Inotropic assessment in engineered 3D cardiac tissues using human induced pluripotent stem cell-derived cardiomyocytes in the BiowireTM II platform.

To develop therapeutics for cardiovascular disease, especially heart failure, translational models for assessing cardiac contractility are necessary for preclinical target validation and lead optimization. The availability of stem cell-derived cardiomyocytes (SC-CM) has generated a great opportunity in developing new in-vitro models for assessing cardiac contractility. However, the immature phenotype of SC-CM is a well-recognized limitation in inotropic evaluation, especially regarding the lack of or diminished positive inotropic response to ß-adrenergic agonists. Recent development of 3D engineered cardiac tissues (ECTs) using human induced pluripotent stem cell derived-cardiomyocytes (hiPSC-CM) in the BiowireTM II platform has shown improved maturation. To evaluate their suitability to detect drug-induced changes in cardiac contractility, positive inotropes with diverse mechanisms, including ß-adrenergic agonists, PDE3 inhibitors, Ca2+-sensitizers, myosin and troponin activators, and an apelin receptor agonist, were tested blindly. A total of 8 compounds were evaluated, including dobutamine, milrinone, pimobendan, levosimendan, omecamtiv mecarbil, AMG1, AMG2, and pyr-apelin-13. Contractility was evaluated by analyzing the amplitude, velocity and duration of contraction and relaxation. All tested agents, except pyr-apelin-13, increased contractility by increasing the amplitude of contraction and velocity. In addition, myosin and troponin activators increase contraction duration. These results indicate that ECTs generated in the BiowireTM II platform can identify inotropes with different mechanisms and provides a human-based in-vitro model for evaluating potential therapeutics.