Proteoglycan metabolism in tissue cultured human articular cartilage. Influence of piroxicam.

Proteoglycan metabolism was investigated in longterm tissue cultured human cartilage. Visually intact cartilage from adult donors showed improving accumulation rates for 35sulfate labelled proteoglycans over a 6-week period. The loss of newly synthesized molecules in the nutrient culture media was low and constant. Fibrillated cartilage from a 17-year-old male showed higher basal 35S incorporation rates and the proportions of 35S proteoglycan aggregates were higher than in normal tissue. These observations may reflect the immature status of the tissue or an attempt at repair. However samples lost increasing amounts of 35S proteoglycans in the incubation media. This material appeared to be monomeric proteoglycan. The amount of 35S activity retained in the fibrillated tissue matrix fell during culture as did the proportion of proteoglycan aggregates. Thus catabolic events were postulated in these fibrillated cartilage samples. When piroxicam was added to the incubation media more newly synthesized proteoglycans were retained in the intercellular matrix of the fibrillated samples. Increased accumulation of 35S activity was seen in some of the batches of visually intact cartilage.