RANK/RANKL/OPG role in distraction osteogenesis

Nanoparticle-Based Rice Husk Liquid Smoke as Periodontitis Therapy through OPG, RANK, and RANKL Expression

Introduction

Periodontitis therapy employing nanomaterials with submicron sizes holds promise for enhancing osteogenesis and facilitating periodontal cell proliferation. This study aims to assess the potential of nanoparticle-based rice husk liquid smoke (n-RHLS) in an animal model of periodontitis by evaluating the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-kβ (RANK), and receptor activator of nuclear factor-kβ ligand (RANKL).

Methods

Twenty-eight male Wistar rats were inoculated with 109 CFU/ml of Porphyromonas gingivalis in the sulcus mandibular incisor region to create periodontitis and subsequently treated with n-RHLS while the control with saline. Immunohistochemical staining was performed on the mandibular incisor to assess OPG, RANK, and RANKL expression 2 and 7 days after treatment.

Results

OPG expression exhibited a significant increase at both 2 and 7 days, while RANKL expression decreased notably after 7 days of treatment using n-RHLS (p < 0.05). In contrast, RANK expression did not show significant differences compared to the control groups (p > 0.05).

Conclusion

Nanostructured liquid smoke derived from rice husk nanoparticles (n-RHLS) demonstrates potential as a therapeutic agent for periodontitis, especially on OPG/RANK/RANKL expression, by modulating OPG and RANKL expression to support periodontal tissue health.

Lithium chloride stimulates bone formation in extraction socket repair in rats

PURPOSE

Previous evidence shows that lithium chloride (LiCl), a suppressor of glycogen synthase kinase-3β (GSK-3β), may enhance bone formation in several medical and dental conditions. Thus, the purpose of the current study was to assess the effects of LiCl on extraction socket repair in rats.

METHODS

Thirty rats were randomly assigned into a control group (administration of water; n = 15) or a LiCl group (administration of 150 mg/kg of LiCl; n = 15). LiCl and water were given every other day, starting at 7 days before the extraction of upper first molars until the end of each experiment period. Histological sections from five rats per group were obtained at 10, 20, and 30 days post-extractions. Histometrical analysis of newly formed bone (NB) and the levels of tartrate-resistant acid phosphatase (TRAP)-stained cells were evaluated at 10, 20, and 30 days post-extractions. Immunohistochemical staining for receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), bone sialoprotein (BSP), osteocalcin (OCN), and osteopontin (OPN) was assessed at 10 days post-extractions.

RESULTS

The LiCl group had a greater proportion of NB than the control group at 20 days (P < 0.05). At 30 days, the rate of TRAP-stained cells was lower in the LiCl group than in the control group (P < 0.05). At 10 days, the LiCl group presented stronger staining for OPG, BSP, OPN, and OCN, when compared to the control group (P < 0.05).

CONCLUSION

Systemic LiCl enhanced extraction socket repair, stimulated an overall increase in bone formation markers, and restricted the levels of TRAP in rats.

Bone-Targeted Nanoparticle Drug Delivery System-Mediated Macrophage Modulation for Enhanced Fracture Healing

Despite decades of progress, developing minimally invasive bone-specific drug delivery systems (DDS) to improve fracture healing remains a significant clinical challenge. To address this critical therapeutic need, nanoparticle (NP) DDS comprised of poly(styrene-alt-maleic anhydride)-b-poly(styrene) (PSMA-b-PS) functionalized with a peptide that targets tartrate-resistant acid phosphatase (TRAP) and achieves preferential fracture accumulation has been developed. The delivery of AR28, a glycogen synthase kinase-3 beta (GSK3β) inhibitor, via the TRAP binding peptide-NP (TBP-NP) expedites fracture healing. Interestingly, however, NPs are predominantly taken up by fracture-associated macrophages rather than cells typically associated with fracture healing. Therefore, the underlying mechanism of healing via TBP-NP is comprehensively investigated herein. TBP-NPAR28 promotes M2 macrophage polarization and enhances osteogenesis in preosteoblast-macrophage co-cultures in vitro. Longitudinal analysis of TBP-NPAR28 -mediated fracture healing reveals distinct spatial distributions of M2 macrophages, an increased M2/M1 ratio, and upregulation of anti-inflammatory and downregulated pro-inflammatory genes compared to controls. This work demonstrates the underlying therapeutic mechanism of bone-targeted NP DDS, which leverages macrophages as druggable targets and modulates M2 macrophage polarization to enhance fracture healing, highlighting the therapeutic benefit of this approach for fractures and bone-associated diseases.

Nociceptor-Macrophage Interactions in Apical Periodontitis: How Biomolecules Link Inflammation with Pain

Periradicular tissues have a rich supply of peripheral afferent neurons, also known as nociceptive neurons, originating from the trigeminal nerve. While their primary function is to relay pain signals to the brain, these are known to be involved in modulating innate and adaptive immunity by initiating neurogenic inflammation (NI). Studies have investigated neuroanatomy and measured the levels of biomolecules such as cytokines and neuropeptides in human saliva, gingival crevicular fluid, or blood/serum samples in apical periodontitis (AP) to validate the possible role of trigeminal nociceptors in inflammation and tissue regeneration. However, the contributions of nociceptors and the mechanisms involved in the neuro-immune interactions in AP are not fully understood. This narrative review addresses the complex biomolecular interactions of trigeminal nociceptors with macrophages, the effector cells of the innate immune system, in the clinical manifestations of AP.

Traditional Chinese Medicine Rhodiola Sachalinensis Borissova from Baekdu Mountain (RsBBM) for Rheumatoid Arthritis: Therapeutic Effect and Underlying Molecular Mechanisms

The lack of effective rheumatoid arthritis (RA) therapies is a persistent challenge worldwide, prompting researchers to urgently evaluate traditional Chinese medicines (TCMs) as potential clinical RA treatments. The present investigation was conducted to evaluate the therapeutic effects and potential molecular mechanisms of the active components isolated from TCM Rhodiola sachalinensis Borissova from Baekdu Mountain (RsB^BM) using an experimental adjuvant arthritis model induced by injection of rats with Freund’s complete adjuvant. After induction of the adjuvant arthritis rat model, the extract-treated and untreated groups of arthritic rats were evaluated for RsB^BM therapeutic effects based on comparisons of ankle circumferences and ELISA-determined blood serum inflammatory factor levels (TNF-α, IL-1β, and PGE2). In addition, the joint health of rats was evaluated via microscopic examination of hematoxylin-eosin-stained synovial tissues. Furthermore, to explore whether NF-κB and RANK/RANKL/OPG signaling pathways participated in observed therapeutic effects from a molecular mechanistic viewpoint, mRNA and protein levels related to the expression of nuclear factor kappa-B (NF-κB), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-Β ligand (RANKL) were analyzed via quantitative RT-PCR and Western blot analysis, respectively. Treatment of arthritic rats with the extract of RsB^BM was shown to reduce ankle swelling, reduce blood serum levels of inflammatory factors, and alleviate arthritis-associated synovial inflammation and joint damage. Moreover, an RsB^BM 50% ethanol extract treatment inhibited bone destruction by up-regulating OPG-related mRNA and protein expression and down-regulating RANKL-related mRNA and protein expression, while also reducing inflammation by the down-regulating of the NF-κB pathway activity. The results clearly demonstrated that the extract of RsB^BM alleviated adjuvant arthritis-associated joint damage by altering activities of inflammation-associated NF-κB and the RANK/RANKL/OPG signaling pathways. Due to its beneficial effects for alleviating adjuvant arthritis, this RsB^BM 50% ethanol extract should be further evaluated as a promising new therapeutic TCM treatment for RA.

