The osteoblast: a sophisticated fibroblast under central surveillance

Biological effects of apatite nanoparticle-constructed ceramic surfaces in regulating behaviours of mesenchymal stem cells

HCA nanoparticle-constructed nanotopography in vivo mediates bone marrow MSCs to condensate and spontaneously differentiate towards the osteogenic lineage.

MMP-2 silencing reduces the osteogenic transformation of fibroblasts by inhibiting the activation of the BMP/Smad pathway in ankylosing spondylitis

Ankylosing spondylitis (AS) is a common type of rheumatoid disease, which has recently been demonstrated to be associated with the expression of matrix metalloproteinase (MMP)-2. The aim of the present study was to investigate whether MMP-2 interference reduced the osteogenic differentiation of fibroblasts and to explore the mechanism involved in the differentiation. Fibroblasts from patients with AS were divided into control, mock and small interfering (si)RNA-MMP-2 groups. Cell viability was assessed using the MTT assay. mRNA and protein expression levels of MMP-2, core-binding factor a1 (Cbfa-1) and bone morphogenetic proteins/Smad-signalling molecules (BMP/Smad) were measured using reverse transcription-quantitative polymerase chain reaction and western blotting. The results indicated that cell viability and fibroblast morphology did not differ significantly between healthy volunteers and patients with AS. However, MMP-2 expression levels in AS fibroblasts were substantially higher. MMP-2 gene silencing markedly downregulated the expression of MMP-2 and Cbfa-1, and inhibitied the activation of the BMP/Smad signalling pathway consequent to the reduction in levels of BMP-2, Smad1, Smad4 and Smad1/5/8. The results showed that MMP-2 gene silencing may reduce the osteogenesis of fibroblasts in AS by inhibiting the activation of the BMP/Smad signalling pathway.

Culture of Human Primary Bone Cells and Phenotype Assessment

Bone engineering scaffolds and biomimetic substitutes are currently the leading techniques to repair and regenerate bone defects. Ideally, bone grafts should imitate the structure and properties of bone extracellular matrix, house osteoprogenitor cells, and provide all the necessary environmental cues to orchestrate the functions of osteoblast and osteoclast cells. Consequently, there is an increasing demand for preclinical models based on in vitro bone-derived cell cultures for screening of novel biomaterials. In this chapter, we provide the protocols for culture of primary human bone cells from explants of cortical mandible bone and for characterization of cell behavior on biomimetic surfaces in terms of strength of adhesion, proliferation, differentiation, and matrix mineralization.

Serum undercarboxylated osteocalcin correlates with hemoglobin A1c in children with recently diagnosed pediatric diabetes

BACKGROUND

Osteocalcin (OC), a hormone secreted by osteoblasts, improves beta-cell function in vitro and in vivo. We aimed to understand the relationship between OC and hemoglobin A1c (HbA1c) in pediatric diabetes.

METHODS

Children (n = 70; mean [SD] age = 11.8 years [3.1]; 34.3% non-Hispanic white, 46.3% Hispanic, 14.9% African-American, 4.5% other) newly diagnosed with diabetes (69.1% type 1 diabetes [T1D], 30.9% type 2 diabetes [T2D]) were studied. We collected clinical data at diagnosis and first clinical visit (V1) 9 weeks later (interquartile range [IQR] = 7.9-12.0). Serum undercarboxylated OC (uOC) and carboxylated OC (cOC) were measured 7.0 weeks (IQR 4.3-8.9) after diagnosis.

RESULTS

Mean [SD] uOC was 20.3 (19.6) ng/mL, cOC 29.7 [13.7] ng/mL and u/cOC 0.68 [0.81]. uOC, cOC, or u/cOC were not different by gender, race/ethnicity, age, diabetes type, BMI percentile, or random C-peptide, glucose or HbA1c at diagnosis. However, among 61 children with V1 within 4 months of diagnosis, uOC was higher in those with V1 HbA1c < 7.5% (HbA1c < 58 mmol/mol) (uOC=33.1 [22.0]) compared with children with HbA1c ≥ 7.5% (uOC=17.4 [2.3], P = .0004). The difference was larger among patients with T2D (34.6 and 4.7 ng/mL, respectively, P = .0001) than T1D (32.2 and 19.3, P = .0169), and in males (36.1 and 17.4, P = .018) than females (27.6 and 17.3, P = .072). Analysis for u/cOC were similar while there were no differences in cOC. uOC was inversely correlated with HbA1c at V1 (Spearman's rho = -0.29, P = .02).

CONCLUSION

Our findings suggest that serum uOC is inversely related to HbA1c shortly after diagnosis of pediatric diabetes. This potentially modifiable factor of glucose metabolism warrants further studies.

Nonmineralized and Mineralized Collagen Scaffolds Induce Differential Osteogenic Signaling Pathways in Human Mesenchymal Stem Cells

The instructive capabilities of extracellular matrix components in progenitor cell differentiation have recently generated significant interest in the development of bioinspired materials for regenerative applications. Previously, a correlation was described between the osteogenic capabilities of nanoparticulate mineralized collagen glycosaminoglycan scaffolds (MC-GAG) and an autogenous activation of small mothers against decapentaplegic ( Smad1/5) in the canonical bone morphogenetic protein receptor (BMPR) pathway with a diminished extracellular signal regulated kinase 1/2 (ERK1/2) activation when compared to nonmineralized collagen glycosaminoglycan scaffolds (Col-GAG). This work utilizes a canonical BMPR inhibitor (dorsomorphin homologue 1, DMH1) and an inhibitor of the mitogen activated protein kinase/ERK kinase (MEK)/(ERK) cascade (PD98059) to characterize the necessity of each pathway for osteogenesis. While DMH1 inhibits runt-related transcription factor 2 (Runx2) and bone sialoprotein II (BSPII) gene expression of primary human mesenchymal stem cells (hMSCs) on MC-GAG, PD98059 inhibits BSPII expression on Col-GAG independent of Runx2 expression. DMH1 inhibits mineralization on both Col-GAG and MC-GAG, however, PD98059 only inhibits mineralization on Col-GAG. DMH1 inhibits both Smad1/5 phosphorylation and Runx2 protein expression, whereas PD98059 inhibits ERK1/2 and c-Jun amino-terminal kinase 1/2 (JNK1/2) phosphorylation without affecting Runx2. Thus, activation of the canonical BMPR signaling is necessary for osteogenic differentiation and mineralization of hMSCs on Col-GAG or MC-GAG. The MEK/ERK cascade, intimately tied to JNK activation, is necessary for Runx2-independent osteogenesis on Col-GAG, while completely dispensable in osteogenesis on MC-GAG.

miR-208a-3p Suppresses Osteoblast Differentiation and Inhibits Bone Formation by Targeting ACVR1

Emerging evidence indicates that many microRNAs (miRNAs) are indispensable regulators of osteoblast differentiation and bone formation. However, the role of miRNAs in mechanotransduction of osteoblasts remains to be elucidated. This study aimed to identify a mechanosensitive miRNA that regulates Activin A receptor type I (ACVR1)-induced osteogenic differentiation. After 4 weeks of hindlimb unloading (HLU) suspension of 6-month-old male C57BL/6J mice, femurs and tibias were harvested to extract total bone RNAs. Elevated levels of miR-208a-3p correlated with a lower degree of bone formation in whole-bone samples of HLU mice. However, in vitro overexpression of miR-208a-3p inhibited osteoblast differentiation, whereas silencing of miR-208a-3p by antagomiR-208a-3p promoted expression of osteoblast activity, bone formation marker genes, and matrix mineralization under mechanical unloading condition. Bioinformatics analysis and a luciferase assay revealed that ACVR1 is a target gene of miR-208a-3p that negatively regulates osteoblast differentiation under mechanical unloading environment. Further, this study also demonstrates that in vivo pre-treatment with antagomiR-208a-3p led to an increase in bone formation and trabecular microarchitecture and partly rescued the bone loss caused by mechanical unloading. Collectively, these results suggest that in vivo, inhibition of miRNA-208a-3p by antagomiR-208a-3p may be a potential therapeutic strategy for ameliorating bone loss.

