DIFFERENTIAL-EFFECTS OF BONE ASSOCIATED FACTORS ON NEWLY SYNTHESIZED ANIONIC GLYCOCONJUGATES BY ARTICULAR CHONDROCYTE CULTURES FROM ADULT AND IMMATURE BOVINES

Objective. To determine if bone associated peptide factors (BAF) diffe rentially affect proteoglycan and hyaluronic acid (HA) synthesis as a result of the maturity of the animal and of the location of chondrocyt es within cartilage zones. Methods. Calf and adult bovine articular ch ondrocytes were isolated and cultured, as high density monolayers, wit h H-3-glucosamine and S-35-sulfate. The effects of commercial transfor ming growth factor beta (TGF-beta) and a preparation from bovine bone that contained the total extractable stimulatory activity for glycosam inogylcan (GAG) synthesis (matrigenin activity) were studied. Results. Calf chondrocytes spontaneously synthesized a higher proportion of pr oteoglycans of larger hydrodynamic size, but the addition of the BAF r esulted in a proportionally greater shift in the adult chondrocytes to wards the synthesis of larger proteoglycans, appearing in the medium. Subpopula tions of adult chondrocytes from the deep zone synthesized s pontaneously more chondroitin sulfate (CS) and less HA than chondrocyt es from the superficial zone, but the calf chondrocytes from the 3 zon es showed similar patterns of GAG synthesis. Adult chondrocytes from t he deep zone had large responses to the BAF for HA but not CS synthesi s, resembling the subpopulations of the calf chondrocytes. Conclusion. BAF differentially modulate HA and CS synthesis of articular chondroc ytes as a result of maturation and topography. We speculate as to how this differential response to BAF may help set the stage for the progr ession of osteoarthritis in weight bearing joints.