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How does a year in space impact the human body?

Researchers from the University of California San Diego School of Medicine examined how a long-term stay in space can affect a human body on a molecular, physiological, and behavioral level via a NASA twin study. The team looked into how space can affect the bodily regulation of proteins and metabolites, and how impact space travel can have on cardiovascular health and vision, among other things.

“This first-of-its-kind investigation has provided clues about how a long duration space flight changes the regulation of molecules in the body and the relationship of these changes with physiological changes in the body due to space flight such as vascular remodeling and vision problems,” said senior author Brinda Rana, PhD, a professor in the Department of Psychiatry at UC San Diego School of Medicine.

She continued, “Not only does the study provide insight into the body’s response to space flight, by simultaneously studying the astronaut’s identical twin brother who served as our ‘ground control,’ we captured an integrated view of the molecular, behavioral and physiological changes experienced by a middle-aged man on Earth over a two-year period.”

Identical twin astronauts Scott and Mark Kelly were studied by 10 teams of investigators while Scott stayed at the International Space Station (ISS) for 342 days in 2015 and 2016, and Mark remained on Earth.

“A primary issue that astronauts have in space is Space-Associated Neuro-ocular Syndrome or SANS,” Rana said. “Many astronauts develop SANS-related vision impairment that may be the result of multiple hits on the vascular system involving microgravity-related fluid shifts, environmental changes, and possibly a genetic predisposition.”

Rana also stated that cardiovascular changes similar to atherosclerosis, an arterial disease, have also been observed in astronauts who have returned home after a long-duration flight. “Both SANS and cardiovascular issues are major physiological hurdles which NASA wants to address before they can embark on longer space flight missions, such as the proposed mission to Mars in the 2030s.”

Biofluid samples were collected and transported from the ISS while Scott was mid-travel. It was difficult to collect enough blood for 10 investigative teams to study, however Rana said researchers put protocols in action to prevent astronaut dehydration.

One such finding from the study, which will be published in Science, was that the teams found Scott exhibited an increase in collagen proteins in his urine while at the ISS compared to his brother at home. This correlates with indications of vascular remodeling during space flight.

“The overall Twins Study demonstrated the resilience and robustness of how a human body can adapt to a multitude of changes induced by the spaceflight environment, such as microgravity, radiation, circadian disruption, elevated CO2, isolation from friends and family and dietary limitations,” Rana said. “The results will serve as a roadmap for future interdisciplinary studies aimed at better understanding potential health risks of long-duration missions and developing personalized countermeasures.”

By Olivia Harvey, Staff Writer

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