Expression changes of gelatinases in human osteoarthritic knees and arthroscopic debridement

Purpose: The purpose of this study was to quantify the expression changes of gelatinase-A and -B (matrix metalloproteinase [MMP]-2 and MMP-9) in a series of chondral, meniscal, and synovial cultures of knee osteoarthritis (OA) for investigation of the possible roles of the cartilage, menisci, and synovia and the efficacy of arthroscopic debridement. Type of Study: A biochemical study. Methods: In 43 consecutive patients with knee OA undergoing arthroscopic debridement, we examined the amount of MMP-2 and MMP-9 in a series of chondral, meniscal, and synovial cultures. We also compared the gene expressions of MMP-2 and MMP-9 and membrane-type 1 MMP (MT1-MMP) in the chondral, meniscal, and synovial cultures using reverse transcription polymerase chain reaction (RT-PCR). Results: Latent and activated forms of MMP-2 were produced in all series of chondral, meniscal, and synovial cultures, and the levels in lesional cultures were significantly higher than those in paralesional ones (P < .001). Moreover, the latent form of MMP-9 (proMMP-9) appeared in 29 of 37 series of synovial cultures and in 13 of 40 series of meniscal. cultures. In meniscal cultures after 24 hours of incubation and synovial cultures after 3 and 24 hours of incubation, the level of proMMP-9 in lesional cultures was significantly higher than that in paralesional ones (P < .001). The activated form of MMP-9 appeared in 10 of 37 series of synovial cultures, and the level in lesional cultures was significantly higher than that in paralesional ones (P < .05). Furthermore, MMP-2, -9, and MT1-MMP mRNA levels of lesional areas also showed the increased expression in RT-PCR. Conclusions: Our data confirm that tissue repair of OA is ascribable to enzymic digestion of the extracellular matrix ex vivo. When technically appropriate, arthroscopic debridement for the pathologic lesions of OA, such as meniscal tears, chondral lesions, and hypertrophic villi, may be beneficial to the process of early cases. Still, it should be carefully studied for its overall effect and mechanism in vivo. Clinical Relevance: The effectiveness of arthroscopic debridement for the treatment of knee OA is controversial. The present study provides the possible mechanism of the positive effects of arthroscopic debridement in basic science.