Inner-ear hair cells offer hope for hard of hearing

The delicate hair cells of the inner ear that are crucial to hearing have been grown successfully in mice for the first time by scientists who believe that the technique may one day be used to restore hearing in profoundly deaf people.

Many problems with hearing are due to defective auditory hair cells, which mammals cannot normally regenerate. In humans, hair cells are naturally lost during a lifetime, causing a corresponding loss of hearing with age. So being able to grow them by a form of gene therapy raises the prospect of being able to treat deafness in a radically different way.

The scientists stimulated the growth of new hair cells in the inner ear of the mice by transferring a key gene into the cochlea – the auditory part of the inner ear – triggering the development of the fine, sensory cells that respond to sound waves of different frequencies.

The study, printed in the journal Nature, was carried out on mice embryos in the womb. "This is just the first step," said John Brigande of the Oregon Health and Science University in Portland, Oregon. "We need to learn if we can restore hearing in deaf mice by gene transfer."