Effect of homologous synovial membrane on adult human articular cartilage in organ culture, and failure to influence it with D-penicillamine

Proteoglycan biosynthesis by rabbit articular chondrocytes treated with D-penicillamine

Rabbit articular chondrocytes in confluent monolayer cultures were treated with D-Penicillamine (D-Pen) during 3 or 5 days. The [35S]-sulfate incorporation in neosynthesized proteoglycans was not modified by D-Pen doses ranging from 50 to 800 micrograms/ml. After treatment during 5 days with D-Pen concentrations of 50 or 400 micrograms/ml, the chemical characteristics of proteoglycans from medium and cell-layer were determined. The aggregation capacity of proteoglycans from medium, the monomer molecular size, the glycosaminoglycan chain length and the relative rates of the different glycosaminoglycans (chondroitins, chondroitin 6-sulfate, chondroitin 4-sulfate, hyaluronic acid) remained unchanged. These results suggest that D-Pen does not alter some of the cartilage mechanical properties due to the presence of proteoglycans.

Proteoglycan biosynthesis is stimulated by D-penicillamine in chondrifying high density cell cultures

Chondrifying high density cell cultures of stage 22-24 chick embryo limb bud mesenchyme were treated with 5, 10 and 15 mmol/l D-penicillamine (DPA) for 4 and 6 days. The cultures were analyzed with morphological and biochemical techniques to learn more about the effect of DPA on the metabolism of cartilage glycosaminoglycans (GAGs). Using light and electron microscopic histochemical reactions for GAG, a considerable increase in the intensity of staining of the cartilage matrix could be detected in cultures treated with DPA as compared to the untreated controls. The uronic acid content of the treated cultures was higher than that of the controls. Liquid scintillation measurements and autoradiography revealed that DPA treatment increased the 35S-sulfate into the cultures. These data suggest that DPA - besides its well known inhibitory effect on collagen crosslink formation - alters the metabolism of sulfated GAGs in differentiating cartilage. It is supposed that DPA stimulates the biosynthesis of these macromolecules.

Matrix depletion of young and old human articular cartilage by cultured autologous synovium fragments: a chondrocyte-independent effect

Human articular cartilage of different ages was cultured for 8 days and proteoglycan (PG) release into the medium was measured. Retinol and synovial co-culture increased the PG release of cartilage of all ages. The effect of retinol was dose-dependent. Synovium increased also the PG release of dead cartilage, whereas retinol did not. The increased PG release by synovial co-culture is therefore mainly the result of synovial enzymes acting directly on the matrix rather than of a factor inducing chondrocyte-mediated breakdown.