Immunohistochemical localization of megalin and cubilin in the human inner ear

Megalin and cubilin are endocytic receptors expressed in many absorptive polarized epithelia. These receptors have been implicated in the transport of gentamicin in the inner ear as possible contributors to ototoxic damage. Megalin and cubilin have been characterized in detail in the mouse and rat inner ear, but not in the human inner ear. In this study, megalin and cubilin were localized by immunohistochemistry using affinity-purified antibodies in formalin fixed frozen cryostat and celloidin embedded sections of the human inner ear. In the cochlea megalin and cubilin were localized in marginal cells of the stria vascularis, epithelial cells of the spiral prominence and the Reissner's membrane. In the macula utricle and cristae ampullaris, megalin and cubilin were localized in transitional and dark cells, but not in vestibular hair cells and supporting cells. In the endolymphatic duct megalin and cubilin were localized in the epithelial cells. The localization of megalin and cubilin in the human inner ear is consistent with previous reports in the inner ear of animal models and suggest that these receptors may play an important role in the inner ear endocytic transport, and maybe potential targets for prevention of ototoxic damage or the delivery of medications.