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Free Fall

Photo of NASA bioreactor
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.


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.

Photo of vascular blood vessel
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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