PLATELET-DERIVED GROWTH-FACTOR STIMULATES HYALURONATE BUT NOT PROTEOGLYCAN SYNTHESIS BY HUMAN GINGIVAL FIBROBLASTS IN-VITRO

The effect of PDGF-BB on human gingival fibroblasts was monitored in a n in vitro system. PDGF was found to be mitogenic for these cells, alt hough it required the presence of low concentrations of fetal calf ser um to be active. Proteoglycan and hyaluronate synthesis was analyzed b y labeling newly synthesized macromolecules with [S-35]sulfate or [H-3 ]-glucosamine, respectively. Identification of specific glycosaminogly cans was achieved by selective enzymatic or chemical degradations. It was found that cells cultured in the presence of PDGF showed no discer nible differences in proteoglycan synthesis relative to the control cu ltures. There were no alterations in amounts of proteoglycans synthesi zed, types of sulfated glycosaminoglycans synthesized, or relative hyd rodynamic sizes of the proteoglycans. In contrast to the proteoglycans , hyaluronate synthesis was significantly increased in the presence of PDGF. The increase in [H-3]-glucosamine incorporation into newly synt hesized hyaluronate correlated with an increase in the activity of the enzyme hyaluronate synthetase but could not be accounted for entirely by changes in the specific activity of sugar nucleotide precursors, w hich did alter slightly under differing culture conditions. It is conc luded from these results that PDGF stimulates gingival fibroblasts to proliferate and is associated with a differential effect on proteoglyc an and hyaluronate synthesis. These observations may correlate with th e observed early events associated with wound healing and repair.