SYNTHESIS OF AGGRECAN CORE PROTEINS BY HUMAN CARTILAGE AND CHONDROCYTES IN-VITRO

Proteoglycans synthesized by human cartilage were studied in explants and in chondrocyte cultures, The D1 fraction proteoglycans radiolabell ed with (SO4)-S-35 were analyzed by 3-16% sodium dodecyl sulfate polya crylamide gel electrophoresis or on 3-5% acrylamide gels, After 24 h i n culture, osteoarthritic and age matched nonarthritic cartilage synth esized one aggrecan core protein (LI) whose apparent size after chondr oitinase ABC/keratanase digestion was similar to 520 kDa. Three proteo glycan core proteins were found in the D1 fraction of the medium compa rtment of nonarthritic chondrocytes, whose apparent sizes were similar to 520 kDa (L(I)), similar to 390 kDa (L(II)), and similar to 480 kDa (L(III)). The L(II) and L(III) core proteins were routinely absent fr om osteoarthritic chondrocytes. Chondrocytes from a 28-year-old patien t with osteoarthritis secondary to congenital hip dysplasia synthesize d principally the L(I) proteoglycan core protein,