RESUMO
Most of deafness have a neuro-sensory origin and are characterized by a loss of hair cells and auditory neurons in the spiral ganglion. At the moment, hearing aids are the only treatment available. To restore hearing in a patient suffering from deafness, it is necessary to study the mechanisms that might lead to the regeneration of neurosensory structures of the inner ear. HAIR CELL REGENERATION: The production of hair cells and supporting cells is terminated during embryonic development of the cochlea in mammals. However, several recent arguments suggest that new hair cells can be produced by the sensory epithelium of mammals. We first identified the presence of progenitor cells in the organ of Corti. In a second approach, the molecular mechanisms underlying the production of new hair cells have been studied. NEURONAL REGENERATION: The study of the development of the ear, cultures of neurons and analysis of animals invalidated for specific genes reveal that a number of growth factors are important for the maintenance and repair of neurons in the inner ear. These molecules induce the survival of auditory neurons in vitro and in vivo. The signaling pathways intra-cellular are analyzed with a better understanding of the mechanisms that lead to survival or death of neurons hearing and with the identification of new pharmacological agents that promote survival of neurons hearing in diseases of the inner ear. These molecules can be administered locally in the inner ear. IN CONCLUSION: Recent studies on the regeneration of neurosensory structures of the inner ear suggest that eventually it will be possible to replace the hair cells in the cochlea of mammals and to reinnervate them by auditory neurons in order to restore hearing in patients suffering from deafness.