Calcium and phosphorus co-doped carbon dots enhance osteogenic differentiation for calvarial defect repairin situ

Calvarial bone defect remains a clinical challenge due to the lack of efficient osteo-inductive agent. Herein, a novel calcium and phosphorus codoped carbon dot (Ca/P-CD) for bone regeneration was synthesized using phosphoethanolamine and calcium gluconate as precursors. The resultant Ca/P-CDs exhibited ultra-small size, stable excitation dependent emission spectra and favorable dispersibility in water. Moreover, Ca/P-CDs with good biocompatibility rapidly entered the cytoplasm through endocytosis and increased the expression of bone differentiation genes. After mixing with temperature-sensitive hydrogel, Ca/P-CDs were injectedin situinto calvarial defect and promoted the repair of bone injury. These Ca/P-CDs provide a new treatment method for the bone repair and should be expended the application in the biomedical fields.

Strontium doped mesoporous silica nanoparticles accelerate osteogenesis and angiogenesis in distraction osteogenesis by activation of Wnt pathway

Distraction osteogenesis (DO) is a powerful method to reconstruct segmented bone defects in the extremities. However, the main shortcoming of DO is the time-consuming consolidation period. To shorten the consolidation process, two biocompatible inorganic ions, strontium and silicone, were applied to design a biocompatible material to enhance bone mineralization ability during DO. In the present study, we integrated strontium into a one-pot synthesis of mesoporous silica nanoparticles to obtain strontium-doped mesoporous silica nanoparticles characterized by a homogeneous spherical morphology and uniform ion-releasing dynamics. This dual-ion releasing osteogenic and angiogenic drug delivery system was investigated to accelerate mineralization in DO. Osteogenesis was promoted by activation of the Wnt/β-catenin pathway, while bone resorption was inhibited by reduction of the osteoclastogenic factor RANKL/OPG. In addition, angiogenesis may have been enhanced indirectly by secretion of vascular endothelial growth factor (VEGF) from bone marrow stem cells. Therefore, strontium-doped mesoporous silica nanoparticles could be a potential biomaterial candidate for accelerating consolidation during DO.

Immunomodulatory effects and mechanisms of distraction osteogenesis

Distraction osteogenesis (DO) is widely used for bone tissue engineering technology. Immune regulations play important roles in the process of DO like other bone regeneration mechanisms. Compared with others, the immune regulation processes of DO have their distinct features. In this review, we summarized the immune-related events including changes in and effects of immune cells, immune-related cytokines, and signaling pathways at different periods in the process of DO. We aim to elucidated our understanding and unknowns about the immunomodulatory role of DO. The goal of this is to use the known knowledge to further modify existing methods of DO, and to develop novel DO strategies in our unknown areas through more detailed studies of the work we have done.

PLC, PTH and NF-κB increased during orthodontic bone remodeling in chronic stress rats

This study was designed to investigate the potential effects of chronic stress on periodontal bone remodeling and its mechanism during orthodontic tooth movement in rats. Forty-eight male SD rats aged 8 weeks were randomly divided into control group and chronic stress group. Chronic unpredictable mild stress model (CUMS) was established in the stress group, which was validated by behavioral experiment as well as cortisol (CORT) and adrenocorticotropic hormone (ATCH) levels. Then, the two groups were further divided into three distinct groups, namely group with no orthodontic force, group with 30 g orthodontic force and group with 50 g orthodontic force respectively to construct orthodontic tooth movement model. The rats were sacrificed after 14 days and maxilla on the loading side was obtained to measure tooth movement distance. It was found that compared with the control group, the chronic stress group displayed increased parathyroid hormone (PTH), amino terminal peptide of type I procollagen (PINP) and c-terminal peptide of type I collagen branch (CTX) levels as measured by enzyme-linked immunosorbent assay (ELISA). Hematoxylin and Eosin (HE) and TRAP staining showed fewer osteoblasts and more number of osteoclasts. The results of western blot showed no significant change in expression of Adenylate cyclase (AC) but increased phospholipase C (PLC) levels were noted. In addition, increased NF-κB expression was observed by immunohistochemistry. Overall, chronic stress can affect bone remodeling during orthodontic tooth movement by increasing the content of PTH in the blood and increasing PLC and NF-κB.

Modulating immune microenvironment during bone repair using biomaterials: Focusing on the role of macrophages

Bone is a self-regenerative tissue that can repair small defects and fractures. In large defects, bone tissue is unable to provide nutrients and oxygen for repair, and autologous grafting is used as the gold standard. As an alternative method, the bone tissue regeneration approach uses osteoconductive biomaterials to overcome bone graft disadvantages. However, biomaterials are considered as foreign components that can stimulate host immune responses. Although traditional principles have been aimed to minimize immune reactions, the design of biomaterials has steadily shifted toward creating an immunomodulatory microenvironment to harness immune cells and responses to repair damaged tissue. Among immune cells, macrophages secrete various immunomodulatory mediators and crosstalk with bone-forming cells and play key roles in bone tissue engineering. Macrophage polarization toward M1 and M2 subtypes mediate pro-inflammatory and anti-inflammatory responses, respectively, which are crucial for bone repairing at different stages. This review provides an overview of the crosstalk between various immune cells and biomaterials, macrophage polarization, and the effect of physicochemical properties of biomaterials on the immune responses, especially macrophages, in bone tissue engineering.

The Development of Molecular Biology of Osteoporosis

Osteoporosis is one of the major bone disorders that affects both women and men, and causes bone deterioration and bone strength. Bone remodeling maintains bone mass and mineral homeostasis through the balanced action of osteoblasts and osteoclasts, which are responsible for bone formation and bone resorption, respectively. The imbalance in bone remodeling is known to be the main cause of osteoporosis. The imbalance can be the result of the action of various molecules produced by one bone cell that acts on other bone cells and influence cell activity. The understanding of the effect of these molecules on bone can help identify new targets and therapeutics to prevent and treat bone disorders. In this article, we have focused on molecules that are produced by osteoblasts, osteocytes, and osteoclasts and their mechanism of action on these cells. We have also summarized the different pharmacological osteoporosis treatments that target different molecular aspects of these bone cells to minimize osteoporosis.

