COMMERCIAL BIOMEDICAL TESTING MODULE: EFFECTS OF OSTEOPROTEGERIN ON BONE
MAINTENANCE IN MICROGRAVITY (CBTM)
Research Area: Animal Biology – Vertebrates
Expedition(s): 4
Principal Investigator(s): ● Ted A. Bateman, PhD, University of North Carolina, Chapel Hill,
North Carolina
RESEARCH OBJECTIVES
Commercial Biomedical Testing Module: Effects of Osteoprotegerin on Bone Maintenance in
Microgravity (CBTM) provides the capability to use the microgravity environment for evaluation
of new pharmaceutical candidates in small mammals. Results may expedite the review of new
pharmaceuticals for allowing immediate access to new disease treatments.
EARTH BENEFITS
In microgravity, the messages received by the
osteoblasts and osteoclasts are altered.
Specifically, without the stresses caused by
the Earth's gravitational pull, osteoclasts
remove more bone and osteoblasts deposit
less new bone. Understanding how these
signals change and how OPG mitigates these
changes gives scientists insight in how to
fight bone loss in crew members during long-
duration spaceflight and in osteoporosis
patients on Earth as osteoporosis is a major
public health threat for an estimated 44
million people worldwide.
SPACE BENEFITS
Crew members suffer from a significant loss of bone mass during spaceflight, the International
Space Station (ISS) Medical Project office has developed some countermeasures to hinder the
rapid loss of bone mass. Despite these countermeasures, bone mass loss continues to be a
problem for crew members. Finding additional countermeasures increases the overall health of
crew members on long-duration missions.
RESULTS
During ISS Expedition 4, 24 female mice were flown to ISS on shuttle flight STS-108 in 3AEMs.
The AEMs remained on STS-108 throughout the 12-day mission.
Mice exposed to microgravity exhibited a 15%-20% decline in femur elastic strength and a 40%-
60% decrease in bone formation when compared to the controls. The femur elastic strength
decline was caused by 3 mechanisms: reduced bone formation, increased bone resorption, and
inhibition of mineralization. OPG treatment in mice exposed to microgravity nearly reversed the
Image on the left shows a microCT image of trabecular
bone from proximal tibia from spaceflight mouse
compared to ground control mouse on right. NASA’s
Marshall Space Center image.