Purpose:
Corneal wound healing involves the migration and proliferation of epithelial cells. In this study we investigated the ability of growth hormone to influence the proliferation of corneal epithelial cells in vitro.
Methods:
A human corneal epithelial cell line [HCE: ATCC (HCE-2; CRL-11135)] was cultured in Keratinocyte Free Medium (KFM; Invitrogen) supplemented with L-Glutamine, Epidermal Growth Factor (EGF), and Bovine Pituitary Extract (BPE). HCE cells were seeded within a 24 well plate at approximately 20,000 cells/well (~10% of the surface area available for growth within a well). Cells were allowed to attach overnight and unbound cells washed away prior to experimentation. Cells were cultured in serial doses (zero, 1ng/ml, 10ng/ml, 100ng/ml, 1µg/ml, 10µg/ml) of growth hormone (Somatotropin, Genotropin, Pfizer) in such variations of culture medium as KFM; KFM + EGF + BPE; KFM + EGF; KFM + BPM. Assays were performed for 48hrs, with one medium change at 24 hrs. Relative cell numbers were determined using CyQuant cell proliferation assay (Invitrogen) and statistics were performed using Graphpad Prism.
Results:
A difference in relative cell number occurred between the varying medium conditions. KFM, supplemented with EGF and BPE, appeared to support higher cell numbers relative to KFM alone. Interestingly, within each medium condition, Genotropin appeared to have an effect on overall cell number and plotted as a charactistic "bell-shaped" curve. Statisitically significant differences were identified (see table).
Conclusions:
Genotropin appeared to influence proliferation of HCE cells, but only in KFM, KFM + EGF, and KFM + BPE mediums. This may be, in part, due to the "masking effects" of Genotropin in the fully supplemented KFM medium. Phase-contrast microscopy revealed that Genotropin-stimulated HCE exhibited a "migratory" morphological phenotype. Genotropin may influence corneal wound healing and warrants further investigation.
Keywords: cornea: epithelium • growth factors/growth factor receptors • cell-cell communication