Twin astronaut study revealed long-term impact of spaceflight health


Twin astronaut study revealed long-term impact of spaceflight health

A NASA-coordinated study of twin astronauts has shown that long-range space flights can change an astronaut's genetic expression and pose other health risks, but are likely to be within the limit for humans under stress.

The study published Thursday in the journal Science reported an integrated multisystem analysis of the changes that occurred in American astronaut Scott Kelly during a one-year space flight, compared to his identical twin and fellow astronaut Mark Kelly who remained on Earth.

A group of researchers from 12 American universities collected and analyzed samples over a 27-month period: before, during and after Scott's space mission on the International Space Station.

The findings revealed that Scott's gene expression or body response to the environment changed, although his DNA did not change.

A team at Johns Hopkins University has identified a difference of less than 5 percent in general methylation, a process of chemical changes in gene expression in the white blood cells of twins.

The biggest difference occurred nine months after the space mission, when 79% of Scott's DNA was methylated, compared to Mark's 83%, according to the study.

"In the last six months of the mission, there have been six times more changes in gene expression than in the first half of the mission," said Christopher Mason of Weill Cornell Medicine, who led one of the investigations.

In addition, Scott's changes occurred near the genes involved in immune system responses during his time in space, causing inflammation.

Among its changes, about 7 percent persisted after six months on Earth, according to NASA.

These genetic changes involve chemical "adjustments" in DNA that can influence how a gene is read or expressed, but do not affect the underlying genetic code.

The study also showed that Scott experienced thickening of the carotid artery and retina, weight loss, changes in intestinal microbes, reduced cognitive abilities and increased risks of accelerated aging.

"Given that most biological and human health variables remained stable or returned to the baseline, these data suggest that human health can be maintained primarily during this period of space flight," according to NASA.

But the US space agency said it was necessary to take measures to prevent any damage to astronauts on a planned three-year space voyage to Mars in 2030.

"As we only have two people in our study, we can not say that these changes are due to their own space travel," said Andrew Feinberg, a professor of medicine at Johns Hopkins. "We need more astronaut studies to draw these conclusions."


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