The expression of cystathionine gamma-lyase is regulated by estrogen receptor alpha in human osteoblasts

Hydrogen sulfide (H2S), generated in the osteoblasts predominantly via cystathionine-γ-lyase (CSE), is bone protective. Previous studies suggested that the onset of bone loss due to estrogen deficiency is associated to decreased levels of H2S and blunted gene expression of CSE. However, there are still a lot of unknowns on how H2S levels influence bone cells function. The present study aims to explore the mechanisms by which estrogen may regulate CSE expression, in particular the role of estrogen receptor alpha (ERα) in human osteoblasts (hOBs). Vertebral lamina derived hOBs were characterized and then assessed for CSE expression by western blot analysis in the presence or absence of ERα overexpression. Bioinformatic analysis, luciferase reporter assay and ChIP assay were performed to investigate ERα recruitment and activity on hCSE gene promoter. Three putative half Estrogen Responsive Elements (EREs) were identified in the hCSE core promoter and were found to participate in the ERα - mediated positive regulation of CSE expression. All osteoblast samples responded to ERα over-expression increasing the levels of CSE protein in a comparable manner. Notably, the ERα recruitment on the regulatory regions of the CSE promoter occurred predominantly in female hOBs than in male hOBs. The obtained results suggest that CSE/H2S system is in relation with estrogen signaling in bone in a gender specific manner.

Role of Galectin-3 in Bone Cell Differentiation, Bone Pathophysiology and Vascular Osteogenesis

Galectin-3 is expressed in various tissues, including the bone, where it is considered a marker of chondrogenic and osteogenic cell lineages. Galectin-3 protein was found to be increased in the differentiated chondrocytes of the metaphyseal plate cartilage, where it favors chondrocyte survival and cartilage matrix mineralization. It was also shown to be highly expressed in differentiating osteoblasts and osteoclasts, in concomitance with expression of osteogenic markers and Runt-related transcription factor 2 and with the appearance of a mature phenotype. Galectin-3 is expressed also by osteocytes, though its function in these cells has not been fully elucidated. The effects of galectin-3 on bone cells were also investigated in galectin-3 null mice, further supporting its role in all stages of bone biology, from development to remodeling. Galectin-3 was also shown to act as a receptor for advanced glycation endproducts, which have been implicated in age-dependent and diabetes-associated bone fragility. Moreover, its regulatory role in inflammatory bone and joint disorders entitles galectin-3 as a possible therapeutic target. Finally, galectin-3 capacity to commit mesenchymal stem cells to the osteoblastic lineage and to favor transdifferentiation of vascular smooth muscle cells into an osteoblast-like phenotype open a new area of interest in bone and vascular pathologies.

Cellular properties of the fermented microalgae Pavlova lutheri and its isolated active peptide in osteoblastic differentiation of MG‑63 cells

Fermented microalgae Pavlova lutheri (P. lutheri), the product of Hansenula polymorpha fermentation, exhibited an increase in alkaline phosphatase (ALP) activity in MG‑63 osteoblastic cells when compared to that of non‑fermented P. lutheri. Fractionation of the fermented P. lutheri resulted in identification of the active peptide [peptide of P. lutheri fermentation (PPLF)] with the sequence of EPQWFL. PPLF significantly increased ALP release from MG‑63 cells and mineralization in a dose‑dependent manner. In addition, the intracellular levels of ALP and osteocalcin (OCN) proteins were augmented by PPLF treatment. To identify the molecular mechanism underlying the effect of PPLF on osteoblastic differentiation, the phosphorylation levels of the mitogen‑activated protein kinases, p38, extracellular signal‑regulated kinases 1/2 and Jun, and nuclear factor (NF)‑κB were determined following PPLF treatment and the differences in expression were analyzed using p38 and NF‑κB selective inhibitors. These results concluded that PPLF from fermented P. lutheri induced osteoblastic differentiation by increasing ALP and OCN release in MG‑63 cells via the p38/p65 signaling pathway, indicating that PPLF supplement may be effective for therapeutic application in the field of bone health.

MicroRNA-146a knockdown suppresses the progression of ankylosing spondylitis by targeting dickkopf 1

Ankylosing spondylitis (AS) seriously threatens healthy and life quality of patients, however, there is no extremely effective drug to cure the disease. Therefore, it is urgent to understand molecular basis in the progression of AS. MicroRNA-146a (miR-146a) has been demonstrated to be associated with the development of AS. However, its molecular mechanism has not been fully established. In this study, it is found that the expression levels of miR-146a and dickkopf 1 (DKK1) were respectively upregulated and downregulated in hip capsule tissues of AS patients. Moreover, a negative correlation was displayed between miR-146a and DKK1 expression. Functional analysis revealed that miR-146a inhibitor restrained cell proliferation and osteogenic potential as well as enhanced apoptosis in AS fibroblasts, while miR-146a overexpression enhanced proliferation and osteogenic potential of AS fibroblasts. Bioinformatics analysis, dual luciferase reporter assays, qRT-PCR and immunoblotting assays revealed that miR-146a inhibited DKK1 expression by directly targeting 3'UTR region of DKK1. Mechanism studies further revealed that loss of DKK1 partly reversed the effect of miR-146a inhibitor on cell proliferation, apoptosis and osteogenic potential in AS fibroblasts. Taken together, our finding revealed that miR-146a knockdown hindered AS progression partially by regulating target DKK1 expression, offering a potential therapy application for AS patients.

The Effects of Cerium Valence States at Cerium Oxide Coatings on the Responses of Bone Mesenchymal Stem Cells and Macrophages

Ideal orthopedic coatings should trigger good osteogenic response and limited inflammatory response. The cerium valence states in ceria are associated with their anti-oxidative activity and anti-inflammatory property. In the study, we prepared two kinds of plasma sprayed CeO₂ coatings with different Ce⁴⁺ concentrations to investigate the effects of Ce valence states on the response of bone mesenchymal stem cells (BMSCs) and macrophage RAW264.7. Both the coatings (CeO₂-A and CeO₂-B) were characterized via XRD, SEM, and X-ray photoelectron spectroscopy. The CeO₂ coatings enhanced osteogenic behaviors of BMSCs in terms of cellular proliferation, alkaline phosphatase (ALP) activity and calcium deposition activity in comparison with the Ti substrate. In particular, the CeO₂-B coating (higher Ce⁴⁺ concentration) elicited greater effects than the CeO₂-A coating (higher Ce³⁺ concentration). RT-PCR and western blot results suggested that the CeO₂-B coating promoted BMSCs osteogenic differentiation through the SMAD-dependent BMP signaling pathway, which activated Runx2 expression and subsequently enhanced the expression of ALP and OCN. With respect to either CeO₂-A coating or Ti substrate, the CeO₂-B coating exerted greater effects on the macrophages, increasing the anti-inflammatory cytokines (IL-10 and IL-1ra) expression and suppressing the expression of the pro-inflammatory cytokines (TNF-α and IL-6) and ROS production. Furthermore, it also upregulated the expression of osteoinductive molecules (TGF-β1 and BMP2) in the macrophages. The regulation of cerium valence states at plasma sprayed ceria coatings can be a valuable strategy to improve osteogenic properties and alleviate inflammatory response.

