Effect of epithelial debridement on glycosaminoglycan synthesis by human corneal explants

The purpose of the present work was to investigate the effects of mechanica l epithelial debridement upon glycosaminoglycan synthesis by human corneal explants Corneal explants were maintained under tissue culture conditions f or 2-72 days and the glycosaminoglycans synthesized in 24 h were metabolica lly labeled by addition of S-35-sulfate to the culture medium. These compou nds were isolated from the tissue explants and analyzed by a combination of agarose gel electrophoresis and enzymatic degradation with specific mucopo lysaccharidases. The glycosaminoglycans synthesized by isolated epithelial cells and by corneas previously submitted to epithelial cell debridement we re compared to controls. Keratan sulfate (26 kDa) and dermatan sulfate (43 kDa) were the main corneal glycosaminoglycans,each one corresponding to abo ut 50% of the total. Nevertheless, the main S-35-labeled glycosaminoglycan was S-35-dermatan sulfate (73%), with smaller amounts of S-35-keratan sulfa te (15%) and S-35-heparan sulfate (12%), suggesting a lower synthesis rate for keratan sulfate. The main glycosaminoglycan synthesized by isolated epi thelial cells was heparan sulfate. The removal of epithelial layer caused a decrease in heparan sulfate labeling and induced the synthesis of dermatan sulfate by stromal cells. This increased synthesis of dermatan sulfate sug gest a relationship between epithelium and stroma and could be related to t he corneal opacity that may appear after epithelial cell debridement. (C) 2 000 Elsevier Science B.V. All rights reserved.