Aspirin inhibits osteoclastogenesis by suppressing the activation of NF-κB and MAPKs in RANKL-induced RAW264.7 cells

Chitosan-based biomaterials for bone tissue engineering

Common critical size bone defects encountered in clinical practice often result in inadequate bone regeneration,primarily due to the extent of damage surpassing the inherent capacity of the body for self-healing. Bone tissue engineering scaffolds possess the desirable characteristics of biomimetic bone structure, simulated extracellular matrix, optimal mechanical strength, and biological functionality, rendering them the preferred option for the treatment of bone defects. Chitosan demonstrates favorable biocompatibility, plasticity, and a range of biological activities, rendering it a highly appealing material. Chitosan and its derivatives have been found to exert an impact on bone repair through their ability to modulate macrophage polarization, angiogenesis, and the delicate equilibrium of bone remodeling. However, the efficacy of pure chitosan is constrained, necessitating its combination with other bioactive substances to achieve an optimal biomimetic scaffold that is compatible with the specific bone defect site. Chitosan is commonly utilized in the field of bone repair in four different application forms: rigid scaffold, hydrogel, membranes, and microspheres. In order to enhance comprehension of the benefits and constraints associated with chitosan, this review provides a comprehensive overview of the structure and biological properties of chitosan, the molecular mechanisms by which chitosan promotes osteogenic differentiation, the diverse methods of chitosan preparation for various applications, and the impacts of chitosan when loaded with bioactive substances.

Application of Mendelian randomization analysis to explore causal associations of aspirin use with bone mineral density and risk of fracture

OBJECTIVE

Previous observational studies on the association between aspirin use, bone mineral density (BMD), and fracture risk have yielded controversial results. This study explored the causal relationship between aspirin use, BMD, and fracture risk using Mendelian randomization (MR).

METHODS

Summary data for aspirin use and BMD of five different body parts (femoral neck, lumbar spine, forearm, heel, and ultra distal forearm) and fractures were obtained from the integrative epidemiology unit open genome-wide association studies database for bidirectional MR analysis. An appropriate model was chosen based on Cochran's Q test, with inverse variance-weighted as the primary method for MR analysis, supplemented by the weighted-median and MR-Egger methods. MR-Egger and MR-PRESSO were used to test for horizontal pleiotropy and exclude significant outliers that could bias the results. Various sensitivity analyses, including leave-one-out analysis, were conducted to ensure the robustness of the findings.

RESULTS

Aspirin use significantly increased lumbar spine BMD (odds ratio [OR] = 4.660; 95% confidence interval [CI]: 1.365-15.906; P = 0.014). No significant causal association was found between aspirin use and fracture risk (beta = 59.951; 95% CI: -265.189-385.091; P = 0.718). No significant reverse causality was observed.

CONCLUSION

This study indicates that aspirin use does not significantly affect fracture risk but has a significant protective effect on lumbar spine BMD, revealing a potential benefit of aspirin against osteoporosis.

Anti-Inflammatory Effects of the Combined Treatment of Resveratrol- and Protopanaxadiol-Enriched Rice Seed Extract on Lipopolysaccharide-Stimulated RAW264.7 Cells

The overproduction of proinflammatory cytokines triggers a variety of diseases. Protopanaxadiol (PPD) and resveratrol are naturally found in plants such as ginseng and have potential anti-inflammatory properties, and resveratrol- and PPD-enriched rice seeds have been previously successfully generated. Herein, the synergistic anti-inflammatory activities of extracts of these enriched seeds were assessed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. In comparison with treatment using extract prepared from PPD-producing transgenic rice (DJ-PPD) alone, cotreatment with DJ526 and DJ-PPD (TR_3) markedly enhanced the anti-inflammatory activities at a similar (compared to DJ526) or higher (compared to DJ-PPD) level. Cotreatment with DJ526 and DJ-PPD markedly inhibited the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Thus, DJ526 and DJ-PPD in combination suppressed the expression of phosphorylated (p)-NF-κB p65, p-p38 MAPK, and p-ERK 1/2. Cotreatment with DJ526 and DJ-PPD downregulated the expression of proinflammatory cytokines (IL-1β, IL-6, and TNF-α), LPS receptor (toll-like receptor-4, TLR-4), proinflammatory mediators (nitric oxide and PGE2), and arachidonic acid pathway critical enzyme (COX-2). These findings demonstrate the synergistic potential anti-inflammatory activities of resveratrol- and PPD-enriched rice seed extract.

