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NASA’s historic twin study studied identical twin astronauts Scott and Mark Kelly and provided new insight into the health effects of spending time in space.
Professor Susan Bailey of Colorado State University was one of more than 80 scientists from 12 universities who conducted research on the textbook experiment; Mark remained on Earth while Scott orbited high for nearly a year. The massive effort was coordinated by NASA’s Human Research Program.
Bailey has continued his research on NASA and now joins more than 200 researchers from dozens of academic, government, aerospace and industrial groups to publish a package of 30 scientific articles in five Cell Press journals on November 25.
Jared Luxton, who recently earned his doctorate in cell and molecular biology from CSU, is the first author of two studies. He is now a data scientist with the United States Department of Agriculture in Fort Collins.
The research – including a general paper covering what investigators have learned about the fundamental characteristics of space flight – represents the largest dataset on space biology and the health effects of astronauts ever produced.
For Bailey, it is also a milestone that marks many years of work with NASA, which included her leading role in basic radiation studies and the honor of being selected as a researcher for the Twins Study and simultaneous research projects that involve astronauts. During this time, several graduate students in his lab earned PhDs under his leadership.
We now have a foundation to build on: things we know to look for in future astronauts, including changes in telomere length and responses to DNA damage. Moving forward, our goal is to get a better idea of the underlying mechanisms, what is happening during long-duration spaceflight in the human body, and how it varies between people. Not everyone responds the same. This was one of the positive aspects of having the largest cohort of astronauts in these studies. “
Professor Susan Bailey, Colorado State University
Studying the ends of chromosomes, with implications for aging
Bailey is an expert on telomere and radiation-induced DNA damage, areas of research that were of great interest around the world when the twin study was published. In that study, she and her team found that Scott’s telomeres in his white blood cells lengthened while they were in space and subsequently returned to near-normal length after he returned to Earth.
Telomeres are protective “caps” at the ends of chromosomes that shorten with aging. Large changes in telomere length could mean that a person is at risk for accelerated aging or diseases that accompany aging, cardiovascular disease and cancer, for example.
In the latest research, Bailey, Luxton, Senior Research Associate Lynn Taylor and the team studied a group of 10 unrelated astronauts, including CSU alum Dr. Kjell Lindgren, comparing the results with the Kelly twins’ results. The researchers didn’t have access to the in-flight blood and other samples for all crew members, but Bailey said they had blood samples before and after the space flight for everyone.
The investigations involved astronauts who spent about six months on the International Space Station in low earth orbit, protected from some space radiation. Despite the protection, the scientists found evidence of DNA damage that could be warning signs of potential health effects.
New discovery of oxidative stress
Among the new findings, the research team found that chronic oxidative stress during space flight contributed to the elongation of the telomeres they observed. They also found that astronauts in general had shorter telomeres after spaceflight than before. The team also observed individual differences in responses.
To get more information on these findings, Bailey’s team also studied two twin climbers who climbed Mt. Everest, an extreme environment on Earth. The non-climber twins remained at a lower altitude, including in Boulder, Colorado. Surprisingly, the team found similar evidence of oxidative stress and changes in telomere length in climbers.
Christopher Mason, associate professor at Weill Cornell Medicine and co-author with Bailey, performed gene expression analyzes on Mt. Everest climbers. It found evidence of a telomerase-independent, recombination-based telomere length maintenance pathway known to result in longer telomeres.
Bailey said that when chronic oxidative stress occurs, it damages telomeres.
“Normal blood cells are dying and trying to survive,” he said. “They are adapting to their new environment. Some cells will activate an alternate pathway to keep their telomeres active. It is similar to what happens with some tumors. Some cells emerge from that process. This is what we think we see during space flight.” .
Luxton said the mechanism described above – known as alternative telomere lengthening, or ALT – was an unexpected discovery.
“You usually see it in cancer or in developing embryos,” he said.
Take care of your telomeres
Similar to the Twins Study conclusions, Bailey said the new findings have implications for future space travelers establishing a base on the Moon or traveling to Mars, or even as a space tourist. Long-duration exploration missions will result in increased time and distance outside of Earth’s protection.
Although longer telomeres in space may seem like a good thing, perhaps even a “fountain of youth,” the scientist said she suspects a somewhat different ending to the story.
“The extended lifespan, or immortality, of cells that have sustained DNA damage induced by space radiation, such as chromosome reversals, is a recipe for increased cancer risk,” he said.
Bailey said she and the team observed a higher frequency of reversals in all crew members, during and after the space flight.
“Telomeres really reflect our lifestyles, both on and off the planet,” Bailey said. “Our choices make a difference in how fast or how well we are aging. It is important to take care of your telomeres.”
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Colorado State University
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