Mouse sperm survive space to spawn

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 baby mice, researchers report 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 — it’s 100 times more powerful on the International Space Station than on Earth. Those doses might cause damaging genetic mutations in banked eggs and sperm.

To test this, Japanese researchers freeze-dried mouse sperm and sent it up to the ISS, where it spent nine months orbiting the Earth in microgravity. When rehydrated back on Earth, the space sperm did show some evidence of DNA damage compared with earthly sperm, the scientists found.

But when researchers used that sperm to fertilize eggs in the lab that were then injected into female mice, the mice birthed pups at a normal rate. Those babies were healthy and were even 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.