Two weeks later, they had a strong yet flexible tissue that, structurally and compositionally, looked a lot like functional vocal cord mucosa.
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And it happens to more people than you might expect, with 20 million people in the U.S. alone suffering from temporary or permanent loss of voice, often as a result of surgery to remove cancerous or benign growths in the throat.
For many people who’ve had cancer or other vocal cord damage, thinking about how to speak, if ever again, is likely a daily thought. And right now, the treatment options are limited. That’s why UW researchers have focused on bioengineered replacements; their efforts are published in a paper in the journal Science Translational Medicine.
A team of researchers at the University of Wisconsin-Madison grew a pair of vocal cords that appear to be able to produce sound. Biology, says co-author Dr. Brian Fry, does most of the work.
It is only the vocal cords that required such kind of biomechanical demands in human body.
To solve this problem they bioengineered vocal fold mucosa from healthy vocal fold cells from two surgical patients, and from one cadaver. From this tissue, they isolated the two types of cells that make up the mucosae – connective fibroblasts and epithelial cells – in a petri dish, before applying them to a 3D collagen scaffold.
Voice therapy, injections of collagen or other synthetic materials, and surgery – sometimes involving transplants of tissue from inside the patient’s cheek – can help, Welham said.
But while the success is exciting, he said, no one knows how this will work out in humans.
Once aligned with a windpipe, the researchers blew warm air through it to analyze both whether it would produce sound and vibrate.
Immediate next steps include preparing for a different humanized mouse model that will allow for longer-term examination that will demonstrate whether it will be tolerated by the immune system over a long period of time and if it will keep its physiologic force production properties. Or fail to function well? Then, the same thing has to be accomplished in human vocal folds in clinical trials, Sataloff says: “All of that’s easy to say, but not so easy to do”. Cell overgrowth would be a potential worry, he explained, since the transplanted tissue would be in the airways.
When the procedure is ready for humans, Welham envisions a future where the tissue is prepared for the patient in a 14-day in-lab process.
At first, the researchers were only interested in learning how vocal cord tissue grew.
To test whether a living animal’s body would accept the lab-grown cords, researchers transplanted the cords into living mice, finding the cords grew and were not rejected by their bodies, and they were able to make sound with them. There are a few tissues, such as the corneas in the eye, that do not stimulate an immune rejection.
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“In my opinion, the timeline would probably be about five to 10 years from now”, Johns said. Vocal cords generate sound waves by vibrating against each other about 100 to 200 times a second-a number that can jump to 1000 times a second for a soprano singing her highest-pitched notes.
