ALTERATION OF CARTILAGE METABOLISM BY CELLS FROM OSTEOARTHRITIC BONE

Objective. To determine whether bone cells alter cartilage metabolism. Methods. Bone cell cultures were established using explants obtained from the hip and knee joints of 9 patients with osteoarthritis (OA) an d 6 subjects without arthritis (nonarthritic [NA]). NA human cartilage biopsy samples were incubated in the presence or absence of bone-deri ved cells, and the effects on glycosaminoglycan (GAG) release from car tilage were measured. Results. Bone cell cultures secreted osteocalcin (OC) and did not contain cells expressing leukocyte common antigen. N one of the 8 cultures established from NA bone, compared with 17 of 32 from OA bone, significantly altered GAG release from cartilage (P = 0 .006). In knees with medial joint damage, 38% of the cultures derived from the medial side of the joint increased GAG release from cartilage . In contrast, 77% of the cultures derived from the lateral side of th e joint had an effect on GAG, with 38% increasing and 38% decreasing G AG release. Seven cytokines were measured in OA bone cell supernatants . No significant difference was apparent in the concentration of any o ne cytokine when supernatants were compared according to their effects on GAG release. Conclusion. Bone cells from OA patients can influence cartilage metabolism. This might explain why increased subchondral bo ne activity can predict cartilage loss.