Aspirin Stimulates the Osteogenic Differentiation of Human Adipose Tissue-Derived Stem Cells In Vitro

This study investigates the impact of acetylsalicylic acid (ASA), also known as aspirin, on adipose tissue-derived stem cells (ASCs), aiming to elucidate its dose-dependent effects on morphology, viability, proliferation, and osteogenic differentiation. Isolated and characterized human ASCs were exposed to 0 µM, 100 µM, 200 µM, 400 µM, 800 µM, 1000 µM, 10,000 µM, and 16,000 µM of ASA in vitro. Cell morphology, viability, and proliferation were evaluated with fluorescent live/dead staining, alamarBlue viability reagent, and CyQUANT® cell proliferation assay, respectively. Osteogenic differentiation under stimulation with 400 µM or 1000 µM of ASA was assessed with alizarin red staining and qPCR of selected osteogenic differentiation markers (RUNX2, SPP1, ALPL, BGLAP) over a 3- and 21-day-period. ASA doses ≤ 1000 µM showed no significant impact on cell viability and proliferation. Live/dead staining revealed a visible reduction in viable cell confluency for ASA concentrations ≥ 1000 µM. Doses of 10,000 µM and 16,000 µM of ASA exhibited a strong cytotoxic and anti-proliferative effect in ASCs. Alizarin red staining revealed enhanced calcium accretion under the influence of ASA, which was macro- and microscopically visible and significant for 1000 µM of ASA (p = 0.0092) in quantification if compared to osteogenic differentiation without ASA addition over a 21-day-period. This enhancement correlated with a more pronounced upregulation of osteogenic markers under ASA exposure (ns). Our results indicate a stimulatory effect of 1000 µM of ASA on the osteogenic differentiation of ASCs. Further research is needed to elucidate the precise molecular mechanisms underlying this effect; however, this discovery suggests promising opportunities for enhancing bone tissue engineering with ASCs as cell source.

Does chronic low-dose aspirin use benefit bone health? A cross-sectional study on patients with type 2 diabetes mellitus

INTRODUCTION

Numerous studies have reported the striking result that aspirin use is associated with higher bone mineral density (BMD), suggesting its potential as a population-wide osteoporosis prevention measure. Therefore, this study aimed to examine the impact of chronic low-dose aspirin use on bone remodeling biomarkers and BMD in an aging population.

MATERIALS AND METHODS

Between September and November of 2019, clinical data regarding the medication use, serum bone remodeling biomarkers, and BMD of 567 consecutively hospitalized patients, a minimum of 50 years old with type 2 diabetes mellitus (T2DM), were collected. The cross-sectional associations between chronic low-dose aspirin use and serum concentrations of bone remodeling biomarkers and BMD were estimated separately using linear regression. Potential confounding variables were controlled for, including age, sex, and comorbidities.

RESULTS

Low-dose aspirin users had significantly lower serum bone alkaline phosphatase (BAP) concentrations than non-users (82.44 ± 28.03 U/L vs 90.71 ± 32.79 U/L, p = 0.025). On the other hand, low-dose aspirin users had insignificantly higher vertebral BMD (0.95 ± 0.19 vs 0.91 ± 0.21, p = 0.185), femoral neck BMD (0.80 ± 0.15 vs 0.78 ± 0.17, p = 0.309) and Ward's triangle BMD (0.46 ± 0.14 vs 0.44 ± 0.13, p = 0.209), regardless of adjustment.

CONCLUSIONS

This cross-sectional study demonstrated that chronic use of low-dose aspirin was associated with significantly lower serum concentrations of BAP in hospitalized patients with T2DM. The mechanism causing the insignificantly higher BMD observed in chronic aspirin users in this study and the significant increments in BMD reported in previous studies requires further clarification in other clinical trials.

The role of non-steroidal anti-inflammatory drugs as adjuncts to periodontal treatment and in periodontal regeneration

Periodontitis is the sixth most prevalent chronic disease globally and places significant burdens on societies and economies worldwide. Behavioral modification, risk factor control, coupled with cause-related therapy have been the "gold standard" treatment for managing periodontitis. Given that host inflammatory and immunological responses play critical roles in the pathogenesis of periodontitis and impact treatment responses, several adjunctive strategies aimed at modulating host responses and improving the results of periodontal therapy and maintenance have been proposed. Of the many pharmacological host modulators, we focused on non-steroidal anti-inflammatory drugs (NSAIDs), due to their long history and extensive use in relieving inflammation and pain and reducing platelet aggregation. NSAIDs have been routinely indicated for treating rheumatic fever and osteoarthritis and utilized for the prevention of cardiovascular events. Although several efforts have been made to incorporate NSAIDs into the treatment of periodontitis, their effects on periodontal health remain poorly characterized, and concerns over the risk-benefit ratio were also raised. Moreover, there is emerging evidence highlighting the potential of NSAIDs, especially aspirin, for use in periodontal regeneration. This review summarizes and discusses the use of NSAIDs in various aspects of periodontal therapy and regeneration, demonstrating that the benefits of NSAIDs as adjuncts to conventional periodontal therapy remain controversial. More recent evidence suggests a promising role for NSAIDs in periodontal tissue engineering and regeneration.

Callerya atropurpurea suppresses inflammation in vitro and ameliorates gastric injury as well as septic shock in vivo via TLR4/MyD88-dependent cascade

BACKGROUND

Callerya atropurpurea is a traditional plant in a tropical zone discovered to have anti-inflammatory functions.

PURPOSE

we want to investigate the mechanism related to anti-inflammation of C. atropurpurea ethanol extract (Ca-EE) both in vitro and in vivo.

STUDY DESIGN

Murine macrophage cells and mouse models for gastritis and septic shock were conducted to evaluate the abilities of Ca-EE in anti-inflammation.

