Expression of Genes Coding Growth Factors and Growth Factor Receptors in Differentiated and Dedifferentiated Human Corneal Endothelial Cells

Growth and differentiation of human corneal endothelial cells are shown to be influenced by growth factors and by the extracellular matrix. Under standard culture conditions, these cells tend to dedifferentiate to a fibroblastlike phenotype. The aim of this study was to examine the expression of genes encoding growth factors and growth factor receptors in differentiated and dedifferentiated human corneal endothelial cells and in keratocytes (stromal fibroblasts) by means of Northern blot analysis. Expression of genes coding basic fibroblast growth factor (FGF), FGF receptor-1 (fig-type), epidermal growth factor receptor, and transforming growth factor-pi in keratocytes and human corneal endothelial cells could be confirmed. In contrast, significant expression of the gene encoding acidic FGF was not detected. However, expression of the genes encoding vascular endothelial growth factor (VEGF) and the high-affinity tyrosine kinase receptor for VEGF (flt-1) in human corneal endothelial cells could be demonstrated for the first time. Moreover, exogenous basic FGF seemed to have a positive influence on the VEGF gene expression level. The flt-1 gene was expressed in dedifferentiated, but not in differentiated human corneal endothelial cells. The results indicate a possible role of VEGF in the differentiation of human corneal endothelial cells.