Mouse sperm survive space to fertilize eggs

Mouse sperm could win awards for resilience. Sperm freeze-dried and sent into space for months of exposure to high levels of solar radiation later produced healthy babies, researchers report online May 22 in Proceedings of the National Academy of Sciences.

If humans ever embark on long-term space flights, we’ll need a way to reproduce. One potential hurdle (beyond the logistical challenges of microgravity) is the high amount of solar radiation in space — radiation exposure is 100 times as high on the International Space Station as on Earth. Those doses might cause damaging genetic mutations in banked eggs and sperm.
To test this possibility, Japanese researchers sent freeze-dried mouse sperm up to the space station, where the sperm spent nine months. When rehydrated back on Earth, the sperm showed some signs of DNA damage compared with earthly sperm.

But when the researchers used the space sperm to fertilize eggs in the lab and then injected the eggs into female mice, the mice birthed healthy pups that were able to have their own offspring. The researchers suspect that some of the initial DNA damage might have been repaired after fertilization.

If mouse sperm can survive a trip to space, perhaps human sperm can, too.