Before we explain this new therapy, it’s important you know it can’t help people who were born Deaf. It can only help people who have lost their hearing over time.
Soon, a group of profoundly deaf volunteers who became deaf because of damage or disease in their ear, will be injected with a harmless virus. Included in the virus will be a gene that should make small hairs in the ear called ‘sensory receptors’ grow again.
Scientists from the University of Kansas Medical Center hope this gene therapy will give deaf people more natural hearing, because a lot of technology, for example cochlear implants, make electrical sounds.
How will the gene therapy work?
How the ear works
- When a person hears, sounds go into part of the ear called the ear drum, making the ear drum vibrate.
- The vibrations move to a part of the inner ear called the cochlea, travelling through three small bones.
- A part of the cochlea called the organ of Corti is covered in thousands of hairs called sensory receptors. Some of these are called inner hair cells, others are called outer hair cells.
- The outer hair cells help the sounds entering the ear to be amplified and made louder, then the inner hair cells vibrate, making small pathways in the ear open to let neurotransmitters flow in. (Neurotransmitters are safe chemicals in the body that help different parts of the body communicate and work together.)
- Small and safe electrical activity happens in the part of the ear called cochlear neurons.
- Finally, sound information is sent to the brain, so the brain can make sense of what the ear has heard.
How the new therapy works
A gene called Atoh1 will be injected directly into the cochlea of profoundly deaf volunteers aged 18-70. All the volunteers will have damaged sensory receptors but other parts of their ear will still be working.
In 2003, the same injection was given to mice who had damaged sensory receptors. Two months later, the mice’s hearing had improved by approximately 20 decibels. “This is about the same difference between hearing with your hands over your ears, and what you hear ordinarily,” says Lloyd Klickstein, head of translational medicine at Novartis, the Swiss drug company collaborating on the trial.’ Read more from the article on newscientist.com.
Volunteers could experience dizziness or sickness after the operation, but this is normal. The injection won’t spread through the body, the gene will stay in the cochlea.
Image Credit: Travis Isaac