Therapeutic approaches to bone diseases

Biomimetic structural design in 3D-printed scaffolds for bone tissue engineering

The rising prevalence of bone diseases in an aging population underscores the urgent need for innovative and clinically translatable solutions in bone tissue engineering. While significant progress has been made in refining the chemical properties of biomaterials, the structural design of scaffolds-a critical determinant of repair success-remains comparatively underexplored. Structural parameters such as porosity, pore size, and interconnectivity are not only essential for achieving mechanical stability but also pivotal in regulating biological processes, including vascularization, osteogenesis, and immune modulation. This review systematically categorizes scaffold architectures documented in the literature and highlights how these design parameters can be optimized to enhance bone regeneration. Advanced fabrication technologies, particularly 3D printing, are emphasized for their transformative potential in creating precise, biomimetic scaffolds that align with the complex functional demands of native bone. Furthermore, this work synthesizes diverse findings to provide a comprehensive framework for designing next-generation scaffolds. By bridging the gap between structural innovation and clinical application, this review delivers actionable strategies and a strategic roadmap for advancing the field toward improved clinical outcomes and transformative breakthroughs in regenerative medicine.

Multiscale metal-based nanocomposites for bone and joint disease therapies

Bone and joint diseases are debilitating conditions that can result in significant functional impairment or even permanent disability. Multiscale metal-based nanocomposites, which integrate hierarchical structures ranging from the nanoscale to the macroscale, have emerged as a promising solution to this challenge. These materials combine the unique properties of metal-based nanoparticles (MNPs), such as enzyme-like activities, stimuli responsiveness, and photothermal conversion, with advanced manufacturing techniques, such as 3D printing and biohybrid systems. The integration of MNPs within polymer or ceramic matrices offers a degree of control over the mechanical strength, antimicrobial efficacy, and the manner of drug delivery, whilst concomitantly promoting the processes of osteogenesis and chondrogenesis. This review highlights breakthroughs in stimulus-responsive MNPs (e.g., photo-, magnetically-, or pH-activated systems) for on-demand therapy and their integration with biocomposite hybrids containing cells or extracellular vesicles to mimic the native tissue microenvironment. The applications of these composites are extensive, ranging from bone defects, infections, tumors, to degenerative joint diseases. The review emphasizes the enhanced load-bearing capacity, bioactivity, and tissue integration that can be achieved through hierarchical designs. Notwithstanding the potential of these applications, significant barriers to progress persist, including challenges related to long-term biocompatibility, regulatory hurdles, and scalable manufacturing. Finally, we propose future directions, including machine learning-guided design and patient-specific biomanufacturing to accelerate clinical translation. Multiscale metal-based nanocomposites, which bridge nanoscale innovations with macroscale functionality, are a revolutionary force in the field of biomedical engineering, providing personalized regenerative solutions for bone and joint diseases.

Effect of clindamycin on human osteoblasts treated with zoledronate: An in vitro study

OBJECTIVE

The objective of this study was to determine the effects of combined treatment with clindamycin and zoledronate on the growth and differentiation of cultured human osteoblasts.

DESIGN

Human osteoblasts, obtained by primary culture from mandibular bone fragments, were cultured in the presence of 50 μM zoledronate, 150 μg/mL clindamycin, or the combination of both (zoledronate + clindamycin). The effect on cell proliferation was evaluated at 24 h by the MTT colorimetric method, using a spectrophotometer at 570 nm. The effect on differentiation was examined by measuring alkaline phosphatase (ALP) activity, and mineralization by the osteoblast was studied by staining with alizarin red. Real-time polymerase chain reaction (RT-PCR) was performed for gene expression analysis. Data were expressed as means±standard deviation, and analysis of variance was performed, applying Bonferroni correction when interactions were significant.

RESULTS

Treatment of osteoblasts with 50 μM zoledronate significantly reduced cell proliferation and differentiation and the gene expression of certain markers versus controls (p < 0.001). However, treatment with 150 μg/mL clindamycin significantly increased cell proliferation and differentiation and the gene expression of certain markers (p < 0.05). The combination of 150 μg/mL clindamycin and 50 μM zoledronate partially counteracted the loss of osteoblast proliferative and differentiation capacity caused by zoledronate.

