Abstract

Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) are a promising in vitro tool for drug development and disease modeling, but their immature electrophysiology limits diagnostic utility. Tissue engineering approaches involving aligned 3D cultures enhance hiPSC-CM structural maturation but are insufficient to induce mature electrophysiology. We hypothesized that mimicking post-natal switching of the hearts primary ATP source from glycolysis to fatty acid oxidation could enhance electrophysiological maturation of hiPSC-CM. We combined hiPSC-CM with microfabricated culture chambers to form 3D cardiac microphysiological systems (MPS) that enhanced immediate microtissue alignment and tissue specific extracellular matrix (ECM) production. Using Robust Experimental design, we identified a maturation media that improved calcium handling in MPS derived from two genetically distinct hiPSC sources. Although calcium handling and metabolic maturation were improved in both genotypes, there was a divergent effect on action potential duration (APD): MPS that started with abnormally prolonged APD exhibited shorter APD in response to maturation media, whereas the same media prolonged the APD in MPS that started with aberrantly short APD. Importantly, the APD of both genotypes was brought near the range of 270-300ms observed in human left ventricular cardiomyocytes. Mathematical modeling explained these divergent phenotypes, and further predicted the response of matured MPS to drugs with known pro-arrhythmic effects. These results suggest that systematic combination of biophysical stimuli and metabolic cues can enhance the electrophysiological maturation of hiPSC-derived cardiomyocytes. However, they also reveal that maturation-inducing cues can have differential effects on electrophysiology depending on the baseline phenotype of hiPSC-CM. In silico models provide a valuable tool for predicting how changes in cellular maturation will manifest in drug responsiveness.