Scientists
at the University of Wisconsin-School of Medicine and Public Health in Madison
have now been able to grow their own vocal cords out of connective fibroblasts
which form the "cords" themselves and epithelial cells which line the
outer surface. Both cells were collected from a human cadaver and four living
people who had their vocal cords removed when they underwent unrelated
surgeries. They surrounded these cells with a 3D collagen matrix and within
about 2 weeks, the cells formed a structure that resembled actual vocal
cords.
They
created the human vocal cords and implanted them into the larynxes of cadaver
dogs and when air was pumped through them, they worked like an actual
vocal cord. This is a very promising health advancement because other
procedures such injecting collagen can bulk up the vocal cords, but the
vibrational ability is still compromised and many cannot talk as well as they
should. Also, with another procedure called atelocollagen sheeting, patients with
vocal fold scarring have an abundantly linked collagen sheeting put on top of their
vocal cords which stimulates healing by recruiting cells from surrounding
tissue. This is was even shown to have problems with rejection in the patient.
These new vocal cords grown at the University of Wisconsin-School of Medicine
were placed in mice for up to three months, who were modified to have human
immune systems and they were not rejected by the mice. Although this procedure occurring
in humans is far from happening, this is the first step to allowing speech impaired
people the ability to speak once again.
The
news article for growing vocal cords is here: http://news.sciencemag.org/biology/2015/11/scientists-grow-working-vocal-cord-tissue-lab
And
the article for the antelocollagen sheeting: Kishimoto,
Y., Hirano, S., Kojima, T., Kanemaru, S., & Ito, J. (2009, September 1).
Implantation of an Anelocollagen sheet for the treatment of vocal fold scarring
and sulcus vocalis. Annals of Otology, Rhinology, and Laryngology, 118(9),
613-620.
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ReplyDeleteAshley,
ReplyDeleteI think this is a really cool development. It's crazy to see that they are able to regenerate vocal cord cells from the exact same cell types in other individuals, and specifically now, in other species. I found a similar study from Kanemaru et al. from the Koyto University Faculty of Medicine in Japan. They were able to redifferentiate multipotent mesenchymal bone marrow stem cells into vocal cord cells. The redifferentiation process proved to be costly, but such was effective in the long run.
This study's aim makes sense, as the precursors form the same physiological function as the desired result. However, I do have a few questions of hesitation:
1. Unlike those formed from stem cells, which can be taken from the same individual, what are the changes of these regenerated cells face rejection? I know they were able to avoid such by using mice with modified human immune systems, but non-rejection was only measured for a relatively brief time (3 months). Further, modifying immune systems in humans (when we got to that point) would be impractical. Would there be a way to regulate the lack of rejection?
2. Does implanting vocal cord cells from a different specifies lead to different sounds produced upon vibration? If so, is there a way of further modifying the cells so as to replicate a higher level of “normalness”?
I know there is much work to still be done before vocal cord regeneration is a viable treatment. It’s great to see the foundations coming together, but I do feel there are some great hurdles needing to still be addressed.
Great find, Ashley!
Cited Source:
Kanemaru, S., Nakamura, T., Magrufov, A., Hirano, S., Ito, J., & Shimizu, Y. (2003).
Regeneration Of The Vocal Fold Using Autologous Mesenchymal Stem Cells.
The Annals Of Otology, Rhinology, And Laryngology, 112, 915-920.