Engineered 3D environments reprogram fibroblast-mediated inflammation in rheumatoid Arthritis

Inflammation is essential for fighting infections and initiating tissue repair, but chronic unresolved inflammation underlies many conditions, like cancer and autoimmune disorders. While dysregulated immune responses drive chronic inflammation, non-immune stromal cells such as fibroblasts also play a critical role. Targeting fibroblasts could enable tissue-specific therapies while avoiding the systemic suppression caused by current drugs. However, traditional culture systems often induce artificial behaviours, limiting progress. Here, we demonstrate the importance of the mechanical properties of the 3D culture environments in fibroblast-mediated inflammation in the context of Rheumatoid Arthritis, a chronic disease that primarily affects joints but also impacts other organs. We isolated fibroblasts from healthy and arthritic mouse joints and expanded them on 2D tissue culture plastic, stiff fibronectin-coated scaffolds, or soft pegylated fibronectin-based hydrogels. Our results highlight the plasticity of fibroblasts, with microenvironmental cues driving inflammatory or regulatory phenotypes. The 3D environment offered by fibronectin-coated scaffolds restored inflammatory gene expression profiles that were lost in flat cultures, while the more physiologically relevant soft hydrogels shifted fibroblasts toward a resolving phenotype. These findings underscore the importance of the 3D environment in modulating fibroblast behaviour and establish a foundation for bioengineered systems that better model disease or guide therapeutic strategies.