A team of scientists at the University of Wisconsin-Madison has bioengineered vocal cord tissue capable of vibrating and generating sound as well as natural tissue. The feat is being hailed as a scientific first.
The lab-grown tissue may one day be used to restore the voices of patients with damaged vocal cords or those who may have lost theirs to cancer surgery or injuries, according to a study published in the journal Science Translational Medicine on Wednesday.
"I was surprised and even shocked at how well the tissue performed," Dr. Nathan Welham, a speech-language pathologist at the university and lead author of the study, told The Huffington Post. "You always engage in research because you hope for the best, but I certainly didn't expect that the function would be as exquisite and comparable to the natural vocal fold function."
The researchers collected cells that make up human vocal cord tissue, and then purified and grew the cells before arranging them on a 3D collagen scaffolding structure.
Over two weeks, the cells continued to grow on the structure. They formed the shape of human vocal cords, taking on the viscosity and elasticity of healthy vocal cord tissue.
"When we first made these tissues, I was struck by how they felt like regular vocal fold tissue," Welham said. "It was at that point when I first felt the tissue that I realized, gosh, this really seems like the real thing and that we should do some more testing."
The researchers tested functionality of the lab-grown tissue by transplanting it into the larynx -- the muscular voice box that forms an air passage to the lungs -- that had been removed from dogs who had previously died. Dogs' voice boxes are about the same size as a human larynx and vibrate in the same way, Welham said.
Once the vocal cord tissue was implanted in the larynx, it was attached to an artificial windpipe, and warm air was blown past it in an attempt to recreate voice. Watch the experiment in the video below.
The researchers found that the lab-grown tissue vibrated and produced sound similar to the natural tissue in a living body. The researchers also transplanted the tissue into lab mice modified to possess human immune systems, and found that the immune systems accepted the lab-grown tissue.
"This is evidence that bioengineered tissues are similar to native tissues," Dr. Sundaram Gunasekaran, materials expert and biological systems engineer at the university and a co-author of the study, told HuffPost.
About 20 million Americans have voice impairment, according to the researchers, and many have damage to vocal cord tissues.
Transplanting bioengineered tissue in patients who have difficulty speaking due to vocal cord tissue damage or loss may restore their communication abilities, the researchers concluded.
Replacing patients' vocal cord tissues with lab-grown material should not dramatically influence the nuances of their voice, such as accent or pitch. Many other factors -- such as the mouth, throat, and even the brain -- influence vocalizations, Welham said. Transplanted tissue would, however, give those with impairments better control of their voice.
"This is the first step," Welham said. "It's not really to put into human patients tomorrow. ... This kind of approach offers some promise in the future."
Next steps would be to place the bioengineered tissue into the vocal cords of living animals and then to do the same thing in humans in clinical trials, Science magazine reported, and get approval from the Food and Drug Administration.
Dr. Robert Sataloff, chairman of the ear, nose, and throat department at Drexel University College of Medicine in Philadelphia, who wasn’t involved in the study, told Science that the next steps are easy to say, but not easy to do.
"There’s still a long way to go before we can replace someone’s scarred vocal fold mucosa with a new, essentially normally functioning one," Sataloff said. He added that the new study is an "admirable start."