CHONDROCYTE PHENOTYPING IN HUMAN OSTEOARTHRITIS

Cell-ECM (extracellular matrix) interactions are believed to play a ke y role in maintaining the normal structure of tissues such as cartilag e. Cell surface adhesion molecules have been reported chondrocyte bind ing to ECM proteins In human normal cartilage but the behaviour of the se molecules in human osteoarthritic cartilage is unknown. We studied receptor matrix proteins on freshly isolated chondrocytes obtained fro m 10 patients with osteoarthritis (OA). Chondrocytes were isolated by enzymatic digestion from three zones of the articular cartilage with a different degree of macroscopic and microscopic damage and chondrocyt e phenotype was defined by flow cytometry. Chondrocytes strongly expre ssed beta(1) integrin but not beta(3) integrin. LFA-1 (CD18/CD11a) and ICAM-1 (CD54) antigens were almost undetectable. Interestingly, beta( 1) expression was significantly higher in the minimally damaged zone t han in the zones with medium and maximum damage. These data show that beta(1)-integrin-mediated chondrocyte-ECM interactions decrease in ost eoarthritic cartilage suggesting that perturbations of chondrocyte-mat rix signalling occurs during OA.