February 28, 2014
Studying The Effects Of Microgravity And Radiation On Human Cells
Lawrence LeBlond for redOrbit.com - Your Universe Online
Life aboard the International Space Station (ISS) may seem like a carefree existence, but a wealth of evidence has proven otherwise. Years of research shows that the effects of microgravity wreaks havoc on the human body.
However, microgravity isn’t the only thing that astronauts need to worry about in space. Going into space means exposure to radiation, which is known to damage our DNA. And when DNA tries to repair itself, errors can occur that increase the odds of developing cancer.
Between the two, humans face serious health risks when journeying into space. But mounting research is not only making spaceflight safer for our astronauts, it is helping to improve the health of people on terra firma as well.
A new study (Micro-7) is now examining the effect of gravity on DNA damage and repair. Because there is no controlled radiation source on the orbiting lab, cells will be treated with the chemotherapy drug bleomycin 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, PhD, at NASA’s Johnson Space Center in Houston. “Cells damaged from radiation exposure in space also experience microgravity, which we know changes gene expressions even without radiation exposure.”
This equals a space double-whammy for the human body, noted Wu.
Previous research exposed cells or organisms on Earth to high-energy charged particles to simulate space radiations. The resulting cell damage helped predict the risk of cancer for astronauts from space radiation. However, the research conducted on Earth in controlled environments do not address the effects of microgravity, which could make any results less accurate than this latest study.
The researchers believe the Micro-7 study will address that by examining the effects of bleomycin-induced DNA damage aboard the ISS.
For the study, Wu and colleagues are using cultured human fibroblasts, non-dividing cells that make up most of the human body. Fibroblasts form the framework for organs and tissues and play a critical role in healing wounds. The study will begin once the samples arrive on the ISS, after a scheduled SpaceX-3 launch on March 16, 2014.
Wu and colleagues will focus their study on how fibroblasts respond to DNA damage in space by examining the changes in a small, non-coding form of RNA known as microRNA, which affects how genes are expressed in cells. The team’s 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. Comparison of the space and Earth-based data will improve scientific knowledge of the fundamental biological processes critical for maintaining normal cell function.
Wu hopes that one day the ISS will have a controlled radiation source that can be used to expose cultured cells or small animals to specific doses of space radiation. In that study, cells or organisms on Earth could be exposed to the same dose of radiation to see how DNA repair occurs in both samples. Wu thinks this may be possible in the near future, perhaps by modifying a bone density scanner or some other equipment on the space station.
The data from Micro-7 may be used for future Earth-based studies to examine whether the cell changes observed during spaceflight are seen in disease states of tissues and organs as well. The ultimate goal of this research is to help scientists better understand disease and the perhaps the development of new drugs to treat such diseases.
“If we learn more about how cells repair DNA damage more efficiently or less efficiently in space, that knowledge also will be helpful for cancer radiotherapy or treatment with radiation,” Wu added. “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.