Lanthanum Chloride Attenuates Osteoclast Formation and Function Via the Downregulation of Rankl-Induced Nf-κb and Nfatc1 Activities

Attenuating Atherosclerosis through Inhibition of the NF-κB/NLRP3/IL-1β Pathway-Mediated Pyroptosis in Vascular Smooth Muscle Cells (VSMCs)

Objective

We investigated the effects of resveratrol (Res) and MCC950 on the pyroptosis of vascular smooth muscle cells (VSMCs) and the potential pathway.

Methods and Results

Compared with the control (Con) group, the atherosclerosis (AS) group showed calcified nodules, which suggested that the calcification medium induced the calcification of VSMCs. VSMCs showed proliferative activity and significantly attenuated calcification under treatment with 10 μmol/L Res. The calcium salt was detected by alizarin red S staining. Res and MCC950 downregulated the calcification, inflammatory, pyroptosis, and transcription factor-related indicators all decreased by RT-qPCR with Western blot and immunofluorescence. The results showed that Res and MCC950 refrained the calcification of VSMCs and that Res has a better effect than MCC950. Plaques and calcium salt deposits were present in the carotid region in the control group. More calcium salt deposits were evident in the plaques of the Par group by HE staining and alizarin red S staining. The calcification indexes BMP2, Runx2, and related indexes declined by immunofluorescence, which showed parthenolide-inhibited AS. The related protein expressions were consistent with the expression of the cell experiments.

Conclusion

Our data demonstrated that inflammatory response and pyroptosis exacerbate AS and unravel the link between VSMCs and the progression of AS lesions. Res and MCC950 inhibited the calcification of VSMCs by regulating NF-κB/NLRP3/IL-1β signaling axis. P53 can exacerbate the AS lesions by acting on NLRP3 inflammasome and pyroptosis. Our findings supported the clinical applications of Res and MCC950 in VSMCs individuals to counteract pyroptosis and AS, and P53 inhibitors also can be a potential treatment for AS.

The Effect of Lanthanum (III) Nitrate on the Osteogenic Differentiation of Mice Bone Marrow Stromal Cells

To study the species of lanthanum (III) nitrate (La[NO3]3) dispersed in cell media and the effect on the osteoblast differentiation of bone marrow stroma cells (BMSCs). Different La-containing precipitations were obtained by adding various concentrations of La(NO3)3 solutions to Dulbecco's modified Eagle medium (DMEM) or DMEM with fetal bovine serum (FBS). A series of characterisation methods, including dynamic light scattering, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and protein quantification were employed to clarify the species of the different La-containing precipitations. The primary BMSCs were isolated, and the cell viability, alkaline phosphatase activity, and the formation of a mineralised nodule of BMSCs were tested when treated with different La-containing precipitations. The La(NO3)3 solutions in DMEM could form LaPO4, which exits in the particle formation, while the La(NO3)3 solutions in DMEM with FBS could form a La-PO4-protein compound. When treated with La(NO3)3 solutions in DMEM, the cell viability of the BMSCs was inhibited at the concentrations of 1, 10, and 100 μM at 1 day and 3 days. Meanwhile, the supernatant derived from the La(NO3)3 solutions in DMEM did not affect the cell viability of the BMSCs. In addition, the precipitate derived from the La(NO3)3 solutions in DMEM added to the complete medium inhibited the cell viability of the BMSCs at concentrations of 10 μM and 100 μM. When treated with La(NO3)3 solutions in DMEM with FBS, the derived precipitate and supernatant did not affect the cell viability of the BMSCs, except for the concentration of 100 μM La(NO3)3. The La-PO4-protein formed from the La(NO3)3 solutions in DMEM with FBS inhibited the osteoblast differentiation of BMSCs at the concentration of 1 μM La(NO3)3 (P < 0.05) but had no effect on either the osteoblast differentiation at the concentrations of 0.001 and 0.1 μM or on the formation of a mineralised nodule at all tested concentrations of La(NO3)3. Overall, La(NO3)3 solutions in different cell culture media could form different La-containing compounds: La-PO4 particles (in DMEM) and a La-PO4-protein compound (in DMEM with FBS). The different La-containing compounds caused different effects on the cell viability, osteoblast differentiation, and the formation of a mineralised nodule of the BMSCs. The La-containing precipitation inhibited the osteoblast differentiation by inhibiting the expression of osteoblast-related genes and proteins, providing a theoretical basis for clinical doctors to apply phosphorus-lowering drugs such as lanthanum carbon.

