Researchers who exposed an animal model to conditions that mimicked a trip to Mars found inflammation, scarring and senescent cells in the liver. Some of the genetic changes resembled those found in astronaut blood samples, but it's still unclear how they translate into a medical risk in humans.
Exposure toCosmic radiation and for the conditions that simulate Microgravity caused molecular changes in the liver of animals similar to those that occur in the processes agingThis is according to a study by researchers from the University of Central Florida and other institutions, published in the journal GeroScience.
The researchers found an increase in signs of cellular aging, inflammation, and fibrosis – the buildup of scar tissue – after exposure to conditions designed to simulate some of the environment an expedition would encounter on its way to Mars.
Some of the genetic changes found in the liver were similar to molecular signatures recorded in blood samples from AstronautsHowever, the research was mainly conducted in animal models and under laboratory conditions, and therefore does not prove thatSpace flight Causes aging in humans The liver Or of the whole body in the same way.
The researchers say the findings could help identify biological pathways that need to be protected during long-duration space missions. They could also provide a faster way to study processes related to aging and age-related diseases on Earth.
Why did the researchers focus on the liver?
The liver is one of the central organs in metabolism. It participates in regulating sugar and fat levels, breaking down toxic substances, processing drugs, and producing proteins essential for the body's activities.
Changes in liver function can affect many other systems. In addition, the liver is susceptible to inflammation, oxidative stress, and metabolic disorders – processes that may be exacerbated by spaceflight conditions.
Prof. Michal Mastranek, who leads research in the field of aging and space medicine at the University of Central Florida's School of Medicine, said that many genetic changes appeared as early as 24 hours after exposure to radiation.
He said the changes were remarkably similar to processes observed during aging. However, he emphasized that in a long-duration space mission the exposure would be more complex and continuous than what could be created in a short experiment.
Simulation of a journey into deep space
To test the combined effect of space conditions, the researchers created a laboratory environment that simulates two major risk factors: microgravity and radiation.
The animal model was kept for 14 days in conditions simulating the effects of microgravity. It was then exposed to radiation at NASA's Radiation Laboratory, in a manner designed to simulate galactic cosmic rays and particle events from the Sun.
Galactic cosmic rays consist of high-energy particles that come from outside the solar system. On Earth, the atmosphere and magnetic field provide considerable protection from them, but astronauts outside low Earth orbit will be more exposed.
Particle events from the Sun can release large amounts of protons and other particles in a short period of time. On a mission to Mars, the crew will not be able to quickly return to Earth, so appropriate shielding, monitoring, and medical solutions are required.
Microgravity affects in a different way. In the absence of the normal gravitational load, muscle and bone activity, fluid distribution in the body, the immune system, and some metabolic processes change.
The researchers wanted to examine how two stressors work together, because in real space flight, astronauts are not exposed to each of them separately.
Cells that do not divide but do not disappear either
One of the findings was an increase in cellular aging, also known as cellular senescence. This is a condition in which a cell stops dividing, but does not die and is not necessarily eliminated from the tissue.
Senescent cells can secrete molecules that promote inflammation and affect neighboring cells. Their accumulation has been linked to tissue aging and various diseases, although they also play beneficial roles in wound healing and tumor protection.
The researchers also found signs of inflammation and fibrosis in the liver. Fibrosis is a process in which excess intercellular material and scar tissue accumulate in the tissue. If the process continues, it can disrupt the organ's structure and function.
This does not mean that the animals in the experiment developed liver failure. The findings relate to molecular signatures and early changes that have been linked in other studies to the progression of liver disease.
Comparison to astronaut blood
After analyzing the liver tissues, the researchers compared the results to published data from human studies, including NASA's Twins Study and the private space mission inspiration4.
In NASA's twin study, astronaut Scott Kelly spent almost a year on the International Space Station, while his twin brother Mark Kelly remained on Earth. Comparing them made it possible to examine genetic, metabolic, and physiological changes associated with prolonged spaceflight.
Inspiration4 was a commercial manned mission that carried four passengers for about three days in orbit around the Earth. During the mission, biological samples were collected that allowed researchers to examine the body's response even during a short spaceflight.
In the astronauts' blood data, the researchers identified several genetic changes similar to those found in the laboratory model.
