Will Research on Chickens Provide a Solution to Needing Hearing Aids?

By Aaron Rodriques

Researchers hope to develop hearing loss treatments by studying the regenerative capabilities inner ear cells in chickens. We discovered some interesting info on these little guys and hearing aids. 

An Alternative to Hearing Aids

Scientists are on the path of a new application that could provide a unique alternative to hearing aids. By studying hair cells found in the inner ears of chickens, researchers are in the process of creating treatments that cure hearing loss in humans, minimizing the demand for hearing aids in the future.

Chickens can regenerate inner ear cells that replace cells damaged from noise and other forms of physical trauma. All vertebrates except mammals can exhibit this phenomenon. 

"The key to restoring hearing in humans is to regenerate cells deep within the inner ear," said Shari Eberts, chairwoman of the board of directors of the Hearing Health Foundation, which is funding the research. "While humans cannot regenerate hair cells in the inner ear after they are damaged, chickens can. In fact, most animals other than mammals can regenerate these delicate cells, restoring their hearing spontaneously after damage."

Hearing Aids and the Hearing Restoration Project

The Hearing Restoration Project (HRP) involves researchers from more than 10 institutions including Harvard Medical School, who are studying chickens in order to find out how humans could possibly regenerate inner ear cells. 

Approximately 36 million adults in the U.S. have some kind of hearing loss, and 25 million have tinnitus, according to the National Institute of Deafness and Other Communication Disorders. The Hearing Health Foundation aims to manufacture a cure by 2024.

According to Eberts, researchers are studying fish and mice as well. Fish can regenerate hair cells like chickens, but mice cannot.

"By analyzing what genes allow for regeneration in fish and chickens, we can compare those to mouse genes to see where the differences occur," she said. "Once we have an understanding of what genes and sets of genes (known as pathways) play a role in allowing for regeneration in fish and chickens, and which inhibit regeneration in mice, we will have a clearer understanding of how to trigger regeneration in humans."

Animal Biology and Hearing Aid Design

Similar studies with different animal species have found them to have unique hearing capabilities that offer promising new innovations for hearing aid technology. This includes the impressive hearing abilities of the Greater Wax Moth, a tiny insect found in beehives, and the unique anatomy of the locust. Hearing aids based on structures found in nature are considered to have a “biomimetic design.”

This article was republished with permission from Audicus.

Can Plants Hear?

By Yishane Lee

As a friend of HHF, you are no doubt well aware that chicks, fish, and reptiles have the ability to regenerate their inner ear hair cells, an ability that means any damage to their hearing is corrected.

Mammals, including humans, cannot, and this is the core of what HHF’s Hearing Restoration Project is working to solve within the next decade—how we can translate the chick’s ability to regrow hair cells to humans, and as a result find a biologic cure for hearing loss and tinnitus.

Now comes news that it is not just the animal world that can hear. Plants can, too. A recent story by Michael Pollan in the New Yorker included this paragraph (italics mine):

“Plants have evolved between 15 and 20 distinct senses, including analogues of our five: smell and taste (they sense and respond to chemicals in the air or on their bodies); sight (they react differently to various wavelengths of light as well as to shadow); touch (a vine or a root ‘knows’ when it encounters a solid object); and, it has been discovered, sound. In a recent experiment, Heidi Appel, a chemical ecologist at the University of Missouri, found that, when she played a recording of a caterpillar chomping a leaf for a plant that hadn’t been touched, the sound primed the plant’s genetic machinery to produce defense chemicals. Another experiment, done in [Italian plant physiologist Stefano] Mancuso’s lab and not yet published, found that plant roots would seek out a buried pipe through which water was flowing even if the exterior of the pipe was dry, which suggested that plants somehow ‘hear’ the sound of flowing water.”

I find this absolutely fascinating. Could it be the plants “hear” via sensing sound vibrations—just like we do? And then they’re able to correctly correlate these vibrations to the category of friend or foe—again, just like we do? To hear the plant biologists in the story put it: Yes, it’s entirely possible, and even likely.

The article raises interesting issues of why animal-based biology deserves primacy, and whether a typical (animal) brain is needed for something to be considered intelligent. In addition to reading the piece, which I highly encourage you to do, there is a TED Talk by Mancuso, if you want to learn more.

