One small step for mice, one giant leap for humanity: Scientists are breeding mouse embryos on the International Space Station for the first time, paving the way for human reproduction in space

Hopes for a future human space colony could be a step closer after scientists managed to grow mouse embryos on the International Space Station (ISS) for the first time.

Researchers from the Japan Aerospace Agency and Yamanashi University sent frozen embryos to the ISS, which were then thawed and cultured for four days.

The scientists found that the embryos developed normally in low gravity and showed no signs of DNA damage from radiation.

Their breakthrough is important because it suggests that human reproduction could be possible outside the influence of Earth’s gravity.

“There is a possibility of pregnancy during a future trip to Mars, as the journey there will take more than six months,” said lead author Teruhiko Wakayama of Yamanashi University in Japan.

Researchers sent specially frozen mouse embryos to the ISS to test whether humans might be able to reproduce in space

“We are conducting research to ensure we can have children safely at this time.”

The mouse embryos were carefully removed and frozen to -95°C (-139°F) in laboratories on Earth before being sent to the ISS aboard a Space X rocket in August 2021.

They were placed in a special device to easily thaw the embryos upon arrival.

After a four-day development period, the longest they could survive outside the womb, the cells were chemically preserved and sent back to Earth.

The researchers found that the embryos developed normally into cell types called blastocysts, which go on to develop into the fetus and placenta.

Until now, scientists were unsure whether mammalian embryos could develop properly in weightlessness.

During the early stages of fetal development, embryos develop into two different types of blastocysts: one that forms the placenta and another that forms the fetus.

However, the cells involved in the formation of the fetus always gather in one place, possibly because they are heavier and sink into position.

The concern was that the blastocysts would not be able to sink in weightlessness and fetal formation would be disrupted, if not impossible.

Embryos were collected by scientists on Earth, frozen with liquid nitrogen and sent to the ISS, where they were thawed and grown in weightlessness for four days

Dr. Wakayama said the results show that mammals may one day be able to reproduce in space.

‘Related to [this] “And our results suggest that reproduction by mammals in space is possible,” he added.

In a joint statement, Yamanashi University and the Riken National Research Institute said the experiment “clearly demonstrated that gravity had no significant influence.”

They added that the research is “the first study ever to show that mammals can potentially thrive in space.”

In the future, the researchers want to test whether mouse embryos that have returned from the ISS can be implanted into female mice and produce healthy offspring.

They also want to test whether mouse eggs and sperm sent to the ISS can be used to create viable embryos.

This would provide further information about whether the effects of microgravity and radiation affect mammalian reproductive systems.

However, the scientists say it is unclear whether mammals can give birth in space.

The findings come as part of a broader effort to allow humans to travel further in space and potentially establish permanent colonies.

As part of its Artemis program, NASA plans to send people back to the moon to learn how to live there long-term in preparation for a trip to Mars, sometime in the late 2030s.

Even in microgravity, the mouse embryos were able to divide normally and differentiate into the different cell types required to form an embryo and a placenta

Recently, NASA astronaut Frank Rubio returned to Earth after the longest spaceflight ever by an American.

After spending 371 days in orbit, Rubio was exposed to the harmful effects of weightlessness and space radiation, which can be very damaging during long stays in space.

While an astronaut might be exposed to up to 250 times more radiation on the space station than on Earth, if they traveled to the Moon or Mars they would be exposed to up to 750 times more radiation.

While the mouse embryos showed no signs of radiation damage, the researchers suspect this could be due to the short time in space.

Any future attempts by humans to live or reproduce in space are at great risk of suffering the harmful effects of this radiation.

The new study was published in the journal iScience.