METHODS

Ca-EE was tested by HPLC and LC-MS/MS. NO outcome was checked by Griess reagent test. Cell viabilities were evaluated using MTT assay. Inflammatory cytokines were determined via RT-PCR and ELISA. The mechanism of Ca-EE in anti-inflammation was investigated by luciferase reporter gene assay and immunoblot in transcription level and protein level respectively. Gastric injury and septic shock administrated with Ca-EE were studied by H&E, PCR, and immunoblot.

RESULTS

Ca-EE significantly decreased LPS-induced NO production, but hardly stimulated the expression of NO itself. It not only showed no cytotoxicity, but also protected cells from LPS damage. Moreover, Ca-EE decreased TLR4 expression, altered MyD88 recruitment and TRAF6, and suppressed the phospho-Src/PI3K/AKT. Ca-EE inhibited downstream signaling P38, JNK and NF-κB. Finally, Ca-EE alleviated HCl/EtOH-induced gastritis and LPS/poly (I:C)-induced septic shock through the previously mentioned signaling cascades.

CONCLUSION

Ca-EE exhibited an integrated and promising mechanism against TLR4-related inflammation, which shows potential for treating gastritis, septic shock, and other inflammatory diseases.

Low dose aspirin associated with greater bone mineral density in older adults

The use of low-dose aspirin in older adults is increasing as is the prevalence of osteoporosis. Aspirin has been shown in numerous studies to affect bone metabolism. However, there is no clear link between low-dose aspirin use and bone mineral density (BMD). This study examined differences in bone mineral density between low-dose aspirin users and non-aspirin users in adults aged 50-80 years. We conducted a cross-sectional study of 15,560 participants who participated in the National Health and Nutrition Examination Survey (NHANES) 2017-March 2020. We used a multivariate logistic regression model to evaluate the relationship between low-dose aspirin and femoral neck BMD, femoral total BMD, intertrochanteric BMD, and the first lumbar vertebra BMD (L1 BMD) in patients aged 50 to 80 years. A total of 1208 (Group 1: femoral neck BMD, total femur BMD, and intertrochanter BMD) and 1228 (Group 2: L1 BMD) adults were included in this study. In both group 1 and group 2, BMD was higher in the low-dose aspirin group than in the non-aspirin group (Total femur BMD β = 0.019, 95% CI 0.004-0.034; Femoral neck BMD β = 0.017, 95% CI 0.002-0.032; Intertrochanter BMD β = 0.025, 95% CI 0.007-0.043; L1 BMD β = 0.026, 95% CI 0.006-0.046). In subgroup analyses stratified by gender, this positive association existed in both gender after adjusting for confounders. On subgroup analyses stratified by age, this positive association existed in three different age groups after adjusting for confounders. To test whether the effect of low-dose aspirin on BMD was affected by gender and age, the interaction P value was greater than 0.05. These findings from a human study looking into the relationship between low-dose aspirin use and BMD suggest that regular low-dose aspirin may be associated with a higher BMD. The association between low-dose aspirin and BMD did not differ by age group or gender.

Aspirin effect on bone remodeling and skeletal regeneration: Review article

Bone tissues are one of the most complex tissues in the body that regenerate and repair themselves spontaneously under the right physiological conditions. Within the limitations of treating bone defects, mimicking tissue engineering through the recruitment of scaffolds, cell sources and growth factors, is strongly recommended. Aspirin is one of the non-steroidal anti-inflammatory drugs (NSAIDs) and has been used in clinical studies for many years due to its anti-coagulant effect. On the other hand, aspirin and other NSAIDs activate cytokines and some mediators in osteoclasts, osteoblasts and their progenitor cells in a defect area, thereby promoting bone regeneration. It also stimulates angiogenesis by increasing migration of endothelial cells and the newly developed vessels are of emergency in bone fracture repair. This review covers the role of aspirin in bone tissue engineering and also, highlights its chemical reactions, mechanisms, dosages, anti-microbial and angiogenesis activities.

Association between osteoporosis or osteopenia and taking antiplatelet agents in general US population of NHANES

BACKGROUND

Osteoporosis (OP) and osteopenia are common bone disorders in old age, and lots of patients suffering from OP or osteopenia need to take antiplatelet agents to treat basic diseases. However, clinical data on the link between osteopenia or OP and antiplatelet agents are limited.

METHODS

Data in this study were collected and screened from the NHANES from 2013 to 2014 and 2017 to 2018. The variables were extracted from interviews and compared between OP or osteopenia participants and normal. The relationship between OP or osteopenia and taking antiplatelet drugs was analyzed by weighted multivariate logistic regression.

RESULTS

After excluding individuals who were not eligible and had invalid data, we finally identified 894 participants for inclusion in the study. We found a negative association between OP or osteopenia and taking antiplatelet agents (OR = 0.53; 95% CI, 0.33-0.84; p < 0.05). These results did not change on multiple imputations (OR = 0.32, 95% CI, 0.19-0.56; p <0.01). In the subgroup analyses, the associations were more significant in women (OR = 0.18, 95% CI, 0.05-0.62; p <0.05).

CONCLUSION

This study demonstrated that the association between OP or osteopenia and taking antiplatelet agents was significant. Therefore, it is necessary to confirm the result by extending further research.

