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Scientists have for the first time successfully created functional vocal cord tissue in the laboratory. This is an innovation to help people whose cords have been too damaged to heal, according to HNGN.

About 20 million Americans have voice problems, due to injuries in their vocal cords. Bioengineering has helped researchers from the University of Wisconsin-Madison  to build up vocal cord tissues that can convey sound when "transplanted" into a voice box.

"Voice is a pretty amazing thing, yet we don't give it much thought until something goes wrong," lead study author Nathan Welham, speech-language pathologist, said in a press release. "Our vocal cords are made up of special tissue that has to be flexible enough to vibrate, yet strong enough to bang together hundreds of times per second. It's an exquisite system and a hard thing to replicate."

Welham collaborated with scientists from various disciplines. He took vocal cord tissues from a corpse as well as from four patients and cultured cells from the mucosa. When they applied the cells to a 3-D collagen scaffold, they found that the cells formed a tissue that "felt like vocal cord tissue." Its basement membrane blocked irritants in the airway, even as it produced proteins that were similar to a natural vocal cord.

Researchers could test the tissue by transplanting it to one side of dogs' larynges. These were linked to artificial windpipes. Passing air through them made the mucosa produce sounds like that produced by the mucosa on the other side, and also vibrating in the same way.

By moving the tissue into living mice, researchers found that the mice's immune system could adopt it. Welham said "the lab-grown vocal cord tissue, like cornea tissue, could be immunoprivileged, meaning it does not cause the host's immune system to react," according to HNGN.

While more tests are needed to be completed before clinical application, Welham called their study a "robust benchmark" in the development of vocal cord tissue replacement.

The study was published in the online Nov. 18 issue of the journal Science Translational Medicine.