rhBMP-2-Conjugated Three-Dimensional-Printed Poly(L-lactide) Scaffold is an Effective Bone Substitute

BACKGROUND@#Bone growth factors, particularly bone morphogenic protein-2 (BMP-2), are required for effective treatment of significant bone loss. Despite the extensive development of bone substitutes, much remains to be desired for wider application in clinical settings. The currently available bone substitutes cannot sustain prolonged BMP-2 release and are inconvenient to use. In this study, we developed a ready-to-use bone substitute by sequential conjugation of BMP to a three-dimensional (3D) poly(L-lactide) (PLLA) scaffold using novel molecular adhesive materials that reduced the operation time and sustained prolonged BMP release. @*METHODS@#A 3D PLLA scaffold was printed and BMP-2 was conjugated with alginate-catechol and collagen. PLLA scaffolds were conjugated with different concentrations of BMP-2 and evaluated for bone regeneration in vitro and in vivo using a mouse calvarial model. The BMP-2 release kinetics were analyzed using ELISA. Histological analysis and microCT image analysis were performed to evaluate new bone formation. @*RESULTS@#The 3D structure of the PLLA scaffold had a pore size of 400 lm and grid thickness of 187–230 lm. BMP-2 was released in an initial burst, followed by a sustained release for 14 days. Released BMP-2 maintained osteoinductivity in vitro and in vivo. Micro-computed tomography and histological findings demonstrate that the PLLA scaffold conjugated with 2 lg/ml of BMP-2 induced optimal bone regeneration. @*CONCLUSION@#The 3D-printed PLLA scaffold conjugated with BMP-2 enhanced bone regeneration, demonstrating its potential as a novel bone substitute.

The Neuropeptide Spexin Promotes the Osteoblast Differentiation of MC3T3-E1 Cells via the MEK/ERK Pathway and Bone Regeneration in a Mouse Calvarial Defect Model

BACKGROUND@#The neural regulation of bone regeneration has emerged recently. Spexin (SPX) is a novel neuropeptide and regulates multiple biological functions. However, the effects of SPX on osteogenic differentiation need to be further investigated. Therefore, the aim of this study is to investigate the effects of SPX on osteogenic differentiation, possible underlying mechanisms, and bone regeneration. @*METHODS@#In this study, MC3T3-E1 cells were treated with various concentrations of SPX. Cell proliferation, osteogenic differentiation marker expressions, alkaline phosphatase (ALP) activity, and mineralization were evaluated using the CCK-8 assay, reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), ALP staining, and alizarin red S staining, respectively. To determine the underlying molecular mechanism of SPX, the phosphorylation levels of signaling molecules were examined via western blot analysis. Moreover, in vivo bone regeneration by SPX (0.5 and 1 lg/ll) was evaluated in a calvarial defect model. New bone formation was analyzed using micro-computed tomography (micro-CT) and histology. @*RESULTS@#The results indicated that cell proliferation was not affected by SPX. However, SPX significantly increased ALP activity, mineralization, and the expression of genes for osteogenic differentiation markers, including runt-related transcription factor 2 (Runx2), Alp, collagen alpha-1(I) chain (Col1a1), osteocalcin (Oc), and bone sialoprotein (Bsp). In contrast, SPX downregulated the expression of ectonucleotide pyrophosphatase/phosphodiesterase 1 (Enpp1). Moreover, SPX upregulated phosphorylated mitogen-activated protein kinase kinase (MEK1/2) and extracellular signal-regulated kinase (ERK1/2). in vivo studies, micro-CT and histologic analysis revealed that SPX markedly increased a new bone formation. @*CONCLUSION@#Overall, these results demonstrated that SPX stimulated osteogenic differentiation in vitro and increased in vivo bone regeneration via the MEK/ERK pathway.

