Laboratory
grown vocal cord tissue that produces realistic sounds is a step toward
creating new vocal cords for patients suffering from diseases such as cancer or
injuries that damage their voice. Vocal cords that produce voice sounds have
been grown in the laboratory from human cells. Details of the research are
reported in the journal Science Translational Medicine.
Investigators
from the University of Wisconsin in Madison harvested connective tissue and
lining cells from the vocal cords of four patients whose voice boxes had been
removed for medical reasons, and one human cadaver. They grew those cells onto
scaffolds that produced strong elastic tissue similar to the one in the natural
voice box. After two weeks of allowing
the cells to grow in the laboratory, the cells assemble into layers that
resembled the structure of healthy vocal cords.
To
test the freshly-grown tissue folds, scientists implanted them into one side of
voice boxes taken from dogs, and attached them to an artificial windpipe and
blew humidified air through them. When air was blown over the tissue it
vibrated, producing sounds that had the same characteristics as those made by
natural dog vocal cords. High speed digital imaging showed that the cords
vibrated like natural tissue too. In follow-up studies using mice the transplants
tissue were not rejected during a three months follow-up. It is unlikely that replacement voice boxes will
be created from vocal cord tissue from patients with cancer. However, vocal cords could be created from
stem cells that are turned into muscle and lining cells to form the cords.
Laboratory
grown replacements for damaged vocal cords are still years away and more research
is needed in animals to show that they work well and do not provoke an immune response,
and the process must be performed with clinical grade cells before the implants
can be tried in humans.
Normal vocal cords