The mice, which spent three months aboard the International Space Station, returned to Earth with thinned skin and unexpected changes in hair follicles. From this we can conclude about the scale of physiological changes in the human body during long space flights.
"Unofficial evidence of astronauts' skin problems in orbit has already been found, including slow healing of scratches, and some crew members have nonspecific rashes," said Discovery News, a NASA space station scientist, told Discovery News. In general, these skin issues were considered as false medical problems, although these changes may be evidence of wider changes in the immune system, she added.
A new study using mice hints that 434 genes are involved in genetic alterations, according to research reports. These figures were obtained after comparing the studies of animals that visited space and their earthly counterparts. Betty Nusgens, with her colleagues from the University of Liege in Belgium, are writing a microgravity paper this week for the new journal Nature Publishing. "We have no clear answer. We have shown in several publications that fibroblasts living in derma cells respond to stress and relaxation in microgravity conditions by disrupting their cytoskeleton. These fibroblasts lost in skin tissue remain an open question," writes Nusgens in an e-mail mail discovery news.
“The results for hair follicles were unexpected,” she added. "Our hypothesis is that stem cells participate in the hair follicle cycle ... And microgravity affects this."
New data is limited to a small sample size. Three of the six mice had a 91-day stay aboard the station, in 2009 they died during the flight, they were not viable for tissue analysis after landing (one mouse died from severe spinal cord injuries, which probably occurred during the shuttle launch the second mouse died of liver disease, and the third because of the failure of its automated food delivery system on board the station, as the authors note).
The surviving trio was euthanized after planting, all individuals showed a "significant reduction in skin thickness," as well as numerous hair follicles in unexpectedly active, growing phases, the researchers write. Changes in the underlying muscles were also noted. "This suggests that astronaut skin may be affected by pathophysiological changes that could damage the body during long flights in space," the researchers sum up.
"These results can be viewed as a warning signal for space programs. And it is necessary to perform clinical studies of astronauts' skin in order to assess potential thinning," Nusgens wrote in an e-mail.
So far, scientists have studied the skin changes of just one astronaut, the European Thomas Reiter.
Additional information can be obtained after the research of the space station by the European Space Agency (the study is called SKIN-B) and the Japanese study called HAIR.