Immune-integrated cardiac fibrosis-on-a-chip: a 3D microfluidic device for region-specific immune-cardiac crosstalk in the fibrotic heart.

Abstract

Cardiac fibrosis following myocardial infarction (MI) is driven by complex interactions among cardiomyocytes (CMs), cardiac fibroblasts (CFs), and immune cells, particularly macrophages. Current <i>in vitro</i> models often fail to capture the spatial heterogeneity and dynamic immune-cardiac crosstalk that are central to post-MI remodeling. Therefore, we aimed to develop a physiologically relevant cardiac fibrosis-on-a-chip model that integrates spatially patterned cardiac tissue architecture with region-specific immune cell delivery and mimic post-MI fibrosis. We engineered a three-layer microfluidic device seeded with human iPSC-derived CMs and CFs at defined ratios to replicate scar, border, and healthy regions. A valve-actuation system enabled the controlled introduction of iPSC-derived macrophages (iMacs) in a gradient pattern, mimicking their spatial distribution <i>in vivo</i>. TGF-β was used as a comparative biochemical stimulus to establish baseline fibrotic signaling. Immunostaining and computational modeling confirmed the spatial patterning of CM/CF and macrophage gradient distribution. This cardiac fibrosis-on-a-chip model provides an innovative and physiologically relevant system to investigate immune-mediated fibrosis. It enables region-specific analysis of immune-cardiac interactions and serves as a valuable model for therapeutic screening in fibrotic heart disease.