(0945) Mapping Progenitor Cells in the Human Tympanic Membrane After In Vivo Traumatization

Introduction: Chronic tympanic membrane defects cause hearing loss for more than a quarter of a billion people in the world, of which a majority lack access to ear surgery. This study aim to identify progenitorcells and regenerative zones in the human tympanic membrane to better understand the normal healing process and contribute to a future conservative treatment.

Methods: Healthy human tympanic membranes were harvested when patients with vestibular schwannoma underwent lateral skull base surgery with occlusion of the outer meatus. One day prior to surgery the tympanic membrane was traumatized superficially either mechanically by a needle or chemically by phenol between umbo and annulus. The membranes were analyzed with immunohistochemistry, stained with specific progenitor-cell and proliferation markers. The specific markers are antibodies against alpha-6 integrin, beta-1 integrin, CK-19, Ki-67 and p63. With light microscopy the staining was evaluated and graded by two otologists single-blinded in order to semi-quantify the results. In specific three different zones of the tympanic membrane were analyzed to map changes in proliferation and identify progenitor cells. Statistical analyzation with Cohen's kappa was used. The study was conducted between 2019-2022.

Results: In total 13 tympanic membranes were traumatized and collected. Preliminary results indicate cell proliferation in the keratinocyte layer of the tympanic membrane one day after traumatization in vivo. All markers used in the study were present in the keratinocyte layer of the tympanic membranes. The results of single- blinded grading between the two otologists showed similar estimations suggesting this method as an alternative approach to semi-quantify histologic studies on tympanic membranes.

Conclusions: This study demonstrates progenitor cells in the keratinocyte layer of the human tympanic membrane. Finding methods to activate these stem cells might accelerate the healing process of chronic tympanic membrane perforations and lay ground for a conservative treatment option.