On a Tuesday back in 2009, the shuttle Discovery was launched into space, delivering supplies, lab gear, and mice to the International Space Station.
Those half dozen mice – including some that were genetically enhanced with a double portion of a bone-building gene – were left on the station as part of a study to figure out why astronauts’ bones break down in the gravity-free world of space, Reuters reports.
They spent 91 days (the longest stay of any rodents in space) in the Mice Drawer System Facility, a habitat developed by Italian aerospace company Thales Alenia Space in Genoa.
The mice came back 3 months later, and this spring… the study findings are in.
The condition of the bones has been likened to osteoporosis, which destroys bone in post-menopausal women in particular. Researchers know it occurs because bone breakdown outpaces replenishment – but they weren’t sure what causes the imbalance.
Different types of bone cells either build bone up or break it down. For weight-bearing bones, breakdown cells become more active when there’s no impact on the bone, such as in microgravity, New Scientist explains.
"Astronauts experience around 20 to 30% bone loss," says study researcher Sara Tavella at the University of Genoa. They exercise and take calcium supplements to limit damage, but it’s very difficult to return the bone to its original state back on Earth.
About half of the mice that were sent into space were genetically modified to produce extra pleiotrophin (PTN), a protein involved in bone development.
Back on Earth, scientists reveal that those mice with extra PTN appear protected from the breakdown of bone. They lost 3% of the volume of their spine – compared with the 41.5% decrease in the control mice.
The study also found that the microgravity-induced bone loss was due to both an increased bone breakdown and a decreased bone deposition – and it suggests that a protein treatment should be investigated for use in astronauts prepping for space.
The findings were published in PLoS ONE last month.
[Via New Scientist]
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