In July 2011, a group of mice aboard the Space Shuttle Atlantis (STS-135) returned to Earth from an approximately 13.5-day mission. Once on Earth, the mice were harvested, their tissues doled out to a myriad of investigators participating in NASA’s Biosopecimen Sharing Program.
Prof. Karen Jonscher, of the University of Colorado’s Anschutz Medical Campus’ Department of Anesthesiology, and her team received liver samples from the space-faring mice.
“The spaceflight environment impacts many physiological systems, resulting in potentially serious consequences, particularly for longer duration space exploration,” she and colleagues wrote in a study published in PLOS ONE Wednesday. “As use of the International Space Station (ISS) is increased, and with the rise of commercial spaceflight and tourism, the systemic effects of microgravity must be carefully investigated to protect human health.”
Hitherto, much research in this area has focused on bone, muscle, brain, and cardiovascular function. However, Jonscher and her team found that after only 13.5 days in space the mice’s livers showed evidence of liver damage. Notably, there was an increase in lipid droplet (fat) accumulation, and a decrease in vitamin A, which is fat-soluble.
“The vitamin A can be metabolized into active lipids that can activate all sorts of transcription factors and metabolic pathways,” Jonscher told R&D Magazine. Primarily, it “can affect how your body, or how your liver metabolizes fat.”
On the ground, such changes are accompanied by inflammation, something the team didn’t see in their space-faring mice group. These markers are indicative of non-alcoholic fatty liver disease and fibrosis. Obesity, high-fat consumption, and alcoholism are contributors to such conditions on Earth, Jonscher said.
For a mice, 13.5 days in space is equivalent to around 1.5 years for humans. That’s not saying that humans in space will be subject to liver degradation.
“We don’t really know how translatable it is to humans,” said Jonscher, noting that the results only indicate that further research is warranted.
“We’re hoping to get funding to do a follow-up study and would love to look certainly at mice that have been up in space longer,” she said.
Additionally, the fact that the mice were harvested back on Earth might have influenced the results. Stress is known to induce lipid accumulation.
“We would like to be able to run our own mouse mission and look at some treatments that might be effective,” she added.
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