In groundbreaking research, Japanese scientist Teruhiko Wakayama, a professor at the University of Yamanashi's Advanced Biotechnology Centre, along with a team from the Japan Aerospace Space Agency (JAXA), sent frozen mouse embryos on board a rocket to the ISS for the first time in August 2021.
Using a specially designed device, astronauts thawed early-stage embryos and nurtured them for four days on board the space station.
According to a study published in the scientific journal iScience, the researchers stated that the experiment unequivocally showed the negligible impact of gravity.
The embryos cultured under microgravity conditions developed normally into blastocysts, cells that develop into the foetus and placenta, the scientists said.
After analysing the blastocysts that were sent back to their laboratories on Earth, the scientists reported that there were no significant changes in the condition of the DNA and genes.
This is "the first-ever study that shows mammals may be able to thrive in space", the University of Yamanashi and Riken National Research Institute said in a joint statement.
It is "the world's first experiment that cultured early-stage mammalian embryos under complete microgravity of ISS", the statement said.
The scientists said that in the future, it will be crucial to transplant blastocysts cultured in microgravity on board the ISS into mice to observe if they are capable of giving birth successfully.
Such research could be important for future space exploration and colonization missions.