠通道具有搏动率依赖性阻滞，正如在成人心肌细胞中报道的那样。总之，起搏使更准确的搏动率和浓度依赖性药物作用评估成为可能。分析 hiPSC-CMs 在自发搏动和速率控制条件下的反应可能有助于更好地评估测试化合物对心脏电生理学的影响，并评估 hiPSC-CM 模型的价值。
