Researchers discover space travel accelerates aging

Spaceflight speeds up the aging of cells which are "vital" to blood and immune system health, say American scientists.

The study, published in the journal Cell Stem Cell, revealed new insights into how space-induced stress can increase the risk of disease during long-duration interstellar travel.

Researchers from the University of California San Diego, Sanford Stem Cell Institute used automated AI-driven stem cell-tracking "nanobioreactor" systems on four SpaceX Commercial Resupply Services missions to the International Space Station (ISS) to track stem cell changes in real time.

The findings show that human hematopoietic stem and progenitor cells, or HSPCs, lost some of their ability to make healthy new cells, became more prone to DNA damage and showed signs of faster aging at the ends of their chromosomes after spaceflight — all signs of accelerated aging.

Professor Catriona Jamieson, director of the Sanford Stem Cell Institute (SSCI), said: "Space is the ultimate stress test for the human body.

“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.

"Understanding these changes not only informs how we protect astronauts during long-duration missions but also helps us model human aging and diseases like cancer here on Earth.

"This is essential knowledge as we enter a new era of commercial space travel and research in low earth orbit."

Previous NASA studies have shown that spaceflight can affect immune function and the length of chromosome ends, known as telomeres.

One landmark, year-long experiment involved astronaut Scott Kelly spending 340 days aboard the ISS while his identical twin, Mark Kelly, remained on Earth.

The NASA Twins Study tracked changes across genetics, physiology, cognition and the microbiome and found altered gene expression, shifts in telomere length and changes in the gut microbiome.

But many of those changes reversed or returned to normal after Scott Kelly returned to Earth.

However, the study did identify some persistent changes - such as increased numbers of short telomeres and disruptions in gene expression - which could be relevant for longer space missions.

The new UC San Diego-led study builds on the findings of the Twins Study and the work of the Space Omics and Medical Atlas group which published 44 scientific papers on aerospace medicine and space biology.

By focusing specifically on HSPCs, the study provides a detailed look at how space triggers molecular aging, something the Twins Study hinted at but could not fully explore at the cellular level.

To conduct the study, researchers developed a novel “nanobioreactor” platform - miniaturised 3D biosensing systems that allowed human stem cells to be cultured in space and monitored with AI-powered imaging tools.

The findings showed that human HSPCs exposed to 32 to 45 days of spaceflight showed "hallmark" features of aging.

Researchers discovered that spaceflight triggers a range of changes in blood-forming stem cells that closely resemble what happens to those cells as we age.

The cells became more active than normal, burning through their reserves and losing the ability to rest and recover - a key trait that allows stem cells to regenerate over time.

Their ability to make healthy new cells declined, while signs of molecular wear-and-tear - such as DNA damage and shorter telomeres - became more pronounced.

The cells also showed signs of inflammation and stress inside their mitochondria - the cell’s energy producers - and began activating hidden sections of the genome that are normally kept quiet to maintain stability.

Such stress responses can impair immune function and increase the risk of diseases, say scientists.

When the space-exposed cells were later placed in a young, healthy environment, some of the damage began to reverse, suggesting it may be possible to rejuvenate aging cells with the right interventions.

The research team say their findings have implications not just for astronaut health, but also for understanding the mechanisms of aging and age-related diseases such as cancer on Earth.

Twyman Clements, president of technology firm Space Tango which was involved in the new research, said: “We're excited this breakthrough work is being published to the wider scientific and space communities.

“Like many accomplishments, this one was a team effort.

"Coupling Space Tango's CubeLab capabilities, specifically the persistent microscopy, has enabled this work and will continue to do so in the future.”

The research team plans to extend the work with additional ISS missions and astronaut-based studies, focusing on real-time monitoring of molecular changes and potential measures to protect human health.

To date, the SSCI has conducted 16 missions to the ISS.

Jamieson added: “Space experiments are so complex that they force you to do better science on the ground.

“Space research has accelerated technological advancements on Earth, making ground-based research easier and more relevant to human health.

"What we have learned about cancer from our studies in space is absolutely remarkable.”