Mars astronauts can use lettuce to fight one of outer space’s greatest threats

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A special kind of lettuce can help anyone going to Mars stay healthy.

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The year 2030 could mark when humans will finally take their first steps on Mars — according to NASA’s timeline, that is. Elon Musk’s recent estimate falls a year earlier, in 2029. But regardless of when it happens, we know one thing for sure.

Astronauts on Mars will have a long journey through space before them, during which they will be subjected to microgravity for months. These conditions put the pioneers at risk of extensive bone loss. But maybe there is a tasty, crunchy and healthy solution.

On Tuesday, scientists presented their blueprint for a new transgenic lettuce at the spring meeting of the American Chemical Society. It’s similar to the salad ingredient we know and love, but genetically engineered to prevent bone loss — and it can be grown in space. Eating the plant would be like collecting a power-up for a video game that protects against the threats of microgravity.

“It’s a very simple and cost-effective way to make a drug,” Karen McDonald, a chemist at the University of California, Davis and one of the researchers behind the plant, said in a media briefing on Tuesday.

This lettuce produces a bone-stimulating hormone that may help reduce bone loss in space and on Earth.

Kevin Yates

On Earth, our bodies maintain a balance between breaking down minerals in our bones and repairing things to make sure we always get the nutrients we need. However, in microgravity, this equation loses its harmony. Bone mineral breakdown still occurs, but subsequent repairs can’t keep up, leading to loss of overall bone density.

To combat such bone loss in space, astronauts often exercise on their spacecraft. For example, the International Space Station has a bicycle, a treadmill and a special weight lifting device. But in the new study, researchers note there isn’t enough evidence to support that exercise is enough to prevent bone density reduction.

That’s why space explorers also carry syringes of drugs that contain what’s called human parathyroid hormone, or PTH. In short, PTH helps stimulate bone formation – but this therapy has its own drawbacks. It requires you to take injections every day, which is not ideal. With the team’s new lettuce concoction, an astronaut would have to “eat about eight cups of lettuce every day to get the right dose,” Kevin Yates, who is also a chemist at the University of California, Davis, told the media briefing.

Astronaut Steven Hawley runs on a treadmill on the center deck of the space shuttle Columbia. The exercise is part of an experiment to evaluate the treadmill’s vibration isolation system as planned hardware for the International Space Station.


Prepare lettuce for space travel

“We decided to use lettuce because lettuce is a plant grown on the International Space Station,” McDonald says. “It’s also a plant that’s very productive when it comes to producing seeds, so our idea is that if we make a transgenic plant, one seed can generate thousands of seeds.”

And unlike standard astronaut medication, the team’s transgenic lettuce has been synthetically engineered to have a gene that correlates with a small variation of PTH. This variation is a combination of PTH and a protein known as — prepare for a mouthful — the fragment crystallizable domain of a human antibody. In many different ways, Fc helps PTH to thrive in the human body.

Mizuna lettuce grows aboard the ISS before being harvested and frozen for return to Earth.


When the team had their synthetic gene ready to use, they used a common gene coding method to transfer it into the genome of common lettuce, they explained, and then grew lettuce plants from the seeds of the first lettuce, harvested seeds from those plants, and the story continues. To make sure that PTH-Fc successfully enters the plants, they can extract and analyze proteins from the growing lettuce.

“I don’t think we can do deep space exploration with a crew of humans without this kind of technology,” Yates said. “It’s not just the lettuce itself, it’s part of a broader mindset where we’re trying to use whatever resources we have at our disposal, whether it’s on spacecraft, on the moon, or on Mars.”

And space exploration aside, the researchers emphasize that their invention can be given to anyone prone to bone loss. “We need ways to produce therapies in a simple way, and also in a cheaper way, and I think using plants to make therapies, like PTH-Fc, would be very valuable here on Earth,” Yates said. .

Before we get to that point, though, the team stresses that they need to run plenty of other tests first, such as animal studies, clinical trials, drug optimization, and even seeing how the plant fares in a space-like environment. In fact, it hasn’t been tasted by humans yet because of those clinical scientific hurdles.

Still, Yates says, “I hope it’s as tasty as regular lettuce and will be a good break from powdered and dehydrated foods that long-term space travelers would usually eat otherwise.”

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