In ongoing studies investigating the effects of spaceflight on the human body, researchers sound the alarm on intense radiation and the potential threat of leukemia in astronauts.
The ongoing NASA-funded study of researchers at the Wake Forest Institute for Regenerative Medicine uses human stem cells on mice to measure the powerful effects of deep space radiation and what can be done to remedy such effects.
Radiation exposure is considered one of the riskiest aspects of the planned journey to planet Mars. The average distance to the planet is 140 million miles, and a roundtrip could stretch three years.
Leukemia As A Lurking Threat
Senior project researcher and associate professor of regenerative medicine Dr. Christopher Porada said that radiation exposure could up the risk of leukemia in space travelers in two ways.
“We found that genetic damage to HSCs directly led to leukemia. Secondly, radiation also altered the ability of HSCs to generate T and B cells, types of white blood cells involved in fighting foreign ‘invaders’ like infections or tumor cells,” he explained in a statement.
The combined exposure to microgravity and radiation occurring during deep space missions leads to a double-whammy effect: mutations in key cells as well as compromised immune response.
Previous research showed that weightlessness or stay in microgravity could lead to significant changes in immune function, even after short-term missions in low Earth orbit where astronauts are mostly shielded from cosmic radiation. In a separate study, MRI scans done on over 20 astronauts revealed that microgravity can take its toll on the human brain, leading the organ to compress and expand during spaceflight.
In the experiments conducted at the NASA Space Radiation Laboratory at Brookhaven National Laboratory, human hematopoietic stem cells (HSCs) from healthy individuals of astronaut age (30 to 55 years old) were exposed to solar energetic particles (SEP) as well as galactic cosmic ray radiation (GCR). The HSCs were incorporated in both in vitro and mouse models.
While such stem cells form less than 0.1 percent of adults’ bone marrow, they produce the different kinds of blood cells circulating the human body and working to move oxygen, fight infection, and get rid of malignant cells.
Radiation practically shut the HSCs down, impeding their ability to produce blood cells by up to 80 percent. Exposed mice developed what researchers deemed to be T-cell acute lymphoblastic leukemia.
The team recommended appropriate countermeasures prior to space travel at major distances.
Ongoing Studies On Spaceflight Effects
NASA’s Human Research Program, which involves this recent study, catalogues the effects of human spaceflight on the body, especially as it has not evolved to deal with conditions such as weightlessness.
For its projected Mars mission, NASA grouped the risks into five categories, namely gravity fields, isolation or confinement, hostile or closed environments, space radiation, and distance from Earth.
“On the six-month trek between the planets, you would be weightless. On the surface of Mars, you would live and work in approximately one-third of Earth’s gravity, and when you return home you will have to readapt to the gravity we take for granted,” NASA cited as an example, where the transition from one gravity field to another is expected to affect head-eye and hand-eye coordination, balance, and locomotion, to name a few.
The space agency is yet to release official results from its unprecedented Twin Study, but early findings on twin brothers Scott and Mark Kelly already indicated that space travel dramatically changes human biology, such as gene expression.
Scott is the first American to spend nearly one year in space aboard the International Space Station (ISS), twice the normal time of stay. That duration is considered a stepping stone to a three-year Mars journey.