Exposure to outer space may accelerate aging, new evidence shows

A fascinating batch of new research papers highlight the various health risks associated with long-duration space missions, including troublesome observations related to the aging process and radiation-induced DNA damage.

Space, as we learn, really sucks for us little humans.

Without the gravity that perpetually pulls us down and without a protective atmosphere to shield us from the deadly rays of the sun, we are exposed to a plethora of health risks – things like loss of bone density and muscle mass, problems cardiovascular and neurological and even eye disorders. And it seems that the longer we stay in space, the more severe the impacts. This could throw a serious monkey key in our plans for the conquest of deep space, whether it’s to build bases on the Moon and Mars or to travel to the Outer Solar System and beyond.

Unfortunately, the risks don’t stop there. A gigantic package of 30 research papers was published today in five Cell Press journals, all related to health issues. posed by long-duration space missions. Collectively, these articles represent “the largest data set on space biology and astronaut health effects ever produced,” according to a press release from Colorado State University.

These new studies of astronauts and model organisms have revealed six potentially damaging aspects of long duration spaceflight: oxidative stress (an imbalance of free radicals and antioxidants leading to tissue damage); DNA damage; mitochondrial dysfunction (mitochondria are the powerhouses of our cells); alterations in telomere length; genome changes and epigenome (i.e. gene expression influenced by the environment); and changes to microbiome (the totality of microorganisms living outside and inside our body).

Of these, two in particular caught my attention: telomere length alternations and DNA damage. All six health characteristics listed in the new studies play an important role in our health, but telomeres and DNA damage in particular may be linked to the aging process.

Telomeres are the protective caps located at the ends of chromosomes (threaded structures in the nucleus of cells that carry our genes). Telomeres gradually shorten as a person ages, and large changes in the length of these plugs can be taken as a sign of accelerated aging. and / or an increased risk of developing age-related diseases such as cancer, cardiovascular disease and dementia.

This exposure to space alters the length of telomeres is not a surprise. Before research involving identical twin astronauts Scott and Mark Kelly (Scott spent almost a year in space while his brother remained on the ground) showed that, for Scott, the telomeres of his white blood cells lengthened in space , but they basically got back to normal once. he returned to normal conditions of gravity.

Colorado State University biologist and pioneering twin study veteran Susan Bailey has now co-authored a new paper, published in Cell, in which her team studied 10 other astronauts, all of whom flew on missions. long-term on board. the ISS. And by long-term missions, we usually talk about relay for about six months or more.

Blood samples were taken from the astronauts before and after their stay on the ISS. Just like in the study of twins, longlong term exposure to space caused telomere elongation. In this case, however, the researchers also found that astronauts, in general, had telomeres shorter after their missions. Biologists call it ALT, or alternate telomere lengthening – and it wasn’t something they expected, as is typically seen in cancer cases or in developing embryos. Shockingly, ALT was observed in the 10 astronauts studied.

Now telomere lengthening may look promising when it comes to extended longevity, but as Bailey explained in an email, that shouldn’t be taken as good news.

“Both short and long telomeres are associated with an increased risk of disease,” Bailey said. “Short telomeres are associated with accelerated aging and associated degenerative pathologies such as cardiovascular disease and certain cancers.”

Long telomeres may be associated with longevity, she said, “but they’re also associated with cancer” because mutated cells live longer, which increases the risk. All 10 astronauts exhibited dramatic changes in telomere length over time, but researchers do not yet know the associated health effects.

“Longer telomeres during space flights, rapid shortening on return to Earth,” she summarizes. “And overall, they ended up with shorter telomeres than they started with, ”adding that“ individual differences in response were also observed. “

As to the cause of the wobbly lengths seen in telomeres, Bailey pointed to chronic oxidative stress.

“Acute exposures to ionizing radiation have been shown to cause oxidative stress,” Bailey explained. “In the space radiation environment, chronic exposures are associated with chronic oxidative stress” and telomeres “are very sensitive to oxidative damage”.

As the new research shows, exposure to space results in DNA damage. In particular, scientists have documented chromosomal inversions, which are signatures of radiation exposure. Chromosome inversions occur when “two breaks occur in the same chromosome and the genetic material between the breaks is reversed.” according to at ScienceDirect.

“Consistent with chronic exposure to the space radiation environment, inversions were elevated during space flight for all crew members,” Bailey said. “And increased frequencies of inversions persisted after space flight, which could indicate genome instability and / or clonal hematopoiesis,” which is an increased risk of cancer.

Along-effects of space on long-term health missions will continue to be Bailey’s primary focus, including ongoing investigations into the dynamics of telomere length (how it changes over time) and persistent DNA damage, which in this case involved the chromosome inversions – biomarkers associated with cancer and cardiovascular disease.

To this end, this team will participate in NASA One year mission project, which Bailey says will be called CIPHER. For this project, the team will conduct similar studies, in which they will monitor the dynamics of telomere length and DNA damage in astronauts involved in long-duration missions.

This work is so important, because it could eventually lead to medical interventions that will allow safer long-term missions. The humble tardigrade, for example, can tolerate high doses of radiation. We could eventually find a way to tailor this ability to ourselves. Indeed, in order for us to live and work in space, we will have to become a a little less human.