Iridoid from Eucommia ulmoides Oliv. Exerts Antiarthritis Effects by Inhibiting the JAK2/STAT3 Signaling Pathway In Vivo and In Vitro

The purpose of this study was to investigate the anti-inflammatory effects of EU-Idd both in vivo and in vitro. In vivo, we used the collagen-induced arthritis (CIA) rat model to investigate the efficacy of EU-Idd on rheumatoid arthritis. Hematoxylin-eosin staining and Safranin O-fast green staining were used to evaluate the pathological status of the ankle joints in CIA rats. Micro-CT scanning was used to investigate bone erosion of the ankle joints. In vitro, the effect of EU-Idd on Th17 cell differentiation was identified by flow cytometry. TRAP staining was used to detect osteoclast cells. HFLS-RA model cells, induced by tumor necrosis factor-α(TNF-α), were used to evaluate the anti-inflammatory effects of EU-Idd while the levels of related inflammatory cytokines and JAK2/STAT3 proteins were detected by RT-qPCR and western blotting. EU-Idd alleviated joint inflammation in CIA rats and exerted protective effects on the ankle joints. EU-Idd also prevented the differentiation of CD4+ T cells into Th17 cells, reduced the number of osteoclasts, and improved the expression levels of bone metabolism-related proteins including OPG and RANKL. Moreover, EU-Idd inhibited the invasion and migration of HFLS-RA cells and downregulated the expression of related inflammatory cytokine genes and the protein expression levels of p-JAK2 and p-STAT3, both in vivo and in vitro. EU-Idd exerts anti-inflammatory and osteoprotective effects by regulating the JAK2/STAT3 pathway in rheumatoid arthritis. These results are beneficial to excavate new pharmaceutical ingredients for rheumatoid arthritis from iridoid.

Copper modified cobalt-chromium particles for attenuating wear particle induced-inflammation and osteoclastogenesis

The nature of aseptic prosthetic loosening mainly relates to the wear particles that induce inflammation and subsequent osteoclastogenesis. The ideal approach to impede wear particle-induced osteolysis should minimize inflammation and osteoclastogenesis. In this work, Co29Cr9W3Cu particles were used as a research model for the first time to explore the response of Co29Cr9W3Cu particles to inflammatory response and osteoclast activation in vitro and in vivo by using Co29Cr9W particles as the control group. In vitro studies showed that the Co29Cr9W3Cu particles could promote the generation of M2-phenotype macrophages and increase the expression level of anti-inflammatory factor IL-10, while inhibiting the formation of M1-phenotype macrophages and down-regulating the expression of inflammatory factors TNF-α, IL-6 and IL-1β; More importantly, the Co29Cr9W3Cu particles reduced the expression of NF-κB and downstream osteoclast related-specific transcription marker genes, such as TRAP, NFATc1, and Cath-K; In vivo results indicated that the Co29Cr9W3Cu particles exposed to murine calvarial contributed to decreasing the amount of osteoclast and osteolysis area. These findings collectively demonstrated that Cu-bearing cobalt-chromium alloy may potentially delay the development of aseptic prosthetic loosening induced by wear particles, which is expected to provide evidence of Co29Cr9W3Cu alloy as an alternative material of joint implants with anti-wear associated osteolysis.

Lanthanides-Substituted Hydroxyapatite for Biomedical Applications

Lately, there has been an increasing demand for materials that could improve tissue regenerative therapies and provide antimicrobial effects. Similarly, there is a growing need to develop or modify biomaterials for the diagnosis and treatment of different pathologies. In this scenario, hydroxyapatite (HAp) appears as a bioceramic with extended functionalities. Nevertheless, there are certain disadvantages related to the mechanical properties and lack of antimicrobial capacity. To circumvent them, the doping of HAp with a variety of cationic ions is emerging as a good alterative due to the different biological roles of each ion. Among many elements, lanthanides are understudied despite their great potential in the biomedical field. For this reason, the present review focuses on the biological benefits of lanthanides and how their incorporation into HAp can alter its morphology and physical properties. A comprehensive section of the applications of lanthanides-substituted HAp nanoparticles (HAp NPs) is presented to unveil the potential biomedical uses of these systems. Finally, the need to study the tolerable and non-toxic percentages of substitution with these elements is highlighted.

