Blood-producing stem cells, known as hematopoietic stem cells (HSCs), function best when they’re stable and well-rested—like managers keeping a factory running smoothly. But when the body faces stress, such as infection or injury, these cells quickly ramp up production of immune cells to defend against threats. Over time, repeated stress wears them down, causing them to age more rapidly and lose efficiency.
The Spaceflight Challenge
Now, imagine putting those “managers” in space. In low Earth orbit (LEO), gravity disappears, radiation levels rise, and biology itself starts to shift. NASA’s Twins Study revealed that astronauts spending nearly a year in orbit showed changes in telomeres, increased chromosomal instability, and heightened activity of inflammatory signals.
Although microgravity’s effects on immunity were already known, little was understood about how spaceflight impacts the stem cells that generate immune defenses. To answer this, the University of California San Diego’s Sanford Stem Cell Institute joined forces with NASA and Space Tango to launch the Integrated Space Stem Cell Orbital Research (ISSCOR) center. Their research examined how LEO conditions influence the health and aging of human blood-forming stem cells (HSPCs) across four SpaceX supply missions to the International Space Station (ISS).
Nanobioreactors and Real-Time Monitoring
For the experiments, the team engineered bone marrow niche nanobioreactors inside AI-driven CubeLabs, enabling real-time monitoring of HSPCs in orbit. These miniature bioreactors, equipped with 3D biosensors and AI cameras, allowed human stem cells to grow in space while researchers tracked their behavior live.
The results showed that stem cells returning from space displayed accelerated aging. They had reduced capacity to generate new, healthy cells, suffered more DNA damage, and exhibited telomere shortening. In essence, cells that left Earth young came back older and more fragile.
Catriona Jamieson, director of the Sanford Stem Cell Institute and professor at UC San Diego, described space as “the ultimate stress test for the human body.” She stressed that microgravity and cosmic radiation both play significant roles in pushing stem cells toward aging.
Implications for Human Health
Jamieson explained: “Learning how these changes occur is critical not only for safeguarding astronauts on long missions but also for advancing our understanding of aging and disease on Earth.”
Expanding on earlier insights from NASA’s Twins Study and the Space Omics and Medical Atlas project, this investigation dug deeper into the molecular drivers of aging in orbit.
Within just 32 to 45 days in space, HSPCs began showing early aging markers. They became hyperactive, burned through energy reserves, and lost their ability to rest—a key trait for long-term regeneration. Their output of healthy cells fell while DNA damage, telomere erosion, and mitochondrial stress signals increased. Even normally inactive parts of the genome lit up, disrupting cellular stability.
Together, these changes mirrored natural aging on Earth and suggested that space accelerates the body’s biological clock, potentially weakening immunity and raising disease risk.
The main driver appears to be genotoxic stress from elevated cosmic radiation. NASA measured radiation levels of 7.6 to 10.7 milligray (mGy) during these missions—comparable to doses from medical scans like CTs or X-rays. While relatively small, such exposure in combination with space stressors triggered significant molecular damage.
Signs of Recovery Back on Earth
Interestingly, once back on Earth in a healthier environment, some of the damaged cells began to recover. This suggests that with the right conditions or interventions, stem cells may regain function—similar to astronauts rejuvenating after their return.
The findings underscore the urgent need to protect stem cells from space hazards and to identify early biological “warning signals” that indicate stress-driven aging.
Looking ahead, the team plans to expand their work, this time including astronauts in real-time monitoring. With over 17 ISS missions behind them, they aim to test pharmaceutical and genetic strategies to safeguard human health during space travel.
Read the original article on: New Atlas
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