A research team at Boston Children’s has tested out a new vector for a gene therapy that significantly improved hearing in mouse models for Usher syndrome, the most common genetic disease that triggers deafness as well as blindness in its victims.
A better vector – marking an improvement over an earlier model – meant that the therapy could do a better job in correcting the performance of outer hair cells in the cochlea, amplifying signals to inner hair cells that emit signals to the brain. And that allowed the rodents to hear sounds below 80 decibels, in 19 of 25 mice, with a few able to hear sounds as soft as 25 decibels.
“Now, you can whisper, and they can hear you,” says Gwenaëlle Géléoc, also an assistant professor of otolaryngology at Harvard Medical School.
Their work was published in Nature Biotechnology.
Géléoc’s crew say that the research also has positive implications for new gene therapies to correct blindness, possibly setting up a dual approach that can address both blindness and deafness at the same time.
Gene therapy has come a long way in recent years, and we’ve seen a growing number of startups looking to treat hearing disorders. But the team acknowledges that they have some big hurdles to clear before this tech is ready for human testing.
One of the big issues: The gene therapy only worked in newborn mice, for reasons they don’t understand. Delay treatment for 10-12 days and it didn’t work. The investigators want to test this approach on larger animals first, to see if they can gain some durable responses.
“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,” said Margaret Kenna, a specialist in genetic hearing loss at Boston Children’s. “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.”
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