Modulation of cartilage proteoglycan synthesis by osteoarthritic synovium.

Conditioned media derived from explant cultures of human osteoarthritic synovial tissue have been shown to contain preformed and newly synthesized factors of variable molecular weight which are capable on a concentration dependent basis of modulating cartilage proteoglycan metabolism. Anabolic inhibitory and stimulatory activity often appeared to coexist, a reversible down-regulation usually dominating in unfractionated preparations. The size of newly synthesized proteoglycan aggregates and monomers and the length of glycosaminoglycan chains produced in the presence of conditioned media were normal. The pattern of anabolic response did not necessarily correlate with the presence of catabolic inducing activity.