|Astronauts lose calcium in their bones and strength in their muscles while in space because of zero-gravity. This image was taken in NASA's Skylab.
Credit: National Space Biomedical Research Institute
Astronauts who travel in space are at risk for bone loss in much the same way that cancer patients who receive radiation therapy are, and both groups are more likely to develop fractures than the general population.
To better understand the causes, Clemson researchers have developed the first model to study the rate of bone loss in those two groups. Their results are published in the Journal of Applied Physiology.
Clemson bioengineering professor Ted Bateman said, Recent exams of astronauts who were on the International Space Station showed signs of bone loss in the neck and vertebrae. Even five years after returning to Earth, they have not completely recovered from this loss.
Bateman said microgravity and radiation from cosmic and solar sources affect the astronauts, and this is a primary concern for long voyages, such as those planned for Mars. The study points out that unprotected astronauts could be exposed to potentially lethal doses of radiation.
Therapeutic radiation in cancer patients is an important tool for survival but long-term effects often result in reduced bone density, fractures and back pain in both adults and children.
In studies at Clemson University and Kennedy Space Center, Bateman and his team from the Osteoporosis Biomechanics Lab mimic solar flares and clinical radiation exposure, then measure bone loss in mice. Their goal is to understand the causes for the bone loss and develop therapies to improve health in space as well as on the ground.
In prior studies, Bateman and his team examined a natural protein, osteoprotegerin, with the biotechnology company Amgen Inc. of Thousand Oaks, Calif. The Bateman group designed a study to test this protein, which prevents bone loss, in mice on space shuttle flight STS-108 in 2001. Osteoprotegerin is currently in Phase III FDA trials (human testing), and may be a key to preventing bone loss caused by radiation from both space and cancer therapy.