Yunnan Baiyao Ameliorates Rheumatoid Arthritis in Rats by Shifting the Th17/Treg Cell Balance and Preventing Osteoclast Differentiation

Yunnan Baiyao (YNB) is a traditional Chinese medicine that possesses anti-inflammatory effects. Previously, we have demonstrated the effects of YNB in rheumatoid arthritis (RA) animal models; however, the underlying mechanisms are unclear. In the present study, we aimed to investigate the effects of YNB on the T-helper (Th)17/T-regulatory (Treg) cell balance in a collagen-induced arthritis rat model orally administrated YNB or methotrexate, a widely used therapeutic agent for treating RA. Our results showed that YNB treatment significantly decreased the voix pedis thickness and joint functionality scores and alleviated joint histopathology in these rats. These YNB-induced effects were achieved by decreasing the number of Th17 cells and increasing that of Treg cells in the spleen. Moreover, the interleukin- (IL-) 17 level considerably decreased in the serum of YNB-treated rats, whereas the IL-10 level significantly increased. Furthermore, YNB could inhibit RANKL-induced osteoclast formation by regulating the tumor necrosis factor receptor-associated factor 6/NF-κB/nuclear factor of the activated T-cell pathway. In summary, our study shows that YNB exhibits antiarthritic activity by decreasing the ratio of Th17/Treg cells, regulating the cytokine balance, and inhibiting osteoclast activation, providing an experimental basis that supports the use of this traditional Chinese medicine for the clinical treatment of RA.

Controlled co-delivery system of magnesium and lanthanum ions for vascularized bone regeneration

For craniofacial bone regeneration, how to promote vascularized bone regeneration is still a significant problem, and the controlled release of trace elements vital to osteogenesis has attracted attention. In this study, an ion co-delivery system was developed to promote angiogenesis and osteogenesis. Magnesium ions (Mg²⁺) and lanthanum ions (La³⁺) were selected as biosignal molecules because Mg²⁺can promote angiogenesis and both of them can enhance bone formation. Microspheres made of poly(lactide-co-glycolide) were applied to load La₂(CO₃)₃, which was embedded into a MgO/MgCO₃-loaded cryogel made of photocrosslinkable gelatin methacryloyl to enable co-delivery of Mg²⁺and La³⁺. Evaluations of angiogenesis and osteogenesis were conducted via bothin vitrocell culture using human bone marrow mesenchymal stromal cells andin vivoimplantation using a rat model with calvarial defect (5 mm in diameter). Compared to systems releasing only Mg²⁺or La³⁺, the combination system demonstrated more significant effects on blood vessels formation, thereby promoting the regeneration of vascularized bone tissue. At 8 weeks post-implantation, the new bone volume/total bone volume ratio reached a value of 40.1 ± 0.9%. In summary, a properly designed scaffold system with the capacity to release ions of different bioactivities in a desired pattern can be a promising strategy to meet vascularized bone regeneration requirements.

Light rare earth elements hinder bone development via inhibiting type H vessels formation in mice

Light rare earth elements (LREEs) are widely used in medical, industrial, and agricultural fields. Wide application of light rare earth and exposure to these elements in human society leads to increasing accumulation of LREE in human skeletal system. However, the effects of LREEs on human bone health is not clear. In this study, we found that LREE reduced CD31highEmcnhigh endothelial cell mediated type H vessels formation at the metaphyseal sites, resulting in reduced bone mass and low bone quality in mouse bone development. To explore the underlying mechanism, we induced bone marrow macrophages (BMMs) to preosteoclasts (pOCs) with exposure of LREE (Pr3+, Nd3+, Sm3+). The cytotoxicity of LREE was evaluated by CCK-8. Platelet-derived growth factor (PDGF-BB) is the cytokine secreted by pOCs that most responsible for inducing Type H vessel formation. We used ELISA kit to determine the PDGF-BB level in pOC supernatant, and mouse serum finding that the PDGF-BB level was reduced by LREEs treatment. Then we tested the ability of migration and tube formation of HUVECs using condition medium from pOCs. The migration and tube formation ability of HUVECs were both suppressed with LREEs pretreatment. We concluded that LREEs hinder mouse bone development by suppressing type H vessels associated bone formation. DATA AND MATERIALS AVAILABILITY: All data generated or analyzed during this study are included in this article. Please contact the corresponding author for unique material requests. Some material used in the reported research may require requests to collaborators and agreements with both commercial and non-profit institutions, as specified in the paper. Requests are reviewed by Third Military Medical University to verify whether the request is subject to any intellectual property or confidentiality obligations. Any material that can be shared will be released via a Material Transfer Agreement.

