Synergistic restoration of dynamic mechanical properties of articular cartilage by hyaluronic acid methacrylate.

The integrity of articular cartilage is essential for a healthy joint. In joint disease, such as osteoarthritis, articular cartilage is degraded, compromising its functions of load transmission and lubrication, ultimately leading to joint pain that limits mobility. Tissue-penetrating bioagents, such as hyaluronic acid, have been used to stabilize and reinforce degenerated cartilage. Yet, the effect of the bioagents on the dynamic mechanical behaviour of articular cartilage is understudied. Here, we investigated the effect of a tissue-penetrating, photocrosslinkable hyaluronic acid methacrylate (HAMA) on the dynamic viscoelasticity of healthy and degraded cartilage. Porcine knee cartilage was artificially degraded by collagenase to model diseased cartilage. Healthy and degraded cartilage were treated with 4% HAMA following 10 min diffusion time and 3 min photocrosslinking. Viscoelastic and dynamic mechanical properties of cartilage samples were measured through a three-step stress relaxation compression test, with a multi-frequency sinusoidal displacement load applied at the end of each stress relaxation. Our data suggest that HAMA treatment synergistically restored the viscoelastic dynamic properties of degraded cartilage to match those of healthy cartilage. Healthy cartilage was minimally affected by HAMA. Notably, the mechanical degradation by collagenase and restoration by HAMA likely occurred in the top 150 µm layer of cartilage, highlighting the importance of superficial zone cartilage for cartilage function. Our study provides support for the use of HAMA in stabilizing and reinforcing the dynamic mechanical properties of enzymatically weakened cartilage. HAMA may be a promising alternative for joint preservation therapy to slow the progression of early osteoarthritis.