PROLONGED EXPOSURE OF HUMAN CHONDROCYTES TO ASCORBIC-ACID MODIFIES CELLULAR BEHAVIOR IN AN AGAROSE-GEL

Using an agarose gel culture system, the response of adult human chond rocytes to prolonged exposure of ascorbic acid was evaluated using his tochemical, immunocytochemical and morphological techniques. The respo nse of these cells to ascorbic acid was different from those previousl y reported in the literature. Many chondrocytes branched within the ag arose gel with continued exposure to ascorbic acid while other chondro cytes maintained a round configuration typical of chondrocytes in vivo . Fibronectin and type I collagen were closely associated with the cel l processes of the branching cells. Type II collagen and an alcian blu e-staining matrix were associated with the rounded cells but not with the branched cells. These data suggest that the chondrocytes are able to express both dedifferentiated and redifferentiated phenotypes with ascorbic acid under these culture conditions. In addition, human chond rocytes were cultured in a collagen gel and began branching within 1 h our of culture. It is possible that an accumulation of type I collagen in the pericellular matrix of ascorbic acid treated cultures may enha nce and explain the branching seen in these cultures. Studies by other s have indicated that ascorbic acid may enhance, reduce, and/or modify the cartilage matrices produced by chondrocytes. These controversial reports in the literature are presumably due to variations between spe cies and the culture methods employed. (C) 1994 Wiley-Liss, Inc.