After 9 months in space, mouse sperm yield healthy mice

If humanity wants to expand into space, sooner or later we are going to need to start having children away from Earth. But anyone traveling to deep-space destinations will be exposed to highly energized particles that can potentially cause a lot more severe DNA damage.

Now, a new study shows that mouse sperm stored for more than 9 months on the International Space Station (ISS)-where radiation levels are roughly 100 times higher than on Earth-can produce healthy, fertile mouse pups.

The scientists detailed their findings online today (May 22) in the journal Proceedings of the National Academy of Sciences. Subsequent whole genome analysis revealed only minor differences, and the pups developed into adults with normal fertility.

The researchers found evidence that space-preserved sperm did experience slightly more DNA damage than Earth-preserved samples.

The fact that the DNA damage didn't end up harming the space pups suggests that whatever damage was incurred by the extra radiation levels aboard the ISS was somehow repaired after fertilisation, at some point during the embryonic stage. Previous studies involving other animals such as sea urchins, fish, amphibians and birds have concluded that it doesn't hamper reproduction.

As the researchers argue, this is good news for any serious efforts to expand into space long-term.

We are starting to consider space colonisation more seriously, but there are still big questions about the viability of human reproduction off Earth. When the sperm were injected into the eggs of female mice, those mice successfully became pregnant and went on to give birth to offspring at the same rate as mice implanted with freeze-dried sperm that had not been in space.

Mammals are more hard to maintain and handle in space so testing has been limited. Considering the current technological limit for sperm preservation is only about two years, this seems fine - for now, anyway.

To address this, Teruhiko Wakayama at the University of Yamanashi in Japan and his colleagues sent freeze-dried sperm from 12 male mice to the International Space Station (ISS) in August 2013.

"The objective of our study is to demonstrate that there is a possibility to breed these domestic animals in space", the study's lead author Teruhiko Wakayama, from the University of Yamanashi (Japan) told IBTimes UK.

"I'm not surprised this sperm is fine", said Donoviel, according to The Verge. Yet, following in vitro fertilization on the ground, healthy offspring resulted.

Prof Joseph Tash, a Nasa-supported physiologist at the University of Kansas Medical Center, said although the latest findings were interesting, the ISS was a somewhat sheltered environment to use as the test zone for space. "There are much higher risks in deep space".

He said the feasibility of mammalian reproduction in space beyond the Van Allen belts would depend on the creation of radiation-hardened facilities that could protect gametes from low energy and space radiation exposure. That's the first time such an experiment has been done for any mammalian species, Wakayama says. The slight damage from radiation had no impact on the birth for or normality of the babies because it was mostly repaired while the embryos were developing, the study said.

  • Carolyn Briggs