Noise-Damaged Hair Cells Can Regrow Stereocilia in Mammals if Rescued in Time

Scientists have been trying to regenerate hair cells — sensory cells in the inner ear named for the hairlike bundles jutting from their tops — out of surrounding non-sensory cells as a way to make up for hair cell loss in ears damaged by noise, some medicines, and other sources. (Unlike other vertebrates, mammals aren’t able to grow new hair cells on their own once the cells are dead or damaged.) But new NIDCD-funded research from Creighton University, Nebraska, and the Chinese PLA General Hospital, Beijing, says that hair cells damaged by noise may have more life in them than we once thought. We may be able to regenerate new hair bundles — called stereocilia — from the original hair cells. The researchers subjected guinea pigs to an impulse noise simulating gunfire, resulting in severe hearing loss. Using scanning electron microscopy, they showed extensive stereocilia damage had occurred throughout the inner ear. However, when the researchers injected math1, a key gene for the development of hair cells, into the inner ear within one week of damage, they found that the stereocilia were able to grow back. Furthermore, key measurements showed that the new stereocilia were able to convert sound vibrations into electrical signals, which is how the brain interprets sound. The researchers caution that there is a window of time when the hair cells are still viable following noise damage. If the hair cells are not rescued within that time frame, they will die. But if researchers are able to intervene early enough — within 10 days — the hair cells can possibly be saved. The researchers plan to conduct tissue culture studies to confirm whether these findings are supported at the cellular level.

The talk "Regeneration of Stereocilia of Cochlear Hair Cells by Math1 Gene Therapy" (#484) takes place Sunday, Feb. 7, at 5:00 p.m. PT in the Disneyland South Ballroom.

http://www.nih.gov/news/health/feb2010/nidcd-04.htm

Creighton professor strives to reverse hearing loss

Here's a recent article that came out last week about a Creighton University professor working on a cure for hearing loss.

It’s a bit of a stretch to describe Kirk Beisel’s research as something akin to seeking “Rogaine for the inner ear.”

But if his work with gene therapy pays off, the Creighton University professor and his team may aid untold numbers of people suffering from hearing loss by restoring the tiny sensory cells, the “hair cells”, inside their ears.

Or, he says, by preventing these hair cells from dying in the first place and thereby slowing down what is the leading cause of deafness in humans.

“The commercial potential is huge because by the time most people reach their 60s, nearly a third of them have hearing loss because these hair cells have died,” says Beisel, whose lab is in the Department of Biomedical Sciences at Creighton.

“When they reach their mid-70s, half have some kind of deafness,” he adds. Beisel is working closely with Lee Fenicle, director of Intellectual Resources Management, who has applied for several patents relating to Beisel’s research.

Click on the link above to read the rest of the article.

Proteins found to help develop auditory neurons

The leading cause of congenital and acquired hearing impairment is loss of spiral ganglion neurons or hair cells in the inner ear.

Researchers at the University of California, San Diego, School of Medicine and the National Institutes of Health found that Sox2, a protein that regulates stem cell formation, is involved in spiral ganglion neuron development. The study was published in the January 13 issue of the Journal of Neuroscience.

"These findings may provide the first step toward regenerating spiral ganglion neurons, the nerve cells that send sound representations to the brain," said Alain Dabdoub, PhD, co-investigator and assistant professor of surgery with the division of otolaryngology at the UC San Diego School of Medicine. "This has significant implications for advances in cochlear implant technology and biological treatments for hearing loss."

In the cochlea, auditory neurons transmit sound vibrations conveyed by hair cells. These vibrations are then converted to nerve impulses that communicate with the brain. If the neurons are lost or damaged, hearing loss occurs. Existing therapies for hearing loss are based on either increasing hair cell stimulation with hearing aids or introducing an electronic substitute for the hair cells with cochlear implants. In either case, the presence of functional spiral ganglion neurons is required for a successful outcome.

Prior research shows that as few as 10 percent of the normal number of spiral ganglion neurons is sufficient for the success of cochlear implants.

"The identification of factors that induce functional neurons has important implications for hearing restoration," said Chandrakala Puligilla, PhD, a research fellow at the National Institutes of Health. "The ability to induce even a small number of cells with gene-based therapy could be enormously beneficial."

Source: - read more.

First case of stem cell treatment on hearing loss on humans?

From what I've found there seems to be two patients with sensorineural hearing loss iare undergoing stem cell treatments in Mexico at the Nepsis Institute from a "Ask the Doctor" which seems to be on the edge of discovering how well these treatments will work in restoring some or all of the hearing nerves.

6) Are you or can you treat sensory neural hearing loss with adult autologous stem cells? If not, do you expect to in the next year? Do you know of any doctors treating hearing loss at this point, if Nepsis does not?

Actually, we have two patients with sensory neural hearing loss who will be undergoing stem cell treatment in the next two months. The approach is unique and proprietary, so I can’t get into specifics at this time.

In time we'll find out whether if this is a success or not and if so would prove ground-breaking so early in this game rather than 10 or 15 years down the road. As always, take this with a grain of salt.

