Efficacy of electrical polarization on a rat femoral bone defect model with a custom-made external fixator.

BACKGROUND: We have developed a technology to electrically polarize living bone. OBJECTIVE: The effects of stored electrical charge in electrical polarized bone on the facilitation of new bone formation were assayed. METHODS: Stimulated depolarized current measurement was performed in electrically polarized and nonpolarized femora of SD rats. These bone specimens were implanted into bone defects of the rat femora and fixed with a custom-made external fixator. X-ray imaging of the implant was performed every week. After 3 weeks, micro-CT scanning was performed to evaluate the displacement rate. Histological observation was performed, and the occupancy ratio of the newly formed bone was calculated from tissue specimens stained with Villanueva's Goldner method. RESULTS: There was a tendency for the displacement rate of the implant to be smaller and the occupancy ratio of the newly formed bone to be larger, especially at the distal end, in the polarized group compared with the nonpolarized group. The time of callus appearance was significantly earlier in the polarized group than in the nonpolarized group, and bridging callus grew from the distal to the proximal end. CONCLUSIONS: Bone specimens can be electrically polarized, and the stored electrical charge can work effectively to facilitate new bone formation.

Antitumor effects of pristimerin on human osteosarcoma cells in vitro and in vivo.

There are very few treatments for musculoskeletal tumors, compared to other cancers; thus, novel therapeutic drugs are needed. Pristimerin (PM) is a triterpene compound isolated from plant extracts that reportedly has antitumor effects on various cancers, such as of the breast and prostate. The purpose of this study was to evaluate the antitumor effects of PM on human osteosarcoma cells. Treatment of the human osteosarcoma cell lines, MNNG and 143B, with PM led to a dose-dependent decrease in cell viability. The effects of PM on apoptosis were evaluated with the Annexin V/propidium iodide assay and analysis of caspases 3, 8, and 9 activities. Western blot analysis showed that PM caused a decrease in the expression of Akt, mTOR, and NF-κB. The volumes and weights of human osteosarcoma xenografts decreased significantly with PM treatment. The results of this study revealed that PM can inhibit human osteosarcoma growth in vitro and in vivo, and may be a novel therapeutic agent for the disease.