Featured Research

from universities, journals, and other organizations

Gene therapy for hearing loss: Potential and limitations

Date:
May 11, 2012
Source:
Emory University
Summary:
Regenerating sensory hair cells could form the basis for treating age- or trauma-related hearing loss. One way to do this could be with gene therapy that drives new sensory hair cells to grow. Researchers have shown that introducing a gene called Atoh1 into the cochleae of young mice can induce the formation of extra sensory hair cells.

Researchers can induce the generation of extra sensory hair cells in the cochlea. Mature sensory hair cells are red, while immature hair cells are green. The arrows indicate locations where hair cells are usually not found.
Credit: Image courtesy of Emory University

Regenerating sensory hair cells, which produce electrical signals in response to vibrations within the inner ear, could form the basis for treating age- or trauma-related hearing loss. One way to do this could be with gene therapy that drives new sensory hair cells to grow.

Researchers at Emory University School of Medicine have shown that introducing a gene called Atoh1 into the cochleae of young mice can induce the formation of extra sensory hair cells.

Their results show the potential of a gene therapy approach, but also demonstrate its current limitations. The extra hair cells produce electrical signals like normal hair cells and connect with neurons. However, after the mice are two weeks old, which is before puberty, inducing Atoh1 has little effect. This suggests that an analogous treatment in adult humans would also not be effective by itself.

The findings were published May 9 in the Journal of Neuroscience.

"We've shown that hair cell regeneration is possible in principle," says Ping Chen, PhD, associate professor of cell biology at Emory University School of Medicine. "In this paper, we have identified which cells are capable of becoming hair cells under the influence of Atoh1, and we show that there are strong age-dependent limitations on the effects of Atoh1 by itself."

The first author of the paper, Michael Kelly, now a postdoctoral fellow at the National Institute on Deafness and Other Communication Disorders, was a graduate student in Emory's Neuroscience program.

Kelly and his coworkers engineered mice to turn on the Atoh1 gene in the inner ear in response to the antibiotic doxycycline. Previous experimenters had used a virus to introduce Atoh1 into the cochleae of animals. This approach resembles gene therapy, but has the disadvantage of being slightly different each time, Chen says. In contrast, the mice have the Atoh1 gene turned on in specific cells along the lining of the inner ear, called the cochlear epithelium, but only when fed doxycycline.

Young mice given doxycycline for two days had extra sensory hair cells, in parts of the cochlea where developing hair cells usually appear, and also additional locations (see accompanying image).

The extra hair cells could generate electrical signals, although those signals weren't as strong as mature hair cells. Also, the extra hair cells appeared to attract neuronal fibers, which suggests that those signals could connect to the rest of the nervous system.

"They can generate electrical signals, but we don't know if they can really function in the context of hearing." Chen says. "For that to happen, the hair cells' signals need to be coordinated and integrated."

Although doxycycline could turn on Atoh1 all over the surface of the cochlea, extra sensory hair cells did not appear everywhere. When they removed cochleae from the mice and grew them in culture dishes, her team was able to provoke even more hair cells to grow when they added a drug that inhibits the Notch pathway.

Manipulating the Notch pathway affects several aspects of embryonic development and in some contexts appears to cause cancer, so the approach needs to be refined further. Chen says that it may be possible to unlock the age-related limits on hair cell regeneration by supplying additional genes or drugs in combination with Atoh1, and the results with the Notch drug provide an example.

"Our future goals are to develop approaches to stimulate hair cell formation in older animals, and to examine functional recovery after Atoh1 induction," she says.

The research was supported by the National Institute on Deafness and Other Communications Disorders, the National Basic Research Program of China and the Natural Science Foundation of China.


Story Source:

The above story is based on materials provided by Emory University. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. C. Kelly, Q. Chang, A. Pan, X. Lin, P. Chen. Atoh1 Directs the Formation of Sensory Mosaics and Induces Cell Proliferation in the Postnatal Mammalian Cochlea In Vivo. Journal of Neuroscience, 2012; 32 (19): 6699 DOI: 10.1523/JNEUROSCI.5420-11.2012

Cite This Page:

Emory University. "Gene therapy for hearing loss: Potential and limitations." ScienceDaily. ScienceDaily, 11 May 2012. <www.sciencedaily.com/releases/2012/05/120511122322.htm>.
Emory University. (2012, May 11). Gene therapy for hearing loss: Potential and limitations. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2012/05/120511122322.htm
Emory University. "Gene therapy for hearing loss: Potential and limitations." ScienceDaily. www.sciencedaily.com/releases/2012/05/120511122322.htm (accessed October 20, 2014).

Share This



More Health & Medicine News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Microneedle Patch Promises Painless Pricks

Microneedle Patch Promises Painless Pricks

Reuters - Innovations Video Online (Oct. 18, 2014) Researchers at The National University of Singapore have invented a new microneedle patch that could offer a faster and less painful delivery of drugs such as insulin and painkillers. Video provided by Reuters
Powered by NewsLook.com
Raw: Nurse Nina Pham Arrives in Maryland

Raw: Nurse Nina Pham Arrives in Maryland

AP (Oct. 17, 2014) The first nurse to be diagnosed with Ebola at a Dallas hospital walked down the stairs of an executive jet into an ambulance at an airport in Frederick, Maryland, on Thursday. Pham will be treated at the National Institutes of Health. (Oct. 16) Video provided by AP
Powered by NewsLook.com
Raw: Cruise Ship Returns to US Over Ebola Fears

Raw: Cruise Ship Returns to US Over Ebola Fears

AP (Oct. 17, 2014) A Caribbean cruise ship carrying a Dallas health care worker who is being monitored for signs of the Ebola virus is heading back to Texas, US, after being refused permission to dock in Cozumel, Mexico. (Oct. 17) Video provided by AP
Powered by NewsLook.com
Spanish Govt: Four Suspected Ebola Cases in Spain Test Negative

Spanish Govt: Four Suspected Ebola Cases in Spain Test Negative

AFP (Oct. 17, 2014) All four suspected Ebola cases admitted to hospitals in Spain on Thursday have tested negative for the deadly virus in a first round of tests, the government said Friday. Duration: 00:55 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins