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Freeze-dried mouse sperm remains viable after being in space for almost six YEARS

Freeze-dried mouse sperm remains viable after being on the International Space Station for almost six YEARS – raising hopes for space babies in the near future

  • Study found freeze-dried mouse sperm still viable after nearly six years in space
  • It had long been thought radiation from cosmic rays would damage sperm DNA
  • Researchers in Japan sent mice sperm to International Space Station to test this
  • They found it did not affect sperm DNA or ability to produce healthy ‘space pups’

The idea of babies being born in space might sound more like the work of science fiction.

But it could soon become a reality after a study found freeze-dried mouse sperm remained viable after being on the International Space Station (ISS) for almost six years.

Not only did radiation not affect the sperm’s DNA or its ability to produce healthy ‘space pups’, scientists estimate it could actually be preserved in space for more than 200 years without damage.

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Discovery: A study by researchers in Japan found that freeze-dried mouse sperm remained viable after being on the International Space Station (ISS) for almost six years

'Space pups: The radiation did not affect the sperm's DNA or its ability to produce healthy mice offspring. The sperm were injected into fresh ovary cells back on Earth (pictured)

‘Space pups: The radiation did not affect the sperm’s DNA or its ability to produce healthy mice offspring. The sperm were injected into fresh ovary cells back on Earth (pictured)

HOW DOES RADIATION AFFECT SPERM IN SPACE? 

To test whether radiation irreparably damages sperm, a study dispatched samples of freeze-dried mouse sperm to be stored on the International Space Station for almost six years.

The sperm samples were preserved in small capsules sealed at a temperature of – 22°F (- 30°C). 

Scientists have long thought that exposure to space radiation from solar winds and cosmic rays could damage the DNA of sperm cells and lead to mutations being passed down to offspring. 

However, a study by researchers at the University of Yamanashi in Japan found that long-term space travel did not damage the DNA of the space-preserved samples, compared with the control samples.

Not only did radiation not affect the sperm’s DNA or its ability to produce healthy ‘space pups’, but scientists estimate it could actually be preserved in space for more than 200 years without damage.

‘The space radiation did not affect sperm DNA or fertility after preservation on ISS, and many genetically normal offspring were obtained without reducing the success rate compared to the ground-preserved control,’ researchers at the University of Yamanashi in Japan said. 

The study allays long-held concerns that space radiation exposure could damage the DNA of cells and lead to mutations being passed down to offspring.

A lack of freezers on the ISS has always prevented long-term research into the area, while previous studies on Earth have been unable to replicate space radiation from solar wind and cosmic rays.

To overcome the problem, lead author Sayaka Wakayama and her colleagues freeze-dried sperm samples from 12 mice and sealed them in small capsules, which were then transported to the ISS without the need for a freezer.

Some of the samples were returned to Earth after nine months to confirm the experiment was working, while two more batches remained on the ISS for almost three years or nearly six, respectively.

Once back on Earth, scientists tested to see how much radiation the samples had absorbed, while also examining if there had been damage to the sperm nuclei. 

They found that the stint in space, whether three years or six, did not lead to DNA damage to the freeze-dried sperm.

Researchers also rehydrated the sperm cells, injected them into fresh ovary cells, and transferred these to female mice, resulting in the birth of healthy pups. 

Using RNA sequencing, they determined that there were no gene expression differences between the ‘space pups’ and controls born from sperm preserved on Earth.

Frozen: Scientists freeze-dried sperm samples from 12 mice and sealed them in small capsules (pictured) at - 22°F (- 30°C). They were transported to the ISS without the need for a freezer

Frozen: Scientists freeze-dried sperm samples from 12 mice and sealed them in small capsules (pictured) at – 22°F (- 30°C). They were transported to the ISS without the need for a freezer

Researchers injected the sperm cells into fresh ovary cells, and transferred these to female mice, resulting in the birth of healthy pups. This picture shows the embryos from the sperm

Researchers injected the sperm cells into fresh ovary cells, and transferred these to female mice, resulting in the birth of healthy pups. This picture shows the embryos from the sperm

In orbit: The International Space Station is a $100 billion (£80 billion) science and engineering laboratory that orbits 250 miles (400 km) above Earth

In orbit: The International Space Station is a $100 billion (£80 billion) science and engineering laboratory that orbits 250 miles (400 km) above Earth

‘We obtained many healthy “space pup” offspring from space-preserved spermatozoa with the same success rate as the ground controls,’ the authors said.

‘These space pups did not show any differences compared to the ground control pups, and their next generation also had no abnormalities.’

Looking ahead to the future, Wakayama and her colleagues said research such as theirs was ‘important for mankind to progress into the space age’.

They suggested that in the far future underground storage on the moon, such as in lava tubes, could be one of the best places to preserve sperm for prolonged periods because of the protection from space radiation and any disasters on Earth. 

‘In the future, when the time comes to migrate to other planets, we will need to maintain the diversity of genetic resources, not only for humans but also for pets and domestic animals,’ the authors said.

‘For cost and safety reasons, it is likely that stored germ cells will be transported by spaceships rather than by living animals.’

The study is published in the journal Science Advances.

EXPLAINED: THE $100 BILLION INTERNATIONAL SPACE STATION SITS 250 MILES ABOVE THE EARTH

The International Space Station (ISS) is a $100 billion (£80 billion) science and engineering laboratory that orbits 250 miles (400 km) above Earth.

It has been permanently staffed by rotating crews of astronauts and cosmonauts since November 2000. 

Research conducted aboard the ISS often requires one or more of the unusual conditions present in low Earth orbit, such as low-gravity or oxygen.

ISS studies have investigated human research, space medicine, life sciences, physical sciences, astronomy and meteorology.

The US space agency, Nasa, spends about $3 billion (£2.4 billion) a year on the space station program, a level of funding that is endorsed by the Trump administration and Congress.

A U.S. House of Representatives committee that oversees Nasa has begun looking at whether to extend the program beyond 2024.

Alternatively the money could be used to speed up planned human space initiatives to the moon and Mars.

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