It is not easy to live and work in space for long periods of time. As NASA's twin study showed, microgravity affects human physiology, followed by a painful transition to normal gravity (just ask Scott Kelly!). Aside from muscle and bone degeneration, there is decreased organ function and cardiovascular health effects, central nervous system and "subtle changes" at the genetic level.
So far, the biggest unanswered question has been what caused this physical impact. After reviewing all of the data from decades of research aboard the International Space Station (ISS), which included the twin study and DNA samples from dozens of astronauts, an international team of researchers concluded that mitochondria could be the driving force behind these changes.
Mitochondria are the tiny membrane-bound organelles that generate most of the chemical energy that drives a cell's biochemical reactions. When this energy production breaks down, many of the body's most important processes and immune functions are threatened. This research shows that it may be this disorder of mitochondrial activity that is behind the health-related hazards astronauts face.
Afshin Beheshti, who was the lead author of the paper, is also a researcher at KBR, an engineering firm that supports NASA's Ames Research Center with contract support. "We found a universal mechanism that explains the kind of changes we see on the body in space and in a place that we did not expect," he said in a recent NASA press release. "Everything is unbalanced and it all starts with the mitochondria."
In addition to the data from the ISS and twin study, the team relied on DNA samples from 59 astronauts as well as the extensive NASA GeneLab database of animal studies at the Ames Research Center. This open source platform is the first of its kind to combine large amounts of data from different areas of biology (i.e. genomics, proteomics, metabolomics, and glycomics, collectively known as "omics").
This data is typically used by researchers to identify biological molecules such as DNA, RNA, proteins, etc. and to characterize and quantify their systematic effects on the structures and functions of organisms. The GeneLab Analysis Working Group was also responsible for enlisting the help of scientists from around the world to collaborate on this study and get the most out of their data.
Valery Boyko, head of the Sample Processing Lab at NASA GeneLab, is setting up an automated liquid handling instrument to quantify the amount of sequencing material in a sample. Credits: NASA / Dominic Hart
The first suggestion that there might be a link between mitochondria and space travel came from research on rodents. Beheshti said:
“When we started comparing tissues from mice that were flown on separate space missions, we found that mitochondrial dysfunction kept popping up. Regardless of whether we were looking at problems in the eyes or in the liver, the same pathways related to mitochondria were the cause of the problem. "
“This is a big step in figuring out how our bodies can live healthily outside of the world. And the good news is that we can already address this problem. We can look at countermeasures and drugs that we are already using for mitochondrial diseases on Earth to see how they might work in space. "
This data was supported by results from the Twins Study, which found changes in Scott Kelly's immune system after spending a year in space aboard the ISS. Blood and urine samples from dozens of astronauts showed further evidence that different cell types have undergone changes that can be attributed to altered mitochondrial activity.
Artist's impression of NASA's deep space transport. Photo credit: NASA
Studies like this are critical to understanding the effects of low gravity on everything from circadian rhythms to cardiovascular changes. With these latest results, biomedical researchers could finally have a starting point to develop possible treatments and mitigation strategies. You will also play an important role in the burgeoning field of space biology, which studies everything from astronaut health to plant and animal health.
Combined with research examining the effects of radiation, confined spaces, and other factors affecting physical and mental health, these studies are essential to NASA's plans to visit the moon and astronauts this and next decade to send back to Mars. They are also essential to the many, many plans for advanced missions into space.
The study, which describes its results, and was recently published in the journal Cell, is the result of a collaboration between researchers from Queens University Belfast, the Children's Hospital of the Philadelphia Center for Mitochondrial and Epigenomic Medicine, NASA's Ames Research Center, and the Johnson Space Center and several universities and medical research hospitals.
Further reading: NASA, Cell