High-Throughput Physiological Assay For Force And Stiffness Quantification In Ips Derived Cardiomyocytes

Introduction: Cardiovascular disease persists as one of the leading causes of death in the U.S. Physiological assays with iPSC-cardiomyocytes have been quickly adopted for cardiac drug discovery, and the study of cardiac disease in vitro. Whereas most of these assays focus on the kinematics of voltage and calcium, assays that quantify contraction forces are less common. Moreover, there is no current high-throughput method to characterize the passive elastic properties of cardyomyocytes that contribute to dyastolic function. Methods and Results: We have developed a method to measure and characterize force of contraction and stiffness of beating cardiomyocytes, solely based on optical measurements. First, we created a device consisting of 96 well plates with soft deformable polyacrylamide gels, doped with fluorescent beads (A). IPSc cardiomyocytes are seeded on the gels and stained with Wheat Germ Agluttining (WGA). We then acquire videos of both membrane and beads (B). Our algorithm processes the videos with Particle Image Velocimetry to obtain instantaneous deformation fields on the cells (C) and the gel. Next, the traction stresses at the cell-substrate interface (D) are computed using Traction Force Microscopy, and the intracellular monolayer stress using Monolayer Stress Microscopy. Our algorithm computes temporal traces of strain on the cells (E), traction forces on the gel (F), and retrieve relevant parameters that characterize the signal (G). The elastic modulus of the cells is inferred by fitting the relationship between the measured intracellular stress and strain maps. We have validated our analysis by performing dose response curves on cardiomyocytes treated with isoproterenol, mavacamten, and omecamtiv mecarbil (H). Conclusions: To our knowledge, we present the first method that measures force and elasticity of cardiomyocytes in a high-throughput set-up, as well as a novel device that allows for the execution of such experiments.