Osteoclasts in Periprosthetic Osteolysis: The Charnley Arthroplasty Revisited

BACKGROUND

Periprosthetic osteolysis by polyethylene wear debris-triggered osteoclasts is viewed as the main pathophysiological pathway in aseptic loosening in total hip arthroplasty. The present aim was to study osteoclast occurrence in osteolytic lesions in early and late revisions of the Charnley low-friction torque arthroplasty (CLFA).

METHODS

Biopsies of the soft interface membrane and the adjacent bone were taken from osteolytic lesions during revision of 16 loose CLFA, early (2-6 years) or late (>10 years) after primary surgery. By light microscopy (LM), cell-dense regions with signs of osteoclast-mediated bone resorption were selected for transmission electron microscopy. Three additional patients were studied in LM for osteoclast markers (tartrate-resistant acid phosphatase and Cathepsin K).

RESULTS

LM disclosed a low-grade chronic inflammation and birefringent particles in most sections. Multiple conglomerates of tartrate-resistant acid phosphatase positive and Cathepsin K positive mononuclear and multinucleated cells were found deep in the fibrous interface membrane. Transmission electron microscopy showed traces of polyethylene-like particles in 67%-100% of the cells. Osteoclast-like cells exhibiting resorptive activity were few (mean, 0.7%; standard deviation, 0.2%), and multinucleated cells, possibly osteoclast precursor cells, located immediately on the bone were also scarce (mean, 2.7%; standard deviation, 5.3%). Multinucleated (odds ratio, 3.0; 95% confidence interval, 1.7-5.5) and macrophage-like cells (odds ratio, 3.6; 95% confidence interval, 2.2-5.6) were typically located deeper in the inflammatory interface membrane with a pathologic appearance with distension and abundance of phagocytic vacuoles. There were no systematic differences in cell populations between early or late revisions.

CONCLUSION

Despite probable ongoing osteoclastogenesis in the osteolytic lesions, there were few sites of osteoclast-mediated bone resorption. These findings attach a contributing biological explanation to the longevity of the CLFA.

IL15RA is required for osteoblast function and bone mineralization

Interleukin-15 receptor alpha (IL15RA) is an important component of interleukin-15 (IL15) pro-inflammatory signaling. In addition, IL15 and IL15RA are present in the circulation and are detected in a variety of tissues where they influence physiological functions such as muscle contractility and overall metabolism. In the skeletal system, IL15RA was previously shown to be important for osteoclastogenesis. Little is known, however, about its role in osteoblast function and bone mineralization. In this study, we evaluated bone structural and mechanical properties of an Il15ra whole-body knockout mouse (Il15ra^-/-) and used in vitro and bioinformatic analyses to understand the role IL15/IL15RA signaling on osteoblast function. We show that lack of IL15RA decreased bone mineralization in vivo and in isolated primary osteogenic cultures, suggesting a cell-autonomous effect. Il15ra^-/- osteogenic cultures also had reduced Rankl/Opg mRNA ratio, indicating defective osteoblast/osteoclast coupling. We analyzed the transcriptome of primary pre-osteoblasts from normal and Il15ra^-/- mice and identified 1150 genes that were differentially expressed at a FDR of 5%. Of these, 844 transcripts were upregulated and 306 were downregulated in Il15ra^-/- cells. The largest functional clusters, highlighted using DAVID analysis, were related to metabolism, immune response, bone mineralization and morphogenesis. The transcriptome analysis was validated by qPCR of some of the most significant hits. Using bioinformatic approaches, we identified candidate genes, including Cd200 and Enpp1, that could contribute to the reduced mineralization. Silencing Il15ra using shRNA in the calvarial osteoblast MC3T3-E1 cell line decreased ENPP1 activity. Taken together, these data support that IL15RA plays a cell-autonomous role in osteoblast function and bone mineralization.

Emodin promotes the osteogenesis of MC3T3-E1 cells via BMP-9/Smad pathway and exerts a preventive effect in ovariectomized rats

Emodin, a natural anthraquinone extracted from the Chinese herbs rhubarb and giant knotweed rhizome, has been reported to enhance osteoblast differentiation. However, the mechanisms underlying its ability to regulate osteogenesis are unclear. The objective of this study was to determine the role of emodin in osteoblast function in vitro and its osteoprotective effect in vivo. Emodin enhanced the differentiation and mineralization of MC3T3-E1 cells, as evidenced by elevated alkaline phosphatase activity and increased number of mineralized nodules. In cultured osteoblasts, emodin significantly induced the mRNA expression of BMP-9 which is one of the least studied but most osteogenic bone morphogenetic proteins (BMPs). Furthermore, the bone morphogenetic protein receptor-Smad (BMPR-Smad) signaling axis and p38 mitogen activated protein kinase (p38 MAPK) were activated. The in vivo function of emodin were evaluated by assessing bone histomorphology, trabecular bone microarchitecture, mechanical properties of the skeleton, and serum parameters of bone turnover in ovariectomized (OVX) rats. Emodin combined with low-dose of estrogen improved trabecular bone microarchitecture in the fourth lumbar vertebra compared with low-dose estrogen alone and enhanced vertebral body strength. Moreover, emodin suppressed the OVX-induced elevation of serum osteocalcin (OC). In addition, there were fewer side effects on uterine hypertrophy with the combination therapy than with high-dose estrogen alone. However, emodin alone did not exert any osteoprotective effect. These results suggest that emodin may be a promising alternative agent for osteoporosis in combination therapy.

A unique heterologous fibrin sealant (HFS) as a candidate biological scaffold for mesenchymal stem cells in osteoporotic rats

Background

The injection of mesenchymal stem cells (MSCs) directly into the bone of osteoporotic (OP) patients for rapid recovery has been studied worldwide. Scaffolds associated with MSCs are used to maintain and avoid cell loss after application. A unique heterologous fibrin sealant (HFS) derived from snake venom was evaluated for the cytotoxicity of its main components and as a three-dimensional biological scaffold for MSCs to repair a critical femur defect in osteoporotic rats.

Methods

The cytotoxicity of HFS was assessed using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) assay and transmission electron microscopy. The cells were cultured, characterized by flow cytometry and differentiated into the osteogenic lineage. Two-month-old rats underwent ovariectomy to induce OP. After 3 months, a 5 mm critical bone defect was made in the distal end of the rat femurs and filled with HFS; HFS + MSCs; and HFS + MSCs D (differentiated into the osteogenic lineage) to evaluate the effects. An injury control group (injury and no treatment) and blank control group (no injury and no treatment) were also included. The animals were observed at days 14 and 28 by microtomographic (micro-CT) analyses, histologic and biochemical analysis, as well as scanning electron microscopy.