Secretoneurin, a Neuropeptide, Enhances Bone Regeneration in a Mouse Calvarial Bone Defect Model

BACKGROUND@#This study investigates the effects of a neuropeptide, secretoneurin (SN), on bone regeneration in an experimental mouse model. @*METHODS@#The effects of SN on cell proliferation, osteoblast marker genes expression, and mineralization were evaluated using the CCK-8 assay, quantitative reverse transcriptase polymerase chain reaction (RT-PCR), and alizarin red S staining, respectively. To examine the effects of SN on bone regeneration in vivo, bone defects were created in the calvaria of ICR mice, and 0.5 or 1 lg/ml SN was applied. New bone formation was analyzed by micro-computed tomography (micro-CT) and histology. New blood vessel formation was assessed by CD34 immunohistochemistry. @*RESULTS@#SN had no significant effect on proliferation and mineralization of MC3T3-E1 cells. However, SN partially induced the gene expression of osteoblast differentiation markers such as runt-related transcription factor 2, alkaline phosphatase, collagen type I alpha 1, and osteopontin. A significant increase of bone regeneration was observed in SN treated calvarial defects. The bone volume (BV), BV/tissue volume, trabecular thickness and trabecular number values were significantly increased in the collagen sponge plus 0.5 or 1 lg/ml SN group (p < 0.01) compared with the control group. Histologic analysis also revealed increased new bone formation in the SN-treated groups. Immunohistochemical staining of CD34 showed that the SN-treated groups contained more blood vessels compared with control in the calvarial defect area. @*CONCLUSION@#SN increases new bone and blood vessel formation in a calvarial defect site. This study suggests that SN may enhance new bone formation through its potent angiogenic activity.

Combined effects of soy isoflavone and lecithin on bone loss in ovariectomized mice

BACKGROUND/OBJECTIVES@#Isoflavones (ISFs) are effective in preventing bone loss, but not effective enough to prevent osteoporosis. Mixtures of soy ISF and lecithin (LCT) were prepared and characterized in an attempt to improve the bone loss.MATERIALS/METHODS: The daidzein (DZ) and genistein (GN) solubility in soy ISF were measured using liquid chromatography-mass spectrometry. The change in the crystalline characteristics of soy ISF in LCT was evaluated using X-ray diffraction analysis.Pharmacokinetic studies were conducted to evaluate and compare ISF bioavailability. Animal studies with ovariectomized (OVX) mice were carried out to estimate the effects on bone loss. The Student's t-test was used to evaluate statistical significance. @*RESULTS@#The solubility of DZ and GN in LCT was 125.6 and 9.7 mg/L, respectively, which were approximately 25 and 7 times higher, respectively, than those in water. The bioavailability determined by the area under the curve of DZ for the oral administration (400 mg/kg) of soy ISF alone and the soy ISF-LCT mixture was 13.19 and 16.09 µg·h/mL, respectively. The bone mineral density of OVX mice given soy ISF-LCT mixtures at ISF doses of 60 and 100 mg/kg daily was 0.189 ± 0.020 and 0.194 ± 0.010 g/mm3 , respectively, whereas that of mice given 100 mg/kg soy ISF was 0.172 ± 0.028 g/mm3 . The number of osteoclasts per bone perimeter was reduced by the simultaneous administration of soy ISF and LCT. @*CONCLUSIONS@#The effect of preventing bone loss and osteoclast formation by ingesting soy ISF and LCT at the same time was superior to soy ISF alone as the bioavailability of ISF may have been improved by the emulsification and solvation of LCT. These results suggest the possibility of using the combination of soy ISF and LCT to prevent osteoporosis.

