Cure for Deafness

Drug could reverse ‘permanent’ deafness by regenerating hair cells in inner ear

A potential cure for permanent deafness has  been found by scientists using a drug that stimulates the inner  ear.

The drug, codenamed LY411575, triggers the regeneration of sensory hair cells.

Until now it has not been possible to restore the cells once they have been lost due to factors such as loud noise exposure,  infection and toxic drugs.

This type of deafness, often suffered by rock  musicians and DJs, is generally assumed to be irreversible.

Too loud? Scientists are developing a drug to reverse damage caused by loud noises
Too loud? Scientists are developing a drug to reverse  damage caused by loud noises

Scientists succeeded in partially restoring hearing to mice that had been deafened by loud noise.

Although the research is at an early stage,  they believe it could lead to effective treatments for acute noise-induced deafness in humans.

The tiny sensory hairs in the cochlea are vital to hearing. Sound vibrations transferred from the eardrum shake the hairs, causing nerve messages to be fired to the brain.

Without the hairs, the hearing pathway is  blocked and no signals are received by the brain’s auditory  centre.

While birds and fish are capable of regenerating sound-sensing hair cells, mammals are not.

Close-up: Tiny inner ear hairs are essential for hearing
Close-up: Tiny inner ear hairs are essential for  hearing

The new approach involves reprogramming inner  ear cells by inhibiting a protein called Notch.

Previous laboratory research had shown that  Notch signals help prevent stem cells in the cochlea transforming themselves  into new sensory hair cells.

The drug LY411575 suppresses Notch. Mice with noise-induced hearing loss generated functioning sensory hair cells after the  drug was injected into their damaged cochleas.

Lead researcher Dr Albert Edge, from Harvard  Medical School in the US, said: ‘We show that hair cells can be regenerated from the surrounding cells in the cochlea.

‘These cells, called supporting cells,  transdifferentiate into hair cells after inhibition of the Notch signalling  pathway, and the new hair cell generation results in a recovery of hearing in  the region of the cochlea where the new hair cells appear.

‘The significance of this study is that  hearing loss is a huge problem affecting 250 million worldwide.’

Hearing loss is a problem affecting 250 million worldwide
Hearing loss is a problem affecting 250 million  worldwide

Details of the study are reported in the journal Neuron.

A green fluorescent protein was used to label  the newly generated hair cells.

Electronic measurements of auditory brainstem responses confirmed that three months after treatment, lost hair cells had been replaced and were working.

Improvement in hearing was seen over a wide range of frequencies.

Dr Edge added: ‘The missing hair cells had been replaced by new hair cells after the drug treatment, and analysis of their location allowed us to correlate the improvement in hearing to the areas where the hair cells were replaced.

‘We’re excited about these results because  they are a step forward in the biology of regeneration and prove that mammalian  hair cells have the capacity to regenerate.

‘With more research, we think that regeneration of hair cells opens the door to potential therapeutic applications  in deafness.’

Vivienne Michael, chief executive of the charity Deafness Research UK, said: ‘As always, we have to be cautious about new research findings but this US research is extremely encouraging.

‘At the moment there is no way of reversing eight in 10 cases of hearing loss, including noise-induced deafness and the progressive deafness so many of us experience as we age – hearing aids are the only answer.

Attribution: Mail Online

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About thecommonconstitutionalist

Brent is not a scholar. He’s not an author or speaker (yet). He hasn’t published a book nor does he write articles for magazines (yet). He has no advanced literary degree or pedigree (never will). He is just an American who writes and shares what interests him. He cares about the salvation of this country and a return to its Constitutional roots. He believes in God, country and family.
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