gms | German Medical Science

Introduction: Cholesteatoma (CH) is a destructive ear condition requiring complete surgical removal. Squamous epithelium remaining in the middle ear causes frequent occurrence of residual CH. Our aim is to develop a laser treatment that is selectively directed against targeted residual CH cells and can be performed after conventional CH surgery in the same session.

Methods: Intraoperatively harvested monolayer-cultured CH cells were stained in vivo with different absorption enhancers and irradiated with argon and diode lasers. Cytotoxicity measurements served to determine the respective amount of damage. CH and mucosa cell cultures as well as paraffin-embedded CH tissue sections were studied immunohistochemically (IHC) to determine the binding of monoclonal mouse antibodies against human cytokeratins (CK5, CK10, CK14) and the epidermal growth factor receptor (EGFR).

Results: Intracellular staining with absorption enhancers and subsequent laser irradiation destroyed up to 92% of cultured CH cells. Unstained irradiated tissue was not affected. In CH cell cultures, IHC staining was positive for CK5, CK14 and EGFR. In embedded CH tissue, CK5 and CK14 were localized in the basal layers of the matrix, while CK10 was situated in the suprabasal layers, and EGFR was present in all layers of the matrix and perimatrix.

Conclusions: The examined lasers and absorption enhancers appeared to be potentially suitable devices of a laser-assisted CH surgery. The investigated antibodies show partly non-specific staining and thus can not realize selective CH cell targeting (cross-reactions with mucosa cells). In future trials, the chromophore should be coupled to a particular antibody that binds solely to an easily accessible specific antigen at the surface of cholesteatoma cells.