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Genetically modified lettuce which can be grown in space created to help astronauts reach Mars

Scientists have created a new kind of genetically-modified lettuce which could transform missions to Mars by protecting astronauts against osteoporosis.

The GM lettuce can be grown in space from miniature seeds. It is the same as a typical Earth-grown lettuce, except that it incorporates a human gene.

This produces a hormone that stimulates bone formation, helping restore bones mass lost in microgravity, according University of California researchers.

They have successfully developed the parathyroid hormone (PTH)-containing lettuce on Earth – while normal lettuces have been grown on space on the ISS, suggesting the new plant could be grown on long space mission to Mars and elsewhere.

“Astronauts can carry transgenic (GM) seeds, which are very tiny — you can have a few thousand seeds in a vial about the size of your thumb — and grow them just like regular lettuce,” said Somen Nandi, of the University of California at Davis.

“They could use the plants to synthesize pharmaceuticals, such as PTH, on an as-required basis and then eat the plants,” he said.

Previous studies of astronauts on extended space missions have shown that they lose, on average, more than 1 per cent of their bone mass every month.

At the moment, astronauts on the International Space Station have certain exercise regimens to try to maintain bone mass – but they’re not typically there for more than 6 months.

By contrast, it takes about 10 months to get to Mars, and the astronauts would remain for about a year to study the planet before making the trip home to Earth.

The three-year mission could leave astronauts vulnerable to osteopenia – a condition when your bones lose mass and get weaker – and later, osteoporosis.

And while there is a medication containing a peptide fragment of human parathyroid hormone (PTH) it requires daily injections. As such, it is impractical to transport such large quantities of the medication and syringes and administer it during space missions is impractical.

So the researchers set out to find a way for astronauts to produce it themselves — while also enjoying some tasty greens, which are severely lacking in astronauts’ mostly canned and freeze-dried diets.

The researchers introduced a gene encoding the PTH protein to lettuce by infecting plant cells with Agrobacterium tumefaciens – a species of bacteria used in the lab to transfer genes to plants.

They screened the GM lettuce plants and their progeny for PTH-production. Preliminary results indicate that, on average, the plants ‘express’ about 10 to 12 milligrams of the hormone per kilogram of fresh lettuce.

The researchers estimate that astronauts would need to eat about 380 grams, or about 8 cups, of lettuce a day to get a sufficient dose of the hormone, which they acknowledge is a “pretty big salad.”

“We’re now screening all of these lettuce lines to find the one with the highest PTH expression,” said Karen McDonald, of UC Davis. “We’ve just looked at a few of them so far, and we observed that the average was 10 to 12 mg/kg, but we think we might be able to increase that further. The higher we can boost the expression, the smaller the amount of lettuce that needs to be consumed.”

The team also wants to test how well the transgenic lettuce grows on the International Space Station and whether it produces the same amount of PTH as on Earth.

The special lettuce might also help treat osteopenia in regions here on Earth that lack access to traditional medications.

The researchers haven’t tasted the lettuce yet because its safety hasn’t been established.

However, they anticipate that it will taste very similar to its regular counterpart, like most other GM plants.

Before the GM lettuce can grace astronauts’ plates, though, the researchers must optimize the ‘PTH-expression’ levels, and then they will test the lettuce for its ability to safely prevent bone loss in animal models and human clinical trials.

“I would be very surprised that if, by the time we send astronauts to Mars, plants aren’t being used to produce pharmaceuticals and other beneficial compounds,” said Kevin Yates, of UC Davis.

He presented the research at the American Chemical Society conference. 

Reference: Microsoft Start: Tom Bawden