Results

The results revealed that one of the compounds of HFS, the thrombin-like enzyme extracted from snake venom, had no cytotoxic effects on the MSCs. OP was successfully induced, as demonstrated by the significant differences in the levels of 17β-estradiol, Micro-CT analyses and alkaline phosphatase between the ovariectomized (OVX) and non-ovariectomized (NOVX) groups. The histological data revealed that at 14 days after surgery in both the OVX and NOVX animals, the HFS + CTMs and HFS + CTMsD showed a higher formation of bone cells at the site in relation to the control group (without treatment). Collagen formation was evidenced through bone neoformation in all treated and control groups. No morphological differences in the femurs of the NOVX and OVX animals were observed after the surgical procedure. Scanning electron microscopy (SEM) confirmed the histological analysis.

Conclusions

The new HFS composed of two non-toxic components for MSCs showed capacity to promote the recovery of the bone lesions in OVX and NOVX animals at 14 days after surgery. In addition, the HFS enabled the differentiation of MSCs into MSCs D in the group treated with HFS + MSCs. Using the MSCs and/or MSCs D together with this biopharmaceutical could potentially enable significant advances in the treatment of osteoporotic fractures. Future clinical trials will be necessary to confirm these results.

Endothelial-to-Osteoblast Conversion Generates Osteoblastic Metastasis of Prostate Cancer

Prostate cancer (PCa) bone metastasis is frequently associated with bone-forming lesions, but the source of the osteoblastic lesions remains unclear. We show that the tumor-induced bone derives partly from tumor-associated endothelial cells that have undergone endothelial-to-osteoblast (EC-to-OSB) conversion. The tumor-associated osteoblasts in PCa bone metastasis specimens and patient-derived xenografts (PDXs) were found to co-express endothelial marker Tie-2. BMP4, identified in PDX-conditioned medium, promoted EC-to-OSB conversion of 2H11 endothelial cells. BMP4 overexpression in non-osteogenic C4-2b PCa cells led to ectopic bone formation under subcutaneous implantation. Tumor-induced bone was reduced in trigenic mice (Tie2^cre/Osx^f/f/SCID) with endothelial-specific deletion of osteoblast cell-fate determinant OSX compared with bigenic mice (Osx^f/f/SCID). Thus, tumor-induced EC-to-OSB conversion is one mechanism that leads to osteoblastic bone metastasis of PCa.

Pigment epithelium derived factor play a positive role in bone mineralization of osteoblasts derived from diabetic patients

Pigment epithelium-derived factor (PEDF) is a multifunctional secreted protein which plays important role in anti-angiogenic, anti-tumorigenic, as well as involves in the metabolism and regeneration of bone. In this study, our aim is to investigate the role of PEDF in regulating mineralization of osteoblasts from diabetic patients (DP). We isolated and cultured osteoblasts derived from DP and non-diabetic patients (NDP), in order to analyze the variable differences via gene expression and calcification assay in vitro. Gene expression analysis and alizarin red S staining revealed that osteoblasts from DP exhibited defective mineralization. PEDF and vascular endothelial growth factor (VEGF) levels were lower in osteoblasts from DP than those from NDP. Interestingly, exogenous PEDF could upregulate the gene expression levels of VEGF and osteoblast-related genes, further to restore mineralization ability in osteoblasts from DP. Our results demonstrated that PEDF played a positive role in maintaining bone development in diabetic osteoblasts, therefore, we confidently believe that PEDF may be a promising cytokine to consider in development of treatments for diabetic bone diseases.

Differential effects of amnion and chorion membrane extracts on osteoblast-like cells due to the different growth factor composition of the extracts

Human amniotic membrane extracts contain numerous growth factors and bioactive substances. However, osteogenic effects of amnion and chorion membrane extracts (AME and CME, respectively) on osteoblasts are unclear. In this study, we explored the ability of AME and CME to promote the osteogenic differentiation of osteoblast-like MG-63 cells. MG-63 cells were cultured in osteogenic induction medium (OIM) with or without exogenous AME and CME. CME enhanced the osteogenic differentiation of MG-63 cells compared with AME, as indicated by increased mineralization; alkaline phosphatase activity; and mRNA expression of osteogenic marker genes encoding integrin-binding sialoprotein (IBSP), RUNX2, OSTERIX, and osteocalcin (OCN). Interestingly, AME and CME contained different combinations of osteogenesis-related growth factors, including basic fibroblast growth factor (bFGF), transforming growth factor beta-1 (TGFβ-1), and epidermal growth factor (EGF), which differentially regulated the osteogenic differentiation of MG-63 cells. bFGF and TGFβ-1 present in CME positively regulated the osteogenic differentiation of MG-63 cells, whereas EGF present in AME negatively regulated the differentiation of MG-63 cells. Moreover, exogenous treatment of EGF antagonized CME-induced mineralization of extracellular matrix on MG-63 cells. We compared the osteogenic efficacy of CME with that of BMP2, bFGF, and TGFβ-1 alone or their combinations. We observed that CME greatly enhanced osteogenesis by providing a conductive environment for the differentiation of MG-63 cells. Together, our results indicated that human AME and CME exerted differential effects on osteogenesis because of the presence of different compositions of growth factors. In addition, our results highlighted a new possible strategy of using CME as a biocompatible therapeutic material for bone regeneration.

Uev1A facilitates osteosarcoma differentiation by promoting Smurf1-mediated Smad1 ubiquitination and degradation

Malignant bone tumor osteosarcoma (OS) displays high metastasis incidence and poor prognosis. Its stem cell properties could serve to explain tumor recurrence and resistance to conventional treatments. In this study, we identified UEV1A as a novel suppressor of OS. Elevated UEV1A diminishes stem cell properties of OS cells and drives them to terminal differentiation. Importantly, UEV1A-overexpressed OS cells delay proliferation and are more sensitive to chemotherapeutic agents than control cells. Uev1A appears to be involved in the BMP signaling pathway in which it collaborates with a ubiquitin E3 ligase Smurf1 to promote Smad1 degradation in a Ubc13-independent manner. Indeed, Smad1 is identified as a dominant downstream effector of Uev1A, which unravels the mechanism underlying Uev1A-orchestrated tumor suppression in OS. The above findings identify UEV1A as a potential OS tumor suppression gene, and shed lights to future OS diagnosis and treatment.

Redifferentiation of aged human articular chondrocytes by combining bone morphogenetic protein-2 and melanoma inhibitory activity protein in 3D-culture

Melanoma inhibitory activity (MIA) affects the differentiation to hyaline cartilage and can inhibit the osteogenic potential of bone morphogenetic protein (BMP)-2 in mesenchymal stem cells (MSC). The aim of this study was to investigate if MIA also inhibits the osteogenic potential of BMP-2 in human articular chondrocytes during redifferentiation, which may lead to a higher grade of differentiation without calcification. HAC of four female patients (mean age: 73.75 ±6.98) were seeded into 3D culture for 28 days; after adding the recombinant proteins, four groups were formed (Control, BMP-2, MIA, BMP-2+MIA). Samples were analysed for gene expression, glycosaminoglycan (GAG) content and histology on day 0, 14 and 28. Collagen type 2 (COL2A1) was significantly increased in the BMP-2 containing groups on day 28; BMP-2 (100-fold, p = 0.001), BMP-2+MIA (65-fold, p = 0.009) and similar to the level of native cartilage. Higher aggrecan (Agg) levels were present in the BMP-2 (3-fold, p = 0.007) and BMP-2+MIA (4-fold, p = 0.002) group after 14 days and in the BMP-2 (9-fold, p = 0.001) group after 28 days. Collagen type 10 (COL10A1) was increased in the BMP-2 containing groups (6-fold, p = 0.006) but these levels were significantly below native cartilage. Alkaline phosphatase (ALP), collagen type 1 (COL1A1) and the glycosaminoglycan (GAG) content did not reveal any relevant differences between groups. BMP-2 is a potent inducer for differentiation of HAC. A significant enhancement of this effect in combination with MIA could not be observed. Furthermore no significant reduction of osteogenic markers during re-differentiation of chondrocytes was present combining BMP-2 and MIA.

