Localization of progenitor/stem cells in the human tympanic membrane

The outer epithelium of the tympanic membrane (TM) initiates the closure of a perforation. Embryonic stem cells have been used in attempts to enhance the healing capacity of induced perforations in experimental animals. More knowledge about epithelial cell proliferation and cell migration is needed for a better understanding of the TM healing process. This includes the identification of regenerative zones within the outer epithelial layer of the TM where progenitor cells may be present.

Normal human TMs from translabyrinthine surgery were investigated using immunohistochemistry and immunofluorescence to detect the progenitor/stem cell markers α₆-integrin, β₁-integrin and cytokeratin 19 (CK19).

α₆-Integrin was detected in the basal layer of the keratinizing epithelium in the umbo, in the annular region and along the malleus but not in the intermediate portion of the pars tensa. β₁-Integrin and CK19 were found in the same locations not only in the basal layer but also in the suprabasal layers of the keratinizing epithelium.

Possible progenitor cells are found in the umbo, the annular region and along the malleus. Further studies are needed to identify the source of these cells.