Icaritin inhibits lung cancer-induced osteoclastogenesis by suppressing the expression of IL-6 and TNF-a and through AMPK/mTOR signaling pathway

Bone metastasis is one of the common phenomena in the late stage of lung cancer. Inhibition of bone metastasis can improve the survival of lung cancer patients. However, the current drugs for the treatment of bone metastasis have shown little effect on overall survival. Therefore, there is an urgent necessity to identify novel drugs capable of preventing and treating bone metastasis of lung cancer. Our study determined that icaritin (ICT) can inhibit lung cancer-mediated osteoclastogenesis and induce the apoptosis of osteoclasts. Exposure to ICT increased the activation of adenosine 5'-monophosphate-activated protein kinase (AMPK), reduced the activation of mammalian target of rapamycin (mTOR) and decreased the expression of bcl-2. The bioactivity of ICT on osteoclastogenesis was associated with the regulation of the AMPK/mTOR signaling pathway. Blocking AMPK significantly increased osteoclast differentiation, decreased osteoclast apoptosis and canceled the effects of ICT on the phosphorylation of AMPK as well as the inhibition of mTOR and bcl-2. Furthermore, ICT decreased the levels of IL-6 and TNF-α in osteoclasts, while the AMPK inhibitor compound C significantly abolished the inhibitory effects of ICT on IL-6 and TNF-α. Thus, the present study demonstrated that ICT may be a potential natural agent for the treatment of bone metastasis in patients with lung cancer.

Protocatechualdehyde Inhibits the Osteoclast Differentiation of RAW264.7 and BMM Cells by Regulating NF-κB and MAPK Activity

Protocatechualdehyde (PCA), an important component of Salvia miltiorrhiza, has many activities, such as anti-inflammatory and antisepsis activities. However, the role of PCA in osteoclasts is not clear. We used RAW264.7 cells (a mouse leukemic monocyte/macrophage cell line) and bone marrow macrophages (BMMs) to probe the role of PCA in osteoclasts and the underlying mechanism. The effects of PCA on cell activity were evaluated with CCK-8 assays. TRAP staining detected mature osteoclasts. Corning Osteo Assay Surface plates were used to examine absorption. The levels of RNA and protein were analyzed, respectively, using RT-PCR and Western blotting. PCA (5 μg/ml) was not toxic to the two cell types but reduced the formation of osteoclasts and bone absorption. Furthermore, PCA restrained the expression of mRNAs encoding proteins associated with osteoclasts and reduced the phosphorylation of proteins in important signaling pathways. The results indicate that PCA inhibits osteoclast differentiation by suppressing NF-κB and MAPK activity.

CaMKII(δ) regulates osteoclastogenesis through ERK, JNK, and p38 MAPKs and CREB signalling pathway

Calcium/calmodulin-dependent protein kinases (CaMKs) are a group of important molecules mediating calcium signal transmission and have been proved to participate in osteoclastogenesis regulation. CaMKII, a subtype of CaMKs is expressed during osteoclast differentiation, but its role in osteoclastogenesis regulation remains controversial. In the present study, we identified that both mRNA and protein levels of CaMKII (δ) were upregulated in a time-dependent manner during osteoclast differentiation. CaMKII (δ) gene silencing significantly inhibited osteoclast formation, bone resorption, and expression of osteoclast-related genes, including nuclear factor of activated T cells c1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), and c-Src. Furthermore, CaMKII (δ) gene silencing downregulated phosphorylation of mitogen-activated protein kinases (MAPKs), including JNK, ERK, and p38, which were transiently activated by RANKL. Specific inhibitors of ERK, JNK, and p38 also markedly inhibited expression of osteoclast-related genes, osteoclast formation, and bone resorption like CaMKII (δ) gene silencing. Additionally, CaMKII (δ) gene silencing also suppressed RANKL-triggered CREB phosphorylation. Collectively, these data demonstrate the important role of CaMKII (δ) in osteoclastogenesis regulation through JNK, ERK, and p38 MAPKs and CREB pathway.

Aspirin inhibits RANKL-induced osteoclast differentiation in dendritic cells by suppressing NF-κB and NFATc1 activation

Background

Aspirin has been demonstrated to promote osteoblast-mediated bone formation and inhibit osteoclast (OC)-mediated bone resorption. However, it remains unclear whether aspirin influences other immune cells during bone resorption. Dendritic cells (DCs), the most potent antigen-presenting cells, can also transdifferentiate into active OCs in the presence of receptor activator of nuclear factor-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). The effects of aspirin on DC-derived OCs (DDOCs) were investigated in the current study.

Methods

Flow cytometry and mixed lymphocyte reaction (MLR) assays were used for DC identification. The proliferative capacity of DCs was determined by BrdU assays. Apoptosis was examined by flow cytometry. The osteoclastic potential of DCs was tested using tartrate-resistant acid phosphatase (TRAP) staining, western blotting, and reverse transcription polymerase chain reaction (RT-PCR). Western blotting was also used to examine signaling pathways. A mandibular bone defect model was established to assess the effect of aspirin on bone resorption.