Comparison of the Effect of Oral Versus Intravenous Bisphosphonate Administration on Osteoclastogenesis in Advanced-Stage Medication-Related Osteonecrosis of the Jaw Patients

It is yet unknown whether the intravenous administration route alone can fully account for the exacerbation of medication-related osteonecrosis of the jaw (MRONJ). The purpose of this retrospective study was to identify the potential role of the bisphosphonate (BP) administration route as an independent prognostic factor for non-cancerous, stage III MRONJ patients. Bone samples were retrospectively obtained from two groups of osteoporosis patients who underwent surgery for the treatment of stage III MRONJ. Among the subjects, 10 had a history of only oral BP consumption and 10 of intravenous (IV) BP administration. The samples were assessed for osteoclast morphology and immunohistochemical expression of the receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), and potassium calcium-activated channel subfamily N member 4 (Kcnn4). Although the osteoclasts derived from both groups exhibited no significant differences in the mean quantity, diameter, and nuclearity, significantly attenuated tartrate-resistant acid phosphatase activity was noted among the IV BP-induced MRONJ bones compared to those of the oral BP group. Significant suppression of the RANKL/OPG ratio and Kcnn4 expression among the retrieved bones of IV BP group patients was also noted. Our results indicate the potential of the BP administration route as an independent prognostic factor for advanced-stage MRONJ, regardless of the dosage or indication for which the BP was prescribed.

The effect of strontium ranelate on titanium particle-induced periprosthetic osteolysis regulated by WNT/β-catenin signaling in vivo and in vitro

Aseptic loosening following periprosthetic osteolysis is the primary complication that limits the lifetime of total joint arthroplasty (TJA). The wear particles trigger a chronic inflammation response in the periprosthetic tissue and turn over the bone balance to bone resorption. The present study aimed to investigate the possible effect and mechanism of strontium ranelate (SR), a clinically safe drug for osteoporosis, on particle-induced periprosthetic osteolysis. Thirty-six female C57BL/6j mice underwent tibial Ti-nail implantation to establish an animal model of aseptic loosening. After 12 weeks, micro-CT results showed that strontium ranelate could inhibit periprosthetic bone resorption. In vitro, Ti particles were used to stimulate RAW264.7 cell line to collect conditioned medium, and co-culture MC3T3-E1 cell line with conditioned medium to establish a cell model of aseptic loosening. The results of alkaline phosphatase (ALP) detection, immunofluorescence, and flow cytometry demonstrated that strontium ranelate could regulate the expression of OPG/RANKL, promote differentiation and mineralization, and inhibit apoptosis in osteoblasts. Moreover, we revealed that SR's exerted its therapeutic effect by down-regulating sclerostin, thereby activating the Wnt/β-catenin signal pathway. Therefore, this research suggests that strontium ranelate could be a potential drug for the prevention and treatment of particle-induced aseptic loosening post-TJA.

RANKL is a new Epigenetic Biomarker for the Vasomotor Symptom During Menopause

During menopausal transition, decreased level of estrogen brings a number of physiological problems and hormonal changes. In this study, promoter methylation of RANKL and FSHR genes were identified in 30 premenopausal and 35 postmenopausal women using methylation-specific high resolution melting (MS-HRM) analysis. The statistical analyses and their association with patient characteristics were performed by Pearson χ² and Fisher's exact test (p <0.05). The methylated RANKL gene was detected in 16 postmenopausal cases, and 12 (75.0%) of the RANKL methylated cases had hot flashes (p = 0.024). The methylated FSHR gene was detected in 18 postmenopausal cases, and 13 (75.0%) of the methylated cases had hot flashes (p = 0.028). In vitro studies demonstrated the association between RANKL expression, FSH level and hot flashes in the mouse. Although lack of epigenetic studies in this field proves our results crucial and therefore, our results showed magnitude of epigenetic profiles of Turkish Cypriot post-menopausal women. This was the first study which has investigated the RANKL and FSHR methylation and their relationship with hot flashes in postmenopausal women.

Involvement of Eotaxins (CCL11, CCL24, CCL26) in Pathogenesis of Osteopenia and Osteoporosis

BACKGROUND

The purpose of this study was to investigate the role of eotaxin family members including C-C motif chemokine 11 (CCL11), C-C motif chemokine 24 (CCL24), and C-C motif chemokine 26 (CCL26) as the subgroups of CC-chemokine in patients affected with osteoporosis and osteopenia.

METHODS

Overall, 19 osteoporotic patients, 18 osteopenic individuals, and 20 healthy subjects were recruited in this study. The bone mineral density (BMD) was then measured at the lumbar spine (L1-L4) and the hip (femoral neck and total hip) using dual-energy X-ray absorptiometry for diagnosis of bone density and related disorders. Additionally, enzyme-linked immunosorbent assay (ELISA) technique was employed to measure the serum levels of CCL11, CCL24, and CCL26.

RESULTS

The circulating levels of CCL11, CCL24, and CCL26 had been increased in both groups of patients with osteopenia and osteoporosis compared to those in healthy subjects (P<0.05); while no significant difference was observed between serum levels of these chemokines in such patients.

CONCLUSION

Eotaxins can play a role in the pathogenesis of osteoporosis and osteopenia; however, further studies are needed to clarify various roles of eotaxins in the pathophysiology of osteoporosis and osteopenia.

Using MgO nanoparticles as a potential platform to precisely load and steadily release Ag ions for enhanced osteogenesis and bacterial killing

Bio-functional fillers including bio-ceramic, degradable metallic and composite particles are commonly introduced into bone tissue engineering (BTE) scaffolds to endow the materials with specific biological functions for enhanced bone defect therapy. In this work, MgO nanoparticles (NPs) were employed as a potential platform for precise loading and sustained release of Ag⁺. The results showed that MgO NPs possessed strong adsorption capacity (almost 100%) towards Ag⁺ in AgNO₃ solutions with different concentrations (0.1, 1 and 10 mM). After the adsorption of Ag⁺ in AgNO₃ solutions, cube-shaped MgO NPs transformed to lamella-structured nano-composites (NCs) composed of Mg(OH)₂ and Ag₂O, which were referred as MgO-xAg (x = 0.1, 1 or 10) NCs depending on the employed concentration of AgNO₃ solution. After being suspended in distilled water, as-prepared positively charged NCs underwent a fast degradation process during the initial 4 days. From day 4 and 14, steady release behaviors of Mg²⁺ and/or Ag⁺ from the NCs were noticed. With the lowest loading amount of Ag⁺, MgO-0.1Ag NCs did not exhibit significant modulatory effect on SaOS-2 cell response. On the contrary, MgO-10Ag NCs loaded with the highest amount of Ag⁺ showed significant cyto-toxicity towards SaOS-2 cells. With appropriate amount of Ag⁺ loading, MgO-1Ag NCs showed significantly stimulatory effects on SaOS-2 cell proliferation and differentiation. This is evidenced by the enhanced cell viability, alkaline phosphatase (ALP) activity and collagen (COL) production as well as the gene expressions of ALP, COL and osteoprotegerin (OPG) in MgO-1Ag group. Moreover, MgO-1Ag exhibited strong bactericidal capacity against both Escherichia coli and Staphylococcus aureus. Together, the results indicate that MgO could be employed as a potential platform for precise loading and sustained release of Ag⁺. MgO-1Ag NCs are promising to be used as bio-functional fillers in BTE scaffolds for simultaneously promoted osteogenesis and bacterial killing.

