Twins study shows how space alters human body

James Marshall
April 14, 2019

What actually happened was that roughly 7 percent of his DNA had changed expression during his time in space.

Results of NASA's Twins Study.

Physiological measurements, immune, cardiovascular, vision-related, and cognitive data were collected from Mark and Scott for 27 months. The twin study is unique: more than 550 people are on the whole already been to space, but only eight missions lasted more than 300 days.

The twins involved in the study were astronaut Scott Kelly, who flew a year-long mission aboard the International Space Station which ended in March 2016, and his twin brother, Mark Kelly, also an astronaut, who stayed on Earth while his brother was in orbit.

But in an interview with The Washington Post, Scott Kelly, now 55, said that after landing he suffered flulike symptoms and felt bad for many weeks, and that altered his cognitive performance.

"The "Twins Study" has been an important step toward understanding epigenetics and gene expression in human spaceflight", said J.D. Polk, chief Health and Medical Officer at NASA Headquarters, in a statement.

Key results from the NASA Twins Study include findings related to gene expression changes, immune system response, and telomere dynamics.

Persistent changes were observed in a few other areas, including some cognitive function.

"This should be taken in context, however, of the fact that this is a study of a single individual in low Earth orbit, and future studies are needed to confirm this finding", he continued.

Scott's telomeres noticeably increased in length in space (by 14.5 percent) but these changes weren't long-lasting and they returned to pre-flight measures within two days of his return to Earth. Six months later, the length returned to average; Mark Kelly's telomere length remained stable through the same period of time. 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. For example, the flu vaccine administered in space worked exactly as it does on Earth.

Telomeres can be thought of as the protective caps at the end of our DNA strands that protect the ends from degrading and stop DNA from producing inappropriate responses to damage, which can lead to development of cancerous cells. These findings help demonstrate how a human body was able to adapt to the extreme environment of space and help researchers better understand how environmental stressors influence the activity of different genes, leading to a better understanding of physiological processes in space.

GREENE: All right. Some other findings - Scott Kelly's gene expression changed, and his immune system went into high alert.

The exception involved "a small percentage" of genes related to DNA fix and the immune system, which didn't return to baseline after Kelly's time in space ended. This needs to be clarified in further studies, to develop strategies against it. But the report shows anew that the human body is adapted for life on the surface of Earth and goes haywire in zero gravity.

What researchers discovered is pretty reassuring for near-Earth space travel - while Scott's body did undergo some changes compared with Mark, things went back pretty much to normal once he returned home. "The data captured from integrated investigations like the NASA Twins Study will be explored for years to come".

Specifically, researchers examined two types of white blood cells (CD4+ and CD8+) isolated from Mark and Scott's blood. They focused on any variations that could show how Scott's time in space affected him physically. Principal investigators at NASA and at research universities across the nation initiated an unprecedented sharing of data and discovery.

The study included the work of 84 scientists, part of 10 teams from 12 universities across the United States. While significant, it is hard to draw conclusions for all humans or future astronauts from a single test subject in the spaceflight environment.

Other reports by Click Lancashire

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