Change in the synthesis of glycosaminoglycans by fibrotic vitreous induced by erythrocytes.

Vitreous fibrosis was induced in rabbit eyes by intravitreal injection of erythrocytes. The fibrotic vitreous removed from experimental animals were then incubated with [3H]glucosamine at 37 degrees C for 24 h. The newly synthesized 3H-labeled glycosaminoglycans were isolated by 4 M guanidium hydrochloride extraction followed by pronase digestion. The 3H-labeled glycosaminoglycans were then characterized by gel filtration column chromatography and by specific enzymatic degradation, i.e., hyaluronidase, chondroitinase AC, and/or chondroitinase ABC. The disaccharides derived from chondroitinase ABC degradation were identified by thin-layer chromatography. We previously demonstrated that 91% of the total glycosaminoglycan synthesized by normal vitreous was hyaluronic acid. Our present results indicate that in the fibrotic vitreous, the synthesis of hyaluronic acid was decreased to 26%, whereas the synthesis of chondroitin sulfate increased to 59% of the total newly synthesized glycosaminoglycans. These results suggest that cells present in fibrotic vitreous resemble fibroblasts with respect to their activities in glycosaminoglycans synthesis.