British singer Adele was forced to cancel two tours last year because of a vocal cord hemorrhage. Laser microsurgery on her vocal cords was performed in November by Dr. Steven Zeitels, director of the Massachusetts General Hospital Voice Center .
Dr. Zeitels has been the "go-to" doctor for many well-known singers suffering problems with their voices, including Julie Andrews and Steven Tyler. Dr. Zeitels' "go-to" person to find a better solution to vocal cord stress is Robert Langer, Institute Professor at the Massachusetts Institute of Technology who runs a lab that has been designing plastics for medical applications since the 1970s.
| Gel mimics vocal cord viscoelasticity. (MIT/MGH)
Langer put his lab to work on the problem in 2002 and he announced at the annual meeting of the American Chemical Society this week in Philadelphia that clinical trials may begin within a year on an injectable polymer gel that mimics key traits of human vocal cords. Langer said it has shown dramatic improvement on animal vocal cords "within an hour".
"We have designed a new gel that has been tested in ferrets and dogs to help restore voice and we hope to start clinical trials in the next year or two," said Langer at a press conference that can be viewed at ACS Live.
The Langer Lab evaluated two possible solutions after Dr. Zeitels' first presented the problem. One potential approach was to develop a plastic material. Another was to engineer artificial vocal-cord tissue. The first approach was chosen in an effort to get a solution to the clinic faster. Initial evaluation focused on materials already approved by the U.S. Food and Drug Administration for applications in the human body.
Lab workers started with polyethylene glycol (PEG) and altered its molecular structure to improve viscoelasticity so that it matched human vocal cords. Viscoelasticity permits vocal cords to vibrate when air comes from the lungs.
Once approved for human use, the gel would have to be re-injected after six months.
"We expect it will be a relatively simple procedure to do once it is fully developed," said Langer. "Our expectation is that it will be a minimal procedure in a doctor's office since the gels can be injected with 25-gauge needles."
Tests to date have focused on the safety of the gel, which is considered a medical device and not a drug. A study published in the Annals of Otology, Rhinology & Laryngology reported that the treated dogs showed no damage to their vocal cords after four months.
"Our expectation is that it will not just be helpful to celebrities," said Langer. "There are six million people in the U.S. who have trouble with hoarseness or difficulty in using their voice, and this could potentially help any or all of them. Singers put an amazing amount of stress on the vocal cords." While they might be more likely to have a need, there are many others who could also benefit, ranging from babies who have been tracheally intubated to people who have suffered throat cancer.
The project is funded by the Institute of Laryngology