For a singer, actor, or anyone whose livelihood depends on their voice, losing their voice can be devastating. Sometimes a bad cold will take it away temporarily, but other, more serious conditions can silence it for good. In this Science Update, you'll hear about new research whose goal is make lost voices speak once more.
Growing a new voice. I'm Bob Hirshon and this is Science Update.
Julie Andrews has always been known for her pure, clear soprano. But in 1997, vocal cord surgery left scarring that robbed her of her singing voice.
According to Patrick Tresco, director of the Keck Center for Tissue Engineering at the University of Utah, not much can be done to correct that kind of scarring. That's why he and his group are developing a strategy to replace damaged vocal cord tissue with a lab-grown material.
That strategy involves a material that would be soft enough to be implanted in the damaged vocal fold tissue, and it would in all likelihood have cells that come from the individual.
The researchers have built a device that grows cells on a piece of foam while gently stretching and vibrating it. This action mimics what happens to vocal cords in the body.
And we're finding that we can actually re-create those microenvironmental conditions to perhaps biologically farm a tissue that might be useful as a graft to repair the damaged cord.
These early studies show that they can reproduce the structure of real vocal cord tissue. Still, that's just the first step toward their ultimate goal of restoring the human voice. For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
Although vocal cord scarring can alter a singing voice, it can also do far more extensive damage. In some cases, even a person's normal speaking voice may be destroyed. Examples of patients who suffer from extensive damage include cancer patients and infants who have been intubated (fitted with a breathing tube, which can be especially rough on a new voice box).
The line of research that Tresco discusses is called tissue engineering, and it's a growing field in biomedical science. The object of tissue engineering is to grow useful tissues in the laboratory that can later be implanted into patients. Tissue engineering research has been conducted with human skin, bone, and cartilage cells, to name a few.
In this case, they're not growing a whole new set of vocal cords that are ready to snap into place. Instead, they're trying to grow a material with many of the physical properties of vocal cords, which could then be grafted onto damaged tissue. The "repair tissue" comes from two main sources: cells from near the vocal fold, and a kind of stem cell derived from bone marrow. Stem cells are prized in biomedical engineering because they're basically immature. With the right kind of prodding, stem cells can be made to develop into many different kinds of tissue.
One of the key challenges is coming up with a material that really works like vocal fold tissue (the stuff your vocal cords are made of). It turns out that it's pretty complex. When you talk, the force that you exert on your vocal fold isn't uniform throughout. What's more, your vocal cords depend on constant exercise in order to develop properly. (It's kind of like breaking in a shoe.) So in order to be truly life-like, their engineered graft tissue should be able to respond to exercise and mature in a similar way.
The research is still in the basic phases, trying to answer questions like these. Tresco hopes to start human trials within two to three years.
Now try and answer these questions:
- What is tissue engineering? How does it differ from something like an organ transplant?
- What properties might an engineered tissue need to have in order to repair vocal cords properly?
- What are stem cells? Why are they useful in tissue engineering?
- Why do you think the researchers want to use the patient's own cells to develop the graft material?
- Think of a material that you know how to repair. Examples include fabrics, wood, metal, plastic, or paper. Compare it to tissue engineering. How are the repair processes alike? How are they different? What challenges do they share in common?
The Keck Center for Tissue Engineering, at the University of Utah, is under Tresco's direction.
The Pittsburgh Tissue Engineering Intiative is an organization that supports the advancement of the field of tissue engineering.
The University of Pittsburgh Voice Center has information about the biology of speech, and proper voice care.