Secretoneurin, a Neuropeptide, Enhances Bone Regeneration in a Mouse Calvarial Bone Defect Model

BACKGROUND@#This study investigates the effects of a neuropeptide, secretoneurin (SN), on bone regeneration in an experimental mouse model. @*METHODS@#The effects of SN on cell proliferation, osteoblast marker genes expression, and mineralization were evaluated using the CCK-8 assay, quantitative reverse transcriptase polymerase chain reaction (RT-PCR), and alizarin red S staining, respectively. To examine the effects of SN on bone regeneration in vivo, bone defects were created in the calvaria of ICR mice, and 0.5 or 1 lg/ml SN was applied. New bone formation was analyzed by micro-computed tomography (micro-CT) and histology. New blood vessel formation was assessed by CD34 immunohistochemistry. @*RESULTS@#SN had no significant effect on proliferation and mineralization of MC3T3-E1 cells. However, SN partially induced the gene expression of osteoblast differentiation markers such as runt-related transcription factor 2, alkaline phosphatase, collagen type I alpha 1, and osteopontin. A significant increase of bone regeneration was observed in SN treated calvarial defects. The bone volume (BV), BV/tissue volume, trabecular thickness and trabecular number values were significantly increased in the collagen sponge plus 0.5 or 1 lg/ml SN group (p < 0.01) compared with the control group. Histologic analysis also revealed increased new bone formation in the SN-treated groups. Immunohistochemical staining of CD34 showed that the SN-treated groups contained more blood vessels compared with control in the calvarial defect area. @*CONCLUSION@#SN increases new bone and blood vessel formation in a calvarial defect site. This study suggests that SN may enhance new bone formation through its potent angiogenic activity.

Combined effects of soy isoflavone and lecithin on bone loss in ovariectomized mice

BACKGROUND/OBJECTIVES@#Isoflavones (ISFs) are effective in preventing bone loss, but not effective enough to prevent osteoporosis. Mixtures of soy ISF and lecithin (LCT) were prepared and characterized in an attempt to improve the bone loss.MATERIALS/METHODS: The daidzein (DZ) and genistein (GN) solubility in soy ISF were measured using liquid chromatography-mass spectrometry. The change in the crystalline characteristics of soy ISF in LCT was evaluated using X-ray diffraction analysis.Pharmacokinetic studies were conducted to evaluate and compare ISF bioavailability. Animal studies with ovariectomized (OVX) mice were carried out to estimate the effects on bone loss. The Student's t-test was used to evaluate statistical significance. @*RESULTS@#The solubility of DZ and GN in LCT was 125.6 and 9.7 mg/L, respectively, which were approximately 25 and 7 times higher, respectively, than those in water. The bioavailability determined by the area under the curve of DZ for the oral administration (400 mg/kg) of soy ISF alone and the soy ISF-LCT mixture was 13.19 and 16.09 µg·h/mL, respectively. The bone mineral density of OVX mice given soy ISF-LCT mixtures at ISF doses of 60 and 100 mg/kg daily was 0.189 ± 0.020 and 0.194 ± 0.010 g/mm3 , respectively, whereas that of mice given 100 mg/kg soy ISF was 0.172 ± 0.028 g/mm3 . The number of osteoclasts per bone perimeter was reduced by the simultaneous administration of soy ISF and LCT. @*CONCLUSIONS@#The effect of preventing bone loss and osteoclast formation by ingesting soy ISF and LCT at the same time was superior to soy ISF alone as the bioavailability of ISF may have been improved by the emulsification and solvation of LCT. These results suggest the possibility of using the combination of soy ISF and LCT to prevent osteoporosis.

Stimulatory Effects of KPR-A148 on Osteoblast Differentiation and Bone Regeneration

