Objectives/hypothesis: Recent years have seen success in establishing methods for cell culture that lead to the creation of a three-dimensional tissue architecture, and this represents a great advance for the ability to carry out research in vitro. Accordingly, the present studies were carried out with the objective of using three-dimensional cultured skin equivalents for the in vitro creation of a model of middle ear cholesteatoma, something that has heretofore been considered to be very difficult.
Study design: A cholesteatoma model was created in vitro, and discussion is presented regarding the immigration theory and the retraction theory that have been proposed as explanations of the causation of cholesteatoma.
Methods: Cultured skin equivalents were prepared, followed by creation of an epidermal and dermal defect in them. Then, the changes in the epidermis were investigated histologically. In addition, immunohistochemical studies were performed with regard to the effects exerted on the epidermis when the skin equivalents were cultured in a retracted state.
Results: It was confirmed that, as a result of the defect in the epidermis and dermis of the cultured skin equivalents, the epidermis at the edge of the defective site migrated subepidermally, and a stratified structure was formed. On the other hand, the retraction of the epidermis and dermis exerted almost no effect on the epidermal cells themselves.
Conclusions: These results lend credence to the immigration theory as an explanation of the growth of the epidermis from the defective site. Conversely, it was surmised that the retraction theory requires some other factors in addition to retraction.