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Free
Fall
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| NASA's
bioreactor mimics the weightlessness of space, where 3D
tissues grow more naturally. |
NASA scientists have learned important lessons about tissue
growth by cultivating cells in the weightlessness of space.
Researchers first sought to investigate how weightlessness
affects astronauts' bodies. Studies showed that, while tissues
that form sheets like cartilage or skin grow better under
forces, cells destined to be part of a three dimensional structure
perform better in microgravity.
Custom organs-on-demand remain the Holy Grail in tissue
engineering.
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To
mimic weightlessness in earth-bound labs, NASA researchers
designed their own bioreactor, with a rotating cylinder that
keeps the growing cells in perpetual free fall. According
to Naughton, liver tissues develop much more naturally in
microgravity, forming spherical clusters of functioning liver
cells.
Structurally
complex organs like the liver, heart and kidney are still
years off in the future; cultivating an entire organ would
require modeling a highly vascularized natural organ right
down to its microscopic capillaries. Custom organs-on-demand
remain the Holy Grail in tissue engineering.
Life
in 3D
In
December of 2000, nearly 74,000 Americans were waiting for
an organ transplant, according to the United Network for Organ
Sharing (UNOS). These candidates represent just a fraction
of the people who could benefit from a stronger heart, a better
kidney or clearer corneas. But shortages of donor organs means
some people never get off this waiting list.
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| This
lab-grown blood vessel developed in the bioreactor just
as it would in the body. |
"To
develop this technology is to solve the rejection problem,"
Joseph Vacanti.
"Tissue
engineering will revolutionize transplant medicine," agrees
Naughton. In
the meantime, Naughton and her colleagues at Advanced Tissue
are working on a patch that will stimulate vessel growth in
and around diseased hearts. According to Naugton, the patch
could obviate the need to grow entire hearts in the lab.
"People talk about the 'heart-in-a-box,'" says Naughton. "I
hope that's never necessary. I hope we can treat disease early
on so that a person never needs a new heart."
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Photos: NASA; Advanced Tissue Sciences
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