Increased biosynthesis of glycosaminoglycans by scleroderma fibroblasts in culture

Fibroblasts from normal and scleroderma skin, grown in culture, were incubated with radioactive glucosamine to study the biosynthesis of glycosaminoglycans (GAG). Incorporation of 3H-glucosamine and GAG biosynthesis was increased in 6 of 9 scleroderma fibroblast cultures examined. This increase ranged from 26 to 96% over normal values and was reproducible. Over 70% of the 3H-glucosamine incorporated was found in the medium of the cultures, and this fraction was used to isolate GAG. Characterization of media GAG from normal and control cultures showed that about 80% of the radioactive GAG could be degraded by a specific fungal hyaluronidase; therefore, it represented hyaluronic acid. Our findings indicate that the majority of scleroderma dermal fibroblasts display increased biosynthesis of GAG in culture and that this increase is mostly in the hyaluronic acid fraction.