Vocal cords from a bioreactor
Working vocal cords have been grown in the laboratory
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A team of scientists from the University of Wisconsin, led by Nathan Welham, managed to grow vocal cord tissue from human cells in the laboratory (Scientists grow working vocal cord tissue in the lab). Moreover, when tested, the bundles turned out to be able to vibrate and generate sound.
The vocal cords are located in the larynx. The central edge of each of them, near which the exhaled air passes, is a tendon, then there is a vocal muscle, and then a mucous tissue attached to the cartilage of the larynx. When the vocal cords come together, they vibrate under the influence of the flow of air from the lungs, in which case a person pronounces vowel sounds and voiced consonants. If the vocal cords are divorced, deaf consonants are pronounced. Various configurations of the gap between the ligaments allow a person to make a whisper, as well as speak in a raspy voice or with a gasp. Usually the ligaments range from 100 to 200 times per second, but when uttering very high sounds, the frequency of vibrations can reach 1000 per second.
Patients who have undergone surgery to remove the vocal cords, for example, with oncological diseases, or who have congenital pathologies of the larynx, lose the ability to speak. Welham and his colleagues decided to help the same people. They took samples of epithelial cells covering the surface of the ligaments and fibroblasts, which make up the bulk of the ligaments, and placed them in volumetric collagen matrices that mimic the structure of the organ.
Two weeks later, scientists discovered that the cells begin to form a structure resembling natural vocal cords. The researchers grew the ligaments to normal size, and then put them to the test. They fixed them in the larynx of five dead dogs, where they then fed an air jet. As it turned out, the vocal cords grown in the laboratory are quite capable of vibration, and therefore of producing sound. Scientists also checked whether such ligaments are rejected by the human immune system. To do this, they were implanted in genetically modified laboratory mice, whose immunity reproduces the human one. This check also ended successfully. In total, 170 vocal cords of different sizes were grown in the laboratory during the research.
The authors hope that in the near future their results will help patients. However, the next stage of the trial will be the transplantation of ligaments in the larynx of live animals. The work of Welham and his colleagues is reported in the journal Science Translational Medicine (Ling et al., Bioengineered vocal fold mucosa for voice restoration).
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20.11.2015