N.C. – March 8, 2017 – Sending a manned mission to
Mars requires more than a powerful launch rocket. Prep work also includes
learning how a three-year space flight could affect the human body. With
funding from the National Aeronautics and Space Administration (NASA), researchers
at the Wake Forest Institute for
Regenerative Medicine and colleagues are using human
stem cells to measure the effects of deep space radiation.
transplanted with human stem cells, the research team has demonstrated for the
first time that the radiation encountered in deep space travel may increase the
risk of leukemia in humans.
“Our results are
troubling because they show radiation exposure could potentially increase the
risk of leukemia in two ways,” said Christopher Porada, Ph.D., associate
professor of regenerative medicine and senior researcher on the project.
As part of this
ongoing project, the group has identified and is currently testing a common dietary
supplement for its ability to protect astronauts from these damaging effects.
“It is rewarding
to use our expertise in stem cells to help NASA evaluate the potential health
risks of space travel and hopefully develop strategies to address them,” said
exposure is believed to be one of the most dangerous aspects of traveling to
Mars, according to NASA. The average distance to the red planet is 140 million
miles, and a roundtrip could take three years.
The goal of the
study, published in the journal Leukemia, was to assess the direct effects of
simulated solar energetic particles (SEP) and galactic cosmic ray (GCR)
radiation on human hematopoietic stem cells (HSCs). These stem cells comprise
less than 0.1% of the bone marrow of adults, but produce the many types of
blood cells that circulate through the body and work to transport oxygen, fight
infection, and eliminate any malignant cells that arise.
For the study,
human HSCs from healthy donors of typical astronaut age (30-55 years) were
exposed to Mars mission-relevant doses of protons and iron ions – the same
types of radiation that astronauts would be exposed to in deep space -- at the
NASA Space Radiation Laboratory at Brookhaven National Laboratory. Researchers
at the Wake Forest Institute for Regenerative Medicine then performed
laboratory and animal studies to define the impact of the exposure.
These exposure levels that
simulated deep space radiation were found to dramatically affect the health and
function of the HSCs. “Radiation exposure at these levels was highly deleterious
to HSC function, reducing
their ability to produce almost all types of blood cells, often by 60-80 percent,” said Porada.
“This could translate into a severely weakened immune system and anemia during
prolonged missions in deep space.”
by other researchers had already demonstrated that exposure to high doses of
earthly radiation, such as from X-rays, can have harmful (even
life-threatening) effects on the body’s ability to make blood cells, and can
significantly increase the likelihood of cancers, especially leukemias.
However, the current study was the first to show a damaging effect of low,
mission-relevant doses of space radiation.
The current study
is significant because it shows that radiation affected cells at the stem cell
level. It caused mutations in genes involved in the hematopoietic process, and
it dramatically reduced the ability of HSCs to give rise to mature blood cells.
The next step
was to assess how the cells would function in the body. Mice were transplanted
with GCR-irradiated human HSCs, essentially “humanizing” the animals. The mice
developed what appears to be T-cell acute lymphoblastic leukemia – the first
demonstration that exposure to space radiation may increase the risk of
leukemia in humans.
show radiation exposure could potentially increase the risk of leukemia in two
ways,” said Porada. “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. This may reduce the ability of the astronaut's
immune system to eliminate malignant cells that arise as a result of
Porada said the
findings are particularly troubling given previous work showing that conditions
of weightlessness/microgravity present during spaceflight can also cause marked
alterations in astronaut’s immune function, even after short duration missions
in low earth orbit, where they are largely protected from cosmic radiation.
Taken together, the results indicate that the combined exposure to microgravity
and SEP/GCR radiation that would occur during extended deep space missions,
such as to Mars, could potentially exacerbate the risk of immune-dysfunction
NASA’s Human Research Program is exploring not only the effects of radiation, but also
conditions of microgravity, isolation and confinement, hostile and closed
environments, and distance from earth. The ultimate goal of the research is to
make space missions as safe as possible.
are: Graça Almeida-Porada, M.D., Ph.D.; Christopher Rodman; Sunil George, Ph.D.;
John Moon; Shay Soker, Ph.,D.; Timothy Pardee, M.D., Ph.D.; Michael Beaty, M.D.;
Satria P. Sajuthi, Ph.D.; Carl D. Langefeld, Ph.D.; and Stephen J. Walker,
Ph.D, Wake Forest Baptist; Peter Guida, Ph.D., Brookhaven National Laboratory;
and Paul F. Wilson, Ph.D., Brookhaven National Laboratory and the Univ. of
California Davis Comprehensive Cancer Center.