• BMB Reports
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• v.49 no.3
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• pp.179-184
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• 2016

Bone morphogenetic protein 9 (BMP9) is a potent inducer of osteogenic differentiation of mesenchymal stem cells. The Wnt antagonist Dickkopf-1 (Dkk1) is involved in skeletal development and bone remodeling. Here, we investigated the role of Dkk1 in BMP9-induced osteogenic differentiation of MSCs. We found that overexpression of BMP9 induced Dkk1 expression in a dose-dependent manner, which was reduced by the P38 inhibitor SB203580 but not the ERK inhibitor PD98059. Moreover, Dkk1 dramatically decreased not only BMP9-induced alkaline phosphatase (ALP) activity but also the expression of osteocalcin (OCN) and osteopontin (OPN) and matrix mineralization of C3H10T1/2 cells. Furthermore, exogenous Dkk1 expression inhibited Wnt/β-catenin signaling induced by BMP9. Our findings indicate that Dkk1 negatively regulates BMP9-induced osteogenic differentiation through inhibition of the Wnt/β-catenin pathway and it could be used to optimize the therapeutic use of BMP9 and for bone tissue engineering.

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.119-130
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• 2002

The nonlinear finite element program has been developed to analyze the design performance of an artificial hip prosthesis and long term behavior of a treated femur with stems made of composite material after cementless total hip arthroplasty(THA). The authors developed the three dimentional FEM models of femoral bone with designed composite stem which was taken with elliptic cross section of 816 brick elements under hip contact load and muscle farce in simulating single leg stand. Using the program, density changes, stress distributions and micromotions of the material femoral bone were evaluated by changing fiber orientation of stems for selected manufacturing method such as plate cut and bend mold. The results showed that the composite materials such as AS4/PEEK and T300/976 gave less bone resorption than the metallic material such as cobalt chrome alloy, titanium alloy and stainless steal. It was found that increasing the long term stability of the prosthesis in the femur could be obtained by selecting the appropriate ply orientation and stacking sequence of composite.

• The Journal of Advanced Prosthodontics
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• v.6 no.3
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• pp.157-164
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• 2014

PURPOSE. This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source. MATERIALS AND METHODS. 40 commercially made pure titanium discs were prepared to produce Ti oxide machined surface (M) and Mg-incorporated Ti oxide machined surface (MM). Surface properties were analyzed using a scanning electron microscopy (SEM). On each surface, alkaline phosphatase (ALP) activity, alizarin red S staining for mineralization of MC3T3-E1 cells, and quantitative analysis of osteoblastic gene expression, were evaluated. Actin ring formation assay and gene expression analysis of TRAP and GAPDH performing RT-PCR were performed to characterize osteoclast differentiation on mouse bone marrow-derived macrophages (BMMs). RESULTS. MM showed similar surface morphology and surface roughness with M, but was slightly smoother after ion implantation at the micron scale. M was more hydrophobic than MM. No significant difference between surfaces on ALP activity at 7 and 14 days were observed. Real-time PCR analyses showed similar levels of mRNA expression of the osteoblast phenotype genes; osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen 1 (Col 1) in cell grown on MM at 7, 14 and 21 days. Alizarin red S staining at 21 days showed no significant difference. BMMs differentiation increased in M and MM. Actin ring formation assay and gene expression analysis of TRAP showed osteoclast differentiation to be more active on MM. CONCLUSION. Both M and MM have a good effect on osteoblastic cell differentiation, but MM may speed the bone remodeling process by activating on osteoclast differentiation.

• Journal of Biomedical Engineering Research
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• v.34 no.1
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• pp.14-23
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• 2013

In this study, biomechanical stability of the newly developed revision total knee arthroplasty (rTKA) was evaluated through strain and stress distribution analysis within the implanted proximal tibia using a three-dimensional finite element (FE) analysis. 2000N of compressive load (about 3 times body weight) was applied to the condyle surface on spacer, sharing by the medial (60%) and lateral (40%) condyles simulating a stance phase before toe-off. The results showed that PVMS within the revision total knee arthroplasty and the proximal tibia were less than yield strength considering safe factor 4.0 (rTKA: less than 10%, Cortical bone: less than 70%, Cancellous bone: less than 70%). The materials composed of them and the strain and stress distributions within the proximal tibia were generally well matched with those of a traditional revision total knee arthoplasty (Scorpio TS revision system, Stryker Corp., Michigan, USA) without the critical damage strain and stress, which may reduce the capacity for bone remodeling, leading to bone degeneration. This study may be useful to design parameter improvement of the revision total knee arthoplasty in biomechanical stability point of view beyond structural stability of revision total knee arthoplasty itself.

