ABSTRACT
Hearing loss is the most frequent sensory deficit in the human population and can occur at any age. Hearing loss ranges from mild to profound, can be conductive, sensorineural or mixed type and may be congenital or acquired. Sometimes, some of hearing loss can be cured by medical or surgical interventions but most of hearing loss is irreversible and many patients struggle in their daily activities and their quality of life suffers. Although hearing aids as well as cochlear implants can give good solution to patients with a hearing loss that cannot be cured, both of them have some limitations and cannot solve the hearing problem perfectly. Recent scientific achievements in cochlear stem cell research and regenerative medicine can suggest ultimate solution to researchers as well as doctors and can give a hope to patients with a hearing loss and their family. Until now, mammalian cochlear hair cells have been known to be never replaced or regenerated, such that insults to the cochlea cause progressive and permanent hearing loss of variable degree. However, non-mammalian vertebrates are capable of replacing lost hair cells and have stem cells in their cochlea, which has recently led to efforts to understand the molecular and cellular basis of regenerative responses in different vertebrate species. In this article, I review the development of mammalian cochlea, focusing on the molecular events related with the development and regeneration. I also introduce the progress in overcoming the limits to mammalian cochlear hair cell regeneration and recent efforts to cochlear regenerative medicine.