Epidermal growth factor and basic fibroblast growth factor are induced in guinea-pig tympanic membrane following traumatic perforation

Abstract

Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF or FGF-2) have been shown to enhance the healing of traumatic tympanic membrane (TM) perforations. The action of EGF and bFGF in the TM repair process remains unknown. This study was designed to determine the expression of EGF and bFGF in normal and injured TM by immunohistochemistry. EGF was detected in normal TM mainly in the annulus tympani area. After a perforation in the TM posterior/superior quadrant, EGF was detected around the perforated area in polynuclear cells, in pericytes and in basal epithelial cells. EGF was also detected in the antero/superior quadrant in basal epithelial cells and pericytes. The peak of EGF detection was observed 3 days after the perforation. bFGF was not detected in normal TM, but it was expressed 3 days after a traumatic perforation mainly in the perforated area in pericytes and in polynuclear cells. This study suggests that EGF and bFGF are involved in the control of TM acute perforation repair. These findings help to explain the accelerated healing of TM perforations that are seen after application of FGF or EGF, and suggest that antibodies against these growth factors would retard the healing process.