It turns out that there may be some bad news for long-term spaceflight. Scientists have found that mice flown aboard the space shuttle Atlantis returned to Earth with early signs of liver disease.
Understanding the impacts of long-term spaceflight is important for longer space missions. More specifically, as space agencies gear up for a mission to Mars, it's crucial to understand what impacts space has on the human body.
"Prior to this study we really didn't have much information on the impact of spaceflight on the liver," said Karen Jonscher, an associate professor at CU Anschutz and one of the researchers involved in the study. "We knew that astronauts often returned with diabetes-like symptoms but they usually resolved quickly."
In all, the mice spent 13.5 days aboard the space shuttle. When they returned, the researchers collected liver samples from the mice and found that the spaceflight seemed to activate specialized liver cells that may induce scarring and cause long-term damage to the organ.
Scientists have spent years looking at the impact of spaceflight on human physiology. However, most of the research focused on bone, muscle, brain and cardiovascular function. Now, though, new studies suggest that astronauts who spent time in space and developed diabetes-like symptoms may be linked to the effect of microgravity on metabolism and the liver.
"We saw the beginning of nascent liver damage in just 13.5 days," Jonshcer said. "The mice also lost lean muscle mass. We have seen this same phenomenon in humans on bedrest-muscles atrophy and proteins break down into amino acids. The question is, how does that affect your liver?"
The researchers found that spaceflight resulted in increased fat storage in the liver. In addition, there was a loss of retinol, which is an animal form of Vitamin A. There were also changes to levels of genes responsible for breaking down fats.
"Further study in this area is merited and analysis of tissues harvested in space from mice flown aboard the International Space Station for several months may help determine whether long-term spaceflight might lead to more advanced hepatic injury and whether damage can be prevented," Jonscher said.
The findings were published in the April 20 issue of the journal PLOS One.
