Effects of tissue inhibitor of metalloproteinases on canine chondrocytes cultured in vitro with tumor necrosis factor-α

Abstract

Objective - To elucidate tissue inhibitor of metalloproteinase (TIMP)-mediated effects on chondrocytes. Sample Population - Articular cartilage from humeral heads of 6 dogs. Procedure - Chondrocytes from harvested specimens were cultured in 3-dimensional (3-D) agarose at 106 cells/mL. We prepared 3-D constructs exposed to only tumor necrosis factor (TNF)-α (50 ng/mL). Recombinant human TIMP-1 (255nM), -2 (285nM), or -3 (250nM) was added to liquid media bathing 3-D constructs cultured with TNF-α. Chondrocytes cultured without TIMP or TNF-α served as control samples. Samples of liquid media were collected on days 6, 9, 15, and 21 of culture for evaluation of glycosaminoglycan (GAG) and nitric oxide concentrations. The 3-D constructs were collected on days 9, 15, and 21 for evaluation of GAG, hydroxyproline (HP), and DNA contents. Results - GAG content in control samples increased significantly during the study, whereas GAG content in 3-D constructs cultured with TNF-α or TNF-α plus TIMP did not increase. On day 9, GAG release from 3-D constructs cultured with TNF-α was significantly higher than that in other constructs. The HP content in control samples increased during the study and was significantly higher than that in all other constructs on day 21. Concentrations of nitric oxide were significantly lower in control samples on day 6, compared with concentrations for all other constructs. Conclusions and Clinical Relevance - Addition of TIMPs did not counteract suppression of GAG and HP accumulation in 3-D constructs exposed to TNF-α. Apparently, adverse effects on chondrocytes exposed to TNF-α cannot be prevented by addition of TIMP alone.