Specific binding of EGF in connective tissue repair.

Epidermal growth factor (EGF) is known to stimulate wound repair, including connective tissue repair as observed in the perforated rat mesentery. In the present study we assessed changes in expression of EGF receptors during healing of connective tissue by measuring the binding of [125I]EGF to perforated and unperforated mesenteric membranes. Autoradiographic grain density was measured on flat mounted or sectioned mesenteric tissue. Laparotomy alone caused an inflammatory reaction in the abdominal cavity and significantly (p < 0.04) increased the binding of [125I]EGF to unperforated membranes by 70% on days 1 and 3 postoperatively. In perforated mesenteric membranes, the binding of EGF in a 1 mm wide zone around the incision was significantly higher (p < 0.05) than EGF binding in the adjacent tissue on days 3 through 7. Furthermore, the average grain density in a 100 microns wide segment around the incision was approximately twice as high (p < 0.008) as the grain density in the mesentery 100 to 500 microns around the incision or in adjacent tissue (p < 0.004). These results indicate that expression of EGF receptor increases in the region of regenerating connective tissue and supports the hypothesis that EGF receptor plays a key role in mesenteric wound healing.