Recombinant human erythropoietin prevents ischemia-induced apoptosis and necrosis in explant cultures of the rat organ of Corti

Abstract

This study was designed to evaluate the effect of recombinant human erythropoietin (rhEPO), insulin-like growth factor-1 (rhIGF-1) and epidermal growth factor (rhEGF) on ischemia-induced hair cell loss in an organotypic cochlea culture. The apical, middle and basal parts of the organs of Corti (newborn rat, postnatal days 3–5) were exposed to ischemia (3.5 h) in glucose-free artificial perilymph ( p O 2 10–20 mmHg) with or without growth factors. Controls were exposed to normoxia. Twenty-four hours after the onset of ischemia, the cultures were stained using tetramethyl rhodamine isothiocyanate (TRITC) phalloidin (hair cells), propidium iodide (membrane integrity) and apoptosis detection kit (DNA-fragmentation). Ischemia (3.5 h) induced a hair cell loss of 20 and 40% in the middle and basal cochlear parts, respectively, and an increase of the numbers of PI-stained and DNA-fragmented nuclei (controls 0–1, ischemia 4–7 nuclei/100 μm). The basal part was more affected than the apical one. rhEPO and rhIGF-1 significantly attenuated the ischemia-induced hair cell loss by reducing processes involved in apoptosis and necrosis. rhEPO has been in clinical use for more than a decade and found to be well tolerated. Therefore, rhEPO could be an effective drug for the prevention of hearing loss via a hair cell protective mechanism.