Aluminum Trichloride Inhibited Osteoblastic Proliferation and Downregulated the Wnt/β-Catenin Pathway

Aluminum (Al) exposure inhibits bone formation. Osteoblastic proliferation promotes bone formation. Therefore, we inferred that Al may inhibit bone formation by the inhibition of osteoblastic proliferation. However, the effects and molecular mechanisms of Al on osteoblastic proliferation are still under investigation. Osteoblastic proliferation can be regulated by Wnt/β-catenin signaling pathway. To investigate the effects of Al on osteoblastic proliferation and whether Wnt/β-catenin signaling pathway is involved in it, osteoblasts from neonatal rats were cultured and exposed to 0, 0.4 mM (1/20 IC₅₀), 0.8 mM (1/10 IC₅₀), and 1.6 mM (1/5 IC₅₀) of aluminum trichloride (AlCl₃) for 24 h, respectively. The osteoblastic proliferation rates; Wnt3a, lipoprotein receptor-related protein 5 (LRP-5), T cell factor 1 (TCF-1), cyclin D1, and c-Myc messenger RNA (mRNA) expressions; and p-glycogen synthase kinase 3β (GSK3β), GSK3β, and β-catenin protein expressions indicated that AlCl₃ inhibited osteoblastic proliferation and downregulated Wnt/β-catenin signaling pathway. In addition, the AlCl₃ concentration was negatively correlated with osteoblastic proliferation rates and the mRNA expressions of Wnt3a, c-Myc, and cyclin D1, while the osteoblastic proliferation rates were positively correlated with mRNA expressions of Wnt3a, c-Myc, and cyclin D1. Taken together, these findings indicated that AlCl₃ inhibits osteoblastic proliferation may be associated with the inactivation of Wnt/β-catenin signaling pathway.

Inhibition of bone formation in rats by aluminum exposure via Wnt/β-catenin pathway

The previous research found that aluminum trichloride (AlCl₃) inhibited rat osteoblastic differentiation through inactivation of Wnt/β-catenin signaling pathway in vitro. On that basis, the experiment in vivo was conducted in this study. Rats were orally exposed to 0 (control group) and 0.4 g/L AlCl₃ (AlCl₃-treated group) for 30, 60, 90 or 120 days, respectively. We found that mRNA expressions of type I collagen and insulin-like growth factor-1, mRNA and protein expressions of Runx2 and survivin, ratio of p-GSK3β/GSK3β and protein expression of β-catenin were all decreased, whereas the mRNA and protein expressions Dkk1 and sFRP1 and the mRNA expressions and activity of Caspase-3 were increased in the AlCl₃-treated group compared with the control group with time prolonged. These results suggest that AlCl₃ inhibits bone formation and induces bone impairment by inhibiting the Wnt/β-catenin signaling pathway in young growing rats.

Investigating the effect of fibulin-1 on the differentiation of human nasal inferior turbinate-derived mesenchymal stem cells into osteoblasts

Many extracellular matrix proteins have positive influences on the adhesion, proliferation, and differentiation of stem cells into specific cell linages. Fibulin-1 (FBLN1), a member of a growing family of extracellular glycoproteins, contributes to the structure of the extracellular matrix. Here, we investigated the effect of FBLN1 on the ability of human nasal inferior turbinate-derived mesenchymal stem cells (hTMSCs) to undergo osteogenic differentiation. After we generated recombinant FBLN1, the characteristics of FBLN1-treated hTMSCs were evaluated using MTT assay, ALP and mineralization activities, and quantitative real-time PCR. FBLN1 significantly enhanced the adhesion activity (p < 0.001) and proliferation of hTMSCs (p < 0.05). The ALP and mineralization activities of cells were dramatically increased (p < 0.01) after 9 and 12 days of FBLN1 treatment, respectively. This indicated the ability of FBLN1 to induce hTMSCs to differentiate into osteoblasts. Furthermore, increasing the mRNA levels of osteogenic marker genes, such as a transcriptional coactivator with a PDZ-binding motif (TAZ), alkaline phosphatase (ALP), collagen type I (Col I), and osteocalcin (OCN), improved bone repair and regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2291-2298, 2017.

Costunolide increases osteoblast differentiation via ATF4-dependent HO-1 expression in C3H10T1/2 cells

AIMS

Costunolide is a sesquiterpene lactones used in many herbal medicines, with well-established anti-inflammatory and anti-oxidant functions modulating endoplasmic reticulum (ER) stress pathways, and which promotes the expression of anti-oxidant genes. The aim of this study is to investigate whether costunolide is involved in osteoblast differentiation and, determine the mechanisms of differentiation in mesenchymal stem cells.

MAIN METHODS

The cytotoxicity of costunolide was identified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The mRNA and protein expression levels of osteogenic genes were determined by RT-PCR and Western blot analysis. Alkaline phosphate (ALP) staining and Alizarin red S (ARS) staining were performed to evaluate ALP activity and matrix mineralization. Transcriptional activity was detected using a luciferase reporter assay.

KEY FINDINGS

In this study, we determined that costunolide increased the expression of distal-less homeobox 5 (Dlx5), runt-related transcription factor 2 (Runx2), ALP, and osteocalcin (OC) in C3H10T 1/2 cells. Furthermore, costunolide increased ALP activity and matrix mineralization. Interestingly, costunolide increased ER stress by Bip, activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP). However, it did not exert effects on expression of activating transcription factor 6 (ATF6). ATF4 activation has a protective role in oxidative stress, and its transcription induces anti-oxidant genes in cells. Heme oxygenase-1 (HO-1) is a major anti-oxidant enzyme, and is regulated by ATF4. We showed that costunolide treatment increased HO-1 expression. Furthermore, the HO-1 inhibitor, Sn(IV) Protoporphyrin IX dichloride (SnPP) was blocked costunolide-induced Runx2 expression.

SIGNIFICANCE

Our results revealed that costunolide-induced osteoblast differentiation is regulated by ATF4-dependent HO-1 expression.

Impact of osteoblast maturation on their paracrine growth enhancing activity on cord blood progenitors

BACKGROUND

Osteoblasts possess strong growth modulatory activity on haematopoietic stem cells and progenitors. We sought to characterise the growth and differentiation modulatory activities of human osteoblasts at distinct stages of maturation on cord blood (CB) progenitors in the context of osteoblast conditioned medium (OCM).

METHODS

OCM was produced from MSC-derived osteoblasts (M-OST) at distinct stages of maturation. The growth modulatory activities of the OCM were tested on CB CD34⁺ cells using different functional assays.

RESULTS

OCMs raised the growth of CB cells and expansion of CD34⁺ cells independently of the maturation status of M-OST. However, productions of immature CB cells including committed and multipotent progenitors were superior with OCM produced with immature osteoblasts. Osteogenic differentiation was accompanied by the upregulation of IGFBP-2, by several members of the Angpt-L family of growth factor, and by the Notch ligands Dll-1 and Dll-4. However, the growth activity of OCM and the in vivo engraftment properties of OCM-expanded CB cells were retained after IGFBP-2 neutralisation. Similarly, OCM-mediated expansion of CB myeloid progenitors was largely independent of Notch signalling.

