Genlai Du, Diyu Wang, Qingqian Chen, Jiaru Sun, Qizhi Shuai, Quanyou Zhang, Shaowei Wang, Qin Zhang, Chongwei Chen, Ruyi Shi
Current clinical management of osteoarthritis (OA) follows a stepwise, symptom-oriented approach that provides analgesia but exhibits limited disease-modifying efficacy. Quercetin (QUE), a natural flavonoid, possesses broad anti-inflammatory and antioxidant properties. However, its chondroprotective capacity against early chondrocyte degenerative injury triggered by inflammatory cytokine and abnormal matrix stiffness, alongside the relevant molecular mechanisms, remain incompletely defined. Existing in vitro OA chondrocyte models, predominantly based on 2D cultures with interleukin-1β (IL-1β) stimulation alone, fail to recapitulate the biomechanical aspects of the disease, particularly the altered matrix stiffness present in vivo. To address this limitation, we developed a physiologically relevant 3D hydrogel system with tunable elastic moduli, composed of alginate, type I collagen, and hyaluronic acid, simulating the progressive changes in microenvironmental stiffness between healthy and osteoarthritic cartilage. A stiffness of 70 kPa was used to mimic healthy cartilage, while a 22 kPa model combined with IL-1β induction replicated the chondrocyte inflammatory injury microenvironment. Using this biomechanically relevant model, we demonstrated that QUE attenuates NF-κB signaling by inhibiting p65 nuclear translocation, thereby reducing the production of pro-inflammatory mediators. Concurrently, QUE enhanced autophagy in chondrocytes, facilitating the clearance of damaged cellular components and mitigating inflammation-driven catabolism. Furthermore, QUE promoted an anabolic shift by upregulating cartilage matrix synthesis, thereby helping to maintain chondrocyte homeostasis and delay chondrocyte inflammatory and degenerative damage triggered by abnormal matrix mechanics and IL-1β. Our findings also underscore the critical influence of matrix stiffness on the efficacy of QUE. This study provides preclinical proof-of-concept for a combined therapeutic strategy that integrates mechanical microenvironment restoration with pharmacological intervention for OA management.