Experiments on the International Space Station reveal the risks of future human spaceflight

An international team of researchers conducted a long-term experiment on the International Space Station to test the effects of
space radiation on mouse embryonic stem cells.
Their findings will help scientists better assess the safety and risks
associated with space radiation in future human spaceflight.

The team published their findings in the journal Heliyon on August 18,
2022.

In their study, the team launched frozen mouse embryonic stem cells from the ground to the International Space Station, exposed them to space radiation for more than 4 years, and quantified the biological effects by examining chromosomal aberrations, allowing a direct quantitative measurement
of the biological effects of space radiation.
Their experimental results show for the first time that the actual biological effects of space radiation are very consistent
with earlier predictions based on physical measurements of space radiation.

Ordinary people can now travel in space, and the possibility of long-term manned flights to deep space, such as to the moon and Mars, is increasing
.
However, space radiation remains a limiting factor
for manned exploration.
Scientists have been conducting intensive studies to measure the physical dose of space radiation in order to better understand its effects
on the human body.
However, since most studies so far have been conducted on the ground, rather than in space, there is uncertainty
about the results considering that space radiation is composed of particles of many different energies and astronauts are continuously exposed to low dose rates.
The actual spatial environment cannot be accurately reproduced
on the ground.

"Our research aims to address the shortcomings
of previous ground experiments by making a direct quantitative measurement of the biological effects of space radiation on the ISS and comparing this real biological effect with physical estimates in ground experiments," said Takashi Morita, a professor at Osaka City University's Graduate School of Medicine.
" "These findings help reduce uncertainty
in human spaceflight risk assessment.
"

The team prepared about 1,500 cryogenic test tubes, which contained highly radioactively-sensitized mouse embryonic stem cells, and sent them into space
.
The scope of their research was complex, taking 7 years before launch, 4 years after launch, and 5 years for analysis
.
Professor Morita said, "Although it was difficult to prepare experiments and interpret the results, we succeeded in obtaining quantitative results related to space radiation, reaching our original goal
.
"

Going forward, the researchers hope their research will go further
.
Professor Morita said: "Considering that human cells are better suited for human risk assessment and easier to analyze chromosomal aberrations, we are considering using human embryonic stem cells instead of mouse embryonic stem cells
in future work.
" Future research may also include firing individual mice or other laboratory animals to analyze their chromosomal aberrations
in space.
Professor Morita concluded: "Such deep space experiments could further contribute to reducing uncertainty
in risk assessment for long-term human travel and stays in space.
"

The research team included Yoshio Yoshida, Kizugan, Mitsuhei Kitada and Takashi Morita from Osaka City University; Megumi Hada and Premkumar Saganti from Prairie View A&M University Kiyomi Eguchi-Kasai and Toshiaki Kokubo, from the National Institute of Quantum Science and Technology; Takeshi Teramura, Kindai University; Sachiko Yano and Aiko Nagamatsu from the Japan Aerospace Exploration Agency (JAXA); Hiromi Hashizume Suzuki, from the Japan Space Forum (JSF); Hitomi Watanabe and Gen Kondoh from Kyoto University; and Francis A.
Cucinotta
from the University of Nevada.

JAXA, JSF and Japan's Ministry of Education, Culture, Sports, Science and Technology funded the research
.

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established by the merger of Osaka City University and Osaka Prefectural University in April 2022.
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