Cellular characterization of the Comprehensive in Vitro Proarrhythmia (CiPA) compound library using 2D and 3D human iPSC cardiomyocyte models

The ability to evaluate pharmaceutical safety using cardiomyocytes from induced pluripotent stem cells (iPSCs) has advanced cardiac therapeutic development. To better understand iPSC-cardiomyocytes' value as a 2D and 3D screening model, we set out to compare the Comprehensive in Vitro Proarrhythmia (CiPA) compound effects using the automated Volta Scanner and a voltage-sensitive dye, Berkeley Red Sensor of Transmembrane Potential (BeRST). Together they embody a well-suited for high-throughput optical voltage sensing screening platform. Human iPSC cardiomyocytes (hiPSC CMs) were dispensed into 96-well microtiter plates in both a monolayer (2D) and cardioid (3D) format. The CiPA library with its array of compounds ranging from nontoxic to toxic to human cardiomyocytes is a well-accepted tool for characterizing sensitivity and selectivity for therapeutic safety. The results were collected in a double-blind fashion, with cardiac toxicity potential determined for each compound. Both the 2D monolayer and 3D cardiac spheroid models demonstrate high selectivity for those compounds known to be highly toxic to cardiomyocytes, denoting low false negatives. Both the 2D and 3D cardiac models demonstrated high specificity for compounds generally considered safe, denoting low false positives. While both 2D and 3D models demonstrated utility for highly toxic compounds, the 3D model demonstrated superior detection capabilities for intermediate toxicity. Accordingly, this study is consistent with other in vitro toxicology results demonstrating the added value of 3D cellular models for safety assessment purposes.