Mighty Mice Can Revolution Human Spaceflight

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There are many risks associated with sending someone into space – this is a completely alien environment where even a small mistake can lead to disaster. Our squishy earth-bound bodies are so unnatural to space that just being in micro gravity can be dangerous long term. The key to securing human space travel may be hidden inside these really fond mice. Scientists have found that blocking a protein in mice makes them resistant to wasting muscles and bones in space. Can humans be next?

The story actually begins 20 years ago when researchers at Johns Hopkins University discovered myostatin, a protein that limits muscle growth. Researchers Si-Jin Lee and Emily Jermaine-Lee showed at the time that deleting the gene made the mouse muscles almost twice as large. They hypothesized that manipulating myostatin could boost muscles in space. Currently, astronauts often have to exercise with resistance devices to prevent impacts. Sending people to Mars with 37 percent Earth’s gravity provides information about SpaceX CEO Elon Musk’s plans.

Lee finally got a chance to do this test with a December cargo run to the International Space Station. Now at the Jackson Laboratory for Genomic Medicine, Lee sent 40 mice to space in the SpaceX CRS-19 mission. Of those mice, 24 were animals with normal controls, and eight were genetically modified to remove the myostatin gene. The remaining eight were treated with a compound that suppressed myostatin and a similar protein called actin A.

The team found that normal mice lost significant muscle and bone mass. For a human, this would make the Earth extremely difficult or impossible. Experimental animals without active myostatin showed significant improvement in muscle and bone. You can see in the image above how large these animals were after several months on the ISS compared to control mice. Giving myostatin inhibitors to mice after returning from space helped them regain muscle.

Lee speculated that this could lead to treatments that help astronauts preserve muscle and bone mass during extended space missions. However, a lot of work has yet to be done. It is not possible to modify the DNA of an astronaut before sending it to space. A molecule that can inhibit myostatin and actin can be extremely helpful, but only after ensuring that it is safe for humans. Such medication can also be helpful in the treatment of muscle wasting, such as muscular dystrophy.

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