HUMAN CORNEAL EPITHELIAL-CELLS REORIENT AND MIGRATE CATHODALLY IN A SMALL APPLIED ELECTRIC-FIELD

Purpose. To test whether human corneal epithelial cells (HCECs) respon d to small applied electric fields (EFs) in a similar manner to bovine corneal epithelial cells (BCECs), the orientation and directed migrat ion in small EFs of both primary cultures and of a human corneal epith elial cell line were quantified.Methods. Primary cultures of human cor neal epithelial cells (PHCECs) and transformed human corneal epithelia l cells (THCECs) were exposed to EFs (100 mV/mm-250 mV/mm) in differen t media. Cell migration was traced using an image analyser. Results. P HCECs and THCECs reoriented and migrated towards the cathode (negative pole) when cultured in small direct current (de) EFs. Both the reorie ntation and directional migration were voltage-and serum-dependent. as shown previously for bovine cells. PHCECs and THCECs showed significa nt perpendicular orientation in EFs at 150 mV/mm in medium with serum, while at the same voltage, no significant orientation was found in se rum free medium. PHCECs started to show perpendicular reorientation ar ound 30 min after onset of EF at 150 mV/mm. They showed significant di rectional migration at 150 mV/mm, with directedness of 0.35 +/- 0.07 a nd a migration rate of 9.1 +/- 0.7 mu m/h (n = 90), both significantly higher than that of cells in serum free medium. Addition of EGF induc ed significant reorientation and directional migration of THCECs at 10 0 mV/mm. Additionally, as for BCECs, which remained viable and respons ive to electric fields for at least 75 h at 150 mV/mm, THCECs also rem ained viable and showed responsiveness during long periods of exposure to EFs (at least 20 h). Conclusions. Cultured human primary CECs and a human corneal epithelial cell line both responded to small EFs with perpendicular reorientation and cathodally-directed migration. Cell re sponses were qualitatively similar to those reported previously for bo vine CECs. The endogenous EFs generated by wounded cornea may play an important role in promoting cell shape changes and directed migration of CECs during the healing process.