Engineered 3D Cardiac Fibrotic Tissue to Study Fibrotic Remodeling

TLDR

Activation of cardiac fibroblasts into myofibroblasts drives remodeling and fibrosis, but 2D cultures cause spontaneous activation that hampers study. The authors present a simplified 3D hydrogel platform of contractile cardiac tissue stimulated by TGF‑β1 to recapitulate a fibrogenic microenvironment, hypothesizing that mimicking native heart stiffness preserves fibroblast quiescence. They engineered a gelatin methacryloyl hydrogel embedding cardiomyocytes and fibroblasts, then assessed fibrotic protein markers and mechanical stiffness changes to validate the model. The tuned hydrogels maintained fibroblast quiescence, beta‑adrenergic agonist increased beating frequency, TGF‑β1 activated fibroblasts, demonstrating the platform’s utility for controlled fibrotic remodeling studies.

Abstract

Activation of cardiac fibroblasts into myofibroblasts is considered to play an essential role in cardiac remodeling and fibrosis. A limiting factor in studying this process is the spontaneous activation of cardiac fibroblasts when cultured on two‐dimensional (2D) culture plates. In this study, a simplified three‐dimensional (3D) hydrogel platform of contractile cardiac tissue, stimulated by transforming growth factor‐β1 (TGF‐β1), is presented to recapitulate a fibrogenic microenvironment. It is hypothesized that the quiescent state of cardiac fibroblasts can be maintained by mimicking the mechanical stiffness of native heart tissue. To test this hypothesis, a 3D cell culture model consisting of cardiomyocytes and cardiac fibroblasts encapsulated within a mechanically engineered gelatin methacryloyl hydrogel, is developed. The study shows that cardiac fibroblasts maintain their quiescent phenotype in mechanically tuned hydrogels. Additionally, treatment with a beta‐adrenergic agonist increases beating frequency, demonstrating physiologic‐like behavior of the heart constructs. Subsequently, quiescent cardiac fibroblasts within the constructs are activated by the exogenous addition of TGF‐β1. The expression of fibrotic protein markers (and the functional changes in mechanical stiffness) in the fibrotic‐like tissues are analyzed to validate the model. Overall, this 3D engineered culture model of contractile cardiac tissue enables controlled activation of cardiac fibroblasts, demonstrating the usability of this platform to study fibrotic remodeling.