Fresh Voices: Researchers Grow New Vocal Cords From Cells

This is a first-stage study, and it will take far more research before the approach could be tested in people, cautioned Dr. Norman Hogikyan, a voice specialist at the University of MI, who wasn’t involved in the new research.

Humans speak by forcing air over their vocal folds or “cords”, which reside in the larynx or voice box. Using cells from the mucosa, they applied them to a collagen scaffold and, over the course of two weeks, grew into tissue resembling vocal cords – including producing proteins that normal cord cells make, and growing the membranes which protect them from pathogens and irritants in the airway.

Example of human vocal folds in action, viewed using a strobe light.

Around 30 percent of Americans have experienced a voice-related issue during their lifetimes, Welham says.

“Certain congenital problems or scarring or tissue loss following surgery … can cause substantial voice loss that can be very challenging to treat with our current methods”, he said.

The research team was led by Nathan Welham, a UW-Madison speech-language pathologist who was excited about the latest discovery because it was created with actual human vocal fold cells and was functioning at an impressive level. “If you have a really poor voice, it draws attention immediately when you open your mouth”. But a few of the fold’s ability to vibrate is still lost.

But while the success is exciting, he said, no one knows how this will work out in humans.

For the experiment, the scientists extracted tissue from a cadaver and four other healthy patients who had their vocal cords removed.

Next, the researchers placed the two cell types in a 3D collagen matrix that mimics conditions in the body.

Vocal cords are formed by two bands of smooth muscle tissue that are lined with a material called mucosa.

“Voice is generated by a complex and handsome biological system”, he said.

The scientists then put the engineered vocal cord tissue to the test. They grew their mucosae to human sizes and put them into the voice boxes of five cadaver dogs, keeping one of the original vocal folds in each. Not anymore. Researchers at University of Wisconsin Medical School have published a preliminary study in the journal Science Translational Medicine wherein they successfully cultured 170 sets of vocal chords in the lab. These organs do not require the course of immunosuppressants that conventional transplants require.

The tissue was then transplanted into mice engineered to have human immune systems and, amazingly, it wasn’t rejected.

One obstacle, Franco said, is making sure transplanted vocal tissue can “auto-regulate” itself – maintaining its size, structure and integrity.

At present there are limited treatment options available for people with a larynx damaged by cancer or other disorders because of the highly specialised nature of the vibrating cells of the vocal cords.

What’s more, the engineered tissue performed better than tissue taken from inside the cheek, the researchers said.

People whose voices are impaired because of severely damaged vocal cords could someday get help from bioengineered cords, researchers suggest. One of the major next steps would be placing the engineered tissue in the vocal cords of living animal models and having it survive and work.

It’s not an easy thing to do.