Dr. Nathan Welham (right), and his team in the Welham Lab at the Wisconsin Institute for Medical Research. Image credit: John Maniaci/UW Health via The Independent
In a world first, scientists have grown human vocal cord tissue that mimics the sounds produced by normal vocal cords. The engineered tissue could one day be used to repair or replace vocal cords that have been damaged by injury, cancer, or other diseases.
Dr Nathan Welham’s team at the University of Wisconsin-Madison engineered the tissue by collecting the two main cell types that make up the vocal fold mucosae, a structure in the larynx (or voice box) that vibrates to create the sounds of the human voice. These cell types—connective fibroblasts and epithelial cells—came from one deceased donor and four living donors who had their healthy voice boxes following unrelated surgeries.
By using these cells as their building blocks, in an environment that replicated the human larynx, Welham’s team were able to grow a structurally comparable tissue to the vocal fold mucosae.
“I remember holding it and thinking, gosh, this feels like the real thing, which has a distinct feel—sort of like Jell-O but stronger and able to return to its shape if you deform it,” Welham says.
Next the team tested the functionality of their new engineered tissue. The tissue was grown to normal human size and then attached to larynxes extracted from dogs that had died of unrelated causes. Welham’s team then attached the larynx to a plastic, replica windpipe and blew through it warm, humidified air. Welham described the resulting vibrations as “exquisite” and comparable to the sound of the normal human larynx.
“We never imagined that we would see the impressive level of function that we did,” said Welham
But would this tissue be accepted in the human body’s immune system?
To answer this, the team implanted the artificial vocal cords into mice that had been genetically engineered to possess a human immune system. The tissue was not rejected by the immune system over a 3 month period, giving hope for the potential of human transplantations in the future.
Although these are promising early results, years of refining and safety testing will be required before the vocal cords could reach clinical trial stages.