The effect of elevated extracellular glucose on migration, adhesion and proliferation of SV40 transformed human corneal epithelial cells

Purpose - To examine the effect of elevated extracellular glucose, thus simulating diabetes, on migration, adhesion and proliferation of SV40 transformed human corneal epithelial (HCE) cells. Methods - HCE cells were maintained in serum supplemented media containing 5 mM, 17.5 mM or 38 mM D-glucose. Cell migration was determined using Blind well chambers fitted with fibronectin/collagen I coated filters. In adhesion experiments, cells were allowed to adhere to extracellular matrix protein-coated wells for 90 min at 37°C. Non-adherent cells were removed by washing, then the fluorochrome calcein-AM was added to quantitate the number of attached cells. Proliferation was determined by plating the cells at low density, then quantitating viable cells with calcein-AM 5 to 7 days later. Results - Raising extracellular glucose from 5 mM to 17.5 mM significantly increased cell migration by 42%. When glucose was further raised to 38 mM, migration was not significantly different from that in 5 mM glucose. Adhesion to fibronectin and collagen I (but not IV) was significantly increased (62% and 32% respectively) when cells were cultured in 17.5 mM glucose. Similarly, proliferation was increased by 44%. Adhesion and proliferation tended to be decreased at 38 mM compared to 17.5 mM glucose, but not significantly so. In the presence of 5 mM glucose and mannitol (12.5 mM or 33 mM), neither migration, adhesion nor proliferation were significantly different from that in 5 mM glucose alone. Conclusion - Elevated extracellular glucose modulates migration, adhesion and proliferation of HCE cells. The effects are dependent on the concentration of glucose and are not due to changes in osmolality since mannitol failed to produce similar results. Our in vitro findings suggest that high-glucose effects may directly contribute to the etiology of impaired corneal wound healing in diabetes.