Traveling to space poses significant challenges to the human body. Spaceflight can lead to a variety of health issues for astronauts, including a loss of bone density, swelling of brain and eye nerves, and alterations in gene expression. Research indicates that spending extended periods in space may accelerate the aging process, mimicking the effects of rapid aging on the body.
One of the most notable studies on this topic was conducted by NASA involving identical twin astronauts Mark and Scott Kelly. This groundbreaking research examined the effects of prolonged space exposure on Scott, who spent 340 days in space, while Mark remained on Earth. The results revealed concerning changes in Scott’s body, such as DNA damage, decreased cognitive function, and the shortening of telomeres—protective caps on chromosomes—some of which persisted even after six months back on Earth. The findings were published in a landmark 2019 study in the journal Science.
A recent study published in the journal Cell Stem Cell has expanded upon these findings, revealing that stem cells also exhibit signs of aging while in space. According to Dr. Catriona Jamieson, director of the Sanford Stem Cell Institute at the University of California, San Diego, stem cells age “ten times faster in space than on the ground.” This accelerated aging of stem cells is particularly concerning, as these cells are vital for repairing tissues and organs within the body. Their decline could lead to serious, chronic health issues such as cancer, neurodegenerative diseases, and heart problems.
This new research emerges during a time of heightened interest in spaceflight, with plans for long-duration missions to the moon by various governments and private companies launching civilians into space. Understanding the health risks associated with space travel is crucial for ensuring astronaut safety and preparing for future missions. Moreover, insights gained from studying the acceleration of aging in cells could also elucidate biological processes occurring more slowly here on Earth.
The researchers collected stem cells from bone marrow donated by individuals who underwent hip replacement surgery. These cells were placed in “nanobioreactors,” small, transparent blood bags designed for biological processes. The nanobioreactors were housed within a monitoring system called a CubeLab. Each participant's stem cell sample was divided into two CubeLabs: one was sent to space, while the other stayed on Earth for comparison. The samples were launched during four commercial resupply missions by SpaceX to the International Space Station, where they spent 32 to 45 days in microgravity.
Upon their return, the researchers conducted a detailed analysis of the space-faring stem cells, comparing them with their ground controls. They sequenced the genomes and performed various tests to study seven hallmark signs of aging in the samples. The results showed clear evidence of aging in the stem cells that had traveled to space, including increased inflammatory signaling and diminished telomere maintenance. Additionally, researchers noted an increase in genomic instability, which refers to an uptick in replication errors within genetic code—factors that can lead to mutations.
Christopher Mason, a geneticist at Weill Cornell Medicine who contributed to the twin study but was not involved in the new research, remarked, “This is probably the most in-depth examination I’ve seen of some of the mutational signatures of spaceflight.” He emphasized that the findings provide compelling evidence of aging due to space travel. Dr. Jamieson believes that this research could ultimately inform the development of therapies benefiting both astronauts and individuals on Earth, particularly as the global population ages and birth rates decline. She stated, “Predicting, preventing, and reversing stem cell aging under conditions of stress or inflammation is where we’re going.”
