Expression of stromelysin and urokinase type plasminogen activator proteinin resection specimens and biopsies at different stages of osteoarthritis of the knee

This study aimed at assessing the possible diagnostic value of cartilage bi opsies as a convenient marker for cartilage matrix degradation. We therefor e examined cartilage specimens from 56 patients with primary osteoarthritis (OA) of the knee. Resection and biopsy cartilage specimens obtained during joint replacement surgery were used for this study. In addition to histomorphology, immunohis tochemistry (ICH) was performed to determine the expression levels and dist ribution patterns of stromelysin and u-PA protein. The latter data were com pared with the degree of histomorphological changes in osteoarthritic carti lage samples, based on a modified version of Mankin's grading score. Compared to the cartilage resection specimens, the biopsies showed comparab le expression patterns for both proteinases: the strongest signals were not ed in the superficial zone and, as matrix destruction increased, also in th e chondrocytes of the transition and deep zones. The strongest signals were ascertained in cell clusters beneath deep matrix fissures. At the immunohi stochemical level, we found a direct correlation in the expression of MMP-3 and u-PA between resection specimens and biopsies. Furthermore, in both ty pes of cartilage samples, we noticed a positive relationship between the ex pression of both proteins and the Mankin score. Analysis of the expression levels revealed significant differences between deep, transition and superf icial zones. Histomorphological and immunohistochemical examinations of MMP-3 and u-PA i n biopsies of osteoarthritic cartilage turned out to be useful for estimati ng the pathological changes within osteoarthritic knee joints. Therefore, i n future, cartilage biopsies from osteoarthritic knee joints I-night serve as a diagnostic tool and thus have an influence on further therapeutic stra tegies.