A team of researchers has successfully restored the hearing of deaf mice. In the study published in the journal Nature Biotechnology, the Boston Children’s research team used gene therapy to penetrate the animal’s cochlea’s inner hair cells.
This is not the first time scientists have tried to restore the hearing of deaf mice. But the new study has restored the mice’s hearing at a higher level or down to 25 decibels, which is the equivalent of a whisper.
The researchers introduced a corrected Ush1c gene, which can cause Usher syndrome, a problem that causes deafness, blindness and balance problems. Although the study was conducted on mice, the same technology may be used in humans.
This mutation causes a protein dubbed harmonin to be useless, which deteriorates the sensory hair cell bundles’ ability to receive sound and bring information to the brain. However, introducing the corrected gene allowed the production of normal full-length harmonin.
Because of this, the hair cells formed normal bundles that responded to sound waves. And based on electrical recordings, it also sent signals to the brain.
The mice that were born deaf but got treated immediately started to hear. They proved this by placing the mice in a startle box where the animal is supposed to jump in response to a surprising loud sound.
Those mice that got treated with the technique heard noise quieter than 80 decibels. A few of them also were able to hear as low as 25 decibels, which is the same as normal mice. The therapy also restored the balance of the animals. The mice were able to stay on a rod that kept on rotating without falling.
The treatment could also help humans. According to Margaret Kenna, a genetic hearing loss specialist at Boston Children’s, restoring the nonfunctional senses in children could improve learning.
She adds in a press release, “Anything that could stabilize or improve native hearing at an early age would give a huge boost to a child’s ability to learn and use spoken language. Cochlear implants are great, but your own hearing is better in terms of range of frequencies, nuance for hearing voices, music and background noise, and figuring out which direction a sound is coming from. In addition, the improvement in balance could translate to better and safer mobility for Usher Syndrome patients.”
However, the researchers say that more research is still needed, which would also allow treatment of blindness. They also found that delaying treatment in mice will not result in benefits, which they need to determine why this happened.