Purpose: The purpose of this study was to determine whether messenger RNA coding for hepatocyte growth factor (HGF), HGF receptor (MET), keratinocyte growth factor (KGF), KGF receptor, and fibroblast growth factor (FGF) receptor-2 were produced in primary cultures of human corneal epithelial, stromal fibroblast, and endothelial cells, as well as ex vivo corneal epithelium, endothelial cells transfected with the SV40 large T antigen, and control embryonic lung fibroblasts. The effects of exogenous HGF and KGF, compared to epidermal growth factor, on the proliferation of first passage corneal cells were also examined.
Methods: Polymerase chain reaction was used to amplify complementary DNA for each modulator from each cell type. Hot blotting was used to demonstrate the specificity of amplification products. Proliferation of first passage corneal epithelial, stromal fibroblast, and endothelial cells in response to varying concentrations of HGF, KGF, and epidermal growth factor was measured.
Results: Specific amplification products for messenger RNA coding for each modulator were detected in each corneal cell type, although very low levels of HGF and KGF messenger RNA appeared to be present in corneal epithelial cells relative to stromal fibroblasts and corneal endothelial cells. Amplification products that may have been derived from alternative transcripts were detected for several of the modulators. HGF and KGF stimulated proliferation in a dose-response manner in first passage corneal epithelial and endothelial cells, but not stromal fibroblast cells.
Conclusions: Human corneal epithelial, stromal fibroblasts, and endothelial cells produce messenger RNA coding for HGF and KGF, although low levels appear to be present in the epithelial cells. All three major cell types of the cornea produce messenger RNA coding for HGF receptor, KGF receptor, and FGF receptor-2. The proliferation of human corneal epithelial and endothelial cells, but not stromal fibroblasts, was stimulated by exogenous HGF and KGF. HGF and KGF likely have intracrine, autocrine, and/or paracrine functions in the cornea. Exogenous HGF and KGF may be useful in corneal preservation and for regulating corneal wound healing.