#Muscular space mice could be astronauts’ new secret weapon

Weightlessness makes it pretty hard to push, pull, lift or perform any other sort of athletic task. In less than two weeks of space travel, astronauts can lose up to 20% of their muscle mass as a result.

But the results of a new experiment, which observed how mice bulk up while in orbit, may hold the key to this anatomical quandary, and could potentially be used as an anti-aging means for terrestrial application.

The study, published in the journal Proceedings of the National Academy of Sciences, began with a discovery made two decades ago.

“Back then, we showed that mice in which we deleted the myostatin gene had dramatic increases in muscle mass throughout the body, with individual muscles growing to about twice the normal size,” said Se-Jin Lee, a geneticist at the Jackson Laboratory for Genomic Medicine in Farmington, Connecticut. He and wife Emily Germain-Lee made the discovery in the 1990s, while studying at Johns Hopkins University.

Lee told Space.com, “This immediately suggested the possibility that blocking myostatin might be an effective strategy to combat muscle loss due to a wide range of diseases. This also suggested the possibility that this might be effective for astronauts during extended space travel.”

The pair waited 20 years to put their hypothesis to the test, but “we finally got the opportunity to do so last year,” said Lee, who launched his rodent recruits from NASA’s Kennedy Space Center to the International Space Station aboard SpaceX’s CRS-19 capsule.

Forty mice were bound for space. Eight had their myostatin genes removed; as an alternative, another eight were treated with a molecule that only suppressed both myostatin and activin A, a protein similar to the former. The remaining 24 individuals were were not altered in any way.

As expected, muscle and bone mass in the control specimens notably decreased during their 33-day tour in space, whereas those without the myostatin gene finished the trip with twice as much mass as their counterparts. Researchers observed that these mice had largely retained their pre-flight measurements.

Scientists also found that mice treated with the protein-suppressive molecule experienced “dramatic” gains in both muscle and bone mass while in space. Moreover, the molecule helped a number of mice, who had served as the control in space, to recover more muscle than their untreated counterparts following their return to Earth.

Germain-Lee suggested this method could be just as useful on the ground, for people “who suffer from disuse atrophy as a result of being bedridden, wheelchair-bound or elderly.” However, she insisted more research is needed.

“It is important to remember that these studies were done using mice,” Lee said. “Although mice have very similar physiology to humans, sometimes what we learn from mice does not translate exactly to humans. There is still a lot of work that would need to be done to develop treatments for humans, but we believe that this type of strategy holds great promise.”