Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells: An In-Vitro Model to Predict Cardiac Effects of Drugs

Introduction: Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) form spontaneously beating syncytia in-vitro. We evaluated whether hiPSC-CM are a compelling model of human cardiac pharmacology useful for early drug development. Methods: We measured hiPSC-CM beating frequency using Ca-sensitive dyes and a high-throughput screening system. We quantified the effects of 640 drugs with various structures and pharmacologies. Results: When tested at 1 μM, most drugs without direct effects on heart rhythm or with effects at high concentrations do not change frequency, indicating specificity. In contrast, the preparation detects compounds with direct activity on heart rhythm, demonstrating sensitivity. In particular, β-adrenergic agonists increase frequency and the model differentiates β2 from β1 agonists, as well as partial from full agonists. Phosphodiesterase inhibitors have subtype-specific actions and PDE4 is particularly important in controlling frequency. The preparation is sensitive to cardiac ion channel blockers: L-type calcium channel blockers, Class-I and Class-III antiarrhythmics change frequency but drugs acting on KATP channels do not. The assay detects compounds blocking the cardiac rapid delayed-rectifier K channel and is an alternative to the classic “hERG test”. Conclusion: hiPSC-CM are a useful in-vitro cardiac model in drug development since they respond appropriately to drugs that modify heart rate in humans.