Abstract P1024: 3d Cardiac Tissue Rings With Exogenous Extracellular Matrix As A Model For Cardiac Fibrosis

Abstract

Introduction: Cardiac fibrosis, or excess deposition of extracellular matrix (ECM) within heart muscle, acts as a protective mechanism following cardiac injury, but causes long-term heart stiffening and impaired contraction. In vitro models aid in understanding cardiac disease mechanisms, but current fibrosis models lack (i) native-like ECM and (ii) interactions between multiple cardiac cell types. Objective: Our 3D model containing induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) and cardiac fibroblasts (CF) with exogenous ECM will reproducibly assess contractile changes under fibrotic conditions. Methods: Human GCaMP-encoded iPSC-CM (day 19) and CF (3:1) were combined in a custom agarose ring mold with collagen I (Col) (0.02 or 0.5 mg/mL), laminin (Lam) (0.01 mg/mL), both Col+Lam (0.03 mg/mL), Matrigel (0.03 mg/mL), or no ECM, n=5 for each condition. Concentrations were based on in vivo ratios of Col and Lam in literature. After 24 hours, cells self-assembled into 3D rings (Fig. 1a). Results: All conditions formed robust rings; average thickness = 460 μm (Fig.1b, c). Spontaneous beating resumed 48 hours after seeding. After 3 days in culture, Ca 2+ flux videos were captured; rings without ECM displayed shorter contraction durations, as did Col+Lam rings (Fig. 1d, e). This suggests that exogenous ECM in ratios found in healthy hearts may aid in contraction. Conclusion: This ring platform provides a reproducible cardiac fibrosis model with native-like ECM conditions and interactions between multiple cardiac cell types. Further assessments of ring stiffness and additional ECM conditions will enable this model to be used in therapeutic development.