CONCLUSION

Treatment with low-dose clindamycin can reverse the negative impact of zoledronate on osteoblast proliferation and differentiation. Follow-up animal studies and clinical trials are needed before topical clindamycin can be considered as a possible therapeutic resource for BP-treated patients who require a GBR procedure.

Biomaterial-based strategies for bone cement: modulating the bone microenvironment and promoting regeneration

Osteoporotic bone defect and fracture healing remain significant challenges in clinical practice. While traditional therapeutic approaches provide some regulation of bone homeostasis, they often present limitations and adverse effects. In orthopedic procedures, bone cement serves as a crucial material for stabilizing osteoporotic bone and securing implants. However, with the exception of magnesium phosphate cement, most cement variants lack substantial bone regenerative properties. Recent developments in biomaterial science have opened new avenues for enhancing bone cement functionality through innovative modifications. These advanced materials demonstrate promising capabilities in modulating the bone microenvironment through their distinct physicochemical properties. This review provides a systematic analysis of contemporary biomaterial-based modifications of bone cement, focusing on their influence on the bone healing microenvironment. The discussion begins with an examination of bone microenvironment pathology, followed by an evaluation of various biomaterial modifications and their effects on cement properties. The review then explores regulatory strategies targeting specific microenvironmental elements, including inflammatory response, oxidative stress, osteoblast-osteoclast homeostasis, vascular network formation, and osteocyte-mediated processes. The concluding section addresses current technical challenges and emerging research directions, providing insights for the development of next-generation biomaterials with enhanced functionality and therapeutic potential.

Leveraging Nanoscience and Strategic Delivery for the Expedition of Osteoporosis

Osteoporosis is a globally affecting bone disease characterized by reduced bone mineral density, in which women are more insidious to the disease. It accounts for 8.9 million fractures annually, and about 50% of repeated hip fractures cause permanent disabilities. With the knowledge of determinants and pathology, various FDA-approved drugs and therapies are available for the management of the disease, but the challenges associated with those therapies lead to the adoption of nanotechnology in osteoporosis management. The nanosystems developed for the management of osteoporosis are nanogenerators, nanobubbles, microneedles, nanogels, implantable delivery systems, nanoparticles, nanofibrous scaffolds, and nanocements that probably address the current challenges related to the diagnosis and cure. In view of targeted accumulation of the cargo, various moieties assisted the nanocarrier system for selective distribution to bone, and the development of different types of nanotechnology-based delivery systems has been briefed in this review.

Ishophloroglucin A Isolated From Ishige okamurae Stimulates Osteoblast Differentiation Through Activation of the Bone Morphogenetic Protein and Wnt/β-Catenin Signaling Pathways in MC3T3-E1 Cells

Current osteoporosis treatments are insufficient as they cause a relatively small increase in bone mass and are unable to recover lost bone structures, in addition to having severe side effects. The bone morphogenetic protein (BMP) and Wnt/β-catenin signaling pathways cooperatively modulate bone formation and osteoblast differentiation and therefore may play a role in treating osteoporosis. This study aimed to investigate the effects of Ishophloroglucin A (IPA), a novel phenolic compound isolated from Ishige okamurae, on osteoblast differentiation by activating the BMP and Wnt/β-catenin signaling pathways. According to our findings, IPA significantly promoted the osteogenic proliferation of MC3T3-E1 osteoblastic cells and increased alkaline phosphatase (ALP) activity and calcium nodule formation in MC3T3-E1 cells compared to the untreated control. IPA also upregulated osteogenesis markers such as type 1 collagen, ALP, p-Smad1/5/8, osterix, osteopontin, runt-related transcription factors (Runx2), and BMP2 in MC3T3-E1 cells in a dose-dependent manner. Moreover, IPA activated Wnt3a, LRP5, DVL2, and β-catenin in MC3T3-E1 cells. Overall, our results demonstrate that IPA promotes the differentiation of MC3T3-E1 osteoblastic cells by activating the BMP and Wnt/β-catenin signaling pathways, suggesting that it may be a potential candidate target for treating or preventing osteoporosis.

