Embryonic stem cells enhance the healing of tympanic membrane perforations

Abstract

Objective: Tympanic membrane perforations may cause hearing impairment and otorhea. It is a common indication for ear surgery. The aim of the study was to test whether stem cells may enhance the healing of fresh tympanic membrane perforations. Methods: In a first assay, the status of the tympanic membrane at 5 days after myringotomy was tested in five Mongolian gerbils that were treated on one side with embryonic stem cells and on the other side with control substance. In a second assay, nine gerbils were treated in the same way, except that fluorescent-labeled embryonic stem cells were used. The integration of the stem cells into the surface layer of the healing tympanic membrane was assessed with fluorescence microscopy, as well as the differentiation of these cells. Results: In the first assay, all perforations in the treated ears were closed, whereas only two of the untreated ears were closed. The strength of the healed perforation was greater in the stem cell treated tympanic membranes (mean rupture pressure 120 daPa in three treated ears compared to 60 daPa in the one control ear). Two stem cell-treated tympanic membranes remained intact throughout the whole sequence of pressures, whereas only one control tympanic membrane remained intact. In three tympanic membranes in the second assay, a group of fluorescence-doped cells was detected in the region of the perforation. Conclusion: These findings indicate that stem cells enhance the healing of tympanic membrane perforations, possibly by differentiation and integration into the tympanic membrane tissue.