If you’ve ever wondered whether freeze-dried sperm can still function after being in space, you’re not alone. In fact, for scientists who are serious about space colonization, sperm viability in space is a huge concern.
Results from a recent study may alleviate some of these worries. Japanese researchers showed that healthy baby mice were born using freeze-dried sperm stored in space. Of course it doesn’t immediately translate to the viability of human sperm, but the results hint at the possibility.
Surviving in the near-weightless environment of space is no easy feat for cells. In space, cosmic radiation is over 100 times more potent than on Earth. This means DNA is much more susceptible to breaking and mutating. Such environments are especially hostile to the sperm and egg, which carry the genetic information to create new life.
To test the long-term effects of space on sperm, researchers stored freeze-dried mouse sperm on the International Space Station for nine months. After that period, the sperm was sent back to Earth, thawed, and used to fertilize female mice.
Surprisingly, the team found that birth rates from these well-traveled sperm were similar to “ground control” mice. The space pups developed into adulthood as normal, and were also able to procreate themselves. As such, fertility seems to be intact, at least for two generations.
But that’s not to say there were no biologic ramifications of being in space for so long. The team showed that sperm DNA did sustain damage, and these alterations likely contributed to the slight differences in the genetic code of the space pups. The team also hypothesized that the DNA damage sustained by the sperm could have been repaired by the egg after fertilization.
"If sperm samples are to be preserved for longer periods in space, then it is likely that DNA damage will increase and exceed the limit of the [egg] oocyte's capacity for repair,” said Sayaka Wakayama, the study’s lead author. "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," he said.
With such promising results, Wakayama and colleagues have their eyes on a space sperm bank. It sounds kooky, but such a repository would, theoretically, preserve the seeds of life in case of unimaginable disasters on Earth.
"Underground storage on the Moon, such as in lava tubes, could be among the best places for prolonged or permanent sperm preservation because of their very low temperatures, protection from space radiation by thick bedrock layers, and complete isolation from any disasters on Earth," the scientists say.
The efforts may be moot, though, if humans can’t get to space or live in space long enough to use such resources.
Additional source: BBC