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Human gene therapy trials for hearing loss have started

Researchers in America have started a clinical trial to test a ground breaking gene therapy which aims to treat hearing loss by restoring sound detecting cells that have been damaged by trauma to the inner ear.

Novartis, a Swiss drug company, is collaborating with University of Kansas Medical Center to run trials on human volunteers with hearing loss. As far as I know, this is the world’s first gene therapy trial for hearing loss.

The volunteers will get an injection of a harmless virus containing a gene that should trigger the regrowth of the sensory receptors in the ear.

“The holy grail is to give people natural hearing back,” says -->Hinrich Staecker at the University of Kansas Medical Center, who is leading the trial. “That’s what we hope to do – we are essentially repairing the ear rather than artificially imitating what it does.”

Hair cells in the ear can be damaged by loud noises, drugs and disease – in 2003, another group of researchers discovered that certain -->genes can transform the cells in the ear, causing them to grow back and improve the subject’s hearing. In 2013, Staecker and colleagues performed tests on mice with damaged hearing to see if one of those genes, called Atoh1, would regrow their ear cells. Two months after being injected with a harmless virus containing the gene, the rodents’ hearing ability improved by about 20%.

In October 2014 Staecker’s team got the go ahead to perform trials on humans and have performed a similar process on the 45 volunteers as they did on the mice: inject the viral gene package directly into the volunteers’ cochlea by peeling back their ear drum and passing a needle through a tiny hole made by a laser. “The biggest risk is that we interfere with residual hearing, so we’re starting with people who have lost almost all hearing already,” said Lloyd Klickstein, head of translational medicine at Novartis.

“Today’s medical treatments are largely limited to hearing aids and cochlear implants, which are essentially just sticking plasters,” says Ralph Holme, head of biomedical research at UK charity Action on Hearing Loss. “This is why the planned trial is extremely encouraging and offers hope to the millions affected by hearing loss that a cure is possible.”

If the human trial volunteers see the same 20% improvement in hearing ability then this treatment can help those with a severe hearing loss improve to a medium one, medium to mild and mild to normal hearing.

Trial results are expected in 2017.