Quantified proarrhythmic potential of selected human embryonic stem cell-derived cardiomyocytes

Abstract

To improve proarrhythmic predictability of preclinical models, we assessed whether human ventricular-like embryonic stem cell-derived cardiomyocytes (hESC-CMs) can be selected following a standardized protocol. Also, we quantified their arrhythmogenic response and compared this to a contemporary used rabbit Purkinje fiber (PF) model. Multiple transmembrane action potentials (AP) were recorded from 164 hESC-CM clusters (9 different batches), and 12 isolated PFs from New Zealand White rabbits. AP duration (APD), early afterdepolarizations (EADs), triangulation (T), and short-term variability of repolarization (STV) were determined on application of the I(Kr) blocker E-4031 (0.03/0.1/0.3/1 muM). Isoproterenol (0.1 muM) was used to assess adrenergic response. To validate the phenotype, RNA isolated from atrial- and ventricular-like clusters (n=8) was analyzed using low-density Taqman arrays. Based on initial experiments, slow beating rate (<50 bpm) and long APD (>200 ms) were used to select 31 ventricular-like clusters. E-4031 (1 muM) prolonged APD (31/31) and induced EADs only in clusters with APD90>300 ms (11/16). EADs were associated with increased T (1.6+/-0.2 vs 2.0+/-0.3) and STV (2.7+/-1.5 vs 6.9+/-1.9). Rabbit PF reacted in a similar way with regards to EADs (5/12), increased T (1.3+/-0.1 vs 1.9+/-0.4), and STV (1.2+/-0.9 vs 7.1+/-5.6). According to ROC values, hESC-CMs (STV 0.91) could predict EADs at least equivalent to PF (STV 0.69). Isoproterenol shortened APD and completely suppressed EADs. Gene expression analysis revealed that HCN1/2, KCNA5, and GJA5 were higher in atrial/nodal-like cells, whereas KCNJ2 and SCN1B were higher in ventricular-like cells (P<0.05). Selection of hESC-CM clusters with a ventricular-like phenotype can be standardized. The proarrhythmic results are qualitatively and quantitatively comparable between hESC-CMs and rabbit PF. Our results indicate that additional validation of this new safety pharmacology model is warranted.

Concise Review: Human Pluripotent Stem Cell-Based Models for Cardiac and Hepatic Toxicity Assessment

“…As an alternative to the comparison of the drug effects with published results from other laboratories, two recent studies have demonstrated concordance between hPSC-derived cardiomyocytes and conventional, well validated, rabbit and canine ex vivo Purkinje fiber models, which are commonly used as follow-up assays [15,16]. Using microelectrodes to measure the transmembrane action potential of hPSC-derived cardiomyocytes, Jonsson et al [15] determined parameters such as reverse use dependence, triangulation of the action potential, and short-term variability of repolarization to assess drug-induced arrhythmic events.…”

“…Using microelectrodes to measure the transmembrane action potential of hPSC-derived cardiomyocytes, Jonsson et al [15] determined parameters such as reverse use dependence, triangulation of the action potential, and short-term variability of repolarization to assess drug-induced arrhythmic events. Importantly, for the comparison with the Purkinje fiber model, all data collection for this study was performed at the same laboratory, using the same experimental setup, and under the same conditions.…”

Recent Progress Using Pluripotent Stem Cells for Cardiac Regenerative Therapy

“…75 Cardiac grafts could possibly contribute to all 3 fundamental arrhythmia mechanisms, namely automaticity, 18 reentry, 39 and triggered activity. 76 As mentioned before, conflicting results have been obtained regarding whether these cardiac grafts cause arrhythmias. 49-53 However, it remains a potential issue to be further explored.…”

We heart cultured hearts. A comparative review of methodologies for targeted differentiation and maintenance of cardiomyocytes derived from pluripotent and multipotent stem cells

“…Caffeine normally triggers an increase in cytosolic Ca 2+ whereas ryanodine decreases the levels of Ca 2+ , therefore, the maintenance of the balance of Ca 2+ levels in cardiomyocytes derived from pluripotent stem cells may not be identical to the balance in normal adult cardiomyocytes. It is also notable that while cardiomyocytes derived by targeted differentiation from embryonic stem cells were shown to alleviate arrhythmia when transplanted in injured myocardium; other authors have demonstrated that cardiomyocytes derived from hESC may possess inherent pro-arrhythmic potential [76,77]. Non-fatal ventricular arrhythmias were observed in macaques that have received intracardially cardiomyocytes derived from differentiation of hESC [59].…”