Bi-directional regulation functions of lanthanum-substituted layered double hydroxide nanohybrid scaffolds via activating osteogenesis and inhibiting osteoclastogenesis for osteoporotic bone regeneration

Rationale: Osteoporotic patients suffer symptoms of excessive osteoclastogenesis and impaired osteogenesis, resulting in a great challenge to treat osteoporosis-related bone defects. Based on the positive effect of rare earth elements on bone metabolism and bone regeneration, we try to prove the hypothesis that the La³⁺ dopants in lanthanum-substituted MgAl layered double hydroxide (La-LDH) nanohybrid scaffolds simultaneously activate osteogenesis and inhibit osteoclastogenesis.

Methods: A freeze-drying technology was employed to construct La-LDH nanohybrid scaffolds. The in vitro osteogenic and anti-osteoclastogenic activities of La-LDH nanohybrid scaffolds were evaluated by using ovariectomized rat bone marrow stromal cells (rBMSCs-OVX) and bone marrow-derived macrophages (BMMs) as cell models. The in vivo bone regeneration ability of the scaffolds was investigated by using critical-size calvarial bone defect model of OVX rats.

Results: La-LDH nanohybrid scaffolds exhibited three-dimensional macroporous structure, and La-LDH nanoplates arranged perpendicularly on chitosan organic matrix. The La³⁺ dopants in the scaffolds promote proliferation and osteogenic differentiation of rBMSCs-OVX by activating Wnt/β-catenin pathway, leading to high expression of ALP, Runx-2, COL-1 and OCN genes. Moreover, La-LDH scaffolds significantly suppressed RANKL-induced osteoclastogenesis by inhibiting NF-κB signaling pathway. As compared with the scaffolds without La³⁺ dopants, La-LDH scaffolds provided more favourable microenvironment to induce new bone in-growth along macroporous channels.

Conclusion: La-LDH nanohybrid scaffolds possessed the bi-directional regulation functions on osteogenesis and osteoclastogenesis for osteoporotic bone regeneration. The modification of La³⁺ dopants in bone scaffolds provides a novel strategy for osteoporosis-related bone defect healing.

Evaluation of La(XT), a novel lanthanide compound, in an OVX rat model of osteoporosis

Purpose

The purpose of this study was to evaluate the efficacy and toxicity of a novel lanthanum compound, La(XT), in an ovariectomized (OVX) rat model of osteoporosis.

Methods

Twenty-four ovariectomized female Sprague Dawley rats were divided into 3 groups receiving a research diet with/without treatment compounds (alendronate: 3 mg/kg; La(XT) 100 mg/kg) for three months. At the time of sacrifice, the kidney, liver, brain, lung and spleen were collected for histological examination. The trabecular bone structure of the tibiae was evaluated using micro-CT and a three-point metaphyseal mechanical test was used to evaluate bone failure load and stiffness.

Results

No significant differences were noted in plasma levels of calcium, phosphorus, creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) between the La(XT) treatment compared to the non-treated OVX group. Alendronate-treated animals (positive control) showed higher BV/TV, Tb.N and lower Tb.Th and Tb.Sp when compared to the non-treated OVX group. Mechanical analysis indicated that stiffness was higher in the alendronate (32.88%, p = 0.04) when compared to the non-treated OVX group. Failure load did not differ among the groups.

Conclusions

No kidney or liver toxicities of La(XT) treatments were found during the three-month study. The absence of liver and kidney toxicity with drug treatment for 3 months, as well as the increased trabecular bone stiffness are encouraging for the pursuit of further studies with La(XT) for a longer duration of time.

