Injectable anti-inflammatory hyaluronic acid hydrogel for osteoarthritic cartilage repair.

Osteoarthritis (OA) is one of the most common cartilage disorder that results from breakdown of joint cartilage and underlying bone tissues. Once OA is induced in the joint, subsequent immune reaction leads to chronic inflammation that results in the progression of OA and deconstruction of the cartilage. In this study, an injectable hydrogel with epigallocatechin-3-gallate (EGCG) is introduced to control inflammation and enhance cartilage regeneration. EGCG has intrinsic properties that can modulate inflammation and scavenge radical species. Hyaluronic acid (HA), as a major component of the cartilage ECM, is commonly used for cartilage tissue engineering. In this study, EGCG was combined with tyramine-conjugated HA and gelatin to create a composite hydrogel at an optimized concentration of 50 μM EGCG and 5% w/v HA. The composite hydrogel provided protection to chondrocytes against the pro-inflammatory factor, IL-1β. Additionally, the composite hydrogel led to chondrogenic regeneration in vitro. Histological analysis in vivo showed that EGCG-HA/Gelatin hybrid hydrogel minimized cartilage loss in surgically induced OA model. This study demonstrates that inflammation-modulating HA-based hydrogel may provide a therapeutic option for OA treatment.