The Oregon Health & Science University researchers said they produced functional auditory hair cells in the cochlea of a mouse inner ear.

"One approach to restore auditory function is to replace defective cells with healthy new cells," Assistant Professor John Brigande said. "Our work shows that it is possible to produce functional auditory hair cells in the mammalian cochlea."

Brigande and his colleagues said they grew hair cells by transferring a key gene, called Atoh1, into the developing inner ears of mice.

The scientists said the gene transfer technique resulted in Atoh1 expression in the organ of Corti, where the sensory hair cells form.

"It remains to be determined whether gene transfer into a deaf mouse will lead to the production of healthy cells that enable hearing," said Brigande. "However, we have made an important step toward defining an approach that may lead to therapeutic intervention for hearing loss."

The study appears in the online edition of the journal Nature.