A new study shows that space travel can mess with rodent skin, disrupting its growth, and possibly causing irritation similar to that experienced by human astronauts. For 91 days in 2009, six mice orbited Earth on board the International Space Station—the longest ever rodent space mission. Only three of the six would survive for the full 3 months, but since their return to Earth, scientists have been studying the animals to investigate the effects of space on mammal bodies. Mice have previously displayed many of the same changes that humans do on long space missions, such as muscle and bone atrophy, making them a promising model. In a new paper, published today in npj Microgravity, scientists have analyzed the mice’s skin to understand the effects of long-term space living.
The mouse results suggest that weightlessness interferes with cycles in normal skin growth and that the changes extend all the way down to the DNA level. Previously, human astronauts have complained about skin dryness and irritation during extended periods in space, and the mouse results suggest that life in space is indeed disrupting our body’s largest organ. Overall, the space mice showed thinner skin with more hair growth and higher collagen turnover than the control mice housed in identical conditions back on Earth. Genetic analyses also showed changes in how the space mice were creating skin and hair proteins, suggesting that weightlessness disrupts the skin at the level of DNA and RNA. Some genetic changes, such as an increase in hair follicle keratin expression, agreed with the larger scale observations. Taken together, the scientists conclude that the atrophy and disruption in the mice’s skin could explain many of the complaints of human astronauts as well. The results should be interpreted cautiously though; the small sample size limits the researchers’ confidence that their data are not the result of random chance.