The effects of TIMP-1 and -2 on canine chondrocytes cultured in three-dimensional agarose culture system

Abstract

Objective: To investigate the effects of tissue inhibitor of metalloproteinase (TIMP)-1 and -2 on chondrocytes cultured with or without interleukin (IL)-1β. Design: Canine articular chondrocytes were cultured in three-dimensional (3-D) agarose constructs. Cells were distributed into each of the two groups, those without IL-1β and those with IL-1β added to the liquid media. Each group was subdivided into three groups, based on the presence of TIMP-1 or -2. IL-1β and TIMPs were added to liquid media bathing the 3-D constructs beginning on day 3. The liquid media and the 3-D constructs were collected on days 9, 15, and 24, and analyzed histologically, biochemically, and immunohistochemically. Results: Addition of TIMP-1 or -2 resulted in decreases in matrix metalloproteinase (MMP)-3 concentrations of 37 and 41%, and MMP-1 immunoreactivity of 32 and 36%, respectively, compared with the IL-1β group, on day 9. Chondrocytes in groups without IL-1β maintained viability and produced abundant extracellular matrix (ECM). Chondrocytes in IL-1β groups appeared less viable and produced less ECM compared with those without IL-1β. Glycosaminoglycan (GAG) concentrations in 3-D constructs (GAG/weight) were significantly ( P<0.001) higher in groups without IL-1β than in those with IL-1β, on days 15 and 24. Conclusions: The addition of TIMP was not detrimental to chondrocytes, as used in this study. Despite evidence of decreased MMP levels, TIMPs did not prevent IL-1β-associated changes in cellular or ECM characteristics. Further study is necessary before clinically relevant conclusions can be drawn regarding the use of TIMPs in the treatment of osteoarthritis.