‘Deafness could be reversed using stem cells’
*Treatment that can allow people to hear again may be ready in 10 years
Scientists believe they are ‘on the brink’ of a cure for hereditary deafness using stem cells.
Researchers have grown new human ear hair cells, which can be used to replace faulty ones in sufferers of genetic deafness. They hope a treatment will be available within ten years.
The new research was published in the journal Stem Cell Reports. Stem cells are a basic type of cell that can change into another type of more specialised cell through a process known as differentiation.
Stem cells have been the focus of lots of medical research in recent decades because they can be used to grow almost any type of cell. Human inner ear hair cells are found in the cochlea – the spiral part of the inner ear – and form a vital component of our ability to hear sound.
If these ‘cochlea cells’ are genetically mutated, patients can be born with severe loss of hearing. Those born this way are currently treated with an artificial cochlear implant or ‘hearing aid’, which helps transfer sound to the patient’s hearing nerves.
But now a team has engineered and grown stem cells that don’t carry any deafness mutation. They hope to one day place these stem cells surgically into the ear, where they will develop and function as normal non-faulty ear hair cells.
The work, which is being carried out at Juntendo University in Tokyo, Japan, aims to correct a mutation in a gene called Gap Junction Beta 2. This gene accounts for deafness or hearing loss for one in every thousand children. In some parts of the world, mutations of the cochlea cells are responsible for as many as half the cases of genetic deafness.
Stem cells are a basic type of cell that can change into another type of specialised cell – such as a muscle cell or a cochlea cell – through a peculiar process known as differentiation. Many scientists believe stem cells could offer a new solution to genetic deafness by restoring the normal function of the ear hair cells and, as a result, the patient’s hearing.
Humans are born with about 11,000 hair cells in each ear that are vital to transmitting sound from the ear to the brain.
As the body ages, it experiences the slow progression of hearing loss due to the death of these cells from excessive noises, exposure to certain drugs, and ageing.
Currently, there are no cures for most types of hearing loss.
The new research follows work from Dr Sarah Boddy of the University of Sheffield, who has been investigating the potential of human bone marrow stem cells as a way to reverse hearing loss.
Boddy’s team has shown that human bone marrow stem cells can be converted into ear-like cells after exposure to a cocktail of natural chemicals produced by foetal cochlear cells.
About a third of 65-year-olds say they are hearing impaired, a number that rises to half by age 75.
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