Preparing a rabbit model of synovitis in knee osteoarthritis based on the “injury-repair-reinjury” method
Su Jianqing1, Sun Bo2, Ding Yunrong3, Liu Guangming2, Ji Wei2, Jiang Enyu2, Yang Jiayu2
1The Second Rehabilitation Hospital of Shanghai, Shanghai 200441, China; 2Xiangshan TCM Hospital of Huangpu District, Shanghai 200020, China; 3The Seventh People’s Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 200137, China
Abstract: BACKGROUND: At present, surgical trauma and intraarticular injection-induced models are the animal models mainly used for synovitis in knee osteoarthritis. There is still a large distance between the modeling method and the mode of disease occurrence.
OBJECTIVE: To establish and evaluate a rabbit model of synovitis in knee osteoarthritis based on the method of “injury-repair-re-injury,” so as to provide model support for the study of synovitis in knee osteoarthritis.
METHODS: Sixteen New Zealand white rabbits were randomly divided into two groups: model group (n=8) and control group (n=8). The rabbit’s right knee was injected with 4% papain and 0.03 mol/L L-cysteine to establish the model of synovitis in knee osteoarthritis on days 1, 4, 7, and 12. The skin temperature of the right knee was recorded. Rabbits in each group were killed under anesthesia and the knee joint samples were collected on day 15. Knee joint effusion and cartilage were observed using magnetic resonance imaging. Synovial tissue changes were observed using hematoxylin-eosin staining. Expression levels of inflammatory factors and prostaglandin E2 in the knee synovial fluid were measured by enzyme-linked immunosorbent assay.
RESULTS AND CONCLUSION: In the model group, the rat knees became red, swollen and hot obviously at the first injection of the preparation, and the skin temperature was significantly higher than that in the control group. Magnetic resonance imaging revealed obvious synovial effusion and slight damage to the knee cartilage in the model group. Hematoxylin-esoin staining showed synovial tissue thickening and a large number of inflammatory cells infiltrated in the model group. Levels of inflammatory factors and prostaglandin E2 in the synovial fluid were significantly higher in the model group than the control group. Rabbit model of synovitis in knee osteoarthritis can be successfully established by the “injury-repair-reinjury” method, which presents similar conditions with clinical synovitis in knee osteoarthritis, by comprehensive evaluation based on the performance of knee joint surface, skin temperature of the knee, synovial effusion and histological changes of the synovial tissue.
Key words: knee osteoarthritis, synovitis, animal model, inflammation, joint effusion, cartilage