Scientists report their success in growing vocal cord tissue in a laboratory, starting with human vocal cord cells, may one day help people with severely damaged cords recover their voices.
The bioengineered tissue, when tested in the lab, vibrated and created sounds similar to what natural vocal cords produce, the researchers said.
There currently is no way to repair vocal cords unavoidably damaged during surgery, through traumatic injury or by diseases like cancer, they point out.
That's why the researchers at the University of Wisconsin have been working on bioengineered replacements, reporting their efforts in the journal Science Translational Medicine.
Starting with vocal cord cells from human donors, they were able to coax them into forming tissue mimicking vocal fold mucosa, the flaps in the human larynx whose vibrations create the sound of the human voice.
The cells were seeded onto a 3D scaffold made of collagen, the main structural component of the body's organs and tissues.
Two kinds of cells were needed to create both the thickest and most elastic tissue found in the vocal folds, and the delicate lining capable of vibrating as fast a thousand times a second.
"No other tissue in the human body is subject to these biomechanical demands," says project leader Nathan Welham of the university's School of Public Health in Madison.
When the bioengineered vocal cords were attached to larynxes taken from dogs, and air was blown through them through a fake windpipe, they produced a steady sound similar to what natural human folds in isolation produce, Welham says.
Sound is only the beginning, he notes, as the human voice and speech are generated through modulating that sound through other structures, including the throat and mouth.
Testing the new cord tissue with mice found it triggered only a minimal immune response, suggesting such lab-grown vocal cords might be successfully implanted into people whose own cords are damaged beyond repair and have been left with impaired voices.
Around 20 million Americans suffer with some level of voice impairment, researchers say.
"I can't overemphasize just how negatively a severe voice problem can impact someone's life," says Welham, an associate professor of surgery. "If you have a really poor voice, it draws attention immediately when you open your mouth.