We can learn much from plants. The promise of the Hearing Restoration Project is that we can also learn much from chicks, fish, and reptiles. Indeed, there has been early success with hair cell regeneration in mice.

Support the search for a cure for hearing loss and tinnitus within a decade.

Do Chickens Hold the Key to a Cure for Hearing Loss?

Chickens have the amazing ability to restore their own hearing, and this trait is inspiring a nonprofit organization in their search for a cure for hearing loss in humans.

The Hearing Health Foundation’s “Chirp the News” video features the group’s new mascot: a baby chick. Locked within the ears of this chick is the potential to restore hearing and cure tinnitus, or ringing in the ears. According to the National Institute on Deafness and Other Communication Disorders, about 36 million adults in the U.S. have some form of hearing loss, and 25 million are affected by tinnitus.

“As someone who lives with hearing loss every day, I am personally thrilled with the prospects for a cure,” said Shari Eberts, chairman of the Hearing Health Foundation’s Board of Directors, in an email to Healthline. “Life with hearing loss can be frustrating. Sometimes you miss the joke when everyone else is laughing, and sometimes you miss important information because you don't hear it. Supportive family and friends can make living with hearing loss easier, but a genuine cure would be life changing.” 

The Chicken’s Magic Ears

The secret to the chicken’s auditory magic is that supporting cells in its inner ear can replace hair cells that have been damaged by loud noises or other causes.

And chickens aren’t the only animals that can restore their own damaged hearing. All vertebrates other than mammals can do the same. And preliminary research has shown that mice can regain some of their hearing using supporting cells that turn into hair cells—in the lab, at least. 

Researchers supported by the Hearing Health Foundation hope to find a way to coax the supporting cells in the inner ears of people to transform into functional hair cells. Their goal is to have a cure within a decade.

The 10-Year Road to a Cure

For people with hearing loss, waiting a decade for a cure can seem like a lifetime. But in the world of research, this is a very short time to travel from initial scientific discoveries all the way to successful clinical trials in humans.

To speed the research along, the Hearing Health Foundation is supporting a collaboration known as the Hearing Restoration Project (HRP) that involves researchers from more than ten institutions, including Harvard Medical School.

To find a successful cure for hearing loss, researchers have plenty o work ahead of them—including identifying how supporting cells in the chicken's ear turn into hair cells, as well as finding potential compounds or drugs that can make this happen in people.

Eberts is optimistic that the project will hit its mark, and so is Ed Rubel, a professor of hearing science at the University of Washington and a member of the project team.

“With sufficient funding,” he says, “the consortium can discover effective pathways and hopefully some lead compounds to promote hair cell regeneration in the mammalian inner ear in the 10-year time frame.”

Many Eggs in Many Baskets

In his lab at the University of Washington, Rubel is working on one piece of the puzzle that may one day lead to hair cell regeneration in people. 

“The project on my own has to do with developing a new mouse model to test the pathways and, eventually, the drugs that come out of the HRP,” he said.

The mice developed in his laboratory will be shared among members of the consortium, so they can avoid having to develop their own mice. This kind of sharing is an important aspect of the collaboration, something that Eberts expects will save time and money.

For Rubel, working with the HRP has other benefits.

“The wonderful thing about the consortium,” he says, “is that it includes only people who really want to play in that kind of sandbox—that want to share information, share early-stage information, share the other things that they’re doing in their laboratories, and work together.”

As a person with hearing loss, Eberts supports the push to highlight the project's potential.

“Even though we are in the early stages of the research, we think it is very important that the public learn about our efforts,” she said. “We want them to know that there is hope for a cure and that there are researchers who consider curing hearing loss and tinnitus to be their life’s most important work.”

This article was repurposed with permission from Healthline.

What Do a Leather Pouch and a Fruit Fly Have in Common?

By Yishane Lee

What is the utricle? Merriam-Webster defines it as “a small anatomical pouch; the part of the membranous labyrinth of the inner ear into which the semicircular canals open.” But to you and me, it may help provide the solution to hair cell regeneration in the inner ear.

