Researchers from the University of Colorado Anschutz Medical Campus discovered that a group of mice flown aboard the space shuttle Atlantis returned to earth with early signs of liver damages. This raises concerns about the probable implications for the manned mission to Mars.

Karen Jonscher, Ph.D., the lead author of the study, associate professor of anesthesiology and a physicist at CU Anschutz, said that prior to this study they didn't have much information on the impact of spaceflight on the liver, according to Science Daily. She further explained that the astronauts often returned having the symptoms of diabetes but they quickly resolved them.

The group of mice spent 13.5 days aboard the space shuttle. The researchers collected liver samples when they returned to earth. They discovered that spaceflight activated the specialized liver cells that may cause scarring and long-term damage to the organ.

"We saw the beginning of nascent liver damage in just 13.5 days," said Jonscher. She also said that the mice also lost lean muscle mass.

ABC News reports that NASA has studied the effects of spaceflight on the human body. These include the cardiovascular function, muscle performance and bone density. Jonscher said that the mice study remains an open question whether the liver damage could have an impact on humans especially the astronauts on deep-space missions.

"We need to look at mice involved in longer duration spaceflight to see if there are compensatory mechanisms that come into play that might protect them from serious damage," said Jonscher. She also put emphasis that the stress of spaceflight and the return to earth might contribute to the liver damage. The study was printed online in the journal PLOS One.

Meanwhile, NASA has been studying how living out of this world would impact the human body through twin astronaut brothers, Mark and Scott Kelly. They have been participating in some tests to gauge everything from bone density and metabolic performances to their state of minds.