Effect of antiseptic gels in the microbiologic colonization of the suture threads after oral surgery

Three different bioadhesive gels were evaluated in a double-blind randomized clinical trial in which microbial growth in the suture thread was assessed following post-surgical application of the aforementioned gels. Also assessed in this trial were, the intensity of post-surgical pain as well as the degree of healing of the patients’ surgical wounds. A total of 21 patients (with 42 wisdom teeth) participated in this trial. Chlorhexidine gel, chlorhexidine-chitosan gel, and hyaluronic acid gel were evaluated, with a neutral water-based gel serving as the control agent. The aerobic and facultative anaerobic bacterial recovery on blood agar was lower in the placebo group than in the experimental groups. The most significant difference (p = 0.04) was observed in the chlorhexidine-chitosan group. in which the growth of Blood Agar and Mitis Salivarius Agar was significantly higher than in the placebo group. The intensity of post-surgical pain was very similar among all the groups. Significantly better healing rates were observed in the patients treated with chlorhexidine-chitosan gel when compared with those who used the placebo gel (p = 0.03), and in particular when compared with those patients who used hyaluronic acid gel (p = 0.01). Through our microbiological analyses, we were able to conclude that none of the bioadhesive gels tested resulted in beneficial reductions in the bacterial/fungal populations. However, the healing rates of patients who were treated with chlorhexidine-chitosan were better than those of the patients who used either the placebo gel or the hyaluronic acid gel.

Effects of receptor activator nuclear factor κB gene polymorphisms on the susceptibility to knee osteoarthritis: A case-control study

The present study aimed to explore genetic association of receptor activator nuclear factor κB (RANK) polymorphisms with individual susceptibility to knee osteoarthritis (OA) in different Kellgren-Lawrence (KL) grades.This case-control study included 138 knee OA patients and 145 healthy individuals. RANK rs1805034 and rs8086340 polymorphisms were genotyped through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The effects of RANK polymorphisms on knee OA risk were analyzed via χ test or Fisher exact test, and the results were expressed using odds ratios (ORs) with corresponding 95% confidence intervals (CIs).The C allele of rs1805034 polymorphism had significantly higher frequency in knee OA patients than in controls (P = .044), indicating that this allele could increase the risk of knee OA (OR = 1.424, 95% CI = 1.010-2.008). Besides, the CC genotype and C allele of the rs1805034 polymorphism were significantly associated with elevated risk of knee OA in moderate grade (CC vs TT: P = .018, OR = 3.071, 95% CI = 1.187-7.941; C vs T: P = .012, OR = 1.787, 95% CI = 1.131-2.823). However, rs8086340 polymorphism had no significant association with knee OA riskThe C allele of RANK rs1805034 polymorphism is closely correlated with increased risk of knee OA, especially for moderate grade.

Protein-Based Salivary Profiles as Novel Biomarkers for Oral Diseases

The Global Burden of Oral Diseases affects 3.5 billion people worldwide, representing the number of people affected by the burden of untreated dental caries, severe periodontal disease, and edentulism. Thus, much more efforts in terms of diagnostics and treatments must be provided in the fight of these outcomes. In this sense, recently, the study of saliva as biological matrix has been identified as a new landmark initiative in the search of novel and useful biomarkers to prevent and diagnose these conditions. Specifically, saliva is a rich reservoir of different proteins and peptides and accessible due to recent advances in molecular biology and specially in targeted and unbiased proteomics technologies. Nonetheless, emerging barriers are an obstacle to the study of the salivary proteome in an effective way. This review aims at giving an overall perspective of salivary biomarkers identified in several oral diseases by means of molecular biology approaches.

Effects of locally applied adipose tissue-derived microvascular fragments by thermoresponsive hydrogel on bone healing

Insufficient vascularization is a major cause for the development of non-unions. To overcome this problem, adipose tissue-derived microvascular fragments (MVF) may serve as vascularization units. However, their application into bone defects needs a carrier system. Herein, we analyzed whether this is achieved by a thermoresponsive hydrogel (TRH). MVF were isolated from CD-1 mice and cultivated after incorporation into TRH, while non-incorporated MVF served as controls. Viability of MVF was assessed immunohistochemically over a 7-day period. Moreover, osteotomies were induced in femurs of CD-1 mice. The osteotomy gaps were filled with MVF-loaded TRH (TRH + MVF), unloaded TRH (TRH) or no material (control). Bone healing was evaluated 14 and 35 days postoperatively. MVF incorporated into TRH exhibited less apoptotic cells and showed a stable vessel morphology compared to controls. Micro-computed tomography revealed a reduced bone volume in TRH + MVF femurs. Histomorphometry showed less bone and more fibrous tissue after 35 days in TRH + MVF femurs compared to controls. Accordingly, TRH + MVF femurs exhibited a lower osseous bridging score and a reduced bending stiffness. Histology and Western blot analysis revealed an increased vascularization and CD31 expression, whereas vascular endothelial growth factor (VEGF) expression was reduced in TRH + MVF femurs. Furthermore, the callus of TRH + MVF femurs showed increased receptor activator of NF-κB ligand expression and higher numbers of osteoclasts. These findings indicate that TRH is an appropriate carrier system for MVF. Application of TRH + MVF increases the vascularization of bone defects. However, this impairs bone healing, most likely due to lower VEGF expression during the early course of bone healing.

STATEMENT OF SIGNIFICANCE

In the present study we analyzed for the first time the in vivo performance of a thermoresponsive hydrogel (TRH) as a delivery system for bioactive microvascular fragments (MVF). We found that TRH represents an appropriate carrier for MVF as vascularization units and maintains their viability. Application of MVF-loaded TRH impaired bone formation in an established murine model of bone healing, although vascularization was improved. This unexpected outcome was most likely due to a reduced VEGF expression in the early phase bone healing.

