Date of Award

Summer 2015

Document Type


Degree Name

Master of Science (MS)



First Advisor

Liu, Dawei

Second Advisor

Lobb, William K.

Third Advisor

Bradley, Gerald T.


Low-magnitude high-frequency (LMHF) mechanical vibration has been demonstrated to enhance bone formation possibly through inhibition of osteoclastogenesis of bone. Earlier research has demonstrated osteoclast formation from RAW264.7 monocytes was inhibited by a chewing cycle mimicking vibration through inhibition of dendritic cell-specific transmembrane protein (DC-STAMP). We hypothesize that application of LMHF mechanical vibration directly inhibits osteoclast formation from RAW264.7 monocytes in a frequency dependent manner. RAW264.7 monocytes (ATCC) were cultured in alpha minimal essential medium (MEM) with 10% fetal bovine serum (FBS ) and 1% Pen/Strep at 37°C and 5% CO2. The cells were seeded at a density of 2000 cells/well in 96-well cell culture plates. After allowing growth overnight, the cells were treated with 20ng/ml receptor activator nuclear factor kappa-B ligand (RANKL) and refreshed every 2 days to induce osteoclast formation. In the meantime, the cells were subjected to a low-magnitude (0.3g acceleration) mechanical vibration at various frequencies (0, 30, 60 and 90 Hz) respectively. For each frequency group, the vibration was applied for 1 hour per day for 5 consecutive days. By the end of the 5th day, the cells were rinsed with 1X PBS and fixed in 4% formaldehyde for 5 minutes. Tartrate-resistant Acidic Phosphatase (TRAP, a marker enzyme of osteoclast) staining was performed. The TRAP+ multi nuclei (> = 3) cells were counted and calculated. For statistical analysis, one-way ANOVA was used to test differences among the different frequency groups with Tukey post hoc comparison was used to compare between the groups, with p value being set at 0.05. Three days after RANKL stimulation, osteoclasts started to form from RAW264.7 monocytes, with a peak observed on the 5th day. After 5 days, the cells underwent apoptosis and death. Compared to the control group (0 Hz), the 30 Hz but not 60 Hz and 90 Hz frequencies of vibration group showed significant reduction of osteoclast formation by approximately 21% (p < 0.05, n = 6). No significant difference was found among the three frequency groups. Low-magnitude high-frequency mechanical vibration directly inhibits osteoclast formation from RAW264.7 monocytes, and is frequency dependent.