Robust,Automated Analysis of Electrophysiology in Induced Pluripotent Stem Cell-Derived Micro-Heart Muscle for Drug Toxicity

Abstract

Drugs are often removed from clinical trials or market progression owing to their unforeseen effects on cardiac action potential and calcium handling. Induced pluripotent stem cell-derived cardiomyocytes and tissues fabricated from these cells are promising as screening tools for early identification of these potential cardiac liabilities. In this study, we describe an automated, open-source MATLAB-based analysis software for calculating cardiac action potentials and calcium transients from fluorescent reporters. We first identified the most robust manner in which to automatically identify the initiation point for action potentials and calcium transients in a user-independent manner, and used this approach to quantify the duration and morphology of these signals. We then demonstrate the software by assessing changes to action potentials and calcium transients in our micro-heart muscles after exposure to hydroxychloroquine, an antimalarial drug with known cardiac liability. Consistent with clinical observations, our system predicted mild action potential prolongation. However, we also observed marked calcium transient suppression, highlighting the advantage of testing multiple physiologic readouts in cardiomyocytes rather than relying on heterologous overexpression of single channels such as the human ether-a-go-go-related gene channel. This open-source software can serve as a useful, high-throughput tool for analyzing cardiomyocyte physiology from fluorescence imaging.

Impact statement

This article describes an open-source code that will allow researchers to assess changes in cardiac action potentials and calcium transients from fluorescent reporters in a fully automated manner. Automated analysis will allow researchers to increase the throughput of their experiments and grant greater insight into cardiac electrophysiology. Here, the usefulness of these pipelines is demonstrated through analysis of the effects of hydroxychloroquine.