Single-cell ionic current phenotyping elucidates non-canonical features and predictive potential of cardiomyocytes during automated drug experiments

Alexander P Clark; Siyu Wei; David J Christini; Trine Krogh-Madsen

doi:10.1113/JP285120

Single-cell ionic current phenotyping elucidates non-canonical features and predictive potential of cardiomyocytes during automated drug experiments

J Physiol. 2024 May 15. doi: 10.1113/JP285120. Online ahead of print.

Authors

Alexander P Clark¹, Siyu Wei², David J Christini^{1

2}, Trine Krogh-Madsen^{3

4}

Affiliations

¹ Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
² Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.
³ Department of Physiology & Biophysics, Weill Cornell Medicine, New York, New York, USA.
⁴ Institute for Computational Biomedicine, Weill Cornell Medicine, New York, New York, USA.

PMID: 38747042
DOI: 10.1113/JP285120

Abstract

All new drugs must go through preclinical screening tests to determine their proarrhythmic potential. While these assays effectively filter out dangerous drugs, they are too conservative, often misclassifying safe compounds as proarrhythmic. In this study, we attempt to address this shortcoming with a novel, medium-throughput drug-screening approach: we use an automated patch-clamp system to acquire optimized voltage clamp (VC) and action potential (AP) data from human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) at several drug concentrations (baseline, 3×, 10× and 20× the effective free plasma concentrations). With our novel method, we show correlations between I_Na block and upstroke slowing after treatment with flecainide or quinine. Additionally, after quinine treatment, we identify significant reductions in current during voltage steps designed to isolate I_f and I_Ks. However, we do not detect any I_Kr block by either drug, and upon further investigation, do not see any I_Kr present in the iPSC-CMs when prepared for automated patch experiments (i.e. in suspension) - this is in contrast to similar experiments we have conducted with these cells using the manual patch setup. In this study, we: (1) present a proof-of-concept demonstration of a single-cell medium-throughput drug study, and (2) characterize the non-canonical electrophysiology of iPSC-CMs when prepared for experiments in a medium-throughput setting. KEY POINTS: Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) offer potential as an in vitro model to study the proarrhythmic potential of drugs, but insights from these cells are often limited by the low throughput of manual patch-clamp. In this study, we use a medium-throughput automated patch-clamp system to acquire action potential (AP) and complex voltage clamp (VC) data from single iPSC-CMs at multiple drug concentrations. A correlation between AP upstroke and I_Na transients was identified and drug-induced changes in ionic currents found. We also characterize the substantially altered physiology of iPSC-CMs when patched in an automated system, suggesting the need to investigate differences between manual and automated patch experiments.

Keywords: electrophysiology; iPSC‐CM; patch clamp; systems biology.

Abstract

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