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There is new hope in the treatment of deafness.  Scientists have successfully proven it is possible to regenerate ear hair cells.

60% - 90% of deafness and hearing impairment is due to the loss of hair cells in the cochlea (inner ear).  The cochlea is responsible for detecting sound and activating nerves which transmit the sensory information to the brain for translation.  Damage to the cochlea hair cells is also connected to tinnitus – a condition that affects 7 million people in the UK.

The research for deafness therapies is principally conducted on mammals.  In this case, the team of scientists were able to grow this specific type of hair cell in mouse embryos in the womb.  Once the mice were born they had a greater number of functional cochlear hair cells than the comparative group of mice.

The Oregon based team discovered that they were able to manipulate a gene called Atoh 1 to create the crucial hair cells.  This therapy will not be available for human trials for some time, however, it offers a significant breakthrough to the 250 million people worldwide who are deaf or live with hearing defects.

John Brigande, head of the research at Oregon Health and Science University, US is profoundly deaf.  His hearing began to deteriorate from the age of 10.  Brigande said: “My hearing loss is an enormous challenge in both my personal and professional lives. I have hope that there will be new restorative therapies for hearing loss in my lifetime.”

The cochlea has around 15,500 hair cells, but because the cells do not regenerate, they are vulnerable to damage from ageing, excessive noise, genetic defects, and drugs and infections.  The result is progressive and irreversible hearing loss.

Brigande added: “There is intense interest in cell replacement strategies to ameliorate the effects of inner ear disease, but until now we didn’t have direct evidence indicating we could make a functional sensory hair cell”.

The team have started further investigations of the possibility of reversing genetic mutations that cause deafness.  This research could lead to developing techniques to regrow hair cells, and ‘curing’ deafness.

Dr. Brigande continued: “We have the first step down: we can induce functional sensory hair cells to form. Now, we need to learn if it’s possible to restore hearing in a deaf mouse mutant, experiments that are ongoing. We know it’s possible to generate sensory hair cells that function, and that’s an important step toward defining rational therapies in humans. I am profoundly hard of hearing. The exciting news for those of us with hearing loss and tinnitus is that we now have hope of having our hearing restored some day.”

There are two possible routes to developing the programme: implantation of hair cells through the combination of gene therapy with embryonic stem cell research; and cochlea gene manipulation which could stimulate hair cell growth.

John Brigande’s team’s research are published in Nature science journal.