Results

Aspirin had no influence on the surface phenotype, proliferation, or apoptosis of DCs, though aspirin significantly inhibited osteoclast differentiation in RANKL-stimulated DCs. DC osteoclast differentiation was modulated by aspirin via the nuclear factor kappa B (NF-κB)/nuclear factor of activated T cell, cytoplasmic 1 (NFATc1) signaling pathway. Aspirin treatment also had favorable therapeutic effects on bone regeneration in the bone defect model, and the number of osteoclasts was decreased.

Conclusions

Aspirin inhibited RANKL-induced OC differentiation in DCs via the NF-κB pathway, downregulating expression of NFATc1. Aspirin treatment promoted bone regeneration by inhibiting DDOC activation in the early stages of inflammation in a rat mandibular bone defect model.

Local administration of aspirin with β-tricalcium phosphate/poly-lactic-co-glycolic acid (β-TCP/PLGA) could enhance osteoporotic bone regeneration

Composite materials β-tricalcium phosphate (β-TCP) and poly-lactic-co-glycolic acid (PLGA) have achieved stable bone regeneration without cell transplantation in previous studies. Recent research shows that aspirin (ASP) has great potential in promoting bone regeneration. The objective of the present study was to incorporate PLGA into β-TCP combined with a lower single-dose local administration of ASP to enhance its in vivo biodegradation and bone tissue growth. After the creation of a rodent critical-sized femoral metaphyseal bone defect, PLGA -modified β-TCP (TP) was prepared by mixing sieved granules of β-TCP and PLGA (50:50, v/v) for medical use, then TP with dripped 50 µg/0.1 ml and 100 µg/0.1 ml aspirin solution was implanted into the defect of OVX rats until death at 8 weeks. The defected area in distal femurs of rats was harvested for evaluation by histology, micro-CT, biomechanics and real time RT-PCR. The results of our study show that a single-dose local administration of ASP combined with the local usage of TP can increase the healing of defects in OVX rats. Single-dose local administration of aspirin can improve the transcription of genes involved in the regulation of bone formation and vascularization in the defect area, and inhibits osteoclast activity. Furthermore, treatments with a higher single-dose local administration of ASP and TP showed a stronger effect on accelerating the local bone formation than while using a lower dose of ASP. The results from our study demonstrate that the combination of a single-dose local administration of ASP and β-TCP/PLGA had an additive effect on local bone formation in osteoporosis rats, and bone regeneration by PLGA/β-TCP/ASP occured in a dose-dependent manner.

[Preparation of aspirin sustained-release microsphere and its in vitro releasing property]

OBJECTIVE

It has been proven that acetylsalicylic acid (aspirin), as a kind of classical non-steroidal anti-inflammatory drug, not only has the effect of anti-inflammatory, but also has the function of immunity regulation and mineralization. However, it needs further investigation to study how to delay release of aspirin for a long time and enable to promote bone regeneration. Herein, we demonstrated that the longterm delayed release pattern of aspirin through the construction of microsphere scaffolds is promising to achieve the excellent bone regeneration.

METHODS

Here we synthesized three kinds of scaffolds as follows: (1) aspirin loaded calcium silicate (CaSiO3) microsphere (CaSiO3-aspirin) via simple immersion; (2) aspirin loaded polylactic-co-glycolic acid (PLGA) microsphere (PLGA-aspirin) via oil/water (O/W) emulsion; (3) aspirin loaded PLGA-CaSiO3 scaffold (PLGA-CaSiO3-aspirin) via O/W emulsion, optimal morphology and structure of PLGA-CaSiO3-aspirin scaffold was acquired through modulating the ratio between PLGA and CaSiO3. Furthermore, spectrophotometer was used to monitor the concentration of the extract of the three scaffolds for different releasing time, including 1, 2, 4, 6, 9, 13, 17, 21, 24, 30, 36, and 45 days, aspirin loading efficiency and its accumulation releasing curves were both achieved according to the concentration of aspirin. Their sustained release effects of aspirin were evaluated eventually.

RESULTS

Environmental scanning electron microscope (ESEM) results showed that the surface structure of the three kinds of scaffolds were smooth and had uniform size distribution. In addition, a small amount of PLGA-aspirin microspheres occurred to aggregation, while a small amount of CaSiO3-aspirin microspheres were broken. Moreover, the PLGA-aspirin microspheres in the PLGA-CaSiO3-aspirin scaffolds were uniformly adhered to the surface of CaSiO3 microspheres. The aspirin loadings of CaSiO3-aspirin, PLGA-aspirin, and PLGA-CaSiO3-aspirin were (1.06±0.04)%, (7.05±0.06)%, and (6.75±0.18)%, respectively. In addition, their corresponding time for releasing 95% of aspirin was 3, 24, and 36 days, respectively. The releasing time of PLGA-CaSiO3-aspirin was longer than that of the others and the releasing rate was more stable.

CONCLUSION

The microsphere scaffold of PLGA-CaSiO3-aspirin composites has excellent delayedrelease effect on aspirin, which is promising for using as osteogenic materials.