CONCLUSIONS

These results demonstrate that immature osteoblasts possess greater regulatory activity over haematopoietic progenitors, and that this activity is not entirely dependent on Notch signalling.

Short term sodium alendronate administration improves the peri-implant bone quality in osteoporotic animals

Sodium alendronate is a bisphosphonate drug that exerts antiresorptive action and is used to treat osteoporosis.

Kuei-Lu-Er-Xian-Jiao extract enhances BMP-2 production in osteoblasts

Osteoporosis is a common skeletal disorder, resulting from an imbalance in bone resorption relative to formation. Bone morphogenetic protein (BMP) is a key regulator in bone formation and osteoblastic differentiation. Hence, compounds that promote BMP expression may be suitable candidates for osteoporosis treatment. This study examined the effects of the traditional Chinese medicinal agent, Kuei-Lu-Er-Xian-Jiao (KLEXJ), on BMP-2 production in osteoblasts. We found that KLEXJ extract promoted osteoblastic differentiation marker ALP activity and increased BMP-2 production; pretreatment with PI3K and Akt inhibitors, or small interfering RNA (siRNA), reduced these effects. KLEXJ also enhanced PI3K and Akt phosphorylation. Treatment of osteoblastic cells with NF-κB inhibitors (TPCK or PDTC) markedly inhibited KLEXJ-enhancement of ALP activity and BMP-2 production. KLEXJ also significantly promoted p65 phosphorylation, while treatment with PI3K and Akt inhibitors antagonized KLEXJ-enhanced p65 phosphorylation. Thus, KLEXJ enhances ALP activity and BMP-2 production of osteoblasts through the PI3K/Akt/ NF-κB signaling pathway and hence may be suitable in the treatment of osteoporosis.

Immobilization of alendronate on titanium via its different functional groups and the subsequent effects on cell functions

Immobilization of alendronate on orthopedic implants offers the possibility of enhancing osteogenesis without potentially adverse effects associated with systemic administration of this drug. In this work, alendronate was immobilized on titanium (Ti) via either its phosphate (Method 1) or amino (Method 2) groups, and responses of osteoblasts and human mesenchymal stem cells (hMSCs) on these surfaces were investigated. These modified substrates have similar surface roughness and are negatively charged. With similar amounts of immobilized alendronate, these two types of modified substrates showed comparable osteogenic stimulating effects in enhancing osteoblasts' alkaline phosphatase (ALP) activity and calcium deposition for the first 10days. However, alendronate immobilized via its phosphate groups was less stable, and gradually leached into the medium. As a result, its stimulating effect on osteoblast differentiation diminished with time. On the other hand, alendronate immobilized via its amino group stimulated osteoblast differentiation over 21days, and with 1655ng/cm2 of immobilized alendronate on the Ti substrate, calcium deposition by osteoblasts and hMSCs increased by 30% and 69%, respectively, compared to pristine Ti after 21days. The expressions of runt-related transcription factor 2, osterix, osteopontin and osteocalcin in hMSCs cultured on this substrate were monitored. The up-regulation of these genes is postulated to play a role in the acceleration of osteogenic differentiation of hMSCs cultured on the alendronate-modified substrate over those on pristine Ti.

Bone-Derived Factors: A New Gateway to Regulate Glycemia

Type 2 diabetes mellitus (T2DM) and osteoporosis are two major disorders which prevalence increases with aging and is predicted to worsen in the coming years. Preclinical investigations suggest common mechanisms implicated in the pathogenesis of both disorders. Recent evidence has established that there is a clear link between glucose and bone metabolism. The emergence of bone as an endocrine regulator through FGF23 and osteocalcin has led to the re-evaluation of the role of bone cells and bone-derived factors in the development of metabolic diseases such as T2DM. The development of bone morphogenetic proteins, fibroblast growth factor 23, and osteoprotegerin-deficient mice has allowed to elucidate their role in bone homeostasis, as well as revealed their potential important function in glucose homeostasis. This review proposes emerging perspectives for several bone-derived factors that may regulate glycemia through the activation or inhibition of bone remodeling or directly by regulating function of key organs such as pancreatic beta cell proliferation, insulin expression and secretion, storage and release of glucose from the liver, skeletal muscle contraction, and browning of the adipose tissue. Connections between organs including bone-derived factors should further be explored to understand the pathophysiology of glucose metabolism and diabetes.

Role of Epithelium Sodium Channel in Bone Formation

Objective:

To review the recent developments in the mechanisms of epithelium sodium channels (ENaCs) induced bone formation and regulation.

Data Sources:

Studies written in English or Chinese were searched using Medline, PubMed and the index of Chinese-language literature with time restriction from 2005 to 2014. Keywords included ENaC, bone, bone formation, osteonecrosis, estrogen, and osteoporosis. Data from published articles about the structure of ENaC, mechanism of ENaC in bone formation in recent domestic and foreign literature were selected.

Study Selection:

Abstract and full text of all studies were required to obtain. Studies those were not accessible and those did not focus on the keywords were excluded.

Results:

ENaCs are tripolymer ion channels which are assembled from homologous α, β, and γ subunits. Crystal structure of ENaCs suggests that ENaC has a central ion-channel located in the central symmetry axis of the three subunits. ENaCs are protease sensitive channels whose iron-channel activity is regulated by the proteolytic reaction. Channel opening probability of ENaCs is regulated by proteinases, mechanical force, and shear stress. Several molecules are involved in regulation of ENaCs in bone formation, including nitride oxide synthases, voltage-sensitive calcium channels, and cyclooxygenase-2.

Conclusion:

The pathway of ENaC involved in shear stress has an effect on stimulating osteoblasts even bone formation by estrogen interference.

Bone remodeling as a spatial evolutionary game

Bone remodeling is a complex process involving cell-cell interactions, biochemical signaling and mechanical stimuli. Early models of the biological aspects of remodeling were non-spatial and focused on the local dynamics at a fixed location in the bone. Several spatial extensions of these models have been proposed, but they generally suffer from two limitations: first, they are not amenable to analysis and are computationally expensive, and second, they neglect the role played by bone-embedded osteocytes. To address these issues, we developed a novel model of spatial remodeling based on the principles of evolutionary game theory. The analytically tractable framework describes the spatial interactions between zones of bone resorption, bone formation and quiescent bone, and explicitly accounts for regulation of remodeling by bone-embedded, mechanotransducing osteocytes. Using tools from the theory of interacting particle systems we systematically classified the different dynamic regimes of the spatial model and identified regions of parameter space that allow for global coexistence of resorption, formation and quiescence, as observed in physiological remodeling. In coexistence scenarios, three-dimensional simulations revealed the emergence of sponge-like bone clusters. Comparison between spatial and non-spatial dynamics revealed substantial differences and suggested a stabilizing role of space. Our findings emphasize the importance of accounting for spatial structure and bone-embedded osteocytes when modeling the process of bone remodeling. Thanks to the lattice-based framework, the proposed model can easily be coupled to a mechanical model of bone loading.