• BMB Reports
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• v.56 no.10
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• pp.545-550
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• 2023

Osteoporosis is a major public health concern, which requires novel therapeutic strategies to prevent or mitigate bone loss. Natural compounds have attracted attention as potential therapeutic agents due to their safety and efficacy. In this study, we investigated the regulatory activities of boeravinone B (BOB), a natural rotenoid isolated from the medicinal plant Boerhavia diffusa, on the differentiation of osteoclasts and mesenchymal stem cells (MSCs), the two main cell components responsible for bone remodeling. We found that BOB inhibited osteoclast differentiation and function, as determined by TRAP staining and pit formation assay, with no significant cytotoxicity. Furthermore, our results showing that BOB ameliorates ovariectomy-induced bone loss demonstrated that BOB is also effective in vivo. BOB exerted its inhibitory effects on osteoclastogenesis by downregulating the RANKL/RANK signaling pathways, including NF-κB, MAPK, and PI3K/Akt, resulting in the suppression of osteoclast-specific gene expression. Further experiments revealed that, at least phenomenologically, BOB promotes osteoblast differentiation of bone marrow-derived MSCs but inhibits their differentiation into adipocytes. In conclusion, our study demonstrates that BOB inhibits osteoclastogenesis and promotes osteoblastogenesis in vitro by regulating various signaling pathways. These findings suggest that BOB has potential value as a novel therapeutic agent for the prevention and treatment of osteoporosis.

• Biomolecules & Therapeutics
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• v.32 no.2
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• pp.205-213
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• 2024

Hydroxychavicol, a primary active phenolic compound of betel leaves, previously inhibited bone loss in vivo by stimulating osteogenesis. However, the effect of hydroxychavicol on bone remodeling induced by osteoclasts is unknown. In this study, the anti-osteoclastogenic effects of hydroxychavicol and its mechanism were investigated in receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclasts. Hydroxychavicol reduced the number of tartrate resistance acid phosphatase (TRAP)-positive multinucleated, F-actin ring formation and bone-resorbing activity of osteoclasts differentiated from RAW264.7 cells in a concentration-dependent manner. Furthermore, hydroxychavicol decreased the expression of osteoclast-specific genes, including cathepsin K, MMP-9, and dendritic cell-specific transmembrane protein (DC-STAMP). For mechanistic studies, hydroxychavicol suppressed RANKL-induced expression of major transcription factors, including the nuclear factor of activated T-cells 1 (NFATc1), c-Fos, and c-Jun. At the early stage of osteoclast differentiation, hydroxychavicol blocked the phosphorylation of NF-κB subunits (p65 and Iκβα). This blockade led to the decrease of nuclear translocation of p65 induced by RANKL. In addition, the anti-osteoclastogenic effect of hydroxychavicol was confirmed by the inhibition of TRAP-positive multinucleated differentiation from human peripheral mononuclear cells (PBMCs). In conclusion, hydroxychavicol inhibits osteoclastogenesis by abrogating RANKL-induced NFATc1 expression by suppressing the NF-κB signaling pathway in vitro.

• The Korean Journal of Zoology
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• v.39 no.3
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• pp.317-324
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• 1996

Osteoclast has been known as a primary responsible cell for the bone resorption. The activation of osteoclast, therefore, may be the key event in the regulation of bone growth and remodeling. Various factors were reported to have influence on the resorbing activity of osteoclast in organ culture. Among those factors, transforming growth factor-$\beta$ (TGF-$\beta$) has been known to have a profound effect on bone metabolism. Since a large amount of TGF-$\beta$ presents in bone tissue, it may be important for the understanding the regulatory mechanism of bone resorption to elucidate the effect of TGF-$\beta$ on the osteoclast. We have reported the dlsaggregated chick embryonic osteoclast culture as an useful assay method for determining the resorption activity of osteoclast. In this culture, we found that TGF-$\beta$ significantly enhaced the osteoclastic bone resorption activity. We also found that the timulatory effect seemed to be an indirect one that is mediated by other cells. As nordihydroguaiaretic acid significantly inhibited the TGF-$\beta$1-induced osteoclastic bone resorption, we suggest that the lipoxygenase derivative of arachidonic acid may participate in the action of TGF-$\beta$ as a paracrine or an autocrine mediator.

• Journal of Periodontal and Implant Science
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• v.46 no.4
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• pp.220-233
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• 2016