BACKGROUND: Xanthine derivatives have been used to treat a variety of medical conditions including respiratory disease and neural degeneration. However, few studies have reported their effects on bone regeneration. Therefore, we investigated the effects of KPR-A148, a synthetic xanthine derivative on osteoblast differentiation in vitro and bone regeneration in vivo. METHODS: The cytotoxicity of KPR-A148 was evaluated using MC3T3-E1 cells by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltertrazolium bromide assay. The effects of KPR-A148 on osteoblast differentiation were examined by alkaline phosphatase staining, Alizarin red S staining, and real-time PCR of osteoblast differentiation marker genes. To investigate the effects of KPR-A148 on in vivo bone regeneration, a KPR-A148-containing collagen sponge was implanted into a mouse calvarial defect and KPR-A148 was injected twice, weekly. Bone regeneration was evaluated quantitatively by micro-CT and qualitatively by hematoxylin and eosin, as well as Masson's Trichrome staining. RESULTS: KPR-A148 did not show toxicity in the MC3T3-E1 cells and promoted osteoblast differentiation in a concentration-dependent manner. 10 µM of KPR-A148 showed the most significant effect on alkaline phospatase staining and matrix mineralization. KPR-A148 increased the expression of osteoblast marker genes in both the early and late stages of differentiation. In addition, KPR-A148 significantly induced new bone formation in the calvarial defect model. CONCLUSION: These results demonstrate that KPR-A148 strongly induces osteoblast differentiation and new bone formation. Therefore, it could be used as a potential therapeutic agent for regenerating bone following its destruction by disease or trauma.

Pentamidine Inhibits Titanium Particle-Induced Osteolysis In Vivo and Receptor Activator of Nuclear Factor-κB Ligand-Mediated Osteoclast Differentiation In Vitro

BACKGROUND: Wear debris-induced osteolysis leads to periprosthetic loosening and subsequent prosthetic failure. Since excessive osteoclast formation is closely implicated in periprosthetic osteolysis, identification of agents to suppress osteoclast formation and/or function is crucial for the treatment and prevention of wear particle-induced bone destruction. In this study, we examined the potential effect of pentamidine treatment on titanium (Ti) particle-induced osteolysis, and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. METHODS: The effect of pentamidine treatment on bone destruction was examined in Ti particle-induced osteolysis mouse model. Ti particles were implanted onto mouse calvaria, and vehicle or pentamidine was administered for 10 days. Then, calvarial bone tissue was analyzed using micro-computed tomography and histology. We performed in vitro osteoclastogenesis assay using bone marrow-derived macrophages (BMMs) to determine the effect of pentamidine on osteoclast formation. BMMs were treated with 20 ng/mL RANKL and 10 ng/mL macrophage colony-stimulating factor in the presence or absence of pentamidine. Osteoclast differentiation was determined by tartrate-resistant acid phosphatase staining, real-time polymerase chain reaction, and immunofluorescence staining. RESULTS: Pentamidine administration decreased Ti particle-induced osteoclast formation significantly and prevented bone destruction compared to the Ti particle group in vivo. Pentamidine also suppressed RANKL-induced osteoclast differentiation and actin ring formation markedly, and inhibited the expression of nuclear factor of activated T cell c1 and osteoclast-specific genes in vitro. Additionally, pentamidine also attenuated RANKL-mediated phosphorylation of IκBα in BMMs. CONCLUSION: These results indicate that pentamidine is effective in inhibiting osteoclast formation and significantly attenuates wear debris-induced bone loss in mice.

Effect of Fibroblast Growth Factor-2 and Retinoic Acid on Lineage Commitment of Bone Marrow Mesenchymal Stem Cells

In this study, we examined the effect of a combination of fibroblast growth factor-2 (FGF-2) and retinoic acid (RA) on osteoblast and adipocyte lineage commitment and differentiation of human bone marrow mesenchymal stem cells (BMSCs). Pretreatment of human BMSCs with FGF-2 or RA for 5 days followed by osteoblast differentiation induction showed high calcium deposition compared to control. A combination of FGF-2 and RA further induced calcium deposition compared to FGF-2 or RA alone. The enhanced mineral deposition was accompanied with the increased expression of osteoblast differentiation markers, alkaline phosphatase and osteocalcin. On the other hand, FGF-2 pretreatment followed by adipocyte differentiation induction also showed increased formation of lipid droplets in human BMSCs, whereas RA pretreatment suppressed formation of lipid droplets. However, a combination of FGF-2 and RA increased formation of lipid droplets and expression of adipocyte marker genes, including adiponectin, ADIPOQ, FABP4, peroxisome proliferator-activated receptor γ (PPARγ), and C/EBPα. During pretreatment of BMSCs with FGF-2, RA or in combination, the cells expressed similar levels of MSC surface markers such as CD29, CD44, CD90, and CD105, indicating that they maintain stem cell potential. To determine how RA cooperates with FGF-2 in osteoblast and adipocyte lineage commitment, the expression of RA receptors and intracellular lipid-binding proteins was examined. A combination of FGF-2 and RA strongly induced the expression of RA receptor α, β, γ, PPAR β/δ, CRABP-II, and FABP5. Collectively, these results demonstrate that combined pretreatment of human BMSCs with FGF-2 and RA enhances the commitment into osteoblast and adipocyte lineages through modulation of the expression of RA-related genes.

