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      Regenerating hair cells – a new approach?

      Once hair cells in the human ear are damaged they do not regrow, so once they’re gone, they’re gone for good. However, new research at Harvard University has suggested that it could potentially be possible to induce regeneration in damaged hair cells in the cochlea. Tracey Pollard, from our Biomedical Research team, tells us more about this research.

      By: Tracey Pollard | 16 June 2015

      Could we regrow hair cells?

      Attempts to regrow lost hair cells in the cochlea to restore hearing are focussed on two main areas – developing stem cell therapies that can be implanted into the inner ear to replace the missing cells, or developing therapies that will induce the inner ear itself to regrow the missing cells using the body’s normal regeneration processes. Unlike other species, such as birds or amphibians, inner ear hair cells in mammals don’t regrow when they’re damaged, so once they’re gone, they’re gone for good. The reasons for this are unknown, but it might be due to the more intricate arrangement of cells in the mammalian cochlea.

      In birds and amphibians, new hair cells are generated from supporting cells, a layer of cells within the inner ear which surround the hair cells, and ‘support’ them. However, in mammals, these supporting cells appear to lose their capacity to proliferate and turn into other cell types (like hair cells) before birth. However, recent research from the laboratory of Albert Edge, at Harvard University, has found that this is not necessarily the case.

      Mammalian supporting cells turn into hair cells in the laboratory

      In 2012, the group published research showing that supporting cells could be grown in culture in the laboratory, and that they formed structures called ‘neurospheres’, made up of dividing cells, some of which then turned into hair cells. The source of these new hair cells was a subset of the supporting cells in which a gene called Lgr5 was activated. The Lgr5 gene produces a protein receptor on the surface of cells which interacts with particular proteins on the surface of other cells known as R-spondins. When Lgr5 and an R-spondin interact, a signalling reaction ensues involving a gene called Wnt, and this signalling leads the supporting cells to proliferate and turn into hair cells.

      Lgr5 is also known to be produced by cells which can regenerate in other areas in the body, such as the intestine, and is used to identify adult stem cells. It is possible therefore, that in the cochlea, Lgr5 similarly identifies a population of cells with regenerative potential, even if they don’t necessarily use it. Not all cochlear supporting cells produce Lgr5 and it is only those that do that can turn into new hair cells.

      However, whilst this happens in tissue culture dishes in the lab, there was no indication that it really happens in the cochlea until new research, published this month by the same group, suggested otherwise.

      Growth of new hair cells after cochlear damage in mice

      Using gentamicin, an ototoxic antibiotic which damages hair cells, the group developed a model of hair cell damage in the newborn mouse cochlea. High doses of gentamicin caused significant levels of hair cell death, but surprisingly, the researchers observed a low level of spontaneous hair cell regeneration in response to this damage. They showed that these new hair cells were derived from the supporting cells which produce Lgr5 as described above.

      In addition, this group had previously shown that blocking another cell-to-cell signalling process (called Notch signalling) promoted hair cell regeneration after noise damage in adult mice and partially restored their hearing. However, they were unable to determine where the new hair cells were coming from. Inhibiting this same process in their new model of hair cell damage had a similar effect, and the group were also able to show that this hair cell regeneration was controlled by the Lgr5/Wnt signalling mentioned previously. This indicated that the Lgr5-producing supporting cells described above are indeed the source of new hair cells in the cochlea.

      Now that the cells in the cochlea that can produce new hair cells after damage have been identified, and as we learn more about the molecular processes that control a cell’s destiny, it may be possible to develop therapies that can target these cells and processes to induce regeneration of hair cells in the cochlea and one day, restore hearing.

      Find out more

      This research was published online last month in the journal Stem Cell Reports and you can read the article here.

      Visit the biomedical research section of our website for more information on our biomedical research programme and to find out how you can support our research.

      Recent Posts

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      For the first time ever, selected mobile phones with EE Pay As You Go plans, tailored for people who are deaf or have hearing loss, are available from Action on Hearing Loss.

      By: Brian Burns
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      REGAIN update on the progress so far and a further opportunity for people with hearing loss to take part in the trial

      A team of researchers and clinicians at UCL’s Ear Institute and the Royal National Throat Nose and Ear Hospital are delighted to announce that the REGAIN trial is approaching its first anniversary and are continuing to recruit people with hearing loss to participate in a ground breaking clinical trial to test the safety and efficacy of a new drug that aims to treat sensorineural hearing loss. The criteria for eligibility to participate in the trial has recently been broadened to include participants with hearing loss of up to 20 years duration (see below for further information).

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      Preventing hearing loss: the search for treatments

      Medicines like aminoglycoside antibiotics or cisplatin are used to combat life-threatening infections and cancer, respectively, but their use may come at the price of someone’s hearing. Several treatments to prevent the loss of hearing caused by these medicines are currently being developed. Our Translational Research Manager, Dr Carina Santos, tells us more.

      By: Dr Carina Santos
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      Shining a light on the cochlea

      We fund research across the globe into treatments for hearing loss and tinnitus. One of our newest projects, at the Bionics Institute in Australia, is investigating if we can improve how well cochlear implants work using light.

      By: Dr Tracey Pollard
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      Recent Posts

      EE partnership brings unbeatable packages

      For the first time ever, selected mobile phones with EE Pay As You Go plans, tailored for people who are deaf or have hearing loss, are available from Action on Hearing Loss.

      By: Brian Burns
      17 October 2018

      REGAIN update on the progress so far and a further opportunity for people with hearing loss to take part in the trial

      A team of researchers and clinicians at UCL’s Ear Institute and the Royal National Throat Nose and Ear Hospital are delighted to announce that the REGAIN trial is approaching its first anniversary and are continuing to recruit people with hearing loss to participate in a ground breaking clinical trial to test the safety and efficacy of a new drug that aims to treat sensorineural hearing loss. The criteria for eligibility to participate in the trial has recently been broadened to include participants with hearing loss of up to 20 years duration (see below for further information).

      By: REGAIN
      16 October 2018

      Preventing hearing loss: the search for treatments

      Medicines like aminoglycoside antibiotics or cisplatin are used to combat life-threatening infections and cancer, respectively, but their use may come at the price of someone’s hearing. Several treatments to prevent the loss of hearing caused by these medicines are currently being developed. Our Translational Research Manager, Dr Carina Santos, tells us more.

      By: Dr Carina Santos
      12 October 2018

      Shining a light on the cochlea

      We fund research across the globe into treatments for hearing loss and tinnitus. One of our newest projects, at the Bionics Institute in Australia, is investigating if we can improve how well cochlear implants work using light.

      By: Dr Tracey Pollard
      11 October 2018

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      We campaign for changes that make life better for people who are confronting deafness, tinnitus and hearing loss.

      Our ears are our organs of hearing and balance. They have three parts: the outer, middle and inner ear.