Space mice pioneer bone research
By Amanda Barnett
(CNN) -- Space shuttle Endeavour has mice. Two dozen of them, in fact. But these mice aren't pests, they're invited guests.
The pioneering mice are part of an experiment on a bone-regulating protein called osteoprotegerin, or OPG. Scientists predict that OPG will protect against bone loss caused by the weightless environment of space. It's also a potential treatment for millions of ground-based Earthlings who have osteoporosis.
OPG was discovered in 1995 by researchers for Amgen, a biotechnology firm based in Thousand Oaks, California.
"It appears to be really safe," said primary investigator Paul Kostenuik, a research scientist with Amgen. The company is testing OPG in partnership with NASA's BioServe Space Technologies at the University of Colorado.
Twelve of the shuttle mice have been treated with OPG; the other 12 were given a placebo.
The mice are in a special animal enclosure module in the shuttle's middeck called the Commercial Biomedical Testing Module. The container automatically provides food and water, and shuttle crew members check in on them. But mostly, the mice just hang out and float.
After the shuttle lands, the mice are to be returned to the scientists, who will examine the effects of spaceflight.
Weighty dilemma for space travelers
An astronaut or cosmonaut may lose 1 to 2 percent of his or her bone density per month in space, said Kostenuik. If astronauts are to someday travel to Mars, or stay on the space station for lengthy missions, they could be at risk for bone fractures when they return to Earth's gravity.
Current osteoporosis treatments have serious downsides for space travelers.
For example, when astronauts swallow pills, the lack of gravity makes them stick in the esophagus, said Kostenuik. And drugs that include estrogen aren't appropriate for male crew members, according to Kostenuik. OPG is injected and does not include estrogen.
"We already know OPG prevents bone loss in a variety of disease states," said Kostenuik. He said scientists predict it also will be safe and effective in near-zero gravity.
OPG still is in early stages of clinical development and Kostenuik said it may be several years before it's available on Earth or in space.
Dr. Felicia Cosman: The facts about osteoporosis
July 25, 2001
Campaign urges osteoporosis testing
July 24, 2001
National Osteoporosis Foundation
NASA Human Spaceflight
Osteoporosis drug found equally effective for men - August 31, 2000
NIH panel issues consensus report on osteoporosis - March 29, 2000
Newest drug for osteoporosis has fewer side-effects - October 13, 1999
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