January 28, 2005

MGH researchers find way of regenerating cells key to hearing

Selectively turning off the activity of a specific protein could allow regeneration of the inner ear's hair cells, which convert sound vibrations into nerve impulses. The discovery by an MGH-based research team runs against current beliefs about these cells and could someday lead to ways of preventing or treating hearing loss. The report will appear in the journal Science and was released online Jan. 13.

"These findings give us a potential strategy for hair cell regeneration, which could have enormous implications for the treatment of hearing and balance disorders," says Zheng-Yi Chen, DPhil, of MGH Neurology, the study's senior author. "It also shows that cells that have been considered incapable of regeneration — like most nerve cells — can reproduce under the right conditions, which may have applications to neurodegenerative diseases."

Located in the cochlea, the organ of the inner ear that senses sound, hair cells translate sonic vibrations into electrical signals carried to the brain by the auditory nerve. Hair cells are very sensitive to damage, and their death accounts for most types of acquired hearing loss.

Chen's group found that embryonic mice in which the retinoblastoma gene is inactivated in the inner ear have significantly more hair cells in their ears than do normal mice. These additional hair cells had indications of active regeneration, which cells in normal animals did not. The researchers hope these findings will form the basis for future work aimed at recovery of hearing through hair cell regeneration.

"My hope and belief is that, if we can achieve functional hair cell regeneration in mice, we'll eventually be able to achieve it in people," says Chen. His MGH co-authors are first author Cyrille Sage, PhD, and Mingqian Huang, PhD, both of MGH Neurology.