Now, scientists at the University of Wisconsin-Madison have engineered lab-grown vocal cord tissue for the first time.
Our vocal cords are two strong but flexible bands of muscle that are covered in a delicate tissue called mucosae. When we speak, we force air over them, causing them to vibrate against each other and produce sound.
Most people’s vocal cords vibrate around 100 to 200 times a second – in soprano singers that can get up to 1,000 vibrations per second – but in patients with vocal cord damage often can’t reach 100 vibrations a second, which means they struggle to produce sound.
Vocal impairment, either temporary or permanent, affects about 20 million people in the U.S. at any given time. Vocal cords that have been scarred by surgery or radiation are particularly difficult to treat. People with that kind of damage could benefit from a lab-grown replacement, especially if such a surgery would require fewer immuno-suppressants than receiving cords from cadavers.
Moving on, according to the researchers report, the lab-grown vocal cord tissue appears to be functional although so far it has only been tested outside of an animal’s body.
Co-author Nathan Welham from the University of Wisconsin School of Medicine and Public Health in Madison and his team started with some rare donations of vocal cords from four patients who had had their larynx removed for non-cancerous reasons, and from one deceased donor. The researchers culled two types of cells that made up most of the tissue, and grew a large supply of them.
Then they arranged the cells on 3-D collagen scaffolding, and the two cell types began mixing and growing. In 14 days, the result was tissue with the shape and elasticity of human vocal cords, and with similar chemical properties.
Now the question is, could it work?
The researchers took a larynx that had been removed from a large dog after its death and attached it to a plastic “windpipe” that blew in warm air to simulate breath. The researchers cut out one of the native canine vocal folds and glued a piece of the new bio engineered tissue in its place.
A buzzing sound, “almost like a kazoo,” as the AP reports — approximately the same sound that of the original dog larynx made under the same conditions, which suggested the possibility of lab-grown vocal cords working inside a body.
However, let us not at all expect something big about this, as the researchers note that the engineered tissue is still in the early research stages, and significant more study is required before the tissue can be tested in humans.