NASA astronauts' blood shows signs of DNA mutations due to spaceflight and they must be monitored

Astronauts’ blood can show signs of DNA mutations after a space flight, so their cancer risk should be monitored, a new study shows.

The study involved 14 astronauts from NASA’s Space Shuttle program who flew on shuttle missions lasting an average of 12 days between 1998 and 2001: 85 percent were male and six were on their first mission for the space agency.

The researchers took whole blood samples from the astronauts twice — ten days before spaceflight and on the day of landing — as well as white blood cells taken just once, three days after landing. These samples were placed in a freezer at minus 112 degrees Fahrenheit and left untouched for 20 years.

“Astronauts work in an extreme environment where many factors can lead to somatic mutations, most notably space radiation, meaning there is a risk that these mutations could develop into clonal hematopoiesis,” said the study’s lead author David Goukassian , a professor of cardiology at the Cardiovascular Research Institute at Icahn Mount Sinai in New York, in a statement.

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“Given the growing interest in both commercial spaceflight and space exploration, and the potential health risks from exposure to various harmful factors associated with repeated or long-duration exploratory space missions such as a trip to Mars, we have decided to research, retrospective somatic mutation,” explained Goukassian.

Somatic mutations are those that take place after a person conceives and in cells other than sperm or egg, meaning they cannot be passed on to future generations.

The mutations identified in the study were characterized by the overrepresentation of blood cells derived from a single clone, a process called clonal hematopoiesis. Various blood cancers, including chronic myeloid leukemia, are examples of clonal hematopoiesis.

Scientists used DNA sequencing and bioinformatics analysis to identify 34 mutations in 17 CH driver genes.

The most common mutations occurred in TP3, a gene that produces a tumor-suppressing protein, and in DNMT3A, one of the most commonly mutated genes in acute myeloid leukemia.

Although the mutations were high for the astronauts’ ages, the researchers said they were still below a worrying threshold.

“The presence of these mutations does not necessarily mean that the astronauts will develop cardiovascular disease or cancer, but there is a risk that this could happen over time through sustained and prolonged exposure to the extreme environment of space,” added Goukassian added.

As NASA ramps up its long-delayed Artemis program to bring American boots to the lunar surface for the first time in 50 years, these types of health observations for astronauts will be key to the future success of spaceflight to the Moon, Mars and beyond.

The researchers showed that they can conduct this type of study to study astronauts’ susceptibility to disease without affecting their ability to work. The study was published August 31 in Nature Communications Biology.

They recommend that NASA and its medical team screen astronauts every three to five years and well into their retirement years for somatic mutations and possible clonal expansion or regression — when those types of mutations have the potential to spread.

“What is important now is to conduct retrospective and well-controlled prospective longitudinal studies with large numbers of astronauts to see how this risk evolves with continued exposure, and then correlate that data with their clinical symptoms, imaging and laboratory results compare,” he told Goukassian.

“This will enable us to make informed predictions about which individuals are more likely to develop disease based on the phenomena we observe, and open the door to individualized precision medicine approaches to early intervention and prevention.”

This work comes two months after a study showed that astronauts participating in spaceflights longer than three months can show signs of incomplete bone recovery, even after a full year on Earth.

“The adverse effect of space travel on skeletal tissue can be profound,” reads the opening line of the study.

“We found that the load-bearing bones in most astronauts recovered only partially a year after spaceflight,” Leigh Gabel, assistant professor of kinesiology and lead author of the study, said in a statement.

“This suggests that permanent bone loss due to space travel is roughly equivalent to a decade of age-related bone loss on Earth.”

This study began in 2017 and followed 17 astronauts before and after a space flight for seven years to determine how or not bones recover after longer space flights.

The researchers went to the Johnson Space Center in Houston, Texas, and scanned the astronauts’ wrists and ankles before they took off into space.

One year after returning from a long-term space flight, most astronauts showed incomplete recovery of bone density, strength, and trabecular thickness at the weight-bearing distal tibia.