A recent study reveals that space travel significantly accelerates the aging process in human blood-forming stem cells. Researchers from the University of California San Diego, in collaboration with NASA, found that even short-duration missions in low Earth orbit lead to cellular changes that mirror aging on Earth, raising new questions about astronaut health for future long-distance space exploration.
Key Takeaways
- New research published in Cell Stem Cell confirms that space travel causes premature aging in human hematopoietic stem cells (HSCs).
- After just one month in orbit, stem cells showed signs of DNA damage, reduced functionality, and hyperactivity, which are hallmarks of cellular aging.
- The findings are critical for developing protective measures for astronauts embarking on long-duration missions to the Moon, Mars, and beyond.
- The study also provides a unique model for understanding aging and age-related diseases like cancer here on Earth.
The Cellular Stress of Space Travel
Human hematopoietic stem cells, or HSCs, are responsible for creating all the blood and immune cells in the body. These cells typically exist in a resting state, activating only when needed to respond to an injury or infection. This careful management ensures they can function for a lifetime.
However, the extreme environment of space disrupts this balance. A study led by the Sanford Stem Cell Institute at UC San Diego examined the effects of low Earth orbit on these vital cells. The research was conducted as part of the Integrated Space Stem Cell Orbital Research (ISSCOR) center, a partnership with NASA and Space Tango.
The investigation utilized four separate SpaceX Commercial Resupply Services missions to the International Space Station (ISS). During these missions, human stem cells were monitored in a specialized environment to observe how they reacted to spaceflight.
Building on Previous Research
This work expands on earlier findings, such as NASA's Twins Study, which identified changes in telomere length and chromosomal instability in an astronaut after nearly a year in space. The new study provides a more detailed, mechanistic look at how spaceflight directly impacts the fundamental building blocks of the blood and immune systems.
Advanced Monitoring in Orbit
To study the cells in space, scientists developed sophisticated bone marrow niche nanobioreactors. These devices mimic the environment of human bone marrow, allowing stem cells to grow and behave as they would inside the body. The nanobioreactors were housed in AI-driven CubeLabs on the ISS.
These automated systems used artificial intelligence and advanced cameras to track the cells in real time. This technology enabled researchers to observe cellular behavior and changes as they happened, providing an unprecedented view of stem cell biology in microgravity.
Signs of Premature Aging Detected
Upon their return to Earth, the stem cells exhibited clear evidence of accelerated aging. The effects were noticeable after missions lasting between 32 and 45 days. The cells showed a diminished capacity to produce new, healthy blood cells and became more susceptible to DNA damage.
Key Cellular Changes Observed:
- Hyperactivity: The stem cells lost their ability to remain in a resting state, consuming their energy reserves too quickly.
- DNA Damage: An increase in DNA breaks and fraying at the telomeres—the protective caps on the ends of chromosomes—was observed.
- Mitochondrial Stress: The cells' power plants, the mitochondria, showed signs of stress, disrupting normal cellular function.
- Genetic Instability: Parts of the genome that are normally inactive were switched on, which can lead to cellular instability.
Catriona Jamieson, the director of the Sanford Stem Cell Institute and a professor at UC San Diego School of Medicine, described space as "the ultimate stress test for the human body."
"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."
The Role of Cosmic Radiation
One of the primary drivers of this cellular aging appears to be genotoxic stress caused by cosmic radiation. The space environment exposes astronauts and biological samples to higher levels of radiation than on Earth, where the planet's magnetic field provides protection.
During the month-long missions, NASA recorded radiation levels ranging from 7.6 to 10.7 milligray (mGy). According to the study, this dosage is roughly equivalent to what a person would receive from a standard medical CT or X-ray scan. While the dose may seem low, continuous exposure combined with other spaceflight stressors like microgravity can cause significant cellular damage.
These findings suggest that the combined environmental pressures of space create a perfect storm for accelerating the biological clock of stem cells. This could potentially weaken an astronaut's immune system over time or increase their risk of developing diseases.
Hope for Recovery and Future Protection
Despite the concerning findings, the research also offered a positive insight. When the space-exposed stem cells were returned to a healthy, controlled environment on Earth, some of the damage began to reverse. This suggests that the aging effects may not be permanent and that interventions could potentially help cells recover.
This discovery highlights the urgent need for strategies to shield stem cells from the harsh environment of space. It also emphasizes the importance of identifying biological markers that can act as early warnings for stress-induced aging before irreversible damage occurs.
Next Steps in Space Health Research
The research team is already planning future studies based on their 17 missions to the ISS. The next phase will involve tracking molecular changes in astronauts in real time during their missions. The goal is to develop and test countermeasures, such as pharmaceutical drugs or genetic tools, that could protect human health from the unique stresses of space.
As humanity prepares for extended missions to the Moon and Mars, ensuring the long-term health of astronauts remains a top priority. This research provides a crucial foundation for developing the technologies and medical protocols needed to make deep space travel safer.