Possible mechanisms of prednisolone-induced osteoporosis in zebrafish larva

Glucocorticoid-induced osteoporosis (GIOP) is a serious clinical bone disease that results from the long-term consumption of glucocorticoids or glucocorticoid-like drugs. Although many studies have attempted to determine the mechanisms of GIOP, they are still unclear. In this study, we established a zebrafish model of glucocorticoid-like drug-induced osteoporosis by treating larvae with prednisolone. We then quantified the expression of a selection of extracellular matrix (ECM)-, osteoblast-, and osteoclast-related genes. Our results showed that at 15 days post fertilization, zebrafish larvae treated with 25 μM prednisolone are a suitable model for GIOP, not only owing to the decrease in robust bone mass but also because of significant alterations in gene expression. The quantification of the expression of ECM-, osteoblast-, and osteoclast- related genes revealed that mmp9 and mmp13 were significantly upregulated and entpd5a, acp5a, and sost were significantly downregulated. These genes may be a target for future research into GIOP. Our study thus provides new insights into GIOP.

RNA sequencing reveals a transcriptomic portrait of human mesenchymal stem cells from bone marrow, adipose tissue, and palatine tonsils

Human mesenchymal stem cells (MSCs) are adult multipotent cells that have plasticity and inhabit the stroma of diverse tissues. The potential utility of MSCs has been heavily investigated in the fields of regenerative medicine and cell therapy. However, MSCs represent diverse populations that may depend on the tissue of origin. Thus, the ability to identify specific MSC populations has remained difficult. Using RNA sequencing, we analyzed the whole transcriptomes of bone marrow-derived MSCs (BMs), adipose tissue-derived MSCs (AMs), and tonsil-derived MSCs (TMs). We categorized highly regulated genes from these MSC groups according to functional gene ontology (GO) classification. AMs and TMs showed higher expression of genes encoding proteins that function in protein binding, growth factor, or cytokine activity in extracellular compartments than BMs. Interestingly, TM were highly enriched for genes coding extracellular, protein-binding proteins compared with AMs. Functional Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis also showed differentially enriched signaling pathways between the three MSC groups. Further, we confirmed surface antigens expressed in common and in a tissue-specific manner on BMs, AMs, and TMs by flow cytometry analysis. This study provides comprehensive characteristics of MSCs derived from different tissues to better understand their cellular and molecular biology.

Mesenchymal stem cells inhibit RANK-RANKL interactions between osteoclasts and Th17 cells via osteoprotegerin activity

Th17 cells play a critical role in several autoimmune diseases, including psoriasis and psoriatic arthritis (PsA). Psoriasis is a chronic inflammatory skin disease associated with systemic inflammation and comorbidities, such as PsA. PsA develops in nearly 70% of patients with psoriasis, and osteoclasts associated bone erosion is a hallmark of the disease. Thus far, the effect of Th17 cells on osteoclastogenesis via direct cell-to-cell interactions is less understood. In this study, we observed that Th17 cells directly promote osteoclast differentiation and maturation via expression of receptor activator of nuclear factor-κ β ligand (RANKL) in vitro. We investigated the impact of conditioned medium obtained from human palatine tonsil-derived mesenchymal stem cells (T-CM) on the interactions between osteoclasts and Th17 cells. T-CM effectively blunted the RANK-RANKL interaction between the osteoclast precursor cell line RAW 264.7 and Th17 cells via osteoprotegerin (OPG) activity. The frequency of tartrate-resistant acid phosphatase (TRAP)-positive cells in the bone marrow of an imiquimod (IMQ)-induced psoriasis mouse model was decreased following T-CM injection. Therefore, our data provide novel insight into the therapeutic potential of tonsil-derived mesenchymal stem cell-mediated therapy (via OPG production) for the treatment of pathophysiologic processes induced by osteoclasts under chronic inflammatory conditions such as psoriasis.

Production of bone mineral material and BMP-2 in osteoblasts cultured on double acid-etched titanium

Background

The study of osteoblasts and their osteogenic functions is essential in order to understand them and their applications in implantology. In this sense, this study try to study BMP-2 production and bone matrix deposition, in addition to other biological variables, in osteoblasts cultured on a rough double acid-etched titanium surface (Osseotite®, Biomet 3i, Palm Beach Garden, Florida, USA) in comparison to a smooth titanium surface (machined) and a control Petri dish.

Material and Methods

An in vitro prospective study. NHOst human osteoblasts from the femur were cultured on three different surfaces: Control group: 25-mm methacrylate dish (n = 6); Machined group: titanium discs with machined surface (n = 6) and Experimental group: titanium discs with a double acid-etched nitric and hydrofluoric Osseotite® acid surface (n = 6). A quantification of the mitochondrial membrane potential, and studies of apoptosis, mobility and adhesion, bone productivity (BMP-2) and cellular bone synthesis were carried out after culturing the three groups for forty-eight hours.

Results

A statistically significant difference was observed in the production of BMP-2 between the experimental group and the other two groups (22.33% ± 11.06 vs. 13.10% ± 5.51 in the machined group and 3.88% ± 3.43 in the control group). Differences in cellular bone synthesis were also observed between the groups (28.34% ± 14.4% in the experimental group vs. 20.03% ± 6.79 in the machined group and 19.34% ± 15.93% in the control group).

Conclusions

In comparison with machined surfaces, Osseotite® surfaces favor BMP-2 production and bone synthesis as a result of the osteoblasts in contact with it.

Key words:BMP-2, Cytoskeleton, cell culture, bone matrix, apoptosis, cell viability.

The Alpha 7 Nicotinic Acetylcholine Receptor of Deciduous Dental Pulp Stem Cells Regulates Osteoclastogenesis During Physiological Root Resorption

The physiological root resorption of deciduous teeth is a normal phenomenon, but the mechanisms underlying this process are still unclear. In this study, deciduous dental pulp stem cells (DDPSCs) and permanent dental pulp stem cells (DPSCs) were derived from deciduous teeth and normal permanent teeth at different stages of resorption. In the middle stage of root resorption, DDPSCs exhibited an increase in the ability to induce osteoclast differentiation. Activation of the alpha 7 nicotinic acetylcholine receptor (α7 nAChR) by secretory mammalian Ly-6 urokinase-type plasminogen activator receptor-associated protein 1 (SLURP-1) caused a significant increase in the expression levels of NF-κB, receptor activator of nuclear factor-kappa B ligand (RANKL), and the ratio of RANKL/osteoprotegerin (OPG). These effects were inhibited by alpha-bungarotoxin (α-BTX). Furthermore, the expression levels of RANKL/OPG were significantly reduced following inhibition of NF-κB. High-strength, dynamic positive pressure increased the expression of SLURP-1 and α7 nAChR in DDPSCs in the stable stage. These data indicated that mechanical stress stimulated the expression of SLURP-1 and α7 nAChR in DDPSCs. Additionally, SLURP-1 activated α7 nAChR, thereby upregulating the expression of NF-κB and enhancing its activity, thus regulating RANKL/OPG expression and affecting the ability of DDPSCs to influence osteoclastogenesis, which likely enhances root resorption and leads to the physiological loss of deciduous teeth.