Extracellular Calcium-Binding Peptide-Modified Ceramics Stimulate Regeneration of Calvarial Bone Defects

Secreted protein, acidic, cysteine-rich (SPARC)-related modular calcium binding 1 (SMOC1) has been implicated in the regulation of osteogenic differentiation of human bone marrow mesenchymal stem cells (BMSCs). In this study, we found that a peptide (16 amino acids in length), which is located in the extracellular calcium (EC) binding domain of SMOC1, stimulated osteogenic differentiation of human BMSCs in vitro and calvarial bone regeneration in vivo. Treatment of BMSCs with SMOC1-EC peptide significantly stimulated their mineralization in a dose-dependent manner without changing their rate of proliferation. The expression of osteogenic differentiation marker genes, including type 1 collagen and osteocalcin, also increased in a dose-dependent manner. To examine the effect of the SMOC1-EC peptide on bone formation in vivo, the peptide was covalently immobilized onto hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) particles. X-ray photoelectron spectroscopy analysis showed that the peptide was successfully immobilized onto the surface of HA/β-TCP. Implantation of the SMOC1-EC peptide-immobilized HA/β-TCP particles into mouse calvarial defects and subsequent analyses using microcomputed tomography and histology showed significant bone regeneration compared with that of calvarial defects implanted with unmodified HA/β-TCP particles. Collectively, our data suggest that a peptide derived from the EC domain of SMOC1 induces osteogenic differentiation of human BMSCs in vitro and efficiently enhances bone regeneration in vivo.

Association of ADIPOR1 polymorphisms with bone mineral density in postmenopausal Korean women

Adiponectin may affect bone through interactions with two known receptors, adiponectin receptors (ADIPOR) 1 and 2. We examined the association between polymorphisms of ADIPOR1 and ADIPOR2 and bone mineral density (BMD) in postmenopausal Korean women. Six polymorphisms in ADIPOR1 and four polymorphisms in ADIPOR2 were selected and genotyped in all study participants (n = 1,329). BMD at the lumbar spine and femur neck were measured using dual-energy X-ray absorptiometry. Lateral thoracolumbar (T4-L4) radiographs were obtained for vertebral fracture assessment and the occurrence of non-vertebral fractures examined using self-reported data. P values were adjusted for multiple testing using Bonferroni correction (Pcorr). ADIPOR1 rs16850799 and rs34010966 polymorphisms were significantly associated with femur neck BMD (Pcorr = 0.036 in the dominant model; Pcorr = 0.024 and Pcorr = 0.006 in the additive and dominant models, respectively). Subjects with the rare allele of each polymorphism had lower BMD, and association of rs34010966 with BMD showed a gene dosage effect. However, ADIPOR2 single nucleotide polymorphisms and haplotypes were not associated with BMD at any site. Our results suggest that ADIPOR1 polymorphisms present a useful genetic marker for BMD in postmenopausal Korean women.

