Background  Dickkopf-3 (DKK3) has possibilities for the treatment of osteoarthritis (OA) and hydroxybutyl chitosan (HBC) thermo-sensitive hydrogel is a promising drug vehicle.

  Objective  To investigate the impact of DKK3-loaded thermo-sensitive HBC hydrogel on rats with OA.

  Methods  DKK3-loaded HBC was prepared, whose gel formation time, cumulative release, and safety were determined by constant temperature water bath, enzyme-linked immunosorbent and Cell Counting Kit-8 assays. Then 24 rats were randomly divided into sham group, OA Model group, OA + DKK3 group, OA + DKK3-loaded HBC group, with 6 rats in each group. After model establishment by anterior cruciate ligament disconnection, rats were intra-articular injected with phosphate buffered solution, DKK3 or DKK3-loaded HBC respectively. After gait analysis, the knee joints of rats were isolated. Bone changes were evaluated by micro computed tomography, and cartilage changes were evaluated by haematoxylin and eosin staining and immunohistochemical staining.

  Results  DKK3-loaded HBC hydrogel could be created in 10 s at 37℃, and DKK3 was released rapidly within 24 h and sustained over 168 h. DKK3 and HBC extraction solutions had extremely slight cytotoxicity and no significant effect on chondrocyte viability. Compared with the OA Model group, the OA + DKK3 loaded HBC group showed an increase in speed, stride length, and single stance (all P<0.05), improved bone and cartilage integrity, decreased cartilage matrix loss and expression of cartilage matrix decomposing enzymes (all P<0.05).

  Conclusion  HBC shows drug sustained release behavior, and the intra-articular injection of DKK3-loaded HBC can slow the progression of OA in rats and improve pain and locomotor performance by reducing the expression of cartilage matrix decomposing enzyme.