Lab-grown vocal cords could soon replace damaged ones

People with damaged vocal cords may one day sing again with the help lab-grown vocal cords.

Researchers at the University of Wisconsin-Madison say they've grown vocal cords in the lab, and these petri dish voice boxes have already managed to make dead dogs bark.

Now, they hope to help humans find a new voice too. CBC Radio science columnist Torah Kachur explains how.

Why did scientists want to grow vocal cords in the lab?

Millions of people every year lose their vocal folds (more commonly called the vocal cords) to cancer, or lose the ability to speak because their vocal folds are damaged. Obviously, these people would benefit tremendously if scientists could grow vocal cords in the lab and transplant them.

And the University of Wisconsin scientists say they've done just that.

How did the researchers grow vocal cords?

They used a very complicated method that started out with cells taken from people whose voice boxes had been removed.

"We isolated the cells, we arranged them in a way that represents how they should be in the organ, and then they did the rest," said Nathan Welham. He's a speech and language pathologist at the University of Wisconsin, and is the main author of the research published this week in the journal Science Translational Medicine.

"They grew, integrated, made the right proteins, and became a functional tissue in a couple of weeks."

The next step was to make sure the lab-grown vocal cords worked. So Welham and his team took half of their in vitro vocal cord, and surgically attached it to voice boxes of dog cadavers.  

Then, when the one side was in place across from the dog cord, they tested it by sending air through it — a test which proved the vocal cord they'd grown worked.

"Normal vocal folds are interesting in that they vibrate somewhat like a musical instrument string," Welham said. He says the performances of the lab-grown vocal folds "were comparable to the performance of a normal vocal fold tissue."

This is still an artificial system they were testing it in, not a talking person quite yet. But all the indications point to the technique working.

Can these lab-grown vocal cords be used in humans?

Not quite yet. But part of this research did involve transplanting vocal folds into something called "humanized mice" — mice that have an immune system similar to humans.

The tissue was transplanted and researchers didn't see rejection, so that's a major step towards eventual human application.

The other really interesting thing about this research is that the technique could allow scientists to use a patient's own cells, and then regrow the tissue and transplant it — which means there's even less likelihood of rejection.

Such a procedure is likely years away, but not decades.  There's a growing list of organs that can be grown in the lab, from kidneys to bladders and now vocal cords.