Tertiary lymphoid structures, drivers of the anti-tumor responses in human cancers

The characterization of the microenvironment of human tumors led to the description of tertiary lymphoid structures (TLS) characterized by mature dendritic cells in a T-cell zone adjacent to B-cell follicle including a germinal center. TLS represent sites of lymphoid neogenesis that develop in most solid cancers. Analysis of the current literature shows that the TLS presence is associated with a favorable clinical outcome for cancer patients, regardless of the approach used to quantify TLS and the stage of the disease. Using several approaches that combine immunohistochemistry, gene expression assays, and flow cytometry on large series of lung tumors, our work demonstrated that TLS are important sites for the initiation and/or maintenance of the local and systemic T- and B-cell responses against tumors. Surrounded by high endothelial venules, they represent a privileged area for the recruitment of lymphocytes into tumors and generation of central-memory T and B cells that circulate and limit cancer progression. TLS can be considered as a novel biomarker to stratify the overall survival risk of untreated cancer patients and as a marker of efficient immunotherapies. The induction and manipulation of cancer-associated TLS using drug agonists and/or biotherapies should open new avenues to treat cancer patients.

Dual effect of WIN-34B on osteogenesis and osteoclastogenesis in cytokine-induced mesenchymal stem cells and bone marrow cells

ETHNOPHARMACOLOGICAL RELEVANCE

As an n-butanol fractionated extracted mixture of Lonicera japonica Thunb, dried flowers and Anemarrhena asphodeloides Bunge, root, WIN-34B has been reported the analgesic, anti-inflammatory, cartilage-repairing and protective effects in previous studies.

AIM OF THE STUDY

To investigate the effect of WIN-34B on osteogenesis and osteoclastogenesis in cytokine-induced mesenchymal stem cells and bone marrow cells.

MATERIALS AND METHODS

To examine the effect of WIN-34B on osteogenic differentiation, human mesenchymal stem cells (hMSCs) were treated with WIN-34B (1μg/mL and 10μg/mL). Alkaline phosphatase (ALP) activity was evaluated and Von Kossa staining was conducted. Mice bone marrow macrophages (BMMs) were obtained and treated with receptor activator of nuclear factor-κB ligand (RANKL) and macrophage colony stimulating factor (m-CSF) to induce osteoclastogenesis. To investigate osteoclast differentiation, tartrate-resistant acid phosphatase (TRAP) staining was conducted after treatment with WIN-34B. Osteoclastogenic conditions were induced by stimulating the cells with interleukin (IL)-1α, IL-17, and tumor necrosis factor (TNF-α) in hMSCs and BMMs co-culture systems. The expression levels of osteoprotegerin (OPG), RANKL, runt-related transcription factor 2 (RUNX2), IL-17, c-Fos, TNF-α, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were measured by reverse transcription polymerase chain reaction (RT-PCR). The expression levels of nuclear factor-kappaB (NF-κB), inhibitory kappa B-α (IκBα), phospho-NF-κB, phospho-IκBα, β-actin, p38 MAPK, phospho-c-Jun N-terminal kinase (JNK), phospho-extracellular-signal regulated kinase (ERK), phospho-p38 mitogen-activated protein kinase (MAPK), phospho-JNK, and phospho-ERK were measured by western blot analysis.

RESULTS

WIN-34B promoted ALP activity and mineralization of hMSCs. In TRAP-stained BMMs, the number of multinucleated cells decreased after WIN-34B treatment. WIN-34B increased the OPG/RANKL ratio and the expression of RUNX2, and suppressed the expression of IL-17, c-Fos, and TNF-α. It also suppressed the activation of NF-κB, IκBα, p38 MAPK, and JNK in a dose-dependent manner.

CONCLUSIONS

These results demonstrated that WIN-34B increased osteogenesis and decreased osteoclastogenesis in cytokine-induced mesenchymal stem cells and bone marrow cells via inhibition of the NF-κB, JNK, and p38 MAPK pathways.

Identification of candidate genes in osteoporosis by integrated microarray analysis

Objectives

In order to screen the altered gene expression profile in peripheral blood mononuclear cells of patients with osteoporosis, we performed an integrated analysis of the online microarray studies of osteoporosis.

Methods

We searched the Gene Expression Omnibus (GEO) database for microarray studies of peripheral blood mononuclear cells in patients with osteoporosis. Subsequently, we integrated gene expression data sets from multiple microarray studies to obtain differentially expressed genes (DEGs) between patients with osteoporosis and normal controls. Gene function analysis was performed to uncover the functions of identified DEGs.

Results

A total of three microarray studies were selected for integrated analysis. In all, 1125 genes were found to be significantly differentially expressed between osteoporosis patients and normal controls, with 373 upregulated and 752 downregulated genes. Positive regulation of the cellular amino metabolic process (gene ontology (GO): 0033240, false discovery rate (FDR) = 1.00E + 00) was significantly enriched under the GO category for biological processes, while for molecular functions, flavin adenine dinucleotide binding (GO: 0050660, FDR = 3.66E-01) and androgen receptor binding (GO: 0050681, FDR = 6.35E-01) were significantly enriched. DEGs were enriched in many osteoporosis-related signalling pathways, including those of mitogen-activated protein kinase (MAPK) and calcium. Protein-protein interaction (PPI) network analysis showed that the significant hub proteins contained ubiquitin specific peptidase 9, X-linked (Degree = 99), ubiquitin specific peptidase 19 (Degree = 57) and ubiquitin conjugating enzyme E2 B (Degree = 57).

Conclusion

Analysis of gene function of identified differentially expressed genes may expand our understanding of fundamental mechanisms leading to osteoporosis. Moreover, significantly enriched pathways, such as MAPK and calcium, may involve in osteoporosis through osteoblastic differentiation and bone formation.

Cite this article: J. J. Li, B. Q. Wang, Q. Fei, Y. Yang, D. Li. Identification of candidate genes in osteoporosis by integrated microarray analysis. Bone Joint Res 2016;5:594–601. DOI: 10.1302/2046-3758.512.BJR-2016-0073.R1.

