Corneal glycosaminoglycan synthesis in long-term organ culture.

Rabbit corneas cultured in a serum-free, dextran-supplemented medium maintained a high rate of incorporation of H-glucosamine into glycosaminoglycans (GAG) for several weeks in culture. The labeled GAG secreted by cultured corneas was identified as keratan sulfate, galactosaminoglycan, and heparan sulfate. Corneal GAG labeled in vivo consisted primarily of keratan sulfate and galactosaminoglycan. Changes in the composition of the culture medium affected the rate of accumulation of H-GAG in cultured corneas but had little effect on the relative abundance of the different GAG types. Physical or enzymatic damage to the cultured corneas resulted in marked changes in the ratio of labeled GAG types secreted. Physical damage to the epithelial or endothelial surfaces and/or mild trypsin treatment of the corneas before culture resulted in a stimulation of galactosaminoglycan secretion and a consequent decrease in the relative abundance of keratan sulfate. The presence of soy trypsin inhibitor prevented these changes. Treatment of the corneas with collagenase resulted in a decrease in all GAG secretion, particularly keratan sulfate. When corneas were removed from chilled, enucleated eyes and rinsed with solutions of soy trypsin inhibitor before incubation, the GAG secreted in culture had a similar ratio of keratan sulfate to galactosaminglycan as GAG labeled in vivo. This ratio was maintained 1 week in culture. These results suggest that secretion of the characteristic connective tissue of the corneal stroma by keratocytes is dependent on interaction between the cells and components of the stromal extracellular matrix. Invest Ophthalmol Vis Sci 24:208-213, 1983