Simulation model tests how immune cells react to space flight

Humans face several health concerns in space due to its hostile environment – the absence of gravity being a major one.
Mrigakshi Dixit
Representational image
Image of astronaut floating in space


​​Life in space alters human physiology in a variety of ways, including stretching the spine, decreasing bone density, and expanding the brain cavity

A new study reveals that spaceflight may also negatively impact astronauts' immune systems.

Through a series of simulation-based tests, a team of researchers from Sweden's Karolinska Institutet evaluated the changes in the T cells under the influence of microgravity.

T cells are white blood cells called lymphocytes that play an important role in resisting germ attacks and protecting our bodies from infections. 

However, in the absence of gravity, T cells' function could plummet, making them less efficient in fighting infection.  

As per the official release, the lower amount of T cells may persist even after astronauts return from their space missions. This switch from space to Earth may make astronauts more susceptible to numerous infections here on Earth, as well as lead to the reactivation of dormant latent viruses in the body.

The simulation-based study 

To better comprehend the changes in T cells, the researchers employed dry immersion (DI), the most extensively used ground model, to imitate microgravity. 

DI accurately replicates the majority of the physiological changes that occur in the body systems during microgravity exposure.  

This technique entails the use of a custom-made waterbed that deceives the body into thinking it is in a weightless state. 

The researchers examined T cells in the blood samples of eight healthy people exposed to simulated microgravity for up to three weeks. 

Blood tests were performed regularly before the trial began, 7, 14, 21 days later, and seven days after the experiment concluded.

The investigation revealed that T cells drastically altered their gene expression and appeared to become more immature in their genetic program. The highest impact was observed after 14 days of weightlessness. 

“The T cells began to resemble more so-called naïve T cells, which have not yet encountered any intruders. This could mean that they take longer to be activated and thus become less effective at fighting tumor cells and infections. Our results can pave the way for new treatments that reverse these changes to the immune cells’ genetic programme,” said Carlos Gallardo Dodd, one of the authors of this study. 

After 21 days, the T cells' gene expression had "adapted" to weightlessness to the point that it had practically reverted to normal, although examination seven days later indicated that some of the alterations had been regained.

Up next, the team now aims to use the Esrange Space Centre's sounding rocket platform in Kiruna, Sweden, to explore how T cells behave and function under weightlessness.

Space is a hostile environment

Human expeditions to the Moon and Mars are the next steps in space exploration. However, humans face several health concerns in space due to its hostile environment – one in which the human body has not evolved to thrive in.  

“If astronauts are to be able to undergo safe space missions, we need to understand how their immune systems are affected and try to find ways to counter harmful changes to it. We’ve now been able to investigate what happens to T cells, which are a key component of the immune system when exposed to weightless conditions,” said Lisa Westerberg, study leader, and principal researcher at the Department of Microbiology, Tumor and Cell Biology at the institute, in an official release. 

Much biology-related research in recent years has relied on astronauts stationed at the International Space Station. 

One recent study closely studied the bone marrow alterations caused by space flight. 

The results highlighted that staying at ISS could reduce red blood cells and bones. It also proposed that after returning to Earth, the bones and RBCs could be restored using fat stored in the bone marrow. 

The results of this new study were reported in the journal Science Advances. 

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