Purpose: The aim of this study was to present new a model that allows the study of the bone healing process, with an emphasis on the biological behavior of different graft-to-host interfaces. A standardized "over-inlay" surgical technique combined with a differential histomorphometric analysis is presented in order to optimize the use of critical-size calvarial defects in pre-clinical testing. Methods: Critical-size defects were created into the parietal bone of 8 male Wistar rats. Deproteinized bovine bone (DBBM) blocks were inserted into the defects, so that part of the block was included within the calvarial thickness and part exceeded the calvarial height (an "over-inlay" graft). All animals were sacrificed at 1 or 3 months. Histomorphometric and immunohistochemical evaluation was carried out within distinct regions of interest (ROIs): the areas adjacent to the native bone (BA), the periosteal area (PA) and the central area (CA). Results: The animals healed without complications. Differential morphometry allowed the examination of the tissue composition within distinct regions: the BA presented consistent amounts of new bone formation (NB), which increased over time ($24.53%{\pm}1.26%$ at 1 month; $37.73%{\pm}0.39%$ at 3 months), thus suggesting that this area makes a substantial contribution toward NB. The PA was mainly composed of fibrous tissue ($71.16%{\pm}8.06%$ and $78.30%{\pm}2.67%$, respectively), while the CA showed high amounts of DBBM at both time points ($78.30%{\pm}2.67%$ and $74.68%{\pm}1.07%$, respectively), demonstrating a slow remodeling process. Blood vessels revealed a progressive migration from the interface with native bone toward the central area of the graft. Osterix-positive cells observed at 1 month within the PA suggested that the periosteum was a source of osteoprogenitor elements. Alkaline phosphatase data on matrix deposition confirmed this observation. Conclusions: The present model allowed for a standardized investigation of distinct graft-to-host interfaces both at vertically augmented and inlay-augmented sites, thus possibly limiting the number of animals required for pre-clinical investigations.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.3
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• pp.191-196
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• 2020

Objectives: Beyond the original application approved by the U.S. Food and Drug Administration, recombinant human bone morphogenetic protein-2 (rhBMP-2) is used for medication-related osteonecrosis of the jaw (MRONJ) treatment because of its bone remodeling enhancement properties. The purpose of the study was to investigate the bone formation effect of rhBMP-2/absorbable collagen sponge (ACS) in patients with MRONJ. Materials and Methods: In this retrospective cohort study, 26 female patients diagnosed with MRONJ and who underwent mandibular sequestrectomy at Ajou University Dental Hospital from 2010 to 2018 were included. The experimental group was composed of 18 patients who received rhBMP-2/ACS after sequestrectomy, while the control group was composed of 8 patients who did not receive rhBMP-2/ACS after sequestrectomy. A total dose of 0.5 mg of rhBMP-2 was used in the experimental group at a concentration of 0.5 mg/mL. Follow-up panoramic X-rays were taken immediately after the surgery and more than 6 months after the surgery. Using those X-rays, a radiographic index of bone defect area was calculated using the modified Ihan Hren method, which measures radiographic density of the normal bone and the defect site. Results: This study suggests that rhBMP-2 contributes to new bone formation. The mean radiographic index immediately after surgery and more than 6 months after the surgery for the experimental group was 68.4% and 79.8%, respectively. The mean radiographic index immediately after surgery and more than 6 months after the surgery for the control group was 73.4% and 76.7%, respectively (Wilcoxon signed rank test, P>0.05). The mean radiographic index increased 11.4% in the experimental group and 3.27% in the control group (Mann-Whitney U-test, P<0.05). Conclusion: Based on the results, use of rhBMP-2/ACS on bone defect sites after sequestrectomy could be a successful strategy for treatment of MRONJ patients.

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.46-53
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• 2003

The current study investigated the effect of Korean safflower (Carthamus tinctorius L.) seed powder and its water and ethanol extracts on bone metabolism during recovery from rib-fracture induced by surgical operation in rats. 10-week-old male Sprague-Dawley rats weighing about 320 g were divided into 9 groups after arrival: 10d control (AIN 76 semi-purified diet), 10d safflower seed powder (10d SS-powder), 10d safflower seed ethanol extract (10d SS-EtOH), 10d safflower seed water extract (10d SS-$H_2O$), 20d control (AIN-76 semi-purified diet), 20d safflower heed powder (20d SS-powder), 20d safflower seed ethanol extract (20d SS-EtOH), 20d safflower seed water extract (20d SS-$H_2O$), and 20d sham-operation (20d sham), The dietary level for all the supplements was 5% based on the raw material weight. The rats were fed the experimental diets for 10 days before the rib fracture operation and for a further 10 or 20 days after the operation. A number 9 rib was fractured surgically and a sham-operation also performed. The rats were then sacrificed on the l0th or 20th day after the operation. The body weight initially decreased after the operation in all the rib-fractured groups, then gradually recovered. The concentrations of plasma osteocalcin were higher in the control group than in all the safflower-supplemented groups 10 and 20 days after the rib-fracture (p < 0.05). The bone-specific ALP (alkaline phosphatase) activity was significantly higher in the SS-EtOH group than in the other groups 20 days after the rib-fracture (p < 0.05). The level of urinary DPD (deoxypridinoline) was significantly higher in the SS-EtOH and SS-$H_2O$ groups than in the other groups 10 days after the rib-fracture. When comparing the PTH (parathyroid hormone) and calcitonin levels, the SS-$H_2O$ group exhibited the highest PTH level among the groups 10 and 20 days after the rib-fracture. Thus, it was concluded that the bone turnover during the fracture-healing period was more rapid in the rats supplemented with safflower seed powder or its fractions than in the control rats. Furthermore, the SS-$H_2O$ fraction was identified as the most effective in stimulating bone remodeling, as bone resorption and bone formation were both significantly increased during fracture healing when compared to the control group.