Epidermal growth factor receptors on corneal endothelium
R. N. Fabricant, A. J. Alpar, Y. M. Centifanto and H. E. Kaufman
If a growth factor could bind to and stimulate human endothelial healing,
corneal disease could be minimized. To this end, primary cultures of feline
and human corneal endothelium were tested in receptor binding assays for
radiolabeled epidermal growth factor (EGF). Both of these cells bound ten
times as much 125I-EGF as did the negative control cell lines. The time
course of association of 125I-EGF to cat corneal endothelium was found to
be complete after approximately 120 minutes at 22 degrees C. The 125I-EGF
was shown not to dissociate greatly when fresh binding buffer was added to
endothelial cultures that had bound the radiolabeled peptide. The pH
optimum for binding was determined to be approximately 6.4. The receptor
number per cell and the affinity constant for binding were determined to be
40,000 receptors per cell and 1.1 x 10(9) L/mole, respectively, using a
Scatchard plot. Parallel cultures of human fetal corneal endothelium grew
in vitro only when the growth medium was supplemented with low
concentrations of EGF. These studies provide evidence that EGF is
specifically bound to the corneal endothelium.