[Preparation of aspirin sustained-release microsphere and its in vitro releasing property]

OBJECTIVE

It has been proven that acetylsalicylic acid (aspirin), as a kind of classical non-steroidal anti-inflammatory drug, not only has the effect of anti-inflammatory, but also has the function of immunity regulation and mineralization. However, it needs further investigation to study how to delay release of aspirin for a long time and enable to promote bone regeneration. Herein, we demonstrated that the longterm delayed release pattern of aspirin through the construction of microsphere scaffolds is promising to achieve the excellent bone regeneration.

METHODS

Here we synthesized three kinds of scaffolds as follows: (1) aspirin loaded calcium silicate (CaSiO₃) microsphere (CaSiO₃-aspirin) via simple immersion; (2) aspirin loaded polylactic-co-glycolic acid (PLGA) microsphere (PLGA-aspirin) via oil/water (O/W) emulsion; (3) aspirin loaded PLGA-CaSiO₃ scaffold (PLGA-CaSiO₃-aspirin) via O/W emulsion, optimal morphology and structure of PLGA-CaSiO₃-aspirin scaffold was acquired through modulating the ratio between PLGA and CaSiO₃. Furthermore, spectrophotometer was used to monitor the concentration of the extract of the three scaffolds for different releasing time, including 1, 2, 4, 6, 9, 13, 17, 21, 24, 30, 36, and 45 days, aspirin loading efficiency and its accumulation releasing curves were both achieved according to the concentration of aspirin. Their sustained release effects of aspirin were evaluated eventually.

RESULTS

Environmental scanning electron microscope (ESEM) results showed that the surface structure of the three kinds of scaffolds were smooth and had uniform size distribution. In addition, a small amount of PLGA-aspirin microspheres occurred to aggregation, while a small amount of CaSiO₃-aspirin microspheres were broken. Moreover, the PLGA-aspirin microspheres in the PLGA-CaSiO₃-aspirin scaffolds were uniformly adhered to the surface of CaSiO₃ microspheres. The aspirin loadings of CaSiO₃-aspirin, PLGA-aspirin, and PLGA-CaSiO₃-aspirin were (1.06±0.04)%, (7.05±0.06)%, and (6.75±0.18)%, respectively. In addition, their corresponding time for releasing 95% of aspirin was 3, 24, and 36 days, respectively. The releasing time of PLGA-CaSiO₃-aspirin was longer than that of the others and the releasing rate was more stable.

CONCLUSION

The microsphere scaffold of PLGA-CaSiO₃-aspirin composites has excellent delayedrelease effect on aspirin, which is promising for using as osteogenic materials.

Aspirin inhibits adipogenesis of tendon stem cells and lipids accumulation in rat injury tendon through regulating PTEN/PI3K/AKT signalling

Tendon injury repairs are big challenges in sports medicine, and fatty infiltration after tendon injury is very common and hampers tendon injury healing process. Tendon stem cells (TSCs), as precursors of tendon cells, have shown promising effect on injury tendon repair for their tenogenesis and tendon extracellular matrix formation. Adipocytes and lipids accumulation is a landmark event in pathological process of tendon injury, and this may induce tendon rupture in clinical practice. Based on this, it is important to inhibit TSCs adipogenesis and lipids infiltration to restore structure and function of injury tendon. Aspirin, as the representative of non‐steroidal anti‐inflammatory drugs (NSAIDs), has been widely used in tendon injury for its anti‐inflammatory and analgesic actions, but effect of aspirin on TSCs adipogenesis and fatty infiltration is still unclear. Under adipogenesis conditions, TSCs were treated with concentration gradient of aspirin. Oil red O staining was performed to observe changes of lipids accumulation. Next, we used RNA sequencing to compare profile changes of gene expression between induction group and aspirin‐treated group. Then, we verified the effect of filtrated signalling on TSCs adipogenesis. At last, we established rat tendon injury model and compared changes of biomechanical properties after aspirin treatment. The results showed that aspirin decreased lipids accumulation in injury tendon and inhibited TSCs adipogenesis. RNA sequencing filtrated PTEN/PI3K/AKT signalling as our target. After adding the signalling activators of VO‐Ohpic and IGF‐1, inhibited adipogenesis of TSCs was reversed. Still, aspirin promoted maximum loading, ultimate stress and breaking elongation of injury tendon. In conclusion, by down‐regulating PTEN/PI3K/AKT signalling, aspirin inhibited adipogenesis of TSCs and fatty infiltration in injury tendon, promoted biomechanical properties and decreased rupture risk of injury tendon. All these provided new therapeutic potential and medicine evidence of aspirin in treating tendon injury and tendinopathy.