A Conditional Knockout Mouse Model Reveals a Critical Role of PKD1 in Osteoblast Differentiation and Bone Development

The protein kinase D family of serine/threonine kinases, particularly PKD1, has been implicated in the regulation of a complex array of fundamental biological processes. However, its function and mechanism underlying PKD1-mediated the bone development and osteoblast differentiation are not fully understood. Here we demonstrate that loss of PKD1 function led to impaired bone development and osteoblast differentiation through STAT3 and p38 MAPK signaling using in vitro and in vivo bone-specific conditional PKD1-knockout (PKD1-KO) mice models. These mice developed markedly craniofacial dysplasia, scapula dysplasia, long bone length shortage and body weight decrease compared with wild-type littermates. Moreover, deletion of PKD1 in vivo reduced trabecular development and activity of osteoblast development, confirmed by Micro-CT and histological staining as well as expression of osteoblastic marker (OPN, Runx2 and OSX). Mechanistically, loss of PKD1 mediated the downregulation of osteoblast markers and impaired osteoblast differentiation through STAT3 and p38 MAPK signaling pathways. Taken together, these results demonstrated that PKD1 contributes to the osteoblast differentiation and bone development via elevation of osteoblast markers through activation of STAT3 and p38 MAPK signaling pathways.

Preparation and biological effects of apatite nanosheet-constructed porous ceramics

A kind of apatite nanosheet-constructed porous ceramics could mediate the osteogenic differentiation of mesenchymal stem cells.

From molecules to macrostructures: recent development of bioinspired hard tissue repair

This review summarizes the bioinspired strategies for hard tissue repair, ranging from molecule-induced mineralization, to microscale assembly to macroscaffold fabrication.

Potassium Channel-blockers as Therapeutic Agents to Interfere with Bone Resorption of Periodontal Disease

Inflammatory lesions of periodontal disease contain all the cellular components, including abundant activated/memory T- and B-cells, necessary to control immunological interactive networks and to accelerate bone resorption by RANKL-dependent and -independent mechanisms. Blockade of RANKL function has been shown to ameliorate periodontal bone resorption and other osteopenic disorders without affecting inflammation. Development of therapies aimed at decreasing the expression of RANKL and pro-inflammatory cytokines by T-cells constitutes a promising strategy to ameliorate not only bone resorption, but also inflammation. Several reports have demonstrated that the potassium channels Kv1.3 and IKCa1, through the use of selective blockers, play important roles in T-cell-mediated events, including T-cell proliferation and the production of pro-inflammatory cytokines. More recently, a potassium channel-blocker for Kv1.3 has been shown to down-regulate bone resorption by decreasing the ratio of RANKL-to-OPG expression by memory-activated T-cells. In this article, we first summarize the mechanisms by which chronically activated/memory T-cells, in concert with B-cells and macrophages, trigger inflammatory bone resorption. Then, we describe the main structural and functional characteristics of potassium channels Kv1.3 and IKCa1 in some of the cells implicated in periodontal disease progression. Finally, this review elucidates some recent advances in the use of potassium channel-blockers of Kv1.3 and IKCa1 to ameliorate the clinical signs or side-effects of several immunological disorders and to decrease inflammatory bone resorption in periodontal disease. ABBREVIATIONS: AICD, activation-induced cell death; APC, antigen-presenting cells; B(K), large conductance; CRAC, calcium release-activated calcium channels; DC, dendritic cell; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IFN-γ, interferon-γ; IP3, inositol (1,4,5)-triphosphate; (K)ir, inward rectifier; JNK, c-Jun N-terminal kinase; I(K), intermediate conductance; LPS, lipopolysaccharide; L, ligand; MCSF, macrophage colony-stimulating factor; MHC, major histocompatibility complex; NFAT, nuclear factor of activated T-cells; RANK, receptor activator of nuclear factor-κB; TCM, central memory T-cells; TEM, effector memory T-cells; TNF, tumor necrosis factor; TRAIL, TNF-related apoptosis-inducing ligand; OPG, osteoprotegerin; Omp29, 29-kDa outer membrane protein; PKC, protein kinase C; PLC, phospholipase C; RT-PCR, reverse-transcriptase polymerase chain-reaction; S(K), small conductance; TCR, T-cell receptor; and (K)v, voltage-gated.

Compressive Force Induces Osteoblast Apoptosis via Caspase-8

Periodontal remodeling during orthodontic tooth movement is a result of mechanical stresses. The application of excessive orthodontic force induces cell death. However, the nature of compressive force-induced cell death is unclear. We examined whether the in vitro application of continuous compressive force would induce apoptosis in human osteoblast-like cells (MG-63 cells), and investigated the mechanism by which apoptosis was initiated. The cells became aligned irregularly, and cell viability decreased, indicating that the compressive force caused cell death. According to the TUNEL analysis, the number of apoptotic cells increased significantly in a time-and force-dependent manner. Caspase-3 activity increased with the magnitude of the compressive force, and this effect was reduced significantly by a caspase-8 inhibitor, whereas a caspase-9 inhibitor had no such effect. We conclude that the in vitro application of compressive force can induce apoptosis in MG-63 cells through the activation of caspase-3 via the caspase-8 signaling cascade.

Preparative Purification of Bioactive Compounds from Flos Chrysanthemi Indici and Evaluation of Its Antiosteoporosis Effect

To understand the material basis and underlying molecular machinery of antiosteoporosis activity of the Flos Chrysanthemi Indici (FCI), the consequences of ethanol extract on the bone loss in mice induced due to ovariectomy (OVX) was evaluated. Also, the antiosteoporosis fraction obtained from the FCI ethanol extract was isolated and purified using a preparative high-speed countercurrent chromatography (HSCCC). The in vitro impact of the compounds was investigated on osteoblast proliferation and differentiation. The results revealed that ethyl acetate fraction with robust in vivo antiosteoporosis activity was obtained. The important compounds purified by HSCCC using gradient elution system included acacetin, apigenin, luteolin, and linarin. The four compounds enhanced the differentiation and proliferation of osteoblasts in MC3T3-E1 cells. They also augmented the mRNA levels of runt-related transcription factor 2 (Runx2), osteocalcin (OCN), osteopontin (OPN), and type I collagen (COL I). The AKT signaling pathway was also activated in MC3T3-E1 cells by the four compounds. The present study demonstrated that the antiosteoporosis effects of FCI did not depend on a single component, and HSCCC efficiently isolated and purified the antiosteoporosis bioactive compounds from FCI.

Obesity, Inflammation, and Periodontal Disease

The prevalence of obesity has increased substantially over the past decades in most industrialized countries. Obesity is a systemic disease that predisposes to a variety of co-morbidities and complications that affect overall health. Cross-sectional studies suggest that obesity is also associated with oral diseases, particularly periodontal disease, and prospective studies suggest that periodontitis may be related to cardiovascular disease. The possible causal relationship between obesity and periodontitis and potential underlying biological mechanisms remain to be established; however, the adipose tissue actively secretes a variety of cytokines and hormones that are involved in inflammatory processes, pointing toward similar pathways involved in the pathophysiology of obesity, periodontitis, and related inflammatory diseases. We provide an overview of the definition and assessment of obesity and of related chronic diseases and complications that may be important in the periodontist’s office. Studies that have examined the association between obesity and periodontitis are reviewed, and adipose-tissue-derived hormones and cytokines that are involved in inflammatory processes and their relationship to periodontitis are discussed. Our aim is to raise the periodontist’s awareness when treating obese individuals.

Alveolar bone in human immunodeficiency virus infection: is it changed by long-term antiretroviral therapy?

