A new study found that freeze-dried mouse sperm preserved on the International Space Station (ISS) for nine months gave rise to healthy mouse pups.
The study suggests that animals, and it’s possible that humans, can one day reproduce safely in space, according to the researchers. The study was published May 22 in the journal PNAS, and researchers noted that the object of the study was to see if sperm experienced extensive DNA damage while in orbit around Earth.
The findings also raise the possibility of a “doomsday vault” for animal or human sperm in space, to help preserve wildlife from catastrophes on Earth, just like Global Seed Vault in Svalbard, Norway, does for plant species.
Freeze-dried mouse sperm allowed healthy mouse pups to be born radiation-free
On the ISS, astronauts receive between 10 to 100 times more radiation that they do on Earth, and studies have found that the parts of the body most sensitive to the exposure are the reproductive organs.
The mouse sperm in space, which was kept in the station for 288 days between 2013 and 2014, had a little more DNA damage when compared to sperm that remained on Earth. However, the scientists noted that it didn’t affect the sperm’s capacity to fertilize eggs back on our planet. They ran tests on the genome of the mouse pups and found that it was totally normal and only had small differences than the pups born from the sperm on Earth.
“We got many healthy offspring from space sperm,” said Teruhiko Wakayama, a biologist at the University of Yamanashi in Japan and lead author of the study, according to The Verge. “Those pups could not have any genetic damage.”
Having children in other planets or space is important for scientists attempting to plan human colonies on Mars or other planets. Discovering how radiation affects reproductive organs is the first step in figuring out if reproduction is possible in outer space. Radiation is the scientists’ primary concern, but another problem is how a fetus would grow in an environment that has no gravity.
Experts are concerned that the new study did not explore the possibilities of mating in space. Dorit Donoviel, an associate professor at the Center for Space Medicine at Baylor University, told The Verge that an ideal experiment would be to have mice mate and deliver a litter of pups in space, as the scientists didn’t even assess whether mating was feasible for mice in zero gravity.
Human reproductive organs can be affected in deep-space
The experiment did not thoroughly analyze the radiation exposure that sperm might experience on a mission to Mars. The two biggest sources of space radiation are highly energized particles from the Sun or deep-space cosmic rays, which are particles traveling near the speed of light that stem from stars within or beyond our galaxy. Our planet is protected from this radiation because of out atmosphere and magnetic field, known as the magnetosphere. The magnetosphere captures or deflects the incoming radiation particles, and the ones that get through are mostly absorbed by our atmosphere.
Since the ISS is outside our atmosphere, it is exposed to doses of radiation particles. The station is still within Earth’s magnetosphere, which provides some protection to the astronauts living there. However, anyone traveling to deep-space sites will be exposed to highly energized particles of radiation that could potentially cause severe DNA damage.
Astronauts on the ISS are protected from a lot of radiation, but they are still counseled about cryopreserving their eggs and sperm, according to Joseph Tash, a professor at the University of Kansas Medical Center who currently studies how space affects male and female reproductive health. Most astronauts return home from lower Earth orbit and find their fertility is just fine, according to Donoviel.
“I’m not surprised this sperm is fine,” said Donoviel, according to The Verge. “We know that astronauts who come back from space have been just fine and have had children normally.”
Animals could be bred in outer space in the future
For the new study, scientists employed in vitro fertilization techniques, using the space and Earth-preserved sperm to produce embryos that were transferred into the mice. The birth rates from the two kinds of samples were comparable.
The scientists believe their findings suggest that DNA damage seen in the space preserved sperm got repaired in the embryos after the in vitro fertilization. They noted that previous studies have found that egg cells have a good potential for repairing damaged DNA. According to the researchers, the study also suggests that healthy animal offspring could be produced using sperm preserved in space.
“If humans live in space for a very long time, then we will want to eat beef steak,” said Wakayama, according to Space.com.
The researchers explained that freeze-dried sperm can be preserved at room temperature for over two years, and in a freezer almost indefinitely.
Source: The Verge