Selective binding of the epidermal growth factor and its specific effects on the epithelial cells of the cornea

A selective binding of ¹³¹I-labeled bioactive epidermal growth factor to rat epidermis and, especially, to the corneal epithelium has been reported. As far as the binding to the corneal epithelial cells is concerned no biochemical and/or metabolic modifications induced by the factor have been demonstrated so far. In the present work the following results have been obtained: 1. (1) The binding in vivo of the epidermal growth factor to the rat corneal epithelium is specific, since the affinity of the receptor cells for this factor is the highest ever found for all other tissues, including epidermis. 2. (2) The cells of adult rabbit corneal epithelium are very sensitive to the metabolic effects of the epidermal growth factor, as demonstrated by the stimulation induced by the factor on the uptakes of DNA, RNA, and, especially, labeled protein precursor in vitro. 3. (3) The epidermal growth factor is able to stimulate in vivo cell-proliferation of the adult rabbit's corneal epithelium to a great extent. 4. (4) The epithelium healing process of simple non-perforating wounds in the corneas treated with the factor proceeds via the formation of a multilayer rather than as in the naturally occurring mechanism via a cellular monolayer. This suggests that the healing process is not only accelerated but that a somewhat different mechanism is triggered by the presence of the epidermal growth factor.