While billionaires like Jeff Bezos and Elon Musk vying to shoot themselves into space, scientists have been busy pushing freeze-dried mouse semen through the stars.
In new research published Friday in Science Advances, researchers studying the effects of space radiation on reproduction reported that freeze-dried mouse semen weathered a nearly six-year journey on the International Space Station without any damage and could eventually last for 200 years. years in space. The finding may not be immediately applicable to civilians watching a trip to space, but scientists believe it could be a springboard for understanding the risks of reproduction if humans ever colonize Mars, as SpaceX CEO Elon Musk plans to do before year 2050.
“I read a lot of science fiction books,”
Space radiation is one of the five biggest health hazards that humans face from the planet, especially for its potential to cause cancer, cardiovascular disease and cognitive problems. For the short-term exploration missions that astronauts typically embark on today, the doses of space radiation to which they are exposed are likely too low to cause reproductive problems.
“But as we move from space exploration to things like colony building and prolonged stay in space, doses from space radiation will accumulate, and these can manifest as fertility and reproductive decline,” said Zarana Patel, a senior researcher with the technology. and engineering company KBR, Inc. and contractor for NASA’s Human Research Program, which was not involved in the study.
Most studies of space radiation and its biological effects to date have taken place, counterintuitively, on Earth. Astronauts are busy people who do not always have time to perform complicated or advanced experiments, and there is not always much space in space. Live animals or cell cultures that require regular maintenance, especially samples such as semen to be stored in freezers, are not stored at the space station for long periods. Yet it is difficult to reproduce the full force of space’s radioactive ions, which differ from radiation on Earth.
“To learn about space biology, we need to perform real space experiments,” Wakayama said.
So in 2013, Wakayama and his team sent 12 freeze-dried sperm samples, which can be stored at room temperature, up to the International Space Station to investigate the long-term effects of space radiation on reproduction. The first sperm samples were returned to Earth after only nine months to ensure that everything was intact and functioning properly. Several samples returned after nearly three years, and the final samples were retrieved after nearly six years in space.
The returned semen was thawed and evaluated for DNA damage before being used to produce two generations of “rumunger”. There were small differences in the conservation of DNA and the number of offspring produced between 3-year-old and 6-year-old sperm, but they were both small enough for researchers to conclude that space radiation did not cause damage. Healthy mice were born from each set of lyophilized samples. Wakayama also analyzed the gene expression of each generation and found no difference between the ruminants and the control group produced with fresh semen.
Experts say it is a new discovery, although there are reservations that make it difficult to draw conclusions about its relevance to humans.
The International Space Station orbits the Earth’s gravitational field, which means that radiation is not as strong as it would be in deep space or on Mars. And the sperm actually strengthen against space radiation in the freeze-drying process, according to the researchers, who also performed experiments on the ground to observe the effects of the freeze-drying process.
In addition, the study looked only at mature sperm, but researchers have known for decades that radiation affects the entire sperm development process. And when the sperm landed back on the ground to be thawed, rehydrated and used to fertilize female cells, the study used only one type of female mouse.
“It’s the diversity of a woman’s ability to repair sperm damage that is most important,” said Andrew Wyrobek, a senior researcher at the Lawrence Berkeley National Laboratory who has studied radiation and the reproductive system since 1975, who was not involved in the study. .
In the short term, experts said the study could bring the necessary attention to the potential dangers of space radiation to the reproductive system. Mars must be explored before the farms are built, and such a mission could take two or three years, said Ulrike Luderer, director of the Center for Occupational and Environmental Health at the University of California, Irvine, who was also not involved in the study. To prepare, experts say there is a need for an integrated approach to earth and space research, as both have limitations.
“It’s a small, very elite population of people, but nonetheless, it is people who will be exposed to these dangers,” Luderer said.
While more research is needed to learn the true dangers of space radiation for human reproductive systems, Wakayama hopes the new study can prove that if humans one day move to Mars, other mammals can be brought in through freeze-dried reproductive cells.
“I think our research findings will give the average person a sense of security around space,” Wakayama said.
When the freeze-dried semen was first launched into space in 2013, Wakayama and his team had been working on the proposal and preparation for four years. At the launch, the whole team cried with joy. Wakayama took a video that day and plays it regularly for students.
“I think I’ve seen the movie more than 100 times, but still every time it makes me cry.”