TTN and dilated cardiomyopathy: While phenotypes have been revealed in hPSC cardiomyocytes cultured in media that promote maturation in single-cell and 2D formats in the case of hypertrophic cardiomyopathy,15 ACM required not only structural and metabolic maturation but also stress conditions, complex 3D models,16–19 and noncardiomyocyte populations.20 Similarly, for mutations in TTN, the gene encoding the large sarcomere protein titin causing dilated cardiomyopathy, contractility in hiPSC cardiomyocytes was unchanged in 2D while it was impaired in 3D.