Working on a Drug to Stimulate Regeneration of Lost Hair Cells in the Inner Ear
One class of the numerous forms of age-related deafness is caused by loss of hair cells in the inner ear. These cells are a necessary part of the chain of systems that leads from sound outside the body to signals passing along nerves into the brain for interpretation. As these hair cells are lost, so is hearing capacity. A range of efforts to reverse this loss are underway at various stages of development, such as reprogramming a cell sample into patient-matched hair cells, or, as in this case, finding ways to provoke regeneration in situ, changing cellular behavior so that they rebuild where they would normally not do so.
Within the inner ear, thousands of hair cells detect sound waves and translate them into nerve signals. Each of us is born with about 15,000 hair cells per ear, and once damaged, these cells cannot regrow. Noise exposure, aging, and some antibiotics and chemotherapy drugs can lead to hair cell death. In some animals, those cells naturally regenerate, but not in humans. However, researchers have now discovered a combination of drugs that expands the population of progenitor cells (also called supporting cells) in the ear and induces them to become hair cells, offering a potential new way to treat hearing loss.
The research team began investigating the possibility of regenerating hair cells during an earlier study on cells of the intestinal lining. In that study, researchers reported that they could generate large quantities of immature intestinal cells and then stimulate them to differentiate, by exposing them to certain molecules. During that study, the team became aware that cells that provide structural support in the cochlea of the ear express some of the same surface proteins as intestinal stem cells. The researchers decided to explore whether the same approach would work in those supporting cells.
They exposed cells from a mouse cochlea, grown in a lab dish, to molecules that stimulate the Wnt pathway, which makes the cells multiply rapidly. At the same time, to prevent the cells from differentiating too soon, the researchers also exposed the cells to molecules that activate another signaling pathway known as Notch. Once they had a large pool of immature progenitor cells, the researchers added another set of molecules that provoked the cells to differentiate into mature hair cells. This procedure generates about 60 times more mature hair cells than the technique that had previously worked the best, which uses growth factors to induce the supporting cochlea cells to become hair cells without first expanding the population.
The researchers found that their new approach also worked in an intact mouse cochlea removed from the body. In that experiment, the researchers did not need to add the second set of drugs because once the progenitor cells were formed, they were naturally exposed to signals that stimulated them to become mature hair cells. "We only need to promote the proliferation of these supporting cells, and then the natural signaling cascade that exists in the body will drive a portion of those cells to become hair cells." Because this treatment involves a simple drug exposure, the researchers believe it could be easy to administer it to human patients. They envision that the drugs could be injected into the middle ear, from which they would diffuse across a membrane into the inner ear.
I wonder if this will help with tinnitus?
I have tinnitus, and when I wear hearing aids (fully in-ear Lyrics from Phonak) the tinnitus almost disappears. My hypothesis is that the brain is attempting to inject the missing frequencies - sort of like a "phantom limb" phenomenon.
David, it could be either this or the fact that the sounds brought by your hearing aids cover the your tinnitus (if it is a relatively mild T).
There's also a chance that it may alleviate some types of tinnitus, but not others. The most recent cases would probably benefit the most from this. But for multi-year cases, it's not obvious.
Anyway, good thing that this about to be tested. Only trials will tell.
A bit of topic: One thing that always puzzled me is the fact when men age they usually loose hairs on the head. In contrast, around certain parts of the outer ear hairs start growing. You can pull them out but they are back in no time. What makes those hair cells so special?
bardu: it seems to be linked to the Y chromosome: https://en.wikipedia.org/wiki/Auricular_hypertrichosis#Genetics
I also have tinnitus, but never consulted a physician. I'm accustomed to it and it's not a big annoyance now.
@ Antonio : Physicians are of little help anyway since there's no real treatment. I advise you to regularly fund the ATA instead (http://ata.org/) as they do channel funding into research.
By doing this you would help yourself even if your tinnitus is currently low, since (surprise, surprise) it can become louder over the years. Lots of feedback about this on forums. Oh and did I mention that it could evolve into hyperacusis ? (Granted, not definitely not systematically.)
(Sorry people for the offtopic).
Well, I have it since more long ago than I can remember (maybe 20 years? 30?) but I will keep an eye on ATA. BTW, the link doesn't work.
I can only wish that your tinnitus remains stable. And it would indeed be wise to have this patients association in mind, should your condition ever worsen. Better "invest" now to get a cure when you need it.
Here's the functional link to the ATA's website : https://www.ata.org/
Mmm still doesn't work. I obtain a "connection interrupted" error.
Ok, I'll donate to them when I have some savings.
OK, now I can see it in another machine. It seems they don't like my old Firefox.
Sorry for the OT.
Any word on this?
This article was published in 2017. When are these treatments going to be available and where can I go to get them or the drugs developed???? I wear hearing aids, which don't help a lot. It is definitely an inner ear thing, and I believe this would be the answer to my hearing loss.