Individual and combined effects of noise-like whole-body vibration and parathyroid hormone treatment on bone defect repair in ovariectomized mice

The effectiveness of intermittent administration of parathyroid hormone (iPTH) and exposure to whole body vibration (WBV) on osteoporotic fracture healing has been previously investigated, but data on their concurrent use are lacking. Thus, we evaluated the effects of iPTH, WBV, and their combination on bone repair in osteoporotic mice. Noise-like WBV with a broad frequency range was used instead of conventional sine-wave WBV at a specific frequency. Mice were ovariectomized at 9 weeks of age, and subjected to drill-hole surgery in the right tibial diaphysis at 11 weeks. The animals were divided into four groups (n=12 each): a control group (C), and groups treated with iPTH (P), noise-like WBV (W), and both (PW). From postoperative day 2, the P and PW groups were subcutaneously administered PTH at a dose of 30 µg/kg/day. The W and PW groups were exposed to noise-like WBV at a root mean squared acceleration of 0.3 g and frequency components of 45 to 100 Hz for 20 min/day. Following 18 days of interventions, the right tibiae were harvested, and the regenerated bone was analyzed by micro-computed tomography and nanoindentation testing. Compared with C, callus volume fraction was 40% higher in P and 73% higher in PW and callus thickness was 35% wider in PW. Indentation modulus was 46% higher in W and 43% higher in PW, and hardness was 31% higher in PW compared with C. There was no interaction between the two treatments for both structure and mechanical indexes. The main effects of iPTH and noise-like WBV on bone repair included increased bone formation and enhanced mechanical function of regenerated bone, respectively. The combined treatment resulted in further regeneration of bone with high indentation modulus and hardness, suggesting the therapeutic potential of the combined use of noise-like WBV and iPTH for enhancing osteoporotic bone healing.

Takeshi Matsumoto, Daisuke Sato, and Yoshihiro Hashimoto, Individual and combined effects of noise-like whole-body vibration and parathyroid hormone treatment on bone defect repair in ovariectomized mice, Proceedings of the Institution of Mechanical Engineers, Part H : Journal of Engineering in Medicine (Volume: 230 issue: 1) pp.30-38. Copyright ©2015 SAGE Publications. DOI: 10.1177/0954411915616987.