An injectable and thermosensitive hydrogel: Promoting periodontal regeneration by controlled-release of aspirin and erythropoietin

Periodontitis is an inflammatory disease induced by complex interactions between host immune system and plaque microorganism. Alveolar bone resorption caused by periodontitis is considered to be one of the main reasons for tooth loss in adults. To terminate the alveolar bone resorption, simultaneous anti-inflammation and periodontium regeneration is required, which has not appeared in the existing methods. In this study, chitosan (CS), β-sodium glycerophosphate (β-GP), and gelatin were used to prepare an injectable and thermosensitive hydrogel, which could continuously release aspirin and erythropoietin (EPO) to exert pharmacological effects of anti-inflammation and tissue regeneration, respectively. The releasing profile showed that aspirin and EPO could be continuously released from the hydrogels, which exhibited no toxicity both in vitro and in vivo, for at least 21 days. Immunohistochemistry staining and micro-CT analyses indicated that administration of CS/β-GP/gelatin hydrogels loaded with aspirin/EPO could terminate the inflammation and recover the height of the alveolar bone, which is further confirmed by histological observations. Our results suggested that CS/β-GP/gelatin hydrogels are easily prepared as drug-loading vectors with excellent biocompatibility, and the CS/β-GP/gelatin hydrogels loaded with aspirin/EPO are quite effective in anti-inflammation and periodontium regeneration, which provides a great potential candidate for periodontitis treatment in the dental clinic. Statement of Significance To terminate the alveolar bone resorption caused by periodontitis, simultaneous anti-inflammation and periodontium regeneration is required, which has not appeared in the existing methods. Here, (1) the chitosan (CS)/β-sodium glycerophosphate/gelatin hydrogels loaded with aspirin/erythropoietin (EPO) can form at body temperature in 5 min with excellent biocompatibility in vitro and in vivo; (2) The faster release of aspirin than EPO in the early stage is beneficial for anti-inflammation and provides a microenvironment for ensuring the regeneration function of EPO in the following step. In vivo experiments revealed that the hydrogels are effective in the control of inflammation and regeneration of the periodontium. These results indicate that our synthesized hydrogels have a great potential in the future clinical application.

Establishing an osteoimmunomodulatory coating loaded with aspirin on the surface of titanium primed with phase-transited lysozyme

BACKGROUND

To improve osseointegration and enhance the success rate of implanted biomaterials, the surface modification technology of bone implants has developed rapidly. Intensive research on osteoimmunomodulation has shown that the surfaces of implants should possess favorable osteoimmunomodulation to facilitate osteogenesis.

METHODS

A novel, green and efficient phase-transited lysozyme (PTL) technique was used to prime titanium discs with a positive charge. In addition, sodium hyaluronate (HA) and self-assembled type I collagen containing aspirin (ASA) nanoparticles were decorated on PTL-primed Ti discs via electrostatic interaction.

RESULTS

The behaviors of bone marrow stromal cells (BMSCs) on the Ti disc surfaces containing ASA were analyzed in different conditioned media (CM) generated by macrophages. Additionally, the secretion of inflammation-related cytokines of macrophages on the surfaces of different Ti discs was investigated in in vitro experiments, which showed that the Ti surface containing ASA not only supported the migration, proliferation and differentiation of BMSCs but also reduced the inflammatory response of macrophages compared with Ti discs without surface modification. After implantation in vivo, the ASA-modified implant can significantly contribute to bone formation around the implant, which mirrors the evaluation in vitro.

CONCLUSION

This study highlights the significant effects of appropriate surface characteristics on the regulation of osteogenesis and osteoimmunomodulation around an implant. Implant modification with ASA potentially provides superior strategies for the surface modification of biomaterials.

Pyropheophorbide-α methyl ester-mediated photodynamic therapy induces apoptosis and inhibits LPS-induced inflammation in RAW264.7 macrophages

BACKGROUND

This study aimed to determine the effect of pyropheophorbide-α methyl ester (MPPa)-mediated photodynamic therapy (MPPa-PDT) on the apoptosis and inflammation of murine macrophage RAW264.7 cells.

METHODS

Uptake and subcellular localization of MPPa was detected by flow cytometry and confocal fluorescence microscope. Cell viability was assessed by CCK-8; ROS levels were assessed by DCFH-DA. Cell apoptosis was measured by flow cytometry and Hoechst 33342 staining, whereas mitochondrial membrane potential was detected by JC-1 staining. Secretion of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) was determined using ELISA kits. Caspase-3, cleaved caspase-3, procaspase-9, cleaved caspase-9, PARP, cleaved PARP, Bcl-2, Bax, NF-κB p-p65, p-IKKα/β, and p-IκBα were measured by western blotting. Nuclear factor κB (NF-κB)-p65 nuclear translocation was observed by immunofluorescence.

RESULTS

MPPa -PDT influenced cell viability in a light dose-dependent manner. It induced ROS formation and RAW264.7 cell apoptosis. It also increased the expression of cleaved caspase-3, cleaved caspase-9, cleaved PARP and Bax, decreased the expression of Bcl-2. While TNF-α, IL-1β, and IL-6 increased in LPS group (model of inflammation), it deceased in LPS-MPPa-PDT group. NF-κB p-p65, p-IKKα/β, and p-IκBα had higher expression in LPS group while that reduced in LPS-MPPa-PDT group. Simultaneously, MPPa-PDT inhibited nuclear translocation of NF-κB-p65 caused by LPS.

CONCLUSIONS

MPPa-PDT can induce apoptosis and attenuate inflammation in mouse RAW264.7 macrophages, thereby suggesting a promising therapy for atherosclerosis.

Preparation and functionalization of acetylsalicylic acid loaded chitosan/gelatin membranes from ethanol-based suspensions via electrophoretic deposition

Ethanol dissolved acetylsalicylic acid was successfully loaded with chitosan/gelatin via EPD and showed outstanding osteogenesis and mechanical properties.

