Microgravity and radiation exposure add up to serious health risks for astronauts

Feb 28, 2014
Human fibroblasts will be grown in the BioServe’s cell culture system. Credit: Bioanalytical Core Laboratory

Astronauts floating weightlessly in the International Space Station may appear carefree, but years of research have shown that microgravity causes changes to the human body. Spaceflight also means exposure to more radiation. Together, microgravity and radiation exposure add up to pose serious health risks. But research is not only making space safer for astronauts, it's helping to improve health care for the Earth-bound as well.

One of the effects of is damage to DNA, or deoxyribonucleic acid, the genetic material in nearly every cell of our bodies. When damaged DNA repairs itself, errors can occur that increase the risk of developing cancer. A new study, MicroRNA Expression Profiles in Cultured Human Fibroblast in Space – Micro-7 for short – will examine the effect of gravity on DNA damage and repair. Because there is no controlled radiation source aboard the space station, the cells will be treated with bleomycin, a chemotherapy drug, to induce DNA damage.

"When a cell in the human body is exposed to radiation, DNA will be broken and repaired, which is considered the initiation stage of tumor development," explains principal investigator Honglu Wu, Ph.D., at NASA's Johnson Space Center in Houston. "Cells damaged from in space also experience microgravity, which we know changes gene expressions even without radiation exposure." That equals the space double-whammy for the human body.

Previous studies have exposed cells or organisms on Earth to high-energy charged particles to simulate space radiation, using the resulting cell damage or induction of tumors to predict the risk of cancer for astronauts from radiation. But those predictions don't include the effects of microgravity, making them potentially less accurate than the space based Micro-7 study. This investigation will address that by examining the effects of bleomycin-induced DNA damage aboard the orbiting laboratory.

Damage in human fibroblasts will be measured by the phosphorylation of a histone protein H2AX after bleomycin treatment. Credit: Bioanalytical Core Laboratory

The study will be the first in space to use cultured human fibroblasts, the non-dividing cells that make up most of the . Fibroblasts form the framework for organs and tissues and play a critical role in wound healing and other bodily functions.

The investigation is scheduled to launch to the orbital complex aboard SpaceX-3 March 16, 2014. Micro-7 is managed by NASA's Ames Research Center, Moffett Field, Calif., and is funded by NASA's Space Biology Program. Bioserve Space Technologies at the University of Colorado, Boulder, Colo. is providing the experiment hardware and implementing the science payload aboard the space station.

Wu will focus on how these cells respond to DNA damage in space by examining changes in a small, non-coding form of RNA known as microRNA, which is known to affect how genes are expressed in cells. The investigation will compare the cells in spaceflight with those on the ground to identify unknown functions of microRNA and the functions they regulate in our bodies. Similarities and differences in the space and Earth data will also improve our knowledge of fundamental biological processes critical for maintaining normal cell function.

In the future, Wu would like to have a controlled , such as a portable X-ray machine, on the space station to expose cultured cells or small animals to specific doses of radiation in space. Cells or organisms on the ground would be exposed to the same dose, and the DNA repair in both compared. Wu says that may be possible in the near future, perhaps by modifying a bone density scanner or other equipment aboard the .

TYPE IV damage to human fibroblasts after bleomycin treatment, shown in a 53BP1 stain. Credit: Bioanalytical Core Laboratory

Researchers can use data from Micro-7 in future Earth-based studies to examine whether the cell changes observed during spaceflight are seen in disease states of tissues and organs as well. Ultimately, this may help scientists better understand disease and this type of research could even lead to development of new treatment drugs.

"If we learn more about how repair DNA damage more efficiently or less efficiently in , that knowledge also will be helpful for cancer radiotherapy or treatment with radiation," Wu adds. "A challenge in medical treatment is that certain tumors are highly resistant to radiation. But there could be various ways to make them more radiosensitive, or less resistant to radiation. That would help provide more effective treatment." And also make those weightless astronauts a bit more carefree.

Explore further: Female astronauts have a lower threshold for space radiation than their male counterparts

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User comments : 11

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freeiam
2 / 5 (3) Feb 28, 2014
Artificial gravity and magnetic field will make this research irrelevant for space flight in the near future.
antialias_physorg
4.3 / 5 (6) Feb 28, 2014
Artificial gravity and magnetic field

Since no one has a clue how to do artificial gravity (and no one is even seriously working on this) that is certainly not going to be 'near future'.

