Vascular endothelial growth factor (VEGF) in normal human corneal epithelium: detection and physiological importance

Corneal neovascularization is a major challenge following chemical burns and corneal inflammation. The factors triggering corneal neovascularization involve various growth factors. In the release and control of these factors the regenerating tissue plays a decisive role. Only recently has vascular endothelial growth factor been shown to be involved in the basic events of retinal neovascularization. From the cornea current knowledge allows only for the statement that corneal epithelium could be able to produce vascular endothelial growth factor. The present study was designed to show the presence of vascular endothelial growth factor-like substances in the corneal epithelium of the normal eye in vivo.

Using specific antibodies to the N-terminus of human vascular endothelial growth factor indirect immuno-histochemistry was applied to sections of normal human corneal epithelium and to five sections of enucleated human eyes with a morphologically normal anterior segment.

In all sections specific staining for vascular endothelial growth factor was found over the entire epithelium. Staining was most intense in the basal layer of epithelial cells. Only a weak staining was detectable in the cell layers closer to the surface. Here, however, the samples of corneal epithelium having been subject to traumatic erosion showed a slightly more intense staining than the sections from the undisturbed corneal tissue of whole globe sections.

It was shown that vascular endothelial growth factor-like protein is present in the human corneal epithelium. Observed differences in the staining pattern could suggest that the expression of vascular endothelial growth factor might be enhanced due to ocular surface trauma. It is suggested that corneal epithel vascular endothelial growth factor might be an important factor in the cascade leading to the onset of corneal neovascularization.