The similarity strengthens the possibility that the biological pathways found are indeed relevant to spaceflight. However, blood and liver tissue are not the same thing, and the comparison does not prove that the same changes occurred in the astronauts' livers.
The role of microRNA
The research focused, among other things, on microRNAs – short RNA molecules that help regulate the activity of genes. They do not typically serve as templates for protein production, but rather bind to other RNA molecules and can reduce the production of certain proteins.
Changes in microRNA can simultaneously affect networks of genes related to inflammation, cellular aging, and fibrosis.
The researchers specifically examined the relationship between microRNAs and the TGF-β signaling pathway. This pathway is involved in regulating growth, tissue repair, immune system activity, and scar tissue formation. Its increased or uncontrolled activity can contribute to fibrosis.
The team identified potential molecules from the group of antagomirs. Antagomirs are synthetic sequences designed to bind to a specific microRNA and block its activity.
In principle, such a blockage could alter genetic pathways related to inflammation and cellular aging. However, the study does not present an approved drug for astronauts, and further trials are needed to test efficacy, dosage, and safety.
Space as an accelerated model for studying aging
Aging processes typically develop over years and decades, making it difficult to examine their onset and the sequence of events that leads to a decline in organ function.
Space conditions can trigger changes similar to some of these processes in a relatively short time. Therefore, researchers see spaceflight and imaging experiments as a way to more quickly study cellular stress, inflammation, loss of muscle and bone mass, and changes in the immune system.
Mastranek emphasized that aging is not limited to wrinkles or external changes. It involves a gradual and cumulative decline in the function of organs and many biological systems.
Understanding the starting point of the process and the pathways that drive it may help in the future development of ways to delay age-related diseases. However, it should not be concluded that spaceflight is an exact or complete replica of normal aging on Earth.
What else should I check?
The study raises several questions that will need to be examined before the findings can be translated into medical protection for astronauts.
First, it is necessary to determine which of the changes are reversible after returning to normal gravity and ceasing radiation exposure. Studies in astronauts have shown that some physiological changes subside after returning to Earth, while others may persist for longer.
Second, it is necessary to examine the effect of prolonged exposures and at different doses. A journey to Mars It may last months, and the radiation dose will depend on the duration of the mission, the orbit, solar activity, and the degree of shielding of the spacecraft.
Third, there is a difference between people in their sensitivity to radiation, metabolic patterns, and predisposition to liver disease. Age, sex, diet, and pre-existing health conditions may affect response.
Finally, it remains to be seen whether blocking microRNA-related pathways will prevent damage without interfering with other essential processes. A single molecule can affect many genes, so treatment may also create unwanted effects.
The study does not state that accelerated aging is an inevitable consequence of space travel. It identifies biological pathways that may be important and suggests possible targets for further medical research – both for astronauts and for aging humans on Earth.
Questions and Answers
Does space flight make astronauts age faster?
Space conditions can cause cellular and physiological changes that resemble some of the aging processes. However, this does not mean that an astronaut's entire body ages at a uniform rate or that the duration of the mission can be translated into a specific number of "aging years."
What is microgravity?
Microgravity is a condition in which a spacecraft and its passengers are in continuous free fall around the Earth or during another orbit. The feeling is almost weightless, even though gravity is still at work.
Why is radiation in space more dangerous?
Outside the protection of Earth's atmosphere and magnetic field, astronauts are exposed to more energetic particles. These particles can damage DNA and other cellular components.
What is cellular aging?
This is a condition in which a cell stops dividing but remains in the tissue. Such cells may secrete substances that promote inflammation and affect nearby cells.
What is fibrosis?
Fibrosis is the excessive buildup of scar tissue in an organ. If the process continues, it can gradually damage the organ's structure and function.
What are microRNAs?
MicroRNAs are short sequences of RNA that regulate the activity of genes. A single molecule can influence the production of many proteins and entire biological pathways.
Have researchers already found a treatment for astronauts?
No. The researchers have identified antagomirs and molecular pathways that may serve as targets for future treatments. Further trials are needed to prove that they are effective and safe.
Could the findings also help people on Earth?
Possibly. The pathways studied are also linked to inflammation, fibrosis, and cellular aging on Earth. The study may help to understand them, but developing a practical treatment will require further research.
The scientific article
Article publication date: June 23, 2026
