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Original Article

Korean J Physiol Pharmacol 2023; 27(3): 267-275

Published online May 1, 2023

Copyright © Korean J Physiol Pharmacol.

New in vitro multiple cardiac ion channel screening system for preclinical Torsades de Pointes risk prediction under the Comprehensive in vitro Proarrhythmia Assay concepta

Jin Ryeol An1, Seo-Yeong Mun2, In Kyo Jung1, Kwan Soo Kim1, Chan Hyeok Kwon1, Sun Ok Choi1,*, and Won Sun Park2,*

1Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju 28159, 2Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea

Correspondence to:Sun Ok Choi
Won Sun Park

Author contributions: J.R.A. conceptualization, writing – original draft, data collection, data analysis. S.Y.M. and I.K.J. data analysis and interpretation. K.S.K. drafting the manuscript. C.H.K. critical revision of the paper. S.O.C. and W.S.P. conceptualization, funding acquisition, and final approval of the completed manuscript.

Received: February 15, 2023; Revised: March 15, 2023; Accepted: March 29, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cardiotoxicity, particularly drug-induced Torsades de Pointes (TdP), is a concern in drug safety assessment. The recent establishment of human induced pluripotent stem cell-derived cardiomyocytes (human iPSC-CMs) has become an attractive human-based platform for predicting cardiotoxicity. Moreover, electrophysiological assessment of multiple cardiac ion channel blocks is emerging as an important parameter to recapitulate proarrhythmic cardiotoxicity. Therefore, we aimed to establish a novel in vitro multiple cardiac ion channel screening-based method using human iPSC-CMs to predict the drug-induced arrhythmogenic risk. To explain the cellular mechanisms underlying the cardiotoxicity of three representative TdP high- (sotalol), intermediate- (chlorpromazine), and low-risk (mexiletine) drugs, and their effects on the cardiac action potential (AP) waveform and voltage-gated ion channels were explored using human iPSC-CMs. In a proof-of-principle experiment, we investigated the effects of cardioactive channel inhibitors on the electrophysiological profile of human iPSC-CMs before evaluating the cardiotoxicity of these drugs. In human iPSC-CMs, sotalol prolonged the AP duration and reduced the total amplitude (TA) via selective inhibition of IKr and INa currents, which are associated with an increased risk of ventricular tachycardia TdP. In contrast, chlorpromazine did not affect the TA; however, it slightly increased AP duration via balanced inhibition of IKr and ICa currents. Moreover, mexiletine did not affect the TA, yet slightly reduced the AP duration via dominant inhibition of ICa currents, which are associated with a decreased risk of ventricular tachycardia TdP. Based on these results, we suggest that human iPSC-CMs can be extended to other preclinical protocols and can supplement drug safety assessments.

Keywords: Ion channels, Patch-clamp techniques, Safety, Stem cell, Torsades de pointes