Synthesis of hyaluronic acid and collagen in skin fibroblasts cultured from patients with osteogenesis imperfecta.

Collagen and hyaluronic acid syntheses were studied in skin fibroblast cultures from patients with osteogenesis imperfecta and age-matched controls by labeling the cultures either with [3H]proline and separating the collagenous proteins with DEAE- and CM-cellulose chromatographies, or double-labeling the cultures with [3H]glucosamine and [14C]glycine and separating radioactive hyaluronic acid from glycoproteins and sulphated proteoglycans by DEAE-cellulose chromatography. The activities of the cell layer hyaluronate synthesizing enzyme complex (hyaluronate synthetase) were also determined. The osteogenesis imperfecta cultures were classified into three variants on the basis of type III collagen synthesis. Type III collagen amounted to approx. 40--50% from total collagen in the first variety and approx. 25--30% in the second variety. No difference was noted in the ratio of type III collagen to total collagen in the third variety in comparison with control cultures. The radioactivities of 3H-labeled hyaluronic acid in DEAE-cellulose chromatograms were compared with those of the 14C-labeled proteins. The ratios ranged 9.2--17.3 in the cultures from the patients and 4.6--8.8 in the control cultures. Hyaluronate synthetase activities were 1.3--2.0-fold higher in the osteogenesis imperfecta cells than in their controls. Increased hyaluronic acid synthesis in skin fibroblasts correlated with the severity of the disease but not with the increase in type III collagen synthesis.