Tissue engineering techniques discovered at Mayo Clinic and Arizona State University created a humanlike vocal cord (fold) structure with the potential to produce a natural-sounding voice. The bioengineered scaffold mimics human vocal folds, with ability to vibrate and make sound. The study team reported the tissue-engineered vocal fold structure suggests potential for growing cells capable of healing scar tissue that impair speech. This research is published in Biomacromolecules.
"Tissue engineering is a promising approach that combines medicine, biology and engineering aimed at regenerating damaged or diseased tissue," says David Lott, M.D., principal investigator. "Tissue engineering strategies that regenerate functional vocal fold tissue following scarring show hope of restoring a normal voice." Dr. Lott is also the associate director of the Center for Regenerative Biotherapeutics in Arizona.
A human vocal fold is made of various concentrations of hyaluronic acid, a substance that keeps bodily functions moving smoothly and flexibly. Dr. Lott's study team combined varying concentrations of hyaluronic acid made in the lab to recreate the multiple layers of tissue like those found in natural vocal folds. The team documented mechanical, vibratory and acoustic properties in the structure that are like natural vocal fold function.
"We were able to manipulate the stiffness of the new vocal fold structure so that we matched the native pitch of the patient. This gives us the ability to personalize the vocal fold structure," says Dr. Lott. "We are hopeful that these exciting findings are a first step toward a tissue engineered vocal fold replacement."
Regenerative medicine and biotherapeutics are shifting the focus of health care from treating disease to rebuilding health. Mayo Clinic's Center for Regenerative Biotherapeutics is leading this effort and supports tissue engineering as part of its objective of delivering new regenerative cures to the practice.
A condition with few therapeutic options
Millions of people in the U.S. suffer from vocal fold damage from overuse, injury or radiation therapy. Scar tissue forms on the vibrating layer of the vocal fold causing a raspy, hoarse or breathy-sounding voice. People with vocal fold scarring often find it difficult to speak or sing. The condition can be difficult to diagnose, and damage from scarring often cannot be reversed. Speech therapy, rest and medication can ease the symptoms but does not heal vocal fold scar tissue.
"We are optimistic by the findings of our study," says Dr. Lott. "In this early research, I was surprised by how similar we were able to make the new vocal fold and by our ability to manipulate vibration to match native pitch."
Future studies are needed to evaluate the safety and effectiveness of the hyaluronic acid vocal fold structure. Depending on the outcome, it could be several years before this technology is available for daily patient care.
This research was conducted in the Head and Neck Regenerative Medicine Laboratory in Arizona in collaboration with Arizona State University. The Mayo Clinic and Arizona State University Alliance Collaborative Research Seed Grant funded this project.