The Early Regenerative Events in the Human Tympanic Membrane After In Vivo Traumatization.

Abstract

To observe the early regenerative response in the keratinocyte layer of the human tympanic membrane (TM) following in vivo traumatization. Thirteen human TMs were in vivo traumatized (with phenol or superficial scratching) and harvested after 20 h. Immunohistochemistry was performed using the specific epidermal progenitor cell markers CK19, p63, and α6-integrin, and the keratinocyte proliferation marker Ki-67. The staining appearance and intensity were evaluated and graded by two blinded evaluators for the different TM regions: the annulus, the malleus, the unattached pars tensa (UPT) close to the trauma (tUPT) and on the untraumatized (uUPT) side. All protein markers were identified in all regions of the TM at 20 h post traumatization. CK19, p63, and Ki-67 were upregulated in the regenerative regions at the annulus and malleus. Moreover, CK19 was significantly upregulated in the tUPT compared to the uUPT. α6-integrin was, at the same timepoint, significantly upregulated in the tUPT in the TMs traumatized by scratching. Ki-67, on the other hand, showed a tendency towards an upregulation in the uUPT. This study shows that traumatization activates a regenerative response in the human TM, activating key proliferative regions already at 20 h after traumatization. The results show an upregulated proliferation activity in the UPT in early healing and confirm the previously described regenerative regions of the annulus and malleus. These insights will be valuable for improving future TM healing strategies. N/A.