Scientists have produced the cells that make up delicate inner ear hairs in mouse embryos, a step that could point the way to reversing hearing loss and curing congenital deafness. Sensory hair cells inside the cochlea, the auditory portion of the inner ear, convert sound waves into electrical impulses that are delivered to the brain. The loss of these minute hairs, or the nerves that control them, is the most common cause of hearing impairment and so-called nerve deafness [ABC Science].
Researchers used gene therapy to create the crucial cells: They used a virus to introduce a gene into the mice embryos, which caused non-sensory cells to turn into cochlear hair cells. While this preliminary experiment was done on normal-hearing mice, the discovery that the engineered cochlear cells functioned as well as natural cells was an important step. Says lead researcher John Brigande: “One approach to restore auditory function is to replace defective cells with healthy new cells…. Our work shows that it is possible to produce functional auditory hair cells in the mammalian cochlea” [Reuters].
Humans are born with about 30,000 inner ear hair cells, which are fairly fragile; loud noises can damage the hair cells and age can deplete them, resulting in hearing loss [ScienceNOW Daily News]. Humans, like other mammals, can’t regenerate these sensory cells naturally, so people who experience hearing loss try to get get around the problem in another way. Currently, people can have a cochlear implant which works by bypassing the damaged cochlear hair cells and stimulating the auditory nerve directly. An implant cannot restore hearing to normal but it does give the sensation of sounds [BBC News].
The new study, published in the journal Nature [subscription required], suggests that deafness could be entirely reversed by creating new cells. But researchers say the current study is only the first step in that direction. As for human tests, Dr Brigande says that the work is at too early a stage to say when they can start: “There is no present plan for tests in humans. The next step is to restore hearing in a deaf mouse [Telegraph].
Image: flickr/sutefani in orlando
August 28th, 2008 at 4:02 pm
This is great news for several years from now. My only concern is that when or if they’re able to perform this on humans they might not be able to help people who currently have cochlear implants because to get the electrodes on there they need to remove all of the existing hair cells and adhere the strip of electrodes. If they can only regrow so many or if removing the electrodes or initially removing the hair cells causes any sort of scar tissue it would be quite a hurdle in the least.
August 28th, 2008 at 4:41 pm
You have a knack for finding the cutest mouse photos.
October 1st, 2008 at 4:27 am
I’m hopeful this is the beginning of gene therapy on the Human ear. As a child I suffered from sudden deafness in my right ear. Diagnosed as damaged/depleted hair cells in the Cochlea, caused by a viral infection. A Cochlea implant in my case and others similar, (with one normal hearing ear, and one profoundly deaf), would be no good. As a Cochlea implant generates distorted sounds, which the Brain will have difficulty in recognising against the normal hearing ear. If, of course, both Cochlea’s were damaged, then Cochea implants would work, as the Brain can be re-tuned to the implants output, normalizing the sound. For the time being there is little that can be done for people like me, with a single non-hearing ear.
February 16th, 2010 at 9:42 am
In March of 2000 I developed a vertigo attack which came out of no where. I was hospitalized for a few days, and after had a few more episodes up to present time. Since 2000 I have loud noises in my ears that never go away, and my heaaring has become impaired more so in my left ear. After many tests, and surgically opening the ear drum for release of pressure, as the Doctor called it, nothing has helped. I live with the ringing, and loss of hearing, but prior I had incredible hearing. I wish to have it back again, please send me more information on this procedure, I would be willing to be a case study.
Thak you for your time.
Sincerely,
Allen
July 5th, 2010 at 11:22 pm
A revolutionary approach like this gets the blood pumping. How wonderful would it be to eliminate the need for hearing aids! The concerns however are numerous. How much would these procedures cost? Would insurance cover them? Would they only make sense for those with extreme hearing loss or how about only those young enough to enjoy a life of hearing?
October 26th, 2010 at 7:59 pm
This is exciting news but it raises a host of ethical and scientific questions. Many people skeeve out at the idea of using stem cells from human embryos, especially aborted fetuses, to obtain the necessary stem cells. Hopefully I way will be found to use ones one cells to regenerate these cells. Now I know the world is running out of places to put people and you can probably generate many billions of embryos that would have no place to live on this planet, but each embryo/fetus COULD have been a great person, or not. You don’t know. Taken to its natural conclusion you could say the same thing about every egg cell or sperm cell that doesn’t reach its full potential. These are complex questions, I have no answer for them.
The other problem is scientific, that of rewiring the nerves.. I suspect that every single hair cell is designed for a specific frequency and is wired into the auditory nerve on a specific pathway. A similar problem would be recreating a damaged retina and then rewiring each rod or cone into the optic nerve. In that case the task is extremely daunting because there are something like 130 Million rods or cones in each retina.
My training is in physics but I can see the complications that are implicit. I can only hope that the brain is plastic enough to rewire itself once the cells are replaced. I have sudden onset tinnitus and this issue is of course of interest to me, not to mention hyperacusis. I am aware this is MORE than just hair cell damage, this is nerve damage and as of this point in time there is no cure for my condition. I suspect that stem cells are the only hope for repair at this point, either that or help of a more miraculous nature. At its initial onset it gave me suicidal thoughts and I am desperate for relief but I know that that relief is years away. If it ever comes.
There are so many desperate conditions, blindness, paralysis, Alzheimer’s , etc. that truly can take the joy out of living and new science is desperately needed, but it should not come at the expense of a potential life. Right?
November 10th, 2010 at 11:03 pm
Ethical and scientific questions are indeed raised by this study, yet I would wonder whether the new cochlear hairs grown by this treatment are actually connected to the proper pathways of the brain – just because there’s cochlear hair doesn’t mean the hearing of the mouse has improved. Small steps first…
June 6th, 2011 at 11:12 pm
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September 8th, 2011 at 9:34 pm
My daughter has a sensoneural hearing loss. This is great news and hope for her. Will this new treatment be available soon and also how affordable would it be.
If it will be available at a reasonable cost then I am sure it will benefit all those seeking treatment.