Fructus Ligustri Lucidi ethanol extract inhibits osteoclastogenesis in RAW264.7 cells via the RANKL signaling pathway

Fructus ligustri Lucidi (FLL) is the fruit of Ligustrum lucidum Ait and a traditional Chinese medicine, primarily known for its role in osteoporosis prevention and treatment. The present study aimed to elucidate the effect and underlying mechanism of action of ethanol extract of FLL on osteoclast differentiation and bone resorption, and to identify the active compounds within it. RAW264.7 murine monocyte/macrophage cells were stimulated with the receptor activator of nuclear factor κB ligand (RANKL) to induce osteoclast differentiation in vitro. The present study demosntrated that FLL extract and its two primary components, oleanolic acid (OA) and ursolic acid (UA), significantly suppressed RANKL‑induced tartrate resistant acid phosphatase (TRAP) activity and multinucleate osteoclast formation without inducing cytotoxicity; however, no effect was observed on the apoptosis of mature osteoclasts. Additionally, RANKL‑induced mRNA expression levels of the key transcription factors, tumor necrosis factor receptor associated factor‑6, nuclear factor of activated T cell‑c1 and c‑Fos, and the osteoclast markers, TRAP, cathepsin K and matrix metalloproteinase‑9 were suppressed by FLL, OA and UA. However, no effect was observed on RANKL‑induced mRNA expression levels of Src. These results demonstrated that FLL may inhibit osteoclastogenesis in RAW264.7 cells via RANKL signaling pathways. OA and UA are active compounds in inducing this effect; however, their specific roles remain to be elucidated.

MicroRNA-145 Mediates Steroid-Induced Necrosis of the Femoral Head by Targeting the OPG/RANK/RANKL Signaling Pathway

Objective

To investigate the role of microRNA-145 (miR-145) in steroid-induced necrosis of the femoral head (SINFH) by evaluating its effects on the OPG/RANK/RANKL signaling pathway.

Methods

A rat model of SINFH was constructed via injection of the lentiviral vector pLV-shRNA-miR-145. Pathological observation was performed via tartrate-resistant acid phosphatase (TRAP) staining, and serum OPG levels were detected by ELISA. The mRNA expression levels of miR-145, OPG, RANK and RANKL in THP-1 cells were assessed by RT-PCR, and the protein expression levels of OPG, RANK and RANKL were assessed by western blotting.

Results

The expression of miR-145 in the lentivirus-mediated miR-145 group was significantly up-regulated compared with that in the control and normal groups (both P < 0.01). Serum OPG levels were decreased in SINFH rats compared with control and normal rats. The mRNA and protein expression levels of OPG in THP-1 cells decreased after transfection (all P < 0.05). By contrast, the mRNA and protein expression levels of RANK and RANKL in THP-1 cells increased after transfection (all P < 0.05). After transfection of 293T cells with an miR-145 overexpression vector, miR-145 expression in 293T cells increased significantly, while OPG mRNA and protein expression decreased significantly (all P < 0.05).

Conclusion

MiR-145 plays a role in the occurrence of SINFH by targeting the OPG/RANK/RANKL signaling pathway.

Impact of CDT Toxin on Human Diseases

Cytolethal distending toxin (CDT) is found in Gram-negative bacteria, especially in certain Proteobacteria such as the Pasteurellaceae family, including Haemophilus ducreyi and Aggregatibacter (Actinobacillus) actinomycetemcomitans, in the Enterobacteriaceae family and the Campylobacterales order, including the Campylobacter and Helicobacter species. In vitro and in vivo studies have clearly shown that this toxin has a strong effect on cellular physiology (inflammation, immune response modulation, tissue damage). Some works even suggest a potential involvement of CDT in cancers. In this review, we will discuss these different aspects.

Involvement of the Nonneuronal Cholinergic System in Bone Remodeling in Rat Midpalatal Suture after Rapid Maxillary Expansion

Few studies sought to analyze the expression and function of the nonneuronal acetylcholine system in bone remodeling in vivo due to the lack of suitable models. We established a rat maxilla expansion model in which the midline palatine suture of the rat was rapidly expanded under mechanical force application, inducing tissue remodeling and new bone formation, which could be a suitable model to investigate the role of the nonneuronal acetylcholine system in bone remodeling in vivo. During the expansion, the expression pattern changes of the nonneuronal cholinergic system components and the mRNA levels of OPG/RANKL were detected by immunohistochemistry or real-time PCR. The value of the RANKL/OPG ratio significantly increased after 1 day of expansion, indicating dominant bone resorption induced by the mechanical stimulation; however after 3 days of expansion, the value of the RANKL/OPG ratio significantly decreased, suggesting a dominant role of the subsequent bone formation process. Increasing expression of Ach was detected after 3 days of expansion which indicated that ACh might play a role in bone formation. The mRNA expression levels of other components also showed observable changes during the expansion which confirmed the involvement of the nonneuronal cholinergic system in the process of bone remodeling in vivo. Further researches are still needed to figure out the detailed functions of the nonneuronal cholinergic system and its components.

In Vivo siRNA Delivery Using JC Virus-like Particles Decreases the Expression of RANKL in Rats

Bone remodeling requires a precise balance between formation and resorption. This complex process involves numerous factors that orchestrate a multitude of biochemical events. Among these factors are hormones, growth factors, vitamins, cytokines, and, most notably, osteoprotegerin (OPG) and the receptor activator for nuclear factor-kappaB ligand (RANKL). Inflammatory cytokines play a major role in shifting the RANKL/OPG balance toward excessive RANKL, resulting in osteoclastogenesis, which in turn initiates bone resorption, which is frequently associated with osteoporosis. Rebalancing RANKL/OPG levels may be achieved through either upregulation of OPG or through transient silencing of RANKL by means of RNA interference. Here, we describe the utilization of a viral capsid-based delivery system for in vivo and in vitro RNAi using synthetic small interfering RNA (siRNA) molecules in rat osteoblasts. Polyoma JC virus-derived virus-like particles are capable of delivering siRNAs to target RANKL in osteoblast cells both in vitro and in a rat in vivo system. Expression levels were monitored using quantitative real-time polymerase reaction and enzyme-linked immunosorbent assay after single and repeated injections over a 14-day period. Our data indicate that this is an efficient and safe route for in vivo delivery of gene modulatory tools to study important molecular factors in a rat osteoporosis model.

