Topical application of transforming growth factor-β1 in acute traumatic tympanic membrane perforations:: an experimental study in rats

High transforming growth factor-beta 1 (TGF-beta 1) expression in combination with fibrotic scar was observed in human tympanic membranes containing a chronic perforation. The purpose of this study was to investigate whether application of exogenous TGF-beta 1 to experimentally created tympanic membrane perforations might induce a nonhealing tympanic membrane perforation. Bilateral myringotomies were performed in 20 rats. In 10 animals, a single dose of TGF-beta 1 (0.1 mu g) was topically applied to the left tympanic membrane after perforation. In the second part of the study with 10 animals, repeated applications of TGF-beta 1 at a higher concentration were tested. In both groups, the opposite ears received vehicle alone. Tympanic membranes were observed for a total of 5 weeks. The effect of TGF-beta 1 on the healing of the tympanic membranes was evaluated by closure rates and histology. In the single application group, the healing process was not delayed. Repeated applications of TGF-beta 1 did cause a faster perforation closure and a thicker tympanic membrane. Topical TGF-beta 1 applied to a traumatic tympanic membrane perforation does not create a chronic perforation at the concentrations and modes of application used in this study.