Bone Mineral Density in Population Long-Term Exposed to Rare Earth Elements from a Mining Area of China

This study aims to investigate the effects of individuals' exposure to rare earth elements (REEs) on bone metabolism. Adopting the inductively coupled plasma mass spectrometry, we measured REEs and eight other elements (Ca, Fe, Cu, Na, K, Zn, Mg, and P) in the hair of 53 miners exposed to REEs from Baiyunebo and 57 healthy farmers as the control group. Furthermore, bone mineral density (BMD) in both groups was assessed by dual-energy X-ray absorptiometry. Analysis of variance showed that the concentrations of La, Ce, Pr, Nd, Tb, Ho, Tm, and Yb in male hair of exposed group were significantly higher compared with the control group, whereas the concentrations of Ca and Fe in exposed group were significantly lower; the results of female hair, except for Ce, Tb, Ho, Tm, and Yb, were consistent with male hair. Student's t test showed that the BMD of exposed males at lumbar vertebrae, femoral neck, greater trochanter, and intertrochanter was significantly lower than that of controls, and exposed females reported lower BMD values at lumbar vertebrae and femoral neck. Multiple linear regression analysis showed that concentrations of differential REEs were inversely related to BMD in males, and concentrations of Ca and Fe were positively related to BMD both in males and females. Our study suggests that long-term environmental and occupational exposure leads to REE accumulation, and a low level of iron and calcium due to the competitive binding of REEs, which together induce bone metabolism disorders, and further reduce BMD.

Vitexin suppresses RANKL-induced osteoclastogenesis and prevents lipopolysaccharide (LPS)-induced osteolysis

Osteolytic diseases are characterized by an increase in the number and/or activity of bone-resorbing osteoclasts. Identification of natural compounds that can suppress osteoclast formation and function is crucial for the prevention and treatment of osteolytic diseases. Vitexin, a naturally-derived flavonoid extracted from various medicinal plant species, demonstrates a broad range of pharmacological properties including anticancer and anti-inflammatory effects. Here in this study, we showed that vitexin exerts antiosteoclastogenic effects by directly inhibiting receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation and bone resorption in vitro and protected against lipopolysaccharide (LPS)-induced inflammatory osteolysis in vivo. Vitexin suppressed the early activation of ERK and p38 MAPK pathways in response to RANKL thereby attenuating the downstream induction of c-Fos and NFATc1, and abrogating the expression of osteoclast marker genes. Collectively, these results provide evidence for the therapeutic application of vitexin in the treatment of osteoclast-mediated bone lytic diseases.

Lanthanum phosphate/chitosan scaffolds enhance cytocompatibility and osteogenic efficiency via the Wnt/β-catenin pathway

BACKGROUND

Fabrication of porous scaffolds with great biocompatibility and osteoinductivity to promote bone defect healing has attracted extensive attention.

METHODS

In a previous study, novel lanthanum phosphate (LaPO4)/chitosan (CS) scaffolds were prepared by distributing 40- to 60-nm LaPO4 nanoparticles throughout plate-like CS films.

RESULTS

Interconnected three dimensional (3D) macropores within the scaffolds increased the scaffold osteoconductivity, thereby promoting cell adhesion and bone tissue in-growth. The LaPO4/CS scaffolds showed no obvious toxicity and accelerated bone generation in a rat cranial defect model. Notably, the element La in the scaffolds was found to promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) through the Wnt/β-catenin signalling pathway and induced high expression of the osteogenesis-related genes alkaline phosphatase, osteocalcin and Collagen I (Col-I). Moreover, the LaPO4/CS scaffolds enhanced bone regeneration and collagen fibre deposition in rat critical-sized calvarial defect sites.

CONCLUSION

The novel LaPO4/CS scaffolds provide an admirable and promising platform for the repair of bone defects.