The effects of α-zearalanol on the proliferation of bone-marrow-derived mesenchymal stem cells and their differentiation into osteoblasts

The aim of this study was to explore the effects of α-zearalanol (α-ZAL) on the proliferation of mouse bone-marrow-derived mesenchymal stem cells (BMSCs) and their differentiation into osteoblasts. Six- to eight-week-old BALB/C mice were used either as recipients or as bone marrow donors. BMSCs were isolated and collected using a differential adhesion method, with use of 10 % fetal bovine serum and Iscove's modified Dulbecco's medium. After the third generation, the BMSCs were randomly placed into the following subgroups: a control group, an osteogenic medium (OM) group, a 17β-estradiol group, an α-ZAL 10(-7) mol/L group, an α-ZAL 10(-6) mol/L group, and an α-ZAL 10(-5) mol/L group. Flow cytometry was used to identify the BMSCs collected from the bone marrow. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test was performed, and markers of the osteoblasts were measured in the different subgroups. In addition, expression of osteoprotegerin and expression of receptor activator of nuclear factor κB ligand were examined using Western blot. In contrast to the control and OM groups, BMSCs in the α-ZAL groups exhibited long fusiform shapes, and contact inhibition was observed when the cells were closely packed. After induction, the BMSCs grew well and exhibited triangular, star, polygonal, or irregular shapes. Clumps and multiple cells were evident. The trends of the proliferation and differentiation for the control, OM, 17β-estradiol, and α-ZAL groups were similar. Compared with the control and OM groups, in the α-ZAL groups the expression levels of alkaline phosphatase, procollagen type I N-terminal propeptide, bone morphogenetic protein 2, and osteocalcin were significantly increased (p < 0.05). In addition, α-ZAL inhibited osteoclastogenesis by increasing the expression of osteoprotegerin and decreasing the expression of nuclear factor κB ligand. In conclusion, α-ZAL can increase the proliferation of BMSCs and their differentiation into osteoblasts and can effectively suppress osteoclastogenesis.

MAGED1 is a negative regulator of bone remodeling in mice

Melanoma antigen family D1 (MAGED1), an important adaptor protein, has been shown to ubiquitously express and play critical roles in many aspects of cellular events and physiological functions. However, its role in bone remodeling remains unknown. We, therefore, analyzed the bone phenotype of Maged1-deficient mice. Maged1-deficient mice displayed a significant osteoporotic phenotype with a marked decrease in bone density and deterioration of trabecular architecture. Histomorphometric analysis demonstrated an increased mineral apposition rate as well as increased osteoclast number and surface in Maged1 knockout mice. At the cellular level, Maged1-deficient osteoblasts exhibited an increased proliferation rate and accelerated differentiation. MAGED1 deficiency also caused a promotion in osteoclastogenesis, and that was attributed to the cell autonomous acceleration of differentiation in osteoclasts and an increased receptor activator of NF-κB ligand/osteoprotegerin ratio, a major index of osteoclastogenesis, in osteoblasts. Thus, we identified MAGED1 as a novel regulator of osteoblastogenesis, osteoclastogenesis, and bone remodeling in a mouse model.

The role and regulation of osteoclasts in normal bone homeostasis and in response to injury

Bone is a dynamic tissue, with a range of diverse functions, including locomotion, protection of internal organs, and hematopoiesis. Optimum treatment of fractures and/or bone defects requires knowledge of the complex cellular interactions involved with bone healing and remodeling. Emerging data have underscored the importance of osteoclasts in this process, playing a key role both in normal bone turnover and in facilitating bone regeneration. In this review, the authors discuss the basic principles of osteoclast biology, including its cellular origins, its function, and key regulatory mechanisms, in addition to conditions that arise when osteoclast function is altered.

Effect of heterologous bone marrow mononuclear cell transplantation on midpalatal expansion in rats

The aim of this study was to explore whether bone marrow mononuclear cell (BMMC) transplantation is able to accelerate the bone remodeling induced by midpalatal expansion in rats. A total of 48 male Sprague-Dawley rats (mean weight, 208.36±7.32 g) were divided into control and midpalatal expansion with or without BMMC transplantation groups. Histological and morphological changes were observed in each group. The osteogenic activities and differential potentials of the transplanted BMMCs labeled with bromodeoxyuridine in the midpalatal bone tissue were assessed by osteocalcin expression. The receptor activator of nuclear factor κB ligand (RANKL)/osteoprotegerin (OPG) ratio was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to reflect the equilibrium between bone resorption and formation. The results demonstrated that the width of the maxillary dental arch increased distinctly within 2 weeks of midpalatal expansion with BMMC transplantation. The morphology of the midpalatal suture in this group changed significantly; the cartilage was completely replaced by fibrous-like tissue expressing osteocalcin. The palatal bone was reorganized from a cancellous form into a mature compact structure after an additional 2-week relapse period. Immunostaining results indicated that the heterologous transplanted BMMCs survived and differentiated into osteoblasts during the remodeling induced by midpalatal expansion. The RANKL/OPG expression ratio significantly decreased after 2 weeks of midpalatal expansion with BMMC transplantation due to the inhibition of RANKL expression. Heterologous BMMC transplantation appears to accelerate the midpalatal bone remodeling induced by expansion of the rats through increasing the number of osteoprogenitor cells and regulating the RANKL-OPG signaling pathway.

Bone Regulates Glucose Metabolism as an Endocrine Organ through Osteocalcin

Skeleton was considered as a dynamic connective tissue, which was essential for mobility, calcium homeostasis, and hematopoietic niche. However more and more evidences indicate that skeleton works not only as a structural scaffold but also as an endocrine organ, which regulates several metabolic processes. Besides osteoprotegerin (OPG), sclerostin (SOST), and Dickopf (DKK) which play essential roles in bone formation, modelling, remodelling, and homeostasis, bone can also secret hormones, such as osteocalcin (OCN), which promotes proliferation of β cells, insulin secretion, and insulin sensitivity. Additionally OCN can also regulate the fat cells and male gonad endocrine activity and be regulated by insulin and the neural system. In summary, skeleton has endocrine function via OCN and plays an important role in energy metabolism, especially in glucose metabolism.

Fructus Ligustri Lucidi (FLL) ethanol extract increases bone mineral density and improves bone properties in growing female rats

Osteoporosis is a chronic disease affecting millions of people worldwide. It is generally accepted that acquisition of a high peak bone mass (PBM) early in life can reduce the risk of osteoporosis later in life. The aims of this study were to investigate the effects of Fructus Ligustri Lucidi (FLL) ethanol extract on bone mineral density and its mechanical properties in growing female rats and to explore the underlying mechanisms. The rats were given different doses of FLL extract mixed with AIN-93G formula (0.40, 0.65 and 0.90 %), and a group given AIN-93G diet treatment only was used as control. The intervention lasted for 16 weeks until the animals were about 5 months old, the time when the animals almost reach their PBM. Our results showed that FLL treatment increased bone mineral density and improved bone mechanical properties in the growing female rats in a dose-dependent manner. In addition, FLL treatment significantly decreased the serum bone-resorbing marker, CTX-I, while significantly increasing serum 25(OH)D3 and thereby increasing Ca absorption and Ca retention. Intriguingly, both in vivo and in vitro results demonstrated that FLL treatment could reduce the RANKL/OPG ratio. In conclusion, FLL ethanol extract exerted beneficial effects on peak bone mass acquisition and the improvement of bone mechanical properties by favoring Ca metabolism and decreasing the RANKL/OPG ratio.