High-throughput, multi-parametric assessment of cardiomyocyte viscoelasticity and contractility to enable HFpEF drug discovery

About This Grant

Heart failure remains the single largest cause of mortality in the U.S. and globally. Over half of heart failure cases are heart failure with preserved ejection fraction (HFpEF), and the incidence is increasing as diabetes and obesity become ever more prevalent. Unlike heart failure with reduced ejection fraction (HFrEF), HFpEF is characterized by marked diastolic dysfunction without an apparent systolic impairment. Few drugs are effective against HFpEF, and none are known to target the underlying mechanisms of diastolic dysfunction. Thus, there is an enormous unmet need to develop drugs to treat diastolic dysfunction. Human induced pluripotent stem cell (hiPSC)-based models of heart disease hold tremendous potential for the development of heart failure drugs because they faithfully model disease and reflect patient genetics. In addition to their well-known ability to reproduce systolic disease, hiPSC-cardiomyocyte tissues also reproduce diastolic dysfunction, i.e., impaired relaxation due to aberrant active and passive mechanics. A major roadblock, however, is that nearly all tools measure contractile forces and rates, which define systolic – but not diastolic – function. There are no easy to use and high throughput quantitative tools to measure diastolic function. Therefore, to enable therapeutic development for HFpEF, this proposal is to develop a high throughput software package and associated protocols to directly measure diastolic mechanics using optical microscopes that are widely available in biopharma and academic research facilities. The platform will read out multidimensional inputs into diastolic function: the cardiomyocyte viscoelastic modulus (i.e., intrinsic cellular properties), active mechanical forces (e.g., contributed by the sarcomere in diastole) and intracellular calcium dynamics. Currently, the viscoelastic modulus is measured in low throughput using specialized equipment such as Atomic Force Microscopy (AFM). We will develop a high throughput optical method based on traction force microscopy and calcium transient recording to biomechanically model and compute the viscoelastic modulus. Standardized protocols will be developed for conventional high content instrumentation using commercially available 96- and 384-well SBS format multiwell plates. The overall platform will be benchmarked by comparison to existing technology (e.g., AFM) and validated for the ability to read out diastolic parameters in bonafide diastolic dysfunction using adult cardiomyocytes isolated from mice with diabetic cardiomyopathy. User friendliness and assay readiness will be established by conducting a functional genomics and small molecule screen, with quantitative performance metrics of success.