Application of human stem cell-derived cardiomyocytes in safety pharmacology requires caution beyond hERG

• Published in: Journal of molecular and cellular cardiology Vol. 52; no. 5; pp. 998 - 1008
• Main Authors: Jonsson, Malin K.B, Vos, Marc A, Mirams, Gary R, Duker, Göran, Sartipy, Peter, de Boer, Teun P, van Veen, Toon A.B
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2012
• Subjects: 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester - pharmacology; Action Potentials; Arrhythmias, Cardiac - drug therapy; Arrhythmias, Cardiac - pathology; Benzazepines - pharmacology; Calcium channel; Calcium Channel Agonists - pharmacology; Calcium Channel Blockers - pharmacology; Calcium Signaling; Cardiac arrhythmias; Cardiovascular; Cells, Cultured; Cisapride - pharmacology; Drug Evaluation, Preclinical; Embryonic Stem Cells - physiology; ERG1 Potassium Channel; Ether-A-Go-Go Potassium Channels - antagonists & inhibitors; Ether-A-Go-Go Potassium Channels - metabolism; Humans; Myocytes, Cardiac - drug effects; Nifedipine - pharmacology; Patch-Clamp Techniques; Potassium channel; Safety pharmacology assay; Sodium channel; Sodium Channels - metabolism; Stem cell-derived cardiomyocytes; inward rectifier potassium current; TdP; action potential duration; Torsade de Pointes; Cardiac arrhythmias; purkinje fibres; I f; late sodium current; human induced pluripotent stem cell-derived cardiomyocyte; L-type calcium current; I Na.late; I K1; Potassium channel; I Ks; I Kr; human embryonic stem cell-derived cardiomyocyte; early afterdepolarization; I Ca,L; APD 50/90; hiPSC-CM; slow delayed rectifier potassium current; EAD; rapid delayed rectifier potassium current (hERG); Stem cell-derived cardiomyocytes; beat-to-beat variability of repolarization; Calcium channel; peak sodium current; action potential duration at 50/90% of repolarization; pacemaker (funny) current; Sodium channel; I Na,peak; APD; PF; hESC-CM; BVR; Safety pharmacology assay; ICa,L; INa.late; INa,peak; IK1; IKs; IKr; If; APD50/90
• ISSN: 0022-2828; 1095-8584
• DOI: 10.1016/j.yjmcc.2012.02.002

Abstract Human embryonic stem cell-derived cardiomyocytes (hESC-CM) have been proposed as a new model for safety pharmacology. So far, a thorough description of their basic electrophysiology and extensive testing, and mechanistic explanations, of their overall pro-arrhythmic ability is lacking. Under standardized conditions, we have evaluated the sensitivity of hESC-CM to proarrhythmic provocations by blockade of hERG and other channels. Using voltage patch clamp, some ion current densities (pA/pF) in hESC-CM were comparable to adult CM: I Kr (− 12.5 ± 6.9), I Ks (0.65 ± 0.12), I Na,peak (− 72 ± 21), I Na,late (− 1.10 ± 0.36), and I Ca,L (− 4.3 ± 0.6). I f density was larger (− 10 ± 1.1) and I K1 not existent or very small (− 2.67 ± 0.3). The low I K1 density was corroborated by low KCNJ2 mRNA levels. Effects of pro-arrhythmic compounds on action potential (AP) parameters and provocation of early afterdepolarizations (EADs) revealed that Chromanol293B (100 μmol/l) and Bay K8644 (1 μmol/l) both significantly prolonged APD90 . ATX-II (< 1 μmol/l ) and BaCl2 (10 μmol/l ) had no effect on APD. The only compound that triggered EADs was hERG blocker Cisapride. Computer simulations and AP clamp showed that the immature AP of hESC-CM prevents proper functioning of I Na -channels, and result in lower peak/maximal currents of several other channels, compared to the adult situation. Lack of functional I K1 channels and shifted I Na channel activation cause a rather immature electrophysiological phenotype in hESC-CM, and thereby limits the potential of this model to respond accurately to pro-arrhythmic triggers other than hERG block. Maturation of the electrical phenotype is a prerequiste for future implementation of the model in arrhythmogenic safety testing.