Sliding Hydrogels Reveal the Modulation of Mechanosensing Attenuates the Inflammatory Phenotype of Osteoarthritic Chondrocytes in <scp>3D</scp>

Osteoarthritis (OA) is a prevalen degenerative joint disease with no FDA-approved therapies that can halt or reverse its progression. Current treatments address symptoms like pain and inflammation, but not underlying disease mechanisms. OA progression is marked by increased inflammation and extracellular matrix (ECM) degradation of the joint cartilage. While the role of biochemical cues has been widely studied for OA, how matrix mechanical cues influence OA phenotype remains poorly understood. Using sliding hydrogels (SGs) as a tool, we examine how local matrix compliance in 3D modulates OA chondrocyte phenotype and associated mechanosensing. We demonstrate that local matrix compliance reduces the inflammatory phenotype of OA chondrocytes, as indicated by decreased gene expression of catabolic markers and proinflammatory cytokine secretion. This is achieved via significantly reduced nuclear NF-κB expression and signaling in OA chondrocytes. Live cell imaging shows enhanced cellular and nuclear dynamics with increased matrix deformation in the compliant SG. Blocking cellular dynamics negates SG compliance-induced benefits in reducing OA inflammatory phenotype. Further, SG alters nuclear mechanosensing in OA as indicated by increased nuclear lamin reinforcement and chromatin condensation. Finally, we demonstrate that a drug inhibiting histone lysine demethylase to modulate chromatin accessibility reduces OA inflammation in 3D hydrogels. These findings advance our understanding of how ECM mechanics regulate OA mechanobiology and progression and highlight potential disease-modifying treatments via epigenetic and mechanosensing-based therapies.