Hearing restored in deaf animals for the first time

Michigan researchers have restored hearing in deaf mammals for the first time – a major step toward the treatment of the 27 million Americans with acquired hearing loss.

By inserting a corrective gene with a virus, the team induced formation of new cochlear hair cells – the key intermediates in converting sound waves into electrical impulses – in the ears of artificially deafened adult guinea pigs.

The researchers later demonstrated that the animals responded to sounds, according to the study published today in the journal Nature Medicine.

“A lot of the techniques would fairly easily translate into a clinical setting” for use in humans, said neuro-scientist Matthew W. Kelley of the National Institute on Deafness and Other Communication Disorders. He was not involved in the research.

Humans have about 16,000 hair cells in the cochlea of each ear, where they convert sound waves into nerve impulses.

The cells are easily damaged by loud noises, aging, infections and certain medications, and once damaged, they cannot regenerate on their own.

It will be the better part of a decade, at least, before the technique can be tried in humans, experts say.