Patient-Derived hiPSC-Cardiomyocytes and Engineered Heart Tissues Reveal Distinct Functional Phenotypes in Inherited Cardiomyopathies

Background Hypertrophic and dilated cardiomyopathies (HCM and DCM) are the most common inherited cardiomyopathies. However, genotype-specific molecular and functional cardiomyocyte phenotypes and responses to neurohormonal stimulation remain incompletely understood. Here, we investigated whether patient-derived HCM and DCM cardiomyocytes exhibit distinct baseline phenotypes or differential responses to hypertrophic stimulation and pharmacological treatment. Methods Three human-induced pluripotent stem cell (hiPSC) lines were used: a control line, an HCM patient-derived line carrying a MYBPC3 mutation, and a DCM patient-derived line carrying an LMNA mutation. The cells were differentiated into hiPSC-cardiomyocytes, which were exposed to endothelin-1 and the GATA4-targeted compound 3i-1262, followed by transcriptional and protein expression analyses. In addition, engineered heart tissues (EHTs) were generated and cultured for 40 days, with endothelin-1 and 3i-1262 treatment applied during the final 20 days. Lastly, {beta}-adrenergic stimulation with isoprenaline was performed. EHT contractile function was quantified using MUSCLEMOTION. Results Patient-derived hiPSC-cardiomyocytes exhibited genotype-dependent responses to endothelin-1 at the transcriptional and protein levels. DCM-cardiomyocytes failed to maintain structural integrity in the EHTs, resulting in tissue fracture or cessation of beating. Functional analyses demonstrated distinct baseline contractile properties between control and cardiomyopathy EHTs, as well as differential responses to endothelin-1 and isoprenaline. Conclusions Patient-derived hiPSC-cardiomyocytes exhibit genotype-specific molecular and functional phenotypes. EHTs generated from HCM hiPSC-derived cardiomyocytes showed a progressive decline in apparent force, whereas DCM EHTs fractured over time, suggesting mutation-associated phenotypes in 3D cardiac tissue models. These findings highlight the utility of hiPSC-based cardiac models for investigating molecular and functional disease mechanisms and pharmacological responses in inherited cardiomyopathies. Keywords: hypertrophic cardiomyopathy, dilated cardiomyopathy, engineered heart tissues, hiPSC-derived cardiomyocytes, GATA4