View of Commercial Biomedical Test Module, or CBTM-2, investigation aboard the shuttle Endeavour as part of the STS-118 mission to the International Space Station. (NASA)
When it comes to the International Space Station, recycling is a great way to get the most from limited resources. This is especially true regarding the research done on the orbiting laboratory, due to flight opportunity and supply constraints. Cooperative agreements help to give researchers the chance to make use of rare samples, such as biological tissue exposed to microgravity. This gives the specimens an extended life in other scientific studies.
NASA's Biospecimen Sharing Program, or BSP, offers the research community the ability to maximize results by taking full advantage of limited samples. Researchers can request specimens to conduct secondary studies that go beyond the original experiment goals, looking into areas such as metabolism, immune function and bone health.
Michael Pecaut, Ph.D., at Loma Linda University and Medical Center in Loma Linda, Calif., is an investigator using previously flown space tissue in his research. He shared his findings in a poster, titled Effects of Spaceflight Environment on Immune Parameters, at last year's American Society for Gravitational and Space Biology, or ASGSB, conference in San Jose, Calif.
"The pros to this type of tissue sharing program are obviously access to tissues that we would otherwise not have," said Pecaut. "The collaborative effort of these flights have made it possible to complete a significant amount of work at a comparatively low cost. In addition, collaboration among groups with expertise in different research areas can sometimes result in synergistic outcomes."
Pecaut's findings were the result of a ground investigation using tissue that flew aboard the space shuttle Atlantis as part of the STS-135 mission to the space station. By teaming up with BioServe at the University of Colorado, Pecaut's lab was able to study the body systems and immune functions of specimens exposed to space radiation.
"As part of a medical university that uses radiotherapy to treat cancer, much of our ground-based work focuses exclusively on radiation-induced changes in immune function," said Pecaut. "However, by comparing our radiation studies with results from STS-135, we can begin to tease out different aspects of the spaceflight environment. This will, in turn, allow us to develop models that help us to better understand human health and ways to address immune function disorders."
This was the third collaboration for Pecaut, building on a previous study that used tissue flown on Endeavour's STS-118 mission in 2007. The earlier investigation suggested increased oxidative stress -- which impairs a cell's ability to repair itself -- due to spaceflight. The team aimed to confirm this using STS-135 samples and to learn more about the combined effect of the space environment on immune function.
Findings from Pecaut's study have ties to the human aging process, since living aboard the space station for long periods brings on similar conditions to those seen in humans as they grow old on Earth. This is because exposure to the spaceflight environment causes immune cell population distributions to change and alters the expression of certain cytokines, which are proteins that regulate numerous body systems.
"I believe that the International Space Station is an ideal laboratory to study age-related diseases," said Pecaut. "The environmental factors experienced by astronauts aboard the station, such as psychological and physiological stressors, and increased oxidative stress due to low-dose/low-dose-rate radiation, are all similar to what occurs with aging."
These factors can dramatically influence the distribution and function of white blood cells, particularly those involving oxidative stress. "It is probably not surprising that low-dose radiation and psychological stress are both important components of the space flight environment," said Pecaut. "What is surprising is that many of these effects are also strikingly similar to those seen in aging, suggesting that some of the same mechanisms are in play."
Pecaut's team also collaborated with NASA's Ames Research Center to use a centrifuge to look at chronic exposure to gravitational conditions that are different from normal Earth gravity. The only way to fully study all factors inherent to the space environment, however, is to use samples flown in orbit.
While the long-term impacts of spaceflight on immune function still are under investigation, each set of results brings scientists closer to answering questions about human health here on Earth. With this efficient use of resources, a single set of samples from one station investigation has the potential to feed numerous ground studies, multiplying the return on investment.