Hearing restored in deaf mice

Around 10,000 people in Switzerland are completely deaf Keystone

A team of scientists from the Lausanne Federal Institute of Technology (EPFL) and Harvard Medical School have used gene therapy to restore hearing in mice with genetic deafness. A therapy for humans could be as close as five years away. 

The results of the study were published in the journal Science Translational Medicine on Wednesday and could pave the way for gene therapy in people with hearing loss caused by genetic mutations. 

The researchers focused on a gene called TMC1 that helps convert mechanical sound waves entering the inner ear into electrical signals that talk to the brain. Mutation of the TMC1 gene results in weaker electrical signals in response to sounds. 

Children with two mutant copies of the TMC1 gene suffer from severe hearing loss from around the age of two, while a single mutant copy causes deafness at around ten to 15 years. 

‘Startle box’

 As part of the gene therapy, a healthy TMC1 gene was inserted into an engineered virus which was then injected into the inner ear of mice that had TMC1-related genetic deafness. Scientists found that this resulted in the sensory cells of the inner ear to respond to sound and produce electrical signals to communicate with the brain.

 The deaf mice regained their ability to hear. Restoration of hearing was tested by placing the mice in a “startle box” and exposing them to abrupt sounds to see if they would jump.

 “Our gene therapy protocol is not yet ready for clinical trials – we need to tweak it a bit more – but in the not-too-distant future we think it could be developed for therapeutic use in humans,” said Jeffrey Holt of Harvard Medical School.

 The Swiss part of the study was led by EPFL president Patrick Aebischer’s lab from the Brain Mind Institute and was mainly funded by the Bertarelli Foundation.

According to the Swiss Federation for the Deaf, around 10,000 people in Switzerland are completely deaf and up to 600,000 are hearing-impaired.