Like the cochlea, the utricle is located in the inner ear and it contains hair cells that are used to detect gravity (versus the sound waves that the cochlear hair cells detect). In a major step forward, Hearing Restoration Project scientist Dr. Jennifer Stone and her colleagues at the University of Washington pioneered the technique of isolating the utricle from the adult mouse and growing it in a dish in the lab.

Why is this important? It is providing for the first time the ability to directly access and experimentally manipulate hair cells and support cells in a lab setting. In other words, we can grow and do experiments on the utricle (a word derived from the Latin for leather bag). The cochlea has proven to be too delicate to isolate and grow in a dish.

As Dr. Andy Groves, Baylor College of Medicine, and an HRP colleague writes in the Winter 2014 issue of Hearing Health:

“Dr. Stone’s lab found that within a few days after hair cells are killed in the utricle, the surrounding supporting cells take the very first genetic steps to activate the program to make hair cells—but then they stop before the hair cells actually form. It is as though the supporting cells have received a signal to regenerate new hair cells, but they cannot ‘seal the deal’ and complete the regeneration program. This situation is very different from the cochlea, where absolutely no hair cell regeneration steps occur in adults.”

Drs. Grove and Stone, along with Dr. Neil Segil of the University of Southern California, are working together to figure out why regeneration takes the first steps and then stops. One area they are focusing on is the Notch signaling pathway, an evolutionarily determined method of cell communication. Notch signaling, among other things, determines the mosaic patterns of various cell types, including the mosaic that organizes the inner ear’s hair cells and supporting cells. The dysfunction of Notch signaling (a name that comes from a notch found in the wings of a fruit fly) has been linked to various cancers and diseases, and as a result it has become a focus of drug intervention.

Read about all of our HRP projects here, and stay tuned for more HRP updates throughout the year.

All Hail Supporting Cells

By Yishane Lee

We have the ability to hear, thanks to the sensitive hair cells located in our ears. They are called hair cells because of their hair-like shape, long and thin (resembling the hairs on your head yet having nothing to do with them). When these hair cells die or are damaged, it is permanent. And so is the resulting loss of hearing. Unlike in other species—such as birds, fish, and amphibians—in mammals including humans, once these cells die, they don’t grow back or repair themselves, which makes it even more critical to keep them alive.

Supporting cells, as their name suggests, support hair cells both structurally and nutritionally. But a new study of supporting cells in the inner ears of mice reveals yet another role—one that is hugely important for researchers working to restore hearing in mammals.

Writing in July in an online edition of the Journal of Clinical Investigation, scientists at the National Institute on Deafness and Other Communication Disorders (NIDCD), found that supporting cells can actually actively help repair damaged sensory hair cells.

Supporting cells and a chemical they produce called heat shock protein 70 (HSP70) appear to play a critical role in protecting damaged hair cells from death in the ears of mice. Senior study author Lisa Cunningham, Ph.D., said, “Our study indicates that when the inner ear is under stress, the cell that responds by generating protective proteins is not a hair cell, but a supporting cell.” Cunningham and her team are collaborating with a clinical team at the NIDCD to design a clinical trial. It will look at ways to induce the production of HSP70 in the inner ear.

Further, our Hearing Restoration Project consortium members Albert Edge, Ph.D. of Harvard Medical School, Stefan Heller, Ph.D. of Stanford University, and Elizabeth Oesterle, Ph.D. of University of Washington are trying to figure out what happens to supporting cells after hair cells die or are damaged. Their project, “Supporting Cell Fate Mapping,” has so far found that some promising news regarding supporting cells and their function. In “Making a Map,” an article in the Fall issue of Hearing Health, Dr. Oesterle writes:

“After some severe insults (damage), the nonsensory supporting cells in the [auditory] epithelium [the organ of Corti] can retain some normal cellular identity for long periods of time. This is encouraging because in non-mammals it is the supporting cells that give rise to new replacement hair cells after hair cells are lost. After various severe insults, our data suggest that the supporting cells die and neighboring cells—cells that are normally abutting the sensory epithelium—move in.”

Both recent research results show that while we still have more to learn about the roles of supporting cells, their support they provide may be crucial to the search for a cure for hearing loss and tinnitus.