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Osteoclasts (OCs) differentiate from monocyte/macrophage-lineage hematopoietic precursor cells, which are known as OC precursors (OCPs). Several studies have investigated cell chemotaxis in the bone microenvironment; however, OCP migration ability in the bone microenvironment during OC differentiation is yet to be elucidated. As an initial investigation of this characteristic, the present study aimed to determine the effects of transforming growth factor (TGF)-β1 on OCP migration in vitro. Pre-osteoclastic RAW264.7 cells were cultured with and without TGF-β1 (2, 5 or 20 ng/ml), receptor activator of NF-κB ligand (RANKL; 50 ng/ml), and/or SB431542 (10 µM), a potent and specific inhibitor of TGF-β1 receptor kinase activity. Cell proliferation was significantly inhibited in the presence of TGF-β1 for 3 days, and the effect was reversed by SB431542. Tartrate-resistant acid phosphatase (TRAP) activity in RAW264.7 cells was significantly increased by RANKL treatment, compared with TRAP activity in control cells on day 3. The highest TRAP activity in RAW264.7 cells was induced by the combined treatment with TGF-β1 (2 ng/ml) and RANKL. When TGF-β1 signaling was inhibited by addition of SB431542 to the medium during culture, OC differentiation was notably suppressed. These findings suggest that TGF-β1 accelerates RANKL-induced OC differentiation, but does not act in a dose-dependent manner. The migration of RAW264.7 cells was promoted at 24 h, but was suppressed at 72 h, during RANKL-induced osteoclast differentiation in the presence of TGF-β1. These results were accompanied with the increased expression of small G-proteins, RhoA and Rac, at 24 h, but their expression decreased at 72 h. RAW264.7 cells treated with TGF-β1 for 24 h underwent morphological changes, from round to polygonal morphology. Furthermore, protrusions were completely lost and the cell morphology reverted from polygonal to round after TGF-β1 treatment for 72 h. Therefore, our findings indicated that OCP migration may be modified by differentiation in vitro. [ABSTRACT FROM AUTHOR]

Aging is a significant risk factor for the development of bisphosphonate-related osteonecrosis of the jaws (BRONJ). Accumulating evidence suggests that bone aging is associated with oxidative stress (OS), and OS is associated with osteonecrosis. To elucidate the mechanisms of the onset of BRONJ, the present study focused on OS and the effects of treatment with the pro-oxidant DL-buthionine-(S,R)-sulfoximine (BSO), an oxidative stressor, on healing of a surgically induced penetrating injury of the palate. Six-week-old C57BL/6J mice were randomly divided into four groups (n=5 each) and treated with or without zoledronic acid (ZOL) and with or without BSO (experimental groups: ZOL, BSO, and ZOL+BSO; control group: saline solution). A penetrating injury of the midline palate was surgically created using a root elevator. ZOL (250 µg/kg/day) was injected intraperitoneally every day from 7 days prior to the surgical treatment to 4 days following the surgical treatment. BSO (500 µg/kg/day) was administered 7 days prior to the surgical treatment as a single intraperitoneal injection. The maxillae were harvested at 5 days following the surgical treatment for histological and histochemical studies. The presence of empty osteocyte lacunae in the palatal bone was increased by ZOL and BSO treatment. The highest number of empty osteocyte lacunae was observed in the ZOL+BSO group. The number of tartrate-resistant acid phosphatase-positive cells was decreased by ZOL treatment and increased by BSO treatment. The number of canaliculi per osteocyte lacuna was significantly decreased by BSO treatment. The mineral apposition rate was significantly lower in the treatment groups than the control group. Bisphosphonates and OS suppressed bone turnover. The present study has demonstrated that BSO treatment affects osteocytes, and OS in osteocytes exacerbates impairment of the osteocytic canalicular networks. As a result, bisphosphonates and OS may induce osteonecrosis following invasive dentoalveolar surgery. OS has been identified as an additional risk factor for the development of BRONJ. [ABSTRACT FROM AUTHOR]

We aimed to evaluate the biological properties of engineering plastics (PC, PSU, PAR) processed using supercritical carbon dioxide (scCO 2 ). Conventional mold process was used to prepare disk-shaped samples that were then plasticized by scCO 2 at temperatures lower than the glass transition temperature (T g ) of the polymers. Surface roughness, contact angle, and amount of adsorbed protein on the surface were increased after treatment. The surface roughness of PC was significantly changed by scCO 2 treatment. Cell adhesion and proliferation changed according to the differences in surface roughness. Initially, the cell adhesion decreased in all scCO 2 -treated polymers. At 3 day, the cell proliferation on scCO 2 -treated PC was lower than that on non-treated PC, while that on treated and non-treated PSU and PAR samples remained unaltered. These results suggest that when supercritical treatment is performed under conditions that affect the surface properties of the material, we should consider that cell adhesion and proliferation may change.