Current Status of Stem Cell Therapy for Cochlear Hair Regeneration

Technologies such as hearing aids and cochlear implants do provide useful benefit to a large number of individuals with hearing loss, but they are incapable of truly “correcting” a hearing loss. In contrast to these, replacement of hair cells via stem cell therapies holds promise for a cure. Despite the discovery of stem/ progenitor cells in the mammalian cochlea, no regeneration of either damaged hair cells or auditory neurons has been observed in mammals, in contrast to what is seen in birds and other vertebrates. Transplantation of exogenous stem cells has been proposed as a treatment to prevent or reverse sensorineural hearing loss. Although there is no clinical trial of stem cell therapies for hair cell regeneration, the research on animal models such as rats and mice is promising and is likely to lead to the development of novel therapeutic approaches for inducing hair cell regeneration in the mammalian cochlea. We review here current status of adult stem cells that are being used for seeding the cochlea for new hair cell formation. Overall, the data are encouraging and indicate that the technical problem of how to implant properly primed precursors into the cochlea or modiolus for hair cell and sensory neuron replacement is solvable. The main obstacles seem to be the identification of a source that provides enough stem cells to allow such therapies to have a good chance of success.