‘Space sperm’ produces healthy mice, could we reproduce in space?

Sperm stored on the International Space Station (ISS) for a nine-month period has successfully been used to give birth to healthy baby mice, indicating that it may possible for humans to have children while flying to other worlds, a team of Japanese researchers announced Monday.

The findings, which were detailed in a Proceedings of the National Academy of Sciences (PNAS) paper that has not yet been released to the public, used freeze-dried sperm samples that had been sent to the ISS in 2013, returned to Earth in 2014, then used to impregnate a mouse via IVF.

According to BBC News and the Associated Press, the sperm’s DNA suffered slight damage due to the intense radiation of space, which is more than 100 times that present on the Earth. Even so, the mother who received it was able to give birth to healthy offspring that grew to adulthood and which experienced no fertility issues of their own, the media outlets reported.

Lead author Sayaka Wakayama of the University of Yamanashi and colleagues called their work a step towards reproducing humans and other mammals using sperm preserved in space and said that it could ultimately make multi-generational missions or off-planet sperm banks possible.

Mice had no genetic damage, some even had their own offspring

According to United Press International, the sperm used in the experiment was stored on the ISS for a total of 288 days, and while its DNA demonstrated more damage than sperm kept on Earth, it was still able to fertilize eggs, and only minor differences in offspring were reported.

As lead author Teruhiko Wakayama, a biologist at the University of Yamanashi, told The Verge in an email, “We got many healthy offspring from space sperm,” and none of the mice who were born from the space sperm demonstrated “any genetic damage” whatsoever. Some of them even went on to have offspring of their own, according to BBC News.

The study authors believe that some of the damage to the sperm’s DNA was repaired by the egg after fertilization but cautioned that if sperm samples were to remain in space for longer periods of time, the amount of damage they suffer may eventually surpass the egg’s ability to repair it.

“If the DNA damage occurring during long-term preservation is found to have a significant effect on offspring, we will need to develop methods to protect sperm samples against space radiation, such as an ice shield,” they wrote. Once all possible issues are resolved or accounted for, the authors said that it could open the door for long-term storage of sperm on or under the moon, which they call ideal due to the low temperatures and protection from space radiation.

Don’t expect to see space babies anytime soon, say experts

However, as Professor Joseph Tash, a NASA-supported physiologist at the University of Kansas Medical Center, told BBC News, the research does not necessarily mean that astronauts will ever be able to have children on long-duration spaceflights – at least, not healthy ones.

“The ISS orbit is within the protection of the Van Allen radiation belt – the magnetic field that diverts most high energy radiation particles from hitting the earth or the ISS,” he explained. On the Moon and in areas further away from Earth, the risk of radiation would be far higher, and in light of “the nine-month gestation for humans,” special “radiation-hardened” facilities would be needed to protect pregnant mothers and their unborn children from harm.

“I’m not surprised this sperm is fine. We know that astronauts who come back from space have been just fine and have had children normally,” Dorit Donoviel, an associate professor at the Baylor University Center for Space Medicine in Houston, Texas, told The Verge.

“No one got pregnant in space and had the baby,” she added. “An ideal experiment would be to really have mice mate and deliver a litter of pups in space, and I don’t even know if the mating is even feasible for mice in zero gravity” – and even if they could, there could be issues with a fetus that develops while in space, due to the affects of gravitational forces on organ formation.


Image credit: Teruhiko Wakayama