Hat-tip: Neuro

Path to cure for sensorineural hearing loss explained

Here's WongTanLim3 blog that does a very good job breaking down the discussion on the path to cure sensorineural hearing loss and does a quick summary along with important links. Reading this blog you will realize that this particular biomedical field is now soon becoming into a race for the cure for hearing loss in the area of nerve deafness. This blog piece is a MUST READ! And a must have blog to add to your favorite link.

Like me, if you're following stem cell or gene therapy research for the treatment or cure for sensorineural hearing loss or nerve deafness which is one of the most promising field of medical research and development into the coming next decade, then this is a must read blog to read. And keep abreast of important news and thoughts like this recent blog post by WongTanLim3.

Be sure send a thank you to WongTanLim3 for keeping a sharp eye on this growing field soon to be a burgeoning biomedical development which will have the potential to affect several hundreds million people around the world with nerve deafness. Of course, this alone would have the greatest impact to those in the Deaf community when compared to the issues and consternations involving cochlear implants.

Will Deaf Culture Die Out Someday?

There is always a possibility that Deaf culture could die out and this is dependent on a variety of factors with some of them going against the spread of Deaf culture and its language, ASL. But at this point it's probably more of a matter of "if" and not "when." Then again that's subject to change.

One of the biggest factor that could affect the outcome on the survivability of Deaf culture would be the fertility rate among married Deaf couples whose deafness genes would be passed onto their deaf offsprings, thus enabling the continuation of their Deaf culture through ASL. According to this latest genetic study it has shown that through "mixing" that Deaf culture is able to survive and grow in this manner but it also comes with a caveat.

In the United States, 80%–90% of individuals with profound deafness currently marry a deaf partner;39 however, the introduction of cochlear-implant technology is profoundly altering the mating structure of the deaf population. By facilitating oral communication and educational mainstreaming, substantially all of the deaf children of hearing parents will be redirected into the hearing mating pool. Even if all of the deaf children of deaf parents eschewed implants, continued to learn sign language, and mated assortatively, the size of the pool would decrease dramatically...

In other words even if they shun cochlear implants completely and continue with ASL the size of the Deaf pool would decrease over time simply because of the introduction of cochlear implants has drastically altered how mating is done. And increasingly many would prefer the hearing group because CI users are able to interact much more readily with the hearing society through talking and listening versus a Deaf community.

The study goes on with even further with another caveat.

On the other hand, if deaf couples begin to embrace cochlear-implant technology for their children, the pool size will continue to decrease, eventually resulting in the substantial disappearance of the deaf culture.

It seems that technology (i.e. cochlear implants and hearing aids) exerts a great deal of influence on mating preferences which brings me to this. The inexorable march for the cure and restoration of hearing loss.

This march for a cure through stem cells and other biotechnological advances may in fact provide the final blow on whether Deaf culture and its society can survive. Technology is already recognized as one of the limiting factor on the spread of Deaf culture, the community and ASL. Imagine the further downward spiral of Deaf culture and its society once people with hearing loss gets treated with a biomedical cure which will alter drastically the mating structure in a population faced with less and less people with hearing loss.

Avdism as a crutch excuse?

This "a-wordism" has lately become vulgarized through the repeated abuse of the word, marketing, and just plain ol' fashioned use of the internet to help spread the word. In the main heading of my blog I stated, "Don't use deafness as your crutch. We all face adversity in our life and don't let it become an obstacle but a challenge!" Yet it is true and a sad fact that people are discriminated for what they are and it shouldn't be like that. But that isn't justification to abuse this a-wordism by over-playing this particular discrimination card. Just like when people use the race card for every single supposed racist act when it never happened or existed a la Gates-Crowley Incident. People on both end purposely practice discrimination. Yes, even Deaf people against hearing people, even discriminate against those who prefer to talk despite their deafness. The horrors!

Maybe the answer to this a-wordism will either be that technology becomes so great and prevalent and accessible to all will ensure that this a-wordism wouldn't be an issue since techology would become that great 'equalizer.'

Or perhaps more likely that biotechnology would come early and a cure for hearing loss is made real where all babies born deaf will become hearing through the help of stem cells, thus the decline of Deaf culture and community would occur through attrition in the next 100 years. Some say this cure for babies born deaf won't happen in our lifetime or that it won't happen so "soon" in 10, 20 or 30 years. Or some simply believe it'll never happen and it'll be impossible for the biomedical technology to come up with a cure for hearing loss. Oh, wait, I think the cure for babies born deaf or acquired hearing loss very early on is already beginning in clinical studies this year.

The CBR Center for Regenerative Medicine is collaborating with two leading medical institutions to initiate a research study that would evaluate using a child's own cord blood stem cells to help restore or improve hearing that's been damaged from injury or sickness.

Specifically, we are looking for children under the age of 18 months whose own cord blood is stored at CBR and who have sustained hearing damage...

Regardless, this a-wordism may eventually go away either wholly or to some extent. Just a matter of time. But for the time being, do not use it as crutch and an excuse for your deafness. Certainly we have really dumb hearing people who don't know better but ignorance is not the same thing as accusing them with the a-wordism. Educate them instead.