Scientists have created a new kind genetically modified salad that could transform missions to Mars by protecting astronauts from osteoporosis.
GM salad can be grown in space from miniature seeds. It is the same as a typical soil-grown lettuce, except that it incorporates a human gene.
This produces a hormone that stimulates bone formation and helps restore bone mass lost in micro-gravity, according to researchers from the University of California.
They have successfully developed the parathyroid hormone (PTH) -containing lettuce on Earth – while normal lettuce has been grown in space on the ISS, suggesting that the new plant could be grown on a long space mission to Mars and elsewhere.
“Astronauts can carry transgenic (GM) seeds, which are very small – you can have a few thousand seeds in a thumb-sized vial – and grow them like regular lettuce,” said Somen Nandi, of the University of California at Davis.
“They could use the plants to synthesize drugs, such as PTH, as needed and then eat the plants,” he said.
Previous studies of astronauts on longer-term space missions have shown that, on average, they lose more than 1 percent of their bone mass each month.
Currently, astronauts on the International Space Station have certain training regimes to try to maintain bone mass – but they are typically not there for more than 6 months.
In contrast, it takes about 10 months to get to Mars, and the astronauts would stay for about a year to study the planet before taking the trip home to Earth.
The three-year mission can leave astronauts vulnerable to osteopenia – a condition in which your bones lose mass and become weaker – and later osteoporosis.
And although there is a drug that contains a peptide fragment of human parathyroid hormone (PTH), it requires daily injections. As such, it is impractical to transport such large amounts of medicine and syringes and administer it during space missions is impractical.
So scientists set out to find a way for astronauts to produce it themselves – while also enjoying some tasty vegetables that are severely deficient in astronauts’ mostly canned and freeze-dried diets.
The researchers introduced a gene that encodes the PTH protein into lettuce by infecting plant cells with Agrobacterium tumefaciens – a bacterial species used in the laboratory to transfer genes to plants.
They screened the GM lettuce plants and their offspring for PTH production. Preliminary results show that the plants on average ‘express’ about 10 to 12 milligrams of the hormone per kilograms of fresh salad.
The scientists estimate that astronauts need to eat about 380 grams, or about 8 cups, of salad a day to get an adequate dose of the hormone, which they recognize is a “fairly large salad.”
“We are now screening all of these salad lines to find the one with the highest PTH expression,” said Karen McDonald of UC Davis. “We’ve just looked at a couple 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 it further. The higher we can boost the expression, the smaller the amount of lettuce to be consumed. ”
The team will also 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 salad can also help treat osteopenia in areas here on Earth that lack access to traditional medicine.
The researchers have not tasted the salad yet because its safety has not been established.
However, they expect it to taste very similar to its regular counterpart, just like most other GM plants.
Before the GM salad can adorn astronauts’ plates, however, scientists must optimize ‘PTH expression’ levels, and then test the salad for its ability to safely prevent bone loss in animal models and clinical trials in humans.
“I would be very surprised that if when we send astronauts to Mars, plants will not be used to produce drugs and other beneficial compounds,” said Kevin Yates, of UC Davis.
He presented the research at the American Chemical Society conference.