Space travel may prompt cartilage damage, study shows

Mouse sent into orbit returned with significant deterioration. Nick Carne reports.

Mice kept in micro-gravity in a Russian spacecraft for 30 days showed "clear-cut" cartilage damage when they returned.

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Space travel may be bad for your joints, research indicates.

Mice that spent a month aboard a Russian spacecraft showed early signs of cartilage breakdown, suggesting that the reduced biomechanical forces in space impact on the musculoskeletal system.

And while it’s too early to translate their finding to humans, researchers from the Henry Ford Hospital in Detroit, US, say the evidence was “clear-cut”.

"We believe this degradation is due to joint unloading caused by the near lack of gravity in space," says lead author Jamie Fitzgerald, the hospital’s head of musculoskeletal genetics. "If this were to happen to humans, given enough time, it would lead to major joint problems."

With funding from NASA, Fitzgerald and colleagues analysed molecular changes in the cartilage of mice that spent 30 days in animal research enclosures aboard an unmanned Russian Bion-M1 spacecraft in 2013. This included performing tissue stains and gene expression studies on the cartilage. The results were compared to mice observed on Earth during the same period.

Video footage shows the mice floating around in their enclosure during the day, then at night struggling to climb over each other and hang onto the grate inside the enclosure.

Fitzgerald says the resultant cartilage breakdown was consistent with changes associated with osteoarthritis. In comparison, the mice on Earth showed no discernible cartilage degradation.

"When there's no gravity pulling down on the cartilage, it's not able to maintain its structure, its integrity," he says. "On Earth, every time you take a step to walk, you're loading that cartilage. In space, there's very little of that."

With plans to send humans to Mars, NASA is obviously interested to know what precautions it may need to take to protect human knees.

"You may have some payload specialists and experienced pilots who already have some degree of pre-symptomatic cartilage damage at the time of their flight," Fitzgerald says.

"Because cartilage in humans doesn't readily repair, the return to Earth could potentially bring long-term health problems."

The study is published in the journal npg Microgravity.

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