A new study reveals that time spent in space induces changes similar to accelerated aging in critical human stem cells. Research published in the journal Cell Stem Cell indicates that while spaceflight harms these cells, some of the damage may be reversible upon returning to Earth.
Key Takeaways
- Human hematopoietic stem cells showed signs of accelerated aging after spending over a month in space.
- The study identified increased DNA damage and a reduced ability for cells to generate new, healthy blood cells.
- Researchers believe microgravity and radiation are the primary causes of these cellular changes.
- Some of the negative effects on the cells were reversed after they were returned to a healthy environment on Earth.
Cellular Impact of Space Exposure
Scientists from the University of California San Diego have identified specific signs of aging in human hematopoietic stem and progenitor cells (HSPCs) that were sent to the International Space Station (ISS). These cells are fundamental to maintaining a healthy blood supply and immune system.
The study found that after spending between 32 and 45 days in orbit, the cells exhibited several aging-like characteristics. Their ability to produce new, healthy cells was diminished. Furthermore, they showed an increased vulnerability to DNA damage, a common indicator of cellular stress and aging.
Changes at the Chromosomal Level
One of the most significant findings relates to telomeres, the protective caps at the ends of chromosomes. In the space-flown cells, these telomeres showed signs of accelerated shortening, which is a classic hallmark of aging. The research team also noted heightened stress within the mitochondria, the energy-producing centers of the cells. This stress led to inflammation and the activation of parts of the genome that are typically dormant.
By the Numbers
The human stem cells were cultured in space for a period of 32 to 45 days. For comparison, a standard astronaut mission to the ISS lasts approximately 180 days, suggesting that the effects could be more pronounced during longer stays in space.
The ISS as a Research Platform
To conduct the experiment, researchers sent four sets of HSPCs to the ISS aboard SpaceX commercial resupply missions. The cells were housed in a specialized platform that allowed them to be cultured and grown in the microgravity environment of the station.
Advanced, AI-powered imaging tools were used to monitor the cells in real-time, providing valuable data on their behavior and health while in orbit. This setup allowed the team to observe the cellular changes as they happened, without the delays associated with returning samples to Earth for analysis.
"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," stated study co-author Catriona Jamieson, a professor at UC San Diego.
Evidence of Cellular Recovery
A hopeful aspect of the study is the potential for recovery. After the HSPCs were returned to Earth, researchers placed them into what they described as a "young, healthy environment." This involved culturing them in bone marrow layers from their original donor or in a cell line known to promote connective tissue growth.
In this new environment, some of the cells began to recover from the stress of spaceflight. This suggests that at least a portion of the damage induced by microgravity and radiation is not permanent. The finding opens the door to developing countermeasures that could help astronauts' bodies heal after long missions.
Building on the NASA Twins Study
This research expands on findings from NASA's landmark Twins Study, which compared identical twin astronauts Scott and Mark Kelly. Scott spent nearly a year in space while Mark remained on Earth. That study also found changes in telomere length, with most of Scott's returning to normal within 48 hours of his return. The new research provides a more focused look at the specific cellular mechanisms at play.
Implications for Long-Duration Missions
The findings have significant implications for the future of human space exploration, particularly for missions to the Moon and Mars that will last for months or even years. Protecting astronaut health from the combined effects of radiation and microgravity is a top priority for space agencies.
According to the University of California San Diego, this study is one of 17 missions it has conducted on the ISS. The institution plans further research, including studies with astronauts and the development of countermeasures to mitigate the cellular aging process during spaceflight.
By understanding the precise ways space affects the human body at a cellular level, scientists can work toward creating therapies and strategies to ensure astronauts remain healthy during their journeys into the solar system.