NASA Twins Study reveals key facts about impact of Space Travel on Human body

NASA has released the results of its Twins
Study. 10 research teams worked for this, and published
the combined summary paper in the Science Magazine. The NASA Twins Study was a 340-day investigation
conducted by NASA’s Human Research Program (HRP). It studied identical twin astronauts — Scott
Kelly and Mark Kelly – while Scott was in space and Mark was on Earth. Scientists conducted a year-long biomedical
study of their health. The Twins Study offered a unique opportunity
for NASA to better understand how long-term spaceflight affects a human body. Because identical twins share the same genetic
makeup, they are physically very similar. Even after Scott landed back on Earth, the
researchers of the Twins Study continued to gather data and analyze the results from their
biomedical investigations. NASA scientiests compared genetic, physiologic
and behavioral changes in the identical twins Scott and Mark Kelly before, during and after
Scott embarked on a one-year mission on the International Space Station from 2015-16. According to this study result, Some biological
functions were not significantly affected by spaceflight. Long-term spaceflight causes more changes
to gene expression than shorter trips, especially to the immune system and DNA repair systems. Scott experienced thickening of the carotid
artery, thickening of the retina, weight loss, shifts in gut microbes, reductions in cognitive
abilities, DNA damage and changes in gene expression, and a lengthening of the ends
of chromosomes called telomeres during the flight. Upon return to Earth, the telomere elongation
was replaced by accelerated shortening and loss, a potentially negative consequence for
cellular health. The study will help scientists better understand
the changes astronauts undergo during long-term spaceflight. It may also help them better treat or prevent
any damage to astronauts’ health caused by prolonged spaceflight, which is especially
important as NASA and other groups prepare for three-year missions to Mars. Given that the majority of the biological
and human health variables remained stable, or returned to baseline, after a 340-day space
mission, these data suggest that human health can be mostly sustained over this duration
of spaceflight. To date, 559 humans have been flown into space,
but long-duration (>300 days) missions are rare. Long-duration missions that will take humans
to Mars and beyond are planned by public and private entities for the 2020s and 2030s;
therefore, comprehensive studies are needed now to assess the impact of long-duration
spaceflight on the human body, brain, and overall physiology. The space environment is made harsh and challenging
by multiple factors, including confinement, isolation, and exposure to environmental stressors
such as microgravity, radiation, and noise. Key results from the NASA Twins Study include
findings related to gene expression changes, immune system response, and telomere dynamics. Other changes noted in the integrated paper
include broken chromosomes rearranging themselves in chromosomal inversions, and a change in
cognitive function. Many of the findings are consistent with data
collected in previous studies, and other research in progress. The telomeres in Scott’s white blood cells,
which are biomarkers of aging at the end of chromosomes, were unexpectedly longer in space
then shorter after his return to Earth with average telomere length returning to normal
six months later. In contrast, his brother’s telomeres remained
stable throughout the entire period. Because telomeres are important for cellular
genomic stability, additional studies on telomere dynamics are planned for future one-year missions
to see whether results are repeatable for long-duration missions. A second key finding is that Scott’s immune
system responded appropriately in space. For example, the flu vaccine administered
in space worked exactly as it does on Earth A third significant finding is the variability
in gene expression. While in space, researchers observed changes
in the expression of Scott’s genes, with the majority returning to normal after six
months on Earth. However, a small percentage of genes related
to the immune system and DNA repair did not return to baseline after his return to Earth.

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