A heart-on-a-chip platform was developed to study interactions between epicardial and myocardial tissue layers under controlled conditions. The system combined engineered epicardial tissue with a myocardial core, enabling measurements of tissue structure and function using micro scale mechanical testing approaches compatible with high throughput micro mechanical testing workflows.

Human pluripotent stem cell–derived cardiomyocytes, fibroblasts, and epicardial cells were introduced using a two-step seeding process. Over time, epicardial cells migrated into the myocardial layer, forming bilayer tissues with maintained organization and evolving functional behavior during culture.

Tissues were subjected to an ischemia–reperfusion injury protocol to examine differential responses. Samples containing an epicardial layer showed reduced cell death and distinct functional recovery patterns compared to myocardial-only constructs. Quantitative imaging, force measurements, and immunostaining were used to track epicardial cell behavior and mechanical response during and after injury.

This platform supports the study of epicardial–myocardial interactions across development and injury models, with mechanical measurements integrated alongside biological readouts.

The resulting datasets were analyzed using principal component analysis and Bayesian probability methods to compare the relative likelihood of several hyperelastic constitutive formulations. Model selection was based on how well each formulation represented variability across samples and loading conditions, rather than on deterministic curve fitting alone.

Across the set of candidate models, the May–Newman formulation showed the highest likelihood for describing the observed biaxial response. The framework provides a structured approach for comparing constitutive descriptions of valve tissue mechanics using probabilistic criteria.