Gene therapy may be applied to cure deafness: Nature magazine
29 Aug 2008
A team of US scientists used gene transfer to produce functioning hair cells in mice that the inner ear needs to interpret sounds. John Brigande and his team from Oregon Health and Science University showed, at least in unborn mice, gene therapy could be used to encourage other cells to become hair cells, holding hope for thousands of people affected by hearing loss.
The results have been published in noted scientific journal Nature.
Normal hearing involves cochlear hair cells converting sound into electrical signals, which are then transmitted to the brain. If those cells are damaged - or lost - they can't be replaced. Most people lose their hearing gradually with age - partly because of hair cell loss in the cochlea, while prolonged loud noise exposure also damaged hair cells.
Currently, people can have a cochlear implant which works by bypassing the damaged cochlear hair cells and stimulating the auditory nerve directly. An implant cannot restore hearing to normal but it does give the sensation of sounds.
Gene therapy uses a harmless virus to insert copies of the key gene into cells that then replicate. The key gene used by the Oregon team was Atoh1, which is essential for hair cell development. 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 are quoted as saying.
However, Brigande, who himself is profoundly hard of hearing, feels the research is still at an early stage to test in humans. "Only after this can we start experiments that will teach us if the approach might work in humans. So there is an enormous amount of work to do," he stressed.
While transferring the technology to humans is not yet imminent, the research suggests a way to repair a cochlea without electrical or mechanical aids, such as the cochlear implants currently used that bypass damaged hair cells to directly stimulate the auditory nerve.
