Cairn Research Ltd 2 articles published in JoVE Bioengineering High-Throughput Cardiotoxicity Screening Using Mature Human Induced Pluripotent Stem Cell-Derived Cardiomyocyte Monolayers Andre Monteiro da Rocha1, Andrew Allan2, Travis Block3, Jeffery Creech1, Todd J. Herron1 1Frankel Cardiovascular Regeneration Core Laboratory, Cardiovascular Medicine-Internal Medicine, University of Michigan, Ann Arbor, 2CAIRN Research, 3StemBioSys, Inc. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) offer an alternative to using animals for preclinical cardiotoxicity screening. A limitation to the widespread adoption of hiPSC-CMs in preclinical toxicity screening is the immature, fetal-like phenotype of the cells. Presented here are protocols for robust and rapid maturation of hiPSC-CMs. Bioengineering Single-Cell Optical Action Potential Measurement in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes Fitzwilliam Seibertz1,2, Martyn Reynolds3, Niels Voigt1,2,4 1Institute of Pharmacology and Toxicology, University Medical Center Goettingen, Goettingen, Germany, 2DZHK (German Center for Cardiovascular Research), Partner Site Goettingen, Germany, 3Cairn Research Ltd, Faversham, United Kingdom, 4Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Goettingen, Germany Here we describe optical acquisition and characterization of action potentials from induced pluripotent stem cell derived cardiomyocytes using a high-speed modular photometry system.