Association of Paraoxonase 1 (PON1) polymorphisms with osteoporotic fracture risk in postmenopausal Korean women

There is increasing evidence of a biochemical link between lipid oxidation and bone metabolism. Paraoxonase 1 (PON1) prevents the oxidation of low-density lipoprotein (LDL) and metabolizes biologically active phospholipids in oxidized LDLs. Here, we performed association analyses of genetic variation in PON1 to ascertain its contribution to osteoporotic fractures (OFs) and bone mineral density (BMD). We directly sequenced the PON1 gene in 24 Korean individuals and identified 26 sequence variants. A large population of Korean postmenopausal women (n = 1,329) was then genotyped for eight selected PON1 polymorphisms. BMD at the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry. Lateral thoracolumbar (T4-L4) radiographs were obtained for vertebral fracture assessment, and the occurrence of non-vertebral fractures (i.e., wrist, hip, forearm, humerus, rib, and pelvis) was examined using self-reported data. Multivariate analyses showed that none of the polymorphisms was associated with BMD at either site. However, +5989A>G and +26080T>C polymorphisms were significantly associated with non-vertebral and vertebral fractures, respectively, after adjustment for covariates. Specifically, the minor allele of +5989A>G exerted a highly protective effect against non-vertebral fractures (OR = 0.59, P = 0.036), whereas the minor allele of +26080T>C was associated with increased susceptibility to vertebral fractures (OR = 1.73, P = 0.020). When the risk for any OFs (i.e., vertebral or non-vertebral) was considered, the statistical significance of both polymorphisms persisted (P = 0.002-0.010). These results suggest that PON1 polymorphisms could be one of useful genetic markers for OF risk in postmenopausal women.

Inhibitory effect of (-)-epigallocatechin gallate on titanium particle-induced TNF-alpha release and in vivo osteolysis

Tumor necrosis factor-alpha (TNF-alpha) and inflammatory cytokines released from activated macrophages in response to particulate debris greatly impact periprosthetic bone loss and consequent implant failure. In the present study, we found that a major polyphenolic component of green tea, (-)-epigallocatechin gallate (EGCG), inhibited Ti particle-induced TNF-alpha release in macrophages in vitro and calvarial osteolysis in vivo. The Ti stimulation of macrophages released TNF-alpha in a dose- and time-dependent manner, and EGCG substantially suppressed Ti particle-induced TNF-alpha release. Analysis of signaling pathway showed that EGCG inhibited the Ti-induced c-Jun N-terminus kinase (JNK) activation and inhibitory kappaB (IkappaB) degradation, and consequently the Ti-induced transcriptional activation of AP-1 and NF-kappaB. In a mouse calvarial osteolysis model, EGCG inhibited Ti particle-induced osteolysis in vivo by suppressing TNF-alpha expression and osteoclast formation. Therefore, EGCG may be a potential candidate compound for osteolysis prevention and treatment as well as aseptic loosening after total replacement arthroplasty.

Genetic association of angiogenesis- and hypoxia-related gene polymorphisms with osteonecrosis of the femoral head

Multiple factors have been implicated in the development of osteonecrosis of the femoral head (ONFH). In particular, non-traumatic ONFH is directly or indirectly related to injury of the vascular supply to the femoral head. Thus, hypoxia in the femoral head caused by impaired blood flow may be an important risk factor for ONFH. In this study, we investigated whether genetic variations of angiogenesis- and hypoxia-related genes contribute to an increased risk for the development of ONFH. Candidate genes were selected based on known hypoxia and angiogenesis pathways. An association study was performed using an Affymetrix Targeted Genotyping 3K Chip array with 460 ONFH patients and 300 control subjects. We showed that single nucleotide polymorphisms (SNPs) in the genes TF, VEGFC, IGFBP3, and ACE were associated with an increased risk of ONFH. On the other hand, SNPs in the KDR and NRP1 genes were associated with protection against ONFH. The most important finding was that one SNP (rs2453839) in the IGFBP3 gene was significantly associated with a higher risk of ONFH (P = 0.0061, OR 7.74). In subgroup analysis, most candidate gene variations that were associated with ONFH occurred in the idiopathic subgroup. Among other SNPs, ACE SNPs were associated with steroid-induced ONFH (P = 0.0018-0.0037, OR > 3). Collectively, our findings suggest that genetic variations in angiogenesis- and hypoxia-related genes may help to identify susceptibility factors for the development of ONFH in the Korean population.

