ORIENTATION AND DIRECTED MIGRATION OF CULTURED CORNEAL EPITHELIAL-CELLS IN SMALL ELECTRIC-FIELDS ARE SERUM DEPENDENT

Reorientation and migration of cultured bovine corneal epithelial cell s (CECs) in an electric field were studied. Electric field application was designed to model the laterally directed, steady direct current e lectric fields which arise in an injured corneal epithelium. Single ce lls cultured in media containing 10% foetal bovine serum showed signif icant galvanotropism, reorienting to lie perpendicular to electric fie ld vector with a threshold field strength of less than 100 mV/mm. Cell s cultured in serum-free medium showed no reorientation until 250 mV/m m. Addition of EGF, bFGF or TGF-beta 1 singly or in combination to ser um free medium significantly restored the reorientation response at lo w field strengths. Both the mean translocation rate and directedness o f cell migration were serum dependent. Cultured in medium with serum o r serum plus added EGF, single cells showed obvious cathodal migration at 100 mV/mm. Increasing electric field strength enhanced the cathoda l directedness of single cell migration. Supplementing serum free medi um with growth factors restored the cathodal directed migration of sin gle cells and highest directedness was found for the combination of EG F and TGF-beta 1. Corneal epithelial sheets also migrated towards the cathode in electric fields. Serum or individual growth factors stimula ted CEC motility (randomly directed). Applied fields did not further a ugment migration rates but added a vector to stimulated migration. Ele ctric fields which are present in wounded cornea interact with other e nvironmental factors and may impinge on CECs migration during wound he aling. Therapies which combine the application of growth factors and e clectric fields may be useful clinically.