How stem cells could cure deafness

Human stem cell-derived otic neurons repopulating the cochlea of deaf gerbils are seen in this undated handout photo courtesy of the University of Sheffield.

Human stem cell-derived otic neurons repopulating the cochlea of deaf gerbils are seen in this undated handout photo courtesy of the University of Sheffield.

Published Sep 13, 2012

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London - Scientists have made a major advance in the pursuit of a cure for deafness, by restoring the hearing of deaf gerbils using human stem cells.

The technique, which is the first to use stem cells to treat hearing loss, could one day benefit hundreds of thousands of sufferers in the UK.

Researchers from the University of Sheffield were able to turn human embryonic stem cells into ear cells, which were then transplanted into the inner ear of gerbils that had been made deaf. On average the deaf gerbils' hearing improved by 46 per \cent. In humans, this would be the equivalent of someone who could not hear a lorry pass by having their hearing improve to the degree that they could conduct a conversation at standard indoor volume.

The pioneering treatment involved implanting the gerbils, which were chosen because their hearing range is similar to that of humans, with around 50,000 inner-ear nerve cells. Although recovery rates varied, some gerbils had their hearing almost totally restored.

The technique could be used to cure a form of deafness known as auditory neuropathy, characterised by damage to the cochlear nerve, which links the inner ear to the brain. As many as 15 percent of hearing problems are understood to be associated with auditory neuropathy, which is usually genetic but can also be exacerbated by environmental factors such as noise exposure and jaundice at birth.

Up to one in six people in the UK has hearing problems, while about three million are profoundly deaf. The researchers estimate 300,000 of them could benefit from stem cell treatment in the future.

“This is an important step forward,” said Dr Marcelo Rivolta, who led the study. “We now have a method to produce human cochlear sensory cells that we could use to develop new drugs and treatments, and to study the function of genes. And more importantly, we have the proof-of-concept that human stem cells could be used to repair the damaged ear.”

The researchers said that, although they could not be “100 percent certain” that cells would react in the same way when implanted into human rather than gerbil ears, the ultimate aim of the study was to trial the technique as a medical treatment. - The Independent

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