Featured Research

from universities, journals, and other organizations

Researchers Learn More About Ways To Regenerate The Ear's Hearing Cells

Date:
April 28, 2006
Source:
Massachusetts General Hospital
Summary:
MGH researchers have made important progress in their ongoing effort to regenerate the inner ear's hair cells, which convert sound vibrations to nerve impulses.

Massachusetts General Hospital (MGH) researchers have made important progress in their ongoing effort to regenerate the inner ear's hair cells, which convert sound vibrations to nerve impulses. In an upcoming issue of Proceeding of the National Academy of Sciences they report successfully creating a mouse model that allows them to build on earlier findings about the effect of deactivating a protein that controls the growth and division of hair cells. The paper, which is receiving early online publication, also finds that suppressing the retinoblastoma (Rb) protein has different effects in specific parts of the inner ear.

"In these first studies of the role of the Rb protein in the ears of postnatal mice, we have confirmed that -- under the right conditions -- mature hair cells can go through the cell cycle and produce new, functioning hair cells. But we've also confirmed that you need to block Rb reversibly and at an early stage of development, otherwise the hair cells will die," says Zheng-Yi Chen, DPhil, of the MGH Neurology Service, the study's senior author.

Named for the hair-like projections on their surfaces, hair cells form a ribbon of vibration sensors along the length of the cochlea -- the organ of the inner ear that senses sound -- where they convert sonic vibrations to electrical signals that are carried to the brain. The cells are very sensitive to damage from excessive noise, infections and toxins. Once damaged, hair cells do not naturally regenerate in mammals, and their death accounts for most types of acquired hearing loss.

All cells grow and divide through a process called the cell cycle, and many proteins have been identified that control different cell cycle phases. In 2005 Chen's group published a paper in the journal Science reporting that the Rb protein, known to suppress the cell cycle, could be important for halting the cell cycle in hair cells. They used a genetically modified mouse strain in which Rb was no longer made in the inner ear. By examining the inner ears of mouse embryos -- that strain did not survive past birth -- the researchers found more hair cells in the knockout mice than in the ears of normal mice at the same stage of development. The additional cells looked and functioned like normal hair cells and appeared to be actively regenerating.

For this followup study, the researchers developed a new strain of inner-ear Rb-knockout mice that survive for up to six months past birth. Their investigation of the effects of Rb deletion on the hair cells of the inner ear finds differences between the auditory portion of the organ, which controls hearing, and the vestibular area, which is involved with balance. While the Rb-negative auditory hair cells in early postnatal mice are dividing and growing, the cells do not mature properly and eventually die, resulting in the mice becoming deaf by the age of 3 months. Vestibular hair cells, however, appear to grow and mature relatively normally and continue cell division even in mature mice. Adult Rb-knockout mice maintain some vestibular function, indicating that those hair cells are contributing to their sense of balance at the system level.

"We've shown that vestibular hair cell regeneration may be achieved and may be less of an obstacle than auditory cell regeneration," Chen says. "Now we need to find ways to create a similar system in the auditory cells, and this new model will help us better understand the mechanisms behind functional hair cell regeneration. Our next step will be developing a transient, reversible block of Rb function to assess its role in both types of hair cell." Chen is an assistant professor of Neurology of Harvard Medical School (HMS).

The report's co-authors are first author Cyrille Sage, PhD, and Mingqian Huang, PhD, of the MGH; Melissa Vollrath, PhD, and David Corey, PhD, Howard Hughes Medical Institute and HMS; M. Christian Brown, PhD, Mass. Eye and Ear Infirmary; Douglas E. Vetter, PhD, and Philip Hinds, PhD, Tufts-New England Medical Center. The research was supported by grants from the National Institutes of Health, the Howard Hughes Medical Institute and a Pfizer/AFAR Innovations in Aging Research Grant.


Story Source:

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


Cite This Page:

Massachusetts General Hospital. "Researchers Learn More About Ways To Regenerate The Ear's Hearing Cells." ScienceDaily. ScienceDaily, 28 April 2006. <www.sciencedaily.com/releases/2006/04/060428141422.htm>.
Massachusetts General Hospital. (2006, April 28). Researchers Learn More About Ways To Regenerate The Ear's Hearing Cells. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2006/04/060428141422.htm
Massachusetts General Hospital. "Researchers Learn More About Ways To Regenerate The Ear's Hearing Cells." ScienceDaily. www.sciencedaily.com/releases/2006/04/060428141422.htm (accessed September 20, 2014).

Share This



More Health & Medicine News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Sierra Leone's Nationwide Ebola Curfew Underway

Sierra Leone's Nationwide Ebola Curfew Underway

Newsy (Sep. 20, 2014) Sierra Leone is locked down as aid workers and volunteers look for new cases of Ebola. Video provided by Newsy
Powered by NewsLook.com
Changes Found In Brain After One Dose Of Antidepressants

Changes Found In Brain After One Dose Of Antidepressants

Newsy (Sep. 19, 2014) A study suggest antidepressants can kick in much sooner than previously thought. Video provided by Newsy
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
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:
from the past week

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