BACKGROUND

Previous studies have reported that human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) can lead to osteoporosis in HIV-infected individuals. However, their effects on alveolar bone are not well established. The objective of this study was to measure the alveolar bone mineral density (BMD) of HIV-infected patients, with and without antiretroviral therapy (ART), in comparison with that of HIV-free individuals, and to determine factors associated with the BMD of alveolar bone.

METHODS

A cross-sectional study was performed in non-HIV-infected individuals and HIV-infected individuals, with and without ART. Medical status and clinical data were recorded. Periapical radiographs of maxillary and mandibular right premolars were analysed for changes of alveolar BMD based on HIV/ART status. Other factors associated with the changes of alveolar BMD were explored using a parametric multivariate analysis of covariance (MANCOVA).

RESULTS

One-hundred and one HIV-infected individuals receiving ART (age range: 23-57 years; median age 39 years), 58 receiving no ART (age range: 20-59 years; median age 34 years) and 50 HIV-negative individuals (age range: 19-59 years; median age 36 years) were enrolled. Neither HIV status nor use of ART was significantly associated with the changes of alveolar BMD.

CONCLUSION

Although osteoporosis has been reported in HIV-infected individuals treated with ART, alveolar BMD does not appear to be changed as a result of the infection, or use of ART.

Cells Recognize and Prefer Bone-like Hydroxyapatite: Biochemical Understanding of Ultrathin Mineral Platelets in Bone

Hydroxyapatite (HAP) nanocrystallites in all types of bones are distinguished by their ultrathin characteristics, which are uniaxially oriented with fibrillar collagen to uniquely expose the (100) faces. We speculate that living organisms prefer the specific crystal morphology and orientation of HAP because of the interactions between cells and crystals at the mineral-cell interface. Here, bone-like platy HAP (p-HAP) and two different rod-like HAPs were synthesized to investigate the ultrathin mineral modulating effect on cell bioactivity and bone generation. Cell viability and osteogenic differentiation of mesenchymal stem cells (MSCs) were significantly promoted by the platy HAP with (100) faces compared to rod-like HAPs with (001) faces as the dominant crystal orientation, which indicated that MSCs can recognize the crystal face and prefer the (100) HAP faces. This face-specific preference is dependent on the selective adsorption of fibronectin (FN), a plasma protein that plays a central role in cell adhesion, on the HAP surface. This selective adsorption is further confirmed by molecule dynamics (MD) simulation. Our results demonstrate that it is an intelligent choice for cells to use ultrathin HAP with a large (100) face as a basic building block in the hierarchical structure of bone, which is crucial to the promotion of MSCs osteoinductions during bone formation.

Core level regulatory network of osteoblast as molecular mechanism for osteoporosis and treatment

To develop and evaluate the long-term prophylactic treatment for chronic diseases such as osteoporosis requires a clear view of mechanism at the molecular and systems level. While molecular signaling pathway studies for osteoporosis are extensive, a unifying mechanism is missing. In this work, we provide experimental and systems-biology evidences that a tightly connected top-level regulatory network may exist, which governs the normal and osteoporotic phenotypes of osteoblast. Specifically, we constructed a hub-like interaction network from well-documented cross-talks among estrogens, glucocorticoids, retinoic acids, peroxisome proliferator-activated receptor, vitamin D receptor and calcium-signaling pathways. The network was verified with transmission electron microscopy and gene expression profiling for bone tissues of ovariectomized (OVX) rats before and after strontium gluconate (GluSr) treatment. Based on both the network structure and the experimental data, the dynamical modeling predicts calcium and glucocorticoids signaling pathways as targets for GluSr treatment. Modeling results further reveal that in the context of missing estrogen signaling, the GluSr treated state may be an outcome that is closest to the healthy state.

Bushen Qiangji Granule () medicated serum inhibits osteogenic differentiation of fibroblasts in ankylosing spondylitis by inhibiting the BMP/Smads signal pathway in vitro

OBJECTIVE

To explore the mechanism of Bushen Qiangji Granule (, BSQJ) in restraining the osteogenic differentiation of ankylosing spondylitis (AS) fifibroblasts.

METHODS

Hip joint capsules were obtained from AS patients (n=10) receiving total hip replacement and healthy hip joint capsules from patients with hip fracture (n=10) receiving surgery as a control. Finite fifibroblast lines were established from these tissue samples to observe the effect of BSQJ on suppressing osteogenic differentiation of fifibroblasts. The expression of osteogenic marker gene corebinding factor a1 (Cbfa1) and Smad family proteins were examined by Western blot and real-time quantitative polymerase chain reaction (qPCR).

RESULTS

The mRNA expression level of Cbfa1 was significantly higher in AS fibroblasts than that in normal fibroblasts and the expression of pSmad1, pSmad5, Smad4 and Cbfa1 in AS fibroblasts was also higher, demonstrating the activation of the BMP/Smads signal pathway in AS fifibroblasts. BSQJ-medicated serum not only restrained the mRNA and protein expression levels of Cbfa1 and inhibited protein expression level of Smad4 but also decreased the expression quantities of pSmad1 and pSmad5.

CONCLUSIONS

BSQJ can inhibit osteogenic differentiation of AS fifibroblasts in vitro by suppressing the activation of the BMP/Smads signal pathway. This may be the important molecular mechanism of BSQJ in regulating AS ossifification.

iTRAQ-Based Quantitative Proteomic Analysis of the Potentiated and Dormant Antler Stem Cells

As the only known organ that can completely regenerate in mammals, deer antler is of real significance in the field of regenerative medicine. Recent studies have shown that the regenerative capacity of the antlers comes from the pedicle periosteum and the cells resident in the periosteum possess the attributes of stem cells. Currently, the molecular mechanism of antler regeneration remains unclear. In the present study, we compared the potentiated and dormant antler stem cells using isobaric tags for the relative and absolute quantification (iTRAQ) labeling of the peptides, coupled with two-dimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS) to compare the proteome profiles. Proteins were identified by searching against the NCBI nr database and our own Cervine transcriptome database, and bioinformatics analysis was conducted to identify the differentially expressed proteins. Based on this searching strategy, we identified 169 differentially expressed proteins in total, consisting of 70 up- and 99 down-regulated in the potentiated vs. dormant antler stem cells. Reliability of the iTRAQ was confirmed via quantitative real-time polymerase chain reaction (qRT-PCR) to measure the expression of selected genes. We identified transduction pathways through the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, such as HIF-1 and PI3K-AKT signaling pathways that play important roles in regulating the regeneration of antlers. In summary, the initiation stage of antler regeneration, a process from dormant to potentiated states in antler stem cells, is regulated by multiple proteins and complicated signal networks.

Loss of Rictor with aging in osteoblasts promotes age-related bone loss

Osteoblast dysfunction is a major cause of age-related bone loss, but the mechanisms underlying changes in osteoblast function with aging are poorly understood. This study demonstrates that osteoblasts in aged mice exhibit markedly impaired adhesion to the bone formation surface and reduced mineralization in vivo and in vitro. Rictor, a specific component of the mechanistic target of rapamycin complex 2 (mTORC2) that controls cytoskeletal organization and cell survival, is downregulated with aging in osteoblasts. Mechanistically, we found that an increased level of reactive oxygen species with aging stimulates the expression of miR-218, which directly targets Rictor and reduces osteoblast bone surface adhesion and survival, resulting in a decreased number of functional osteoblasts and accelerated bone loss in aged mice. Our findings reveal a novel functional pathway important for age-related bone loss and support for miR-218 and Rictor as potential targets for therapeutic intervention for age-related osteoporosis treatment.