Stiffness-tunable alginate-hyaluronic acid-collagen hydrogel mimics chondrocyte microenvironment for osteoarthritis pathophysiological modeling.

Osteoarthritis (OA) is a degenerative joint disease characterized by an increasing prevalence and complex pathogenesis. Despite significant research efforts, understanding its mechanisms and developing effective treatments remain challenging. The development of in vitro models that accurately mimic the native articular microenvironment while preserving chondrocyte phenotype is crucial for advancing OA research. In this study, we constructed an Alginate-Hyaluronic Acid-Type I Collagen (Alg-HA-Col) composite hydrogel through physical mixing and chemical cross-linking. This composite matrix exhibited exceptional stability over 28 days under simulated physiological conditions. Neonatal murine chondrocytes encapsulated within Alg-HA-Col hydrogels for 28 days maintained their phenotype better than those cultured in monolayer, as evidenced by higher expression levels of SOX9, type II collagen, and aggrecan. Furthermore, by adjusting the component ratios, the stiffness of Alg-HA-Col hydrogels could mimic the stiffness of the pericellular matrix (PCM) in both physiological and pathological states, referred to as Firm and Soft. Chondrocytes cultured in Alg-HA-Col hydrogels with varying stiffness showed decreased expression of marker proteins, increased cellular mortality, and elevated inflammatory factor expression as stiffness decreased. Therefore, Alg-HA-Col hydrogels with tunable stiffness effectively simulated the physiological and pathological states of cartilage, providing an ideal three-dimensional (3D) matrix for chondrocyte culture. Additionally, this model's long-term culture stability offers potential applications in osteoarthritis drug therapy and cartilage tissue engineering.