As for radiation: there are also uncharged particles out there (neutrons and gamma rays) which don't care diddly squat about any magnetic field you care to erect - so the problem stays.
shavera
3.7 / 5 (3) Feb 28, 2014
The irony of all of this seems to be "the bigger the ship you build, the safer it is to fly" Put tons of water and fuel between the crew and the sun... and you have some effective shielding in place. But getting all that up there in the first place is this side of impossible given current technological, economic, and political realities.
antialias_physorg
5 / 5 (3) Feb 28, 2014
Put tons of water and fuel between the crew and the sun

Don't forget all other direction. There's plenty of nasty (read: high energy) stuff coming from all over the place - particularly from the direction of the galactic plane.
Adam
5 / 5 (1) Feb 28, 2014
Artificial gravity via a centrifuge, I believe what is meant.

Artificial gravity and magnetic field

Since no one has a clue how to do artificial gravity (and no one is even seriously working on this) that is certainly not going to be 'near future'.


As for the uncharged components, the charged stuff is more problematic. X-rays from solar flares can be handled by mass-shielding, with drinking water being the usual suggestion. Neutrons aren't much of an issue in space. Cosmic-rays, however, are very high energy and much harder to deflect with magnetic fields. The real question is how high a rigidity do we need protection from?

As for radiation: there are also uncharged particles out there (neutrons and gamma rays) which don't care diddly squat about any magnetic field you care to erect - so the problem stays.

adave
not rated yet Mar 01, 2014
CRC Handbook of the Pharmacology of Chinese Herbs has a long section on the effect of ginseng on radiation damage. Not a solution for chronic energetic exposure but it might point the way.
Skepticus
not rated yet Mar 01, 2014
Can't wait for the Chinese to really get to space and start using nuclear reactors/propulsion on board as their political system don't have the effing PC problem in dealing with a technical challenge. With gigawatts of power, they can build big, fast ship with the superconducting magnetic shields and leave the rest behind sniffing their radioactive exhaust!
Skepticus
not rated yet Mar 01, 2014
Logic dictates that we can't understand well things that we don't have much experience with. Only by working with nuclear reactors had scientists discover water and Li-6 absorb neutrons very well, for example. By using nuclear power widely everyday, some smart people will come up with better shielding for radiation. If you don't do anything, you'll never accomplish anything.
alfie_null
not rated yet Mar 02, 2014
Logic dictates that we can't understand well things that we don't have much experience with. Only by working with nuclear reactors had scientists discover water and Li-6 absorb neutrons very well, for example. By using nuclear power widely everyday, some smart people will come up with better shielding for radiation. If you don't do anything, you'll never accomplish anything.

At what cost? Would you volunteer to be a data point as someone figures out how effective a new strategy is? Or an involuntary data point as some nation's nuclear-bearing rocket fails on launch. I'm not saying nuclear rocket research should be avoided, just that there is a balance in the pros and cons; a lot of good reasons it shouldn't happen as fast as you would like.
antialias_physorg
5 / 5 (1) Mar 02, 2014
By using nuclear power widely everyday, some smart people will come up with better shielding for radiation.

Nucelar power has been used widely. And the best scientists and engineers have made it happen. What they came up with was: put quite a few meters of lead (or cheaper: concrete) between you and the source.

Avoiding radiation is a stochastic process. Get material with good cross section to the type of radiation you're producibg between you and it. The cross section is only dependent on the atom types you use. Another factor is the density. Then there is the fact that materials have different effective cross sections for different radiation types/energies (what may shield you from type X may create lethal secondary radiation from type Y).

There is no miracle radiation shield. It's straight up physics. You can't cheat physics.
Skepticus
not rated yet Mar 03, 2014
"There is no miracle radiation shield. It's straight up physics. You can't cheat physics."
I didn't know that physics has all been worked out. And as such, the latest chips in your computer has been pulled out of thin air by scientists and engineers sitting with their minds in neutral and their hands under their arses while rote mumbling the learned wisdom of their predecessors.