Abstract
Cardiac fibrosis in hypertrophic cardiomyopathy (HCM) is characterized by extracellular matrix (ECM) post-translational modifications. These are driven by cardiac fibroblasts (CFs), mechanosensitive cells that respond to ECM stiffness, potentially accelerating disease progression [1]. A key regulator of fibrosis is TGF-β, which activates CFs and promotes ECM remodeling. Recent advances in 3D cell culture have enabled the study of microtissue biomechanics in cell spheroids (CSs), yet conventional models, i.e. Hertz theory, fail to capture their large deformations. Here, we utilized the extended Tatara model [2], incorporating Mooney-Rivlin hyperelasticity and nonlinear boundary effects, to investigate the mechanics of four CS groups (CU: control untreated; CT: control+TGF-β; HCMU: diseased untreated; HCMT: diseased+TGF-β) derived from human cardiac fibroblasts. To evaluate the effectiveness of the model, results were compared to ones derived from Hertz, Ding and simple Tatara models. The extended Tatara model demonstrates superior accuracy, enabling a more comprehensive mechanical analysis of CSs under parallel-plate compression of up to 50% strain (Fig1a), compared to the other models used. In addition, video footage captured during compression enabled estimation of Poisson’s ratio through image segmentation and shape analysis. This allowed further refinement of the calculated compression modulus (Fig1b). Our findings reveal that HCM CSs are nearly three times stiffer than control CSs. TGF-β treatment increased stiffness two-fold in both groups (Fig1c). This study provides a robust framework for assessing micromechanics in patient-derived models of fibrosis, which may serve as an endpoint readout for testing drugs in a patient-specific setting.