Sensitive ears. Mice that received extra copies of a protein during fetal development produced more of a key hearing cell (bottom) than control mice did.
Credit: David Woessner, John Mitchell, and John V. Brigande
Posted on 08/27/2008 10:30:49 PM PDT by neverdem
Sensitive ears. Mice that received extra copies of a protein during fetal development produced more of a key hearing cell (bottom) than control mice did.
Credit: David Woessner, John Mitchell, and John V. Brigande
A cure for hearing loss could be closer, now that a team of scientists has produced key ear cells in mice--and for the first time verified that the cells work just like natural ones.
The inner ear turns sound waves into electrical signals inside the organ of Corti, which is lined with rows of 15,000 to 20,000 hairlike cells. The cells respond to vibrations by producing electrical impulses that travel via nerves to the brain. It's a fragile system; loud noises can damage the hair cells and age can deplete them, resulting in hearing loss. Researchers guessed that they could restore some hearing by replacing those hair cells. Previous studies isolated a protein called Atoh1, which triggers hair-cell growth. But it wasn't clear that the engineered cells would have the same mechanical and electrical properties as normal ones when produced in an animal.
To address that concern, John Brigande, a developmental neurobiologist at Oregon Health and Science University in Portland, and colleagues injected embryonic mice with DNA containing several copies of Atoh1. The researchers inserted the genes about a week before birth--after they could identify tissue that would become the inner ear and before the natural development of hair cells had begun. Four days after the mice were born, the researchers examined their hair cells.
Mice that produced the extra Atoh1 had almost twice as many hair cells as did control mice, the researchers report today in Nature. Electron microscopy revealed that the extra hair cells were divided into inner and outer hair cells, just like the normal ones, and they made the same proteins. Next, the researchers determined that the engineered cells responded to sound waves and turned them into electrical signals.
The findings show that Atoh1 replacement therapy can produce viable hair cells in animals, Brigande says. "That's exciting because it offers a strong rationale to pursue cell-replacement strategies for hearing loss."
Other auditory experts agree. Matthew Kelley, a developmental neuroscientist at the National Institute on Deafness and Other Communication Disorders in Bethesda, Maryland, applauds the method of introducing the Atoh1 during the embryonic stage. "It's a brand-new technique. This has been one of the major challenges and roadblocks in inner ear research."
Yehoash Raphael, an auditory neuroscientist at the University of Michigan, Ann Arbor, says the findings provide a new delivery model for researchers trying to use developmental genes to restore lost hearing. But before researchers can develop a treatment for humans, they have to answer questions such as how many copies of Atoh1 are necessary to stimulate hair-cell regrowth and what is the best way to deliver the gene to a human organ of Corti.
And then when you get older and develop hearing loss, your stereo music doesn't sound quite as good as it did 20 years ago.
And if you develop tinnitus, your ears scream at you every waking hour.
Not that any of you youngsters will listen, I was the same way when I was your age.
What did you say? ;-)
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus
SPEAK UP !
Did I speak up good enough?
No one hopes for hearing loss.
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FReepmail me if you want on or off my health and science ping list.
My hearing was far above average when I was a freshman in high school.
I was a stereo nut that could appreciate what the "Golden-Eared Audiophiles" could hear, 20 Hz - 20 KHz.
And I had a science teacher who said way back then in the mid-70's, "Invest in hearing aids", because he could see where all us idiots were going.
And now I hear all these idiots driving down the street with their 2000 watt subwoofers...
They're not going to listen to us old farts, but they're messing up....
Once you lose a ton of your hearing, you find out how valuable it is.
It is one of your most basic senses, and when you lose it, there is a gap.....
You just don't appreciate your hearing until you start to lose it.
The next 10-20 years will be like a Star Trek script.
Ping to a thread that might be of interest to you. :^)
saving
While they're at it, they should pinpoint the gene that makes older men grow hair on their back instead of where it belongs on their head...
Cheers, sonny!
So as long as I can still hear Bach Double (Concerto for Two Violins in D minor) I am fine.
“So as long as I can still hear Bach Double (Concerto for Two Violins in D minor) I am fine.”
Agreed...and Vivaldi, and Mozart, and Beethoven, and Chopin.
By the way, Michelle Malkin suffered hearing lose in one ear from all the shouting this week during that scuffle as some ass threaten to kill her.
It must have been quite bad seeing that she must have consulted an MD to have made that statement.
Obligatory photo please.
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