Hesperetin Prevents Bone Resorption by Inhibiting RANKL-Induced Osteoclastogenesis and Jnk Mediated Irf-3/c-Jun Activation

Bone homeostasis and resorption is regulated by the proper activation of osteoclasts, whose stimulation largely depends on the receptor activator of nuclear factor κB ligand (RANKL)-RANK signaling. Herein, for the first time, we showed that interferon regulatory factor (Irf)-3 was intimately involved in RANKL-induced osteoclast formation. In addition, hesperetin (Hes) derived from citrus fruit could inhibit RANKL-induced osteoclast differentiation and maturation among three types of osteoclast precursors with inhibited formation of F-actin rings and resorption pits on bone slices. More importantly, by using SP600125, a selective Jnk inhibitor, we showed that Hes was able to significantly attenuate the Jnk downstream expression of Irf-3 and c-Jun, thereby inactivating NF-κB/MAPK signaling and transcriptional factor NFATc-1, leading to suppression of osteoclast-specific genes, which resulted in impaired osteoclastogenesis and functionality. An ovariectomized (OVX) osteoporosis mouse model demonstrated that Hes could increase trabecular bone volume fractions (BV/TV), trabecular thickness, and trabecular number, whereas it decreased trabecular separation in OVX mice with well-preserved trabecular bone architecture and decreased levels of TRAP-positive osteoclasts. This is further evidenced by the diminished serum expression of bone resorption marker CTX and enhanced production of osteoblastic ALP in vivo. Taken together, these results suggested that Hes could inhibit Jnk-mediated Irf-3/c-Jun activation, thus attenuating RANKL-induced osteoclast formation and function both in vitro and in vivo.

La(iii) biodistribution profiles from intravenous and oral dosing of two lanthanum complexes, La(dpp)3 and La(XT), and evaluation as treatments for bone resorption disorders

Trivalent lanthanum (La³⁺) has the potential to treat bone resorption disorders (such as osteoporosis) by eliciting a bone-building response in the cells which control skeletal remodelling. Because La³⁺ suffers from extremely poor intestinal absorption, specifically designed chelators are required in order that a biologically active form of lanthanum can be administered orally. Two such chelators, 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdpp) and bis-{[bis(carboxymethyl)amino]methy}phosphinic acid (H₅XT), have previously been the subjects of extensive physical, in vitro, and in vivo testing as the tris- and mono-lanthanum(iii) complexes La(dpp)₃ and La(XT), respectively. In this manuscript, we expand upon those studies to include 4-week intravenous (IV) and oral La³⁺ biodistribution profiles, which show that the metal ion initially accumulates in the liver followed by preferential redistribution and retention by bone. Of the two compounds, La(XT) demonstrates the more favourable in vivo characteristics, therefore dose-dependent oral biodistribution studies were carried out with this complex. These show drug saturation above a dose of 100 mg kg^-1 day^-1, so liver histology was performed in order to assess any potential toxicity. Finally, we improve upon the physical characterization of La(dpp)₃ to include a single crystal X-ray structure, which exhibits an 8-coorindate La³⁺ centre with two bound water molecules, and a disordered exoclathrate-type hydrogen bonded network.

Bone-seeking agents for the treatment of bone disorders

The targeting and delivery of therapeutic and diagnostic agents to bone tissue presents both a challenge and opportunity. Osteoporosis, Paget's disease, cancer, and bone metastases are all skeletal diseases whose treatment would benefit from new targeted therapeutic strategies. Osteoporosis, in particular, is a very prevalent disease, affecting over one in three women and one in five men in Canada alone with the cost to the healthcare system estimated at over $2.3 billion in 2010. Bone tissue is often considered a rigid structure when in reality there is a process of continuous remodeling that takes place via complex endocrine-regulated cell signaling pathways in addition to the signaling pathways unique to bone tissue. It is these specific boneremodeling processes that provide unique targeting opportunities but also present a number of challenges.

Stattic inhibits RANKL-mediated osteoclastogenesis by suppressing activation of STAT3 and NF-κB pathways

