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Muscular mice stay stacked even on the International Space Station

Back in December, a collection of 40 mice (as in rodents, not computer peripherals) was delivered to the International Space Station aboard a SpaceX rocket for a one-month stay. While some of these mice were regular mice, others had been genetically enhanced for extra muscle growth, making them so-called “mighty mice.” The aim of their insertion into the ISS was to aid scientists in better understanding the effects of microgravity on muscle and bone degradation.

Approximately nine months after their trip to the ISS, and eight after their return to Earth, the researchers have now published details of how well the mice retained their muscle mass in microgravity. The answer? Pretty darn well. While the untreated mice lost up 18% of their muscle and bone mass in space, the mighty mice stayed comparable to the mighty mice left on Earth to act as controls at NASA’s Kennedy Space Center.

Even more impressively, a group of regular mice that received mighty mouse treatment on the ISS came back to Earth with much bigger muscles than they left with. The treatment works by blocking proteins, which ordinarily limit muscle mass. This is done via injection.

Ultimately, the goal isn’t to make ultra-muscular space mice, of course. (As much as fans of ‘90s cartoon Biker Mice From Mars might wish otherwise!) Instead, it’s to develop potential therapies that could be used to help human astronauts during prolonged space travel. But it might also turn out to have more Earthbound applications, too.

In an abstract, the researchers — led by Se-Jin Lee of the Jackson Laboratory in Connecticut — write that: “We show that targeting this signaling pathway has significant beneficial effects in protecting against both muscle and bone loss in microgravity, suggesting that this strategy may be effective in preventing or treating muscle and bone loss not only in astronauts on prolonged missions, but also in people with disuse atrophy on Earth, such as in older adults or in individuals who are bedridden or wheelchair-bound from illness.”

However, the researchers note that it could be some time before human trials are carried out. “We’re years away. But that’s how everything is when you go from mouse to human studies,” co-author Emily Germain-Lee of Connecticut Children’s Medical Center told The Associated Press.

A paper describing the work was recently published in the journal Proceedings of the National Academy of Sciences.

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