• Posted September 8, 2025

Space Travel Accelerates Cellular Aging, Researchers Say

Space travel takes a significant toll on the human body, and a new study reveals that it can speed up the aging of crucial blood and immune cells. 

Researchers from the University of California San Diego found that blood-forming stem cells showed signs of rapid aging after spending just over a month in space.

The study used automated artificial intelligence (AI)-driven imaging on four SpaceX supply missions to the International Space Station (ISS) to track astronauts’ stem cell changes in real time.

The findings were published Sept. 4 in the journal Cell Stem Cell.

For the study, scientists developed a novel “nanobioreactor” technology platform to culture human stem cells in real time in the space environment. The cells were then exposed to space flight for more than a month.

Over that time, researchers found, the fitness and function of the cells got worse, similar to an aging cell in the cosmic world.

“Space is the ultimate stress test for the human body,” said Dr. Catriona Jamieson, director of the Sanford Stem Cell Institute at UC San Diego. 

“These findings are critically important because they show that the stressors of space — like microgravity and cosmic galactic radiation — can accelerate the molecular aging of blood stem cells,” she added in a news release.

The findings build upon previous research, including NASA's groundbreaking Twins Study, which investigated the effects of spaceflight on gene expression and on telomeres, protective structures on chromosomes. 

This new research provides a more detailed look at how these changes occur at a cellular level.

After being in space for 32 to 45 days, the blood stem cells showed several hallmarks of aging. They became overactive, burning through their reserves and losing their ability to rest and regenerate, a key function of stem cells. 

The cells' ability to produce healthy new cells declined. They also showed increased signs of DNA damage and shorter telomeres, the protective caps at the ends of chromosomes. 

Chromosomes are structures made of protein and DNA code, and would unravel and lose proper function without the telomeres keeping them intact, according to the National Human Genome Research Institute. These endcaps, or telomeres, also play a role in cancer.

Further, the study found signs of inflammation and stress within cells’ mitochondria, their energy-producing parts. They also began activating dormant parts of their genetic code, which can harm immune function and increase the risk of disease.

Notably, when the space-exposed cells were brought back to Earth and placed in a healthy environment, some of the damage began to reverse. 

This suggests that it may be possible to develop interventions to protect or even rejuvenate these cells, a key focus of future research.

The findings may have practical applications here on Earth, researchers said. Understanding how spaceflight accelerates aging could provide new insights into the aging process and age-related diseases, such as cancer. 

Researchers plan to continue studying astronauts to try to pinpoint real-time protective health measures during long space missions.

Jamieson added that the challenges of space research have a surprising benefit for science on Earth. 

“Space experiments are so complex that they force you to do better science on the ground,” she said. “What we have learned about cancer from our studies in space is absolutely remarkable.”

More information

The National Aeronautics and Space Administration has more about research on the International Space Station.

SOURCES: University of California San Diego, news release, Aug. 28, 2025; Cell Stem Cell, Sept. 4, 2025