Tofacitinib, a small molecule JAK inhibitor, has been widely used to reduce inflammation and inhibit progression of bone destruction in rheumatoid arthritis. STAT3, a downstream signaling molecule of JAK, plays a key role in the activation of signaling in response to inflammatory cytokines. Thus, targeting STAT3 may be an inspiring strategy for treating osteoclast-related diseases such as rheumatoid arthritis. In this study, we first investigated the effects of Stattic, a STAT3 inhibitor, on receptor activator of NF-κB ligand (RANKL)-mediated osteoclastogenesis. Stattic inhibited osteoclast differentiation and bone resorption in RANKL-induced RAW264.7 cells in a dose-dependent manner. Stattic also suppressed RANKL-induced upregulation of osteoclast-related genes tartrate-resistant acid phosphatase, matrix metalloproteinase 9, cathepsin K, RANK, tumor necrosis factor receptor-associated factor 6, and osteoclast-associated receptor in RAW264.7 cells. Moreover, Stattic exhibited an inhibitory effect on cell proliferation and cell cycle progression at higher dosages. At the molecular level, Stattic inhibited RANKL-induced activation of STAT3 and NF-κB pathways, without significantly affecting MAPK signaling. In addition, Stattic inhibited RANKL-induced expression of osteoclast-related transcription factors c-Fos and NFATc1. Importantly, Stattic also prevented bone loss caused by ovariectomy. Together, our data confirm that Stattic restricts osteoclastogenesis and bone loss by disturbing RANKL-induced STAT3 and NF-κB signaling. Thus, Stattic represents a novel type of osteoclast inhibitor that could be useful for conditions such as osteoporosis and rheumatoid arthritis.

Proinflammatory and osteolysis-inducing effects of 3D printing Ti6Al4V particles in vitro and in vivo

Ti6Al4V printing particles have been recently used for fabricating orthopedic implants. Removing these particles completely from fabricated implants is challenging. Furthermore, recycled particles are commonly used in fabrication without additional analysis. Ti6Al4V wear particles derived from orthopedic implants are known to induce inflammatory responses and osteolysis. However, the biosafety of printing particles remains unknown. Here, we investigated the proinflammatory and osteolysis-inducing effects of commonly used original and recycled Ti6Al4V printing particles in vitro and in vivo. Our results indicated that although less serious effects were induced compared to wear particles, inflammatory responses and osteoclast-mediated bone resorption were induced by the original printing particles in a particle size-dependent manner. Recycled particles were found to more strongly stimulate bone resorption and inflammatory responses than the original particles; the in vivo effect was enhanced with an increase in particle concentration. Furthermore, the results of our in vitro experiments verified that the printing particles activate macrophages to secrete inflammatory cytokines and promote osteoclastogenesis, which is closely related to particle size and concentration. Taken together, our findings provide a valuable reference for the use of raw printing materials and examination of recycling procedures for implant fabrication.

RAW 264.7 co-cultured with ultra-high molecular weight polyethylene particles spontaneously differentiate into osteoclasts: an in vitro model of periprosthetic osteolysis

Wear-particle osteolysis affects prosthesis survival leading to implant loosening up to 70% of revisions. Therapeutic strategies are increasing, however alternative testing methods to experimentally evaluate such treatments are lacking. The aim of this study was to reproduce an in vitro osteolysis model recapitulating the events that, starting from the exposure of macrophages to polyethylene, lead to the establishment of osteoclastogenesis and inflammation. Responses to polyethylene, at 3 and 7 days, in a macrophage cell line, RAW 264.7, were determined by DNA quantification, immunofluorescence, pit assay, gene expression, cytokine production and NF-kB activation. Results showed that 3 days exposure to particles could induce a significant production of Tumor Necrosis Factor alpha (p < 0.0005) and Prostaglandin E₂ (p < 0.005) compared to controls. Particles also induced macrophages to spontaneously differentiate into mature and active osteoclasts, in terms of identification of multinucleated cells by Phalloidin staining and by the analysis of osteoclast-specific gene markers. In particular, at 3 days polyethylene induced a significant up-regulation of Nuclear Factor of Activated T-cells, cytoplasmic 1, Receptor Activator of Nuclear factor Kappa-B and Receptor Activator of Nuclear Factor Kappa-B Ligand genes (p < 0.0005) compared to controls. At protein level, the particles induced a significant increase of Receptor Activator of Nuclear Factor Kappa-B Ligand at day 7 over controls (p < 0.0005). Osteoclasts were capable to resorb bone even in absence of differentiating factors. The possible mechanism, beside spontaneous osteoclastogenesis mediated by wear debris, was identified in an autocrine up-regulation of Receptor activator of nuclear factor kappa-B ligand gene expression and protein synthesis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 510-520, 2017.

Fabrication of a novel chitosan scaffold with asymmetric structure for guided tissue regeneration

Asymmetric chitosan scaffold with a loose layer and a dense layer exhibited outstanding bone regenerative ability and appropriate degradability.