Good news for those with scratched, lost or damaged vocal cords through surgery or disease; a team at the University of Wisconsin-Madison has made the first ever lab-grown human vocal chords from scratch – which could be used to restore the power of speech.
Alongside a lab-grown kidney, hearts and the successful insertion of a lab-grown windpipe, this heralds a new surgical era as scientists get closer to customisable repairs for body parts and engineering clinically relevant tissues.
Vocal cords are two strong, flexible bands of muscle covered in a delicate a membrane which form flaps inside the human larynx called ‘mucosae’. Human cells from donors (one from a cadaver and four from surgically-removed larynxes) were coaxed into becoming tissue that replicates those vocal fold mucosa.
The cells were grown for two weeks around a collagen scaffold structure until the folds were one millimetre thick and 16 millimetres long. By blowing warm air along them inside an artificial windpipe, the team produced a sound they describe as a ‘robotic kazoo’. “It was an eeee-like sound,” says project leader Nathan Welham.
When we speak or sing, most people’s vocal cords vibrate around 100 to 200 times a second, and in soprano singers that can escalate to 1,000 vibrations per second. Mouth and throat modulations are required alongside this to produce the recognisable sounds of speech.
Welham knows demand for better vocal treatments is out there, as voice impairment already affects approximately 20 million in the US alone. He envisages a future with transplantable folds grown two ways; through a ‘bespoke’ bank of donated vocal cells grown on-demand and off-the-peg varieties in different shapes and sizes.
While incredibly exciting for those without a voice, there’s still a long way to go. Just as we auto-tune popstars today, we could be one step nearer to a future where singers could upgrade their vocal cords for a richer tone.
Nathan Welham, Associate Professor, Department of Surgery Otolaryngology, University of Wisconsin-Madison