August 28, 2008

Gene Therapy May Offer Hearing Restoration

Scientists in Oregon have discovered that gene therapy may be able to restore working hair cells that are essential for the inner ear to interpret sounds.

Writing in the journal Nature, researchers said that these cochlear hair cells send electrical signals to convert sounds and transmit them to the brain. Cochlear cells are naturally irreplaceable.

Most people who suffer from hearing loss gradually lose it through the reduction of hair cells in the cochlea. Loud noise is a key contributor to damage to these cells.

John Brigande and his team from Oregon Health and Science University showed, at least in unborn mice, gene therapy can be used to encourage other cells to become hair cells.

Bringande's team used a gene named Atoh1, which is essential for hair cell development. Cells are treated by using a harmless virus to insert copies of the gene into the cells which replicate.

The cells treated with Atoh1 functioned exactly like original hair cells.

"This capability is a crucial first step in defining translational therapies to ameliorate the effects of inner-ear disease in humans," the researchers said.

Right now, the only option for restoring hearing is cochlear implants, which work by bypassing damaged cochlear hair cells and stimulating the auditory nerve directly.

"Although still a long way from the clinic, the work shows that gene therapy is a potential treatment to combat some forms of congenital deafness," said Andy Forge, Professor of Auditory Cell Biology and advisor to Deafness research UK.

"With one in 2,000 children born deaf because of genetic defects, such a therapy would clearly be of value."


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