Aspirin inhibits LPS-induced macrophage activation via the NF-κB pathway

Aspirin (acetylsalicylic acid, ASA) has been shown to improve bone marrow mesenchymal stem cell-based calvarial bone regeneration by promoting osteogenesis and inhibiting osteoclastogenesis. However, it remains unknown whether aspirin influences other immune cells during bone formation. In the present study, we investigated whether ASA treatment influenced macrophage activation during the LPS inducement. We found that ASA could downregulate the expressions of iNOS and TNF-α both in mouse peritoneum macrophages and RAW264.7 cells induced by LPS via the IκK/IκB/NF-κB pathway and a COX₂/PGE₂/EP₂/NF-κB feedback loop, without affecting the expressions of FIZZ/YM-1/ARG1 induced by IL-4. Furthermore, we created a rat mandibular bone defect model and showed that ASA treatment improved bone regeneration by inhibiting LPS-induced macrophage activation in the early stages of inflammation. Taken together, our results indicated that ASA treatment was a feasible strategy for improving bone regeneration, particularly in inflammatory conditions.

Aspirin enhances the osteogenic and anti-inflammatory effects of human mesenchymal stem cells on osteogenic BFP-1 peptide-decorated substrates

Several bone diseases, including arthritis, fracture and osteoporosis, have a pathophysiologically important inflammatory component. Sustained inflammation can result in delayed bone healing. Therefore, to promote bone repair, it is important to inhibit inflammatory bone erosion and suppress pro-inflammatory mediators. In this study, aspirin significantly enhanced immunomodulation and osteogenic differentiation in human mesenchymal stem cells (hMSCs). Additionally, an osteogenic BFP-1 peptide-decorated substrate (PS-PEP) enhanced osteogenic differentiation of aspirin-treated hMSCs compared to a pristine substrate. Alkaline phosphatase assay, quantitative real-time polymerase chain reaction, immunostaining and Alizarin Red S staining revealed that aspirin-treated hMSCs cultured on PS-PEP exhibited enhanced osteogenesis compared with untreated cells. Thus, we report here that the anti-inflammatory and osteogenic effects of aspirin promote the activity and osteogenesis of hMSCs. The combination of aspirin and an osteogenic BFP-1 peptide-decorated substrate suppresses the production of pro-inflammatory mediators and promotes osteogenic differentiation of hMSCs; therefore, this novel strategy has potential for application in cell therapy and bone tissue engineering.

Ginsenoside Rb2 inhibits osteoclast differentiation through nuclear factor-kappaB and signal transducer and activator of transcription protein 3 signaling pathway

Ginsenoside-Rb2 (Rb2) is a 20(S)-protopanaxadiol glycoside extracted from ginseng possessing various bioactivities which has drawn considerable interest regarding the area of bone metabolism. However, the effect of Rb2 on osteoclast differentiation remains unknown. In this study, we aimed to investigate the potential role of Rb2 in regulating osteoclast differentiation and the underlying molecular mechanisms. Osteoclast differentiation was induced by receptor activator nuclear factor-kappaB (NF-κB) ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in mouse RAW 264.7 cells. The results showed that Rb2 dose-dependently inhibited the formation of the tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells and TRAP expression. Furthermore, Rb2 promoted osteoprotegerin expression and bone resorption. The expression of osteoclast marker genes including nuclear factor of activated T cells c1 (NFATc1), c-Fos, OSCAR, and cathepsin K were also markedly inhibited by Rb2 treatment. Moreover, Rb2 significantly inhibited the RANKL-induced NF-κB activation. In addition, Rb2 also markedly suppressed the activation of signal transducer and activator of transcription protein 3 (STAT3) signaling pathway. Interestingly, the knockdown of STAT3 significantly strengthened the inhibitory effect of Rb2 on osteoclast differentiation. Taken together, our study suggests that Rb2 inhibits osteoclast differentiation associated with blocking NF-κB and STAT3 signaling pathways.

A Review on the Relationship between Aspirin and Bone Health

Aspirin is a cyclooxygenase inhibitor commonly used in primary prevention of cardiovascular diseases and cancers. Its users are elderly population susceptible to osteoporosis. It also inhibits the synthesis of prostaglandin E₂ essential in bone remodeling. This prompts the question whether it can influence bone health among users. This review aimed to summarize the current literature on the use of aspirin on bone health. A literature search on experimental and clinical evidence on the effects of aspirin on bone health was performed using major scientific databases. In vitro studies showed that aspirin could enhance the survival of bone marrow mesenchymal stem cells, the progenitors of osteoblasts, and stimulate the differentiation of preosteoblasts. Aspirin also inhibited the nuclear factor kappa-B (NFκB) pathway and decreased the expression of receptor activator of NFκB ligand, thus suppressing the formation of osteoclast. Aspirin could prevent bone loss in animal models of osteoporosis. Despite a positive effect on bone mineral density, the limited human epidemiological studies revealed that aspirin could not reduce fracture risk. A study even suggested that the use of aspirin increased fracture risk. As a conclusion, aspirin may increase bone mineral density but its effect on fracture prevention is inconclusive. More data are needed to determine the effects of aspirin and bone health in human.