Scientists create fully functional, lab-grown vocal chords [Video]

A team of scientists have succeeded in growing functional vocal-cord tissue in the laboratory, which can benefit people who have lost their vocal cords to cancer surgery or other injuries.

Researchers from the University of Wisconsin were able to bioengineer tissue that “felt like vocal-cord tissue” that are able to transmit sound. In a study published in the journal Science Translational Medicine, the team said that materials testing showed that it had qualities of viscosity and elasticity similar to normal tissue.

Vocal cords are difficult to replicate since they are made up of a special tissue that has to be flexible enough to vibrate yet strong enough to bang together hundreds of times per second, said Dr Nathan Welham, a speech-language pathologist and an associate professor of surgery in the UW School of Medicine and Public Health.

For the study, Welham and his colleagues began with vocal-cord tissue from a cadaver and four patients who had their larynxes removed but did not have cancer. The researchers isolated, purified and grew the cells from the mucosa then applied them to a 3-D collagen scaffold, similar to a system used to grow artificial skin in the laboratory.

In about two weeks, the researchers observed that the cells grew together to form a tissue with a pliable but strong connective tissue beneath and layered epithelial cells on top. According to the team, the cells produced many of the same proteins as normal vocal cord cells, while the epithelial cells also began to form an immature basement membrane, which helped create a barrier against pathogens and irritants in the airway.

To see if it could transmit sound, the researchers transplanted the bioengineered tissue onto one side of larynges that had been removed from cadaver dogs. The larynges were attached to artificial wind pipes, and warm, humidified air was blown through them. Not only did the tissue produce sound, but high-speed digital imaging showed the engineered mucosa vibrating like the native tissue on the opposite side. Acoustic analysis also showed that the two types of tissue had similar sound characteristics.

The researchers also found that the tissue grew and was not rejected by mice that had been engineered to have human immune systems.

However, the team notes that the tissue was not as good as the real thing, since its fibre structure was less complex than adult vocal cords. They said that this was not surprising though, because human vocal cords continue to develop for at least 13 years after birth.

While clinical applications of the findings are still years away, Welham said that the proof-of-principle study is a “robust benchmark” in replacing vocal-cord tissue. To move the promising work forward, more testing of safety and long-term function is required, Welham added.

Meanwhile, there are several options to prevent vocal cord damage. According to VisiHow, eating an apple a day provides 25 percent of the recommended intake of vitamin C. Apples also contain a decent amount of vitamin E, which protects one's body tissues through extermination of free radicals that are responsible for tissue deterioration. Smokers who have a higher chance of damaging their vocal cords also stand to benefit from apples since they contain flavonoids, which are nutrients that the body needs to combat tissue and organ damage.