Association of Common Vitamin D Receptor Gene Variations with Fracture Risk and Bone Mineral Density in Postmenopausal Korean Population

Osteoporosis is characterized by impaired osteogenesis. BMD is a major determinant of bone strength. The role of the VDR gene in predisposition to primary osteoporosis has been recognized. However, population-based case-control studies have been reported controversial results for known candidate genes in an ethnically distinct group. To determine the genetic effects of VDR variants on osteoporosis and BMD, we directly sequenced the VDR gene in 24 unrelated Korean individuals and identified eighteen sequence variants. We investigated the potential involvement of eight SNPs in osteoporosis in postmenopausal women (n = 729). Two SNPs (LD) in intron 2, -5294G > C (rs2238135) and -4817G > A (rs17882443) showed the evidence of association with enhanced BMD of the femoral neck (p(additive) =0.031 for rs2238135; p(additive)=0.017 and p(dominant)= 0.019 for 17882443). Moreover, VDR -4817G > A was significantly associated with protective effect on all fracture risk (p(recessive)=0.035, OR=0.2, 95% CI=0.05~0.89), and tended to be higher BMD values at various proximal femur sites. Therefore, we suggest that the -4817G > A may be useful genetic marker for vitamin D-related metabolism and may have an important role in the increased BMD of the proximal femur in postmenopausal Korean women.

Association of polymorphisms in the Interleukin 23 receptor gene with osteonecrosis of femoral head in Korean population

Osteonecrosis of the femoral head (ONFH) is known as death of the cellular portion of the femoral head due to an interruption in the vascular supply. The underlying pathophysiology regarding bone cell death remains uncertain. Recently, several studies have shown that autoimmune disorders were related to the development of osteonecrosis. This study investigated the genetic effects of Interleukin 23 receptor (IL23R) polymorphisms regarding the risk of ONFH. Ten SNPs were selected and genotyped in 443 ONFH patients and 273 control subjects in order to perform the genetic association analysis. It was found that polymorphisms of the IL23R gene (rs4655686, rs1569922 and rs7539625) were significantly associated with an increased risk of ONFH (P values; 0.0198-0.0447, OR; 1.30-1.49). Particularly, a stratified analysis based on etiology (alcohol, steroid or idiopathic) showed that the associations between these polymorphisms and ONFH were most significant in idiopathic ONFH patients (P values; 0.0001-0.0150, OR; 1.45-2.17). These results suggest that IL23R polymorphisms may play an important role in the development of ONFH.

gp130 is important for the normal morphogenesis of Meckel's cartilage and subsequent mandibular development

gp130-mediated signaling is involved in both chondrogenesis and osteogenesis, but its direct role in the formation of embryonic Meckel's cartilage and associated mandibular development has not yet been elucidated. In this study, we examined the influence of gp130 ablation on the developing mandibular Meckel's cartilage by evaluating the morphological and histological changes as well as the gene expression patterns in developing embryonic gp130-/- mice. The ablation of the gp130 gene showed no change in region-specific collagen mRNA expression except for a slight delay in its expression but caused shortened embryonic Meckel's cartilage, delayed hypertrophic chondrocyte maturation and subsequent bony replacement with characteristic bending of the intramandibular Meckel's cartilage. The bending of Meckel's cartilage led to a narrow mandibular arch at the rostral area with poor cortical plate formation. These findings indicate that gp130-mediated signaling is important for the normal morphogenesis of Meckel's cartilage and subsequent mandibular development.

