Biosynthesis of stromal matrix proteoglycans and basement membrane components by human corneal fibroblasts

The proteoglycans produced by intact human corneas and corneal cells in culture were compared by characterizing the biosynthetically radiolabeled proteoglycans and by using antibodies to detect their core proteins. Organ cultures of corneas primarily produce a keratan sulfate proteoglycan (KSPG) and a chondroitin and dermatan sulfate proteoglycan (decorin). Immunostaining with antibodies specific for the core proteins of KSPG and decorin showed that these proteoglycans are localized to the corneal stroma. The stroma also contained trace amounts of matrix that stained with antibodies to basement membrane heparan sulfate proteoglycan (perlecan) and laminin. Corneal fibroblasts in culture produced decorin, but the synthesis of KSPG appeared to be blocked at the level of core protein synthesis. Corneal fibroblasts in culture, however, produced perlecan in greater amounts than they did in organ cultures, and they synthesized both perlecan and laminin in greater amounts than did corneal epithelial cells in culture. These results indicate that the synthesis of proteoglycans by human corneal fibroblasts in culture is altered, resulting in increased production of basement membrane-associated proteoglycans and decreased synthesis of corneal stroma-associated proteoglycans.