A week in the microgravity of space ages muscle cells so that their genetic activity looks similar to Earth-bound cells that have been ageing for years. This finding could explain why spending time in space impairs muscle function.
We know that astronauts are at risk of losing bone density and muscle mass due to extremely low gravity in space. Now, at Stanford University in California and her colleagues have analysed the effects of microgravity on muscle cell genetics.
The researchers grew human muscle cells within a scaffold made from collagen fibres 鈥� this directed the cells to assume the same structure as they would in the body. They packaged the cells on a chip that could withstand flight and sent it to the International Space Station (ISS) for a week.
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When the cells returned to Earth, the researchers found higher activity in genes associated with fat formation, which is linked to muscle degradation. They also found that the gene expression related to functioning of the muscle cells鈥� mitochondria, which produce energy inside cells, was compromised.
鈥淚t seems that microgravity is an environment that is accelerating ageing,鈥� says Huang.
These changes are more similar to what happens in sarcopenia, or age-related muscle atrophy, than in muscle loss that occurs due to diminished activity, says Huang. While the cells were aboard the ISS, astronauts added drugs that can potentially stimulate muscle growth to some of the cells. The genetic activity of those cells was less affected by the microgravity.
This study may inform how space tourists, as well as astronauts on long missions, prepare for future trips 鈥� the effects of microgravity could potentially be mitigated by exercising or taking tailored cocktails of drugs. The findings could also be useful for studying ageing more broadly, says Huang. For instance, researchers could mimic microgravity in the lab to speed up the simulation of sarcopenia-like conditions in cells and more quickly test treatments, which are largely experimental at this point, she says.
Stem Cell Reports
Article amended on 26 July 2024
We clarified the type of drug used in experiments on the ISS
