According to a study published in Science Advances on June 11, the "space rats" were born as a result of insemination with the sperm of mice that had been freeze-dried and preserved and orbited the planet for nearly 6 years aboard a station International Space.

The sperm, which had been preserved in space for 6 years, were injected into the eggs using the ICSI method, and the embryos developed normally in the laboratory after fertilization with sperm that had been frozen, dried and stored in space.

The researchers say this is good news because the DNA-damaging radiation on the International Space Station is more than 100 times stronger than the radiation found on Earth.

"It is very important to study the effects of space radiation not only on living organisms but also on future generations before the advent of the space age," they wrote in the research paper.

new way

According to a Live Science report, Japanese researchers dried the sperm of mice, a technique that allowed them to keep the sperm at room temperature for more than a year.

Drying enabled the team to cut the costs of launching sperm to the International Space Station in 2013, as they used "light and small" ampoules to store them. Once at the station, the astronauts stored them in a refrigerator at minus 95 degrees Celsius.

Some samples returned to Earth infrequently, and after 9 months, researchers found slightly more damage to sperm DNA and male gamete nucleus than the control reference samples, but fertilization and birth rates were similar, they reported in a study published in 2017.

The freeze-dried sperm showed a "strong tolerance" to space radiation.

The researchers hypothesize that this may be due to a lack of water molecules inside the frozen cells because radiation causes DNA damage through free radicals produced when the active molecules interact with the water molecules inside the cells.

Sperm preserved in space for years were injected into the cytoplasm (Teruhiko Wakayama - Yamanashi University)

Long-term effects study

The researchers examined the samples by using modern instruments that measure the amount of radiation absorbed by the sperm, then tested the amount of DNA damage to the nucleus, and found that long-term storage aboard the International Space Station did not significantly damage its DNA.

After the sperm was rehydrated, they injected it into female mice, and they found that the mice gave birth to 8 healthy hens, showing no differences in gene expression compared to the controls.

According to the study, most studies of the effects of space radiation have been conducted in conditions simulating space, and this presents a challenge because space radiation includes many types of energetic particles - such as the solar wind, solar cosmic rays and galactic cosmic rays - that cannot be reproduced on Earth.

The researchers say that there is no easy way to study the long-term effects of space radiation on biological materials, because it is difficult to send animals or living cells to the International Space Station because they need constant monitoring.

Embryos developed normally in the laboratory after fertilization with dried sperm (Teruhiko Wakayama-University of Yamanashi)

Necessary and important to mankind

After deep space exploration, space radiation may damage the DNA of cells and lead to the inheritance of mutations in the offspring.

As climate change and a potentially horrific future are prompting humans to look beyond the boundaries of our planet and possibly migrate to potential planets or moons to live in space, researchers are trying to understand whether these radiations will damage the DNA of mammals and other animals and make it impossible to reproduce and keep humanity alive life.

If human sperm are similarly resilient in space, and if Earth becomes uninhabitable in the future, then freeze-dried sperm could potentially play an important role in human reproduction in human space colonies.

If this method turns out to be reliable for sperm preservation, then in the distant future, subsurface storage could be for long-term or permanent preservation, the researchers wrote, "These discoveries are necessary and important for humanity to advance in the space age."