Methionine synthase reductase polymorphisms are associated with serum osteocalcin levels in postmenopausal women

Homocysteine (Hcy) is thought to play an important role in the development of osteoporosis and fracture. Methionine synthase reductase (MTRR) is an enzyme involved in the conversion of Hcy to methionine. We hypothesized that certain genetic polymorphisms of MTRR leading to reduced enzyme activity may cause hyperhomocysteinemia and affect bone metabolism. We therefore examined the associations of the A66G and C524T polymorphisms of the MTRR gene with bone mineral density (BMD) and serum osteocalcin levels in postmenopausal women. Although we did not detect any significant associations between MTRR polymorphisms and BMD or serum osteocalcin levels, we found that the 66G/524C haplotype, which has reduced enzyme activity, was significantly associated with serum osteocalcin levels in a gene-dose dependent manner (P=0.002). That is, the highest osteocalcin levels (34.5+/-16.8 ng/ml) were observed in subjects bearing two copies, intermediate osteocalcin levels (32.6+/-14.4 ng/ml) were observed in subjects bearing one copy, and the lowest levels of osteocalcin (28.8+/-10.9 ng/ml) were observed in subjects bearing no copies. These results suggest that the 66G/524C haplotype of the MTRR gene affect bone turn over rate.

Analysis of Bone Mineral Density and Biochemical Markers in Hip Fractures Injured by Low-energy Trauma / 대한정형외과학회잡지

PURPOSE: This study was conducted to compare bone mineral density (BMD) and biochemical markers of bone metabolism of an osteoporotic hip fracture group with those of a control group. MATERIALS AND METHODS: The fracture group included 76 patients with hip fractures who were injured by low energy trauma from November, 1999 to August, 2003. The control group consisted of 83 patients recruited over the same period. There were 22 men and 54 women in the fracture group, with an average age of 67.2 years for men and 71.1 years for women. In the control group, there were 22 men and 61 women, of average age 67.9 years for men and 70.1 years for women. There were no siginificant differences in age, height, weight, or body mass index. We analyzed BMD by a dual energy X-ray absorptiometry (DEXA). Bone specific alkaline phosphatase (B-ALP) and osteocalcin were used as markers of bone formation and urine-deoxypyridinoline (DPD) as a maker of bone resorption. RESULTS: B-ALP showed a significant decrease in the fracture group (p<0.05). Also, average serum osteocalcin showed a significant decrease in the fracture group (p<0.05). There was no significant difference in urine-DPD between the two groups. The mean values of BMD in men and women were significantly decreased in the fracture group. CONCLUSION: The results of this study suggest that a decreased BMD contributes to hip fractures in elderly people and that B-ALP and serum osteocalcin rather than urine-DPD are reliable biochemical markers of bone metabolism in osteoporotic hip fractures.

Cellular Biocompatibility and Stimulatory Effects of Calcium Metaphosphate on Osteoblastic Differentiation of Human Bone Marrow-derived Stromal Cells / 대한정형외과연구학회지

PURPOSE: The in vitro biocompatibility of Calcium Metaphosphate (CMP) with human bone marrow stromal cells (HBMSCs) and its effect on osteoblastic differentiation have been evaluated. MATERIALS AND METHODS: The effects of CMP on the HBMSCs undergoing osteoblastic differentiation were evaluated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Morphologies of the HBMSCs were examined using scanning electron microscopy and confocal laser scanning microscopy. Osteoblastic differentiation of the HBMSCs was analyzed by alkaline phosphatase (ALP) staining and RTPCR. RESULTS: The CMP powder and disk did not exert cytotoxic effect on the HBMSCs. In addition, the HBMSCs were adhered on the surface of CMP disk as successfully as on the culture plate or HA disk and displayed similar actin arrangement and cellular phenotypes. Furthermore, the HBMSCs grown on three different matrices were able to support osteoblastic differentiation of the HBMSCs as accessed by ALP staining. However, the CMP disk compared to the HA disk has a better ability to induce expression of osteoblast-related genes such as ALP, osteopontin (OPN) and osteoprotegerin (OPG). CONCLUSION: The results demonstrate that, in addition to biocompatibility of the CMP with the HBMSCs, the CMP has an ability to stimulate osteoblastic differentiation of the HBMSCs in vitro.