Low Magnitude and High Frequency Vibration Prevents Simulated Microgravity-Induced Decrease in a Bone Formation Response in Osteoblasts
- Paper number
IAC-06-A1.4.09
- Author
Ms. Mamta Patel, Georgia Institute of Technology, United States
- Coauthor
Mr. Roger Talish, United States
- Coauthor
Dr. Clinton Rubin, United States
- Coauthor
Dr. Hanjoong Jo, Emory University, United States
- Year
2006
- Abstract
Microgravity induces bone loss in astronauts, and this pathology must be addressed for safe, long-term manned spaceflights such as missions to Mars. Recently, we have shown that exposure of 2T3 pre-osteoblasts to a microgravity simulator called the Random Positioning Machine (RPM) inhibits alkaline phosphatase (ALP) enzyme activity, a marker of bone formation (Pardo and Patel, et al., AJP Cell Physiol, 2005). As a potential countermeasure for osteoporosis associated with aging and/or reduced physical activity, it has been shown in both animals (Rubin, et al., FASEB, 2001) and humans (Rubin, et al., JBMR, 2004) that brief (<20 minutes per day) exposure to extremely low magnitude (0.3g) and high frequency (30-90Hz) mechanical vibration can serve as an anabolic signal to the musculoskeletal system. Here, we examined the hypothesis that a low magnitude, high frequency vibration applied to osteoblasts would prevent simulated microgravity-induced decrease in bone formation. To test our hypothesis, pre-osteoblast 2T3 cells were exposed to static 1g conditions or simulated microgravity using the RPM with or without the mechanical vibration using a custom-built vibration platform (Juvent, Inc). Experiments were performed for 3 days, and the cells were exposed to a vibration of 0.3g magnitude and 30Hz frequency for 10 minutes/day before measuring ALP activity. The experimental groups included: 1) Static: cells incubated at static 1g conditions, 2) Static+Vibration: an additional group of static cells mechanically vibrated, 3) RPM: cells exposed to simulated microgravity, 4) RPM+Vibration: an RPM group removed from the RPM and exposed to mechanical vibration, and 5) RPM+Static: an RPM group removed and exposed to static 1g conditions for 10 minutes/day. Compared to static 1g control at 100%, the vibration increased ALP activity in static cells (Static-Vibrated) by 33% (p<0.001, n=9), and the RPM decreased ALP activity by 24% (p<0.001, n=9). This RPM-induced decrease was completely prevented by exposing the cells to a mechanical vibration (RPM+Vibration) with an increase in ALP activity of 25% (p<0.01, n=9). However, exposure to static 1g conditions (RPM-Static) did not recapture ALP activity (p>0.10, n=3). This is the first in vitro study demonstrating that exposure of osteoblasts to a low magnitude and high frequency mechanical vibration promotes their anabolic activity in simulated microgravity conditions. Our results suggest the possibility that a low magnitude and high frequency mechanical vibration could provide an effective countermeasure against bone loss induced by microgravity conditions during long-term spaceflight and for musculoskeletal pathologies in the general population.
- Abstract document
- Manuscript document
IAC-06-A1.4.09.pdf (🔒 authorized access only).
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