In a new study, researchers discovered that deep space radiation which could be encountered during Mars missions can have a huge impact on the human body including a higher risk of leukemia. This means that harmful cosmic rays can change the function and even health of human stem cells.

This powerful radiation comes from galactic cosmic rays that are originally from outside our solar system in deep space. Another source is our host star, the sun, which ejects powerful solar flares that can cause solar storms via electromagnetic particles.

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Earth's magnetosphere or magnetic shield protect us from these harmful space radiation, however, if you are in space or even Mars, you are very much in danger of these powerful cosmic rays. NASA recently suggested an artificial magnetic shield for Mars to protect the first human explorers on the Red Planet, including manned missions for the first human colony.

A new study by a team from the Wake Forest Baptist Medical Center sought to assess the health impact of human stem cells called human hematopoietic stem cells (HSCs) when exposed to space radiation. HSCs are immature cells that can, later on, develop into different kinds of red blood cells. They can also grow into infection fighting cells and combat malignant cells that could be useful tools for researchers to fight leukemia and HIV. 

During this study, scientists collected healthy stem cells from donors between 30 to 55 years old and exposed them to solar energetic particles and galactic cosmic ray simulations within the same levels as astronauts will experience during a mission to Mars. The results revealed that this radiation impact caused genetic mutations within cells that affected their ability to produce healthy blood cells.

According to Christopher Porada from the Wake Forest Baptist Medical Center, this kind of radiation exposure can reduce HSC function, by stopping them from producing almost all types of blood cells at a rate of 60 to 80 percent. In other words, this can result in a severely weak immune system and even anemia for those in long spaceflight missions.

In another experiment, the team transferred these stem cells from the laboratory to inside a body and transplanted these irradiated HSCs into mice. These mice developed T-cell acute lymphoblastic leukemia in the end.

"Our new findings reveal that radiation exposure can potentially increase leukemia risk in two ways. First, there is genetic damage of the HSCs that leads to leukemia and second, radiation can change the ability of the stem cells to produce T and B cells which are white blood cells that can fight infections and tumor cells. Overall, this can deteriorate an astronaut's immune system by not removing malignant cells due to irradiated mutated cells," Porada explained.

This new study was published in the journal Leukemia.