Global trends in osteoimmunology and osteoporosis research: A bibliometric analysis from 2013 to 2022

BACKGROUND

A large number of studies have shown that osteoporosis is closely related to bone immunology. The purpose of this study is to conduct bibliometrics and visual analysis of the fields related to osteoimmunology and osteoporosis from 2013 to 2022 and to summarize the research hotspots and trends in this field.

METHODS

We searched the Web of Science core collection database for articles on osteoimmunology and osteoporosis published between 2013 and 2022. Vosviewer 1.6.18 and CiteSpace.6.2. R4 were used to analyze the retrieved data.

RESULTS

A total of 3218 articles on osteoimmunology and osteoporosis were included in this study. A total of 76 countries, 347 institutions, and 502 authors were included in the articles examined in this study. The main research countries were China, the United States, and South Korea. Shanghai Jiaotong University, Harvard University, and the University of California system were the main research institutions. The author who published the most papers was Xu, Jiake.

CONCLUSIONS

This study is the first to summarize the global research trends in the field of osteoimmunology and osteoporosis from 2013 to 2022. That helps researchers quickly understand the research hotspots and directions in this field.

Osteo-inductive potential of homoeopathy potencies of Asafoetida on multipotent mesenchymal stem cells in vitro

The musculoskeletal system is the main framework of the human system. Poor osteogenesis is related to poor diet, improper exercise, autoimmune diseases, or age-related conditions. This tends to compromise the quality of human life, especially gait and mobility. Calcium, magnesium, and vitamin D supplements are the prescriptions that address the issues above. Moreover, various natural products in alternative medicines have also been found to have applications in improving bone health. One such finding in our study is the homeopathy potency of Asafoetida, 200CH, which has exhibited a promising osteo-inductive potential in vitro for murine multipotent mesenchymal stem cell line C3H10T1/2. Ferula asafoetida is otherwise a known herb for addressing gastric issues. In this work, the homoeopathy clinician (first author) first repurposed the F. asafoetida potency (dilution) to ameliorate bone disorders such as avascular necrosis and loose body dissolution. Following clinical success, we have proven the osteo-inductive properties of this particular homoeopathy potency of the drug in vitro. Most importantly, the osteo-inductive (osteogenesis) properties of homoeopathy potency 200CH are more pronounced than the native compound combinations in the Mother tincture (Q) of the drug. This homoeopathy drug, hence, can be used for treating osteoarthritis alone or else as an adjuvant with conventional treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-025-04245-1.

Modulation of the gut-bone axis: Lacticaseibacillus paracasei LC86 improves bone health via anti-inflammatory metabolic pathways in zebrafish models of osteoporosis and cartilage damage

Aim

Osteoporosis and cartilage injury are major health concerns with limited treatment options. This study investigates the therapeutic effects of Lacticaseibacillus paracasei LC86 (LC86) on osteoporosis and cartilage damage in a zebrafish (Danio rerio) model, focusing on its modulation of the gut-bone axis and its potential mechanisms for enhancing bone health.

Methods

A Dexamethasone-induced zebrafish model was used to mimic osteoporosis and cartilage injury. Zebrafish were divided into control, model, and LC86 treatment groups (3×107 CFU/mL). Bone and cartilage health were assessed using Alizarin red staining and fluorescence microscopy. Bone marker expression (sp7, runx2a, bmp2a, bmp4, and col2a1a) was quantified via qPCR. Metabolic alterations were analyzed using untargeted metabolomics, and changes in gut microbiota were examined through 16S rRNA gene sequencing.

Results

LC86 treatment significantly improved bone and cartilage health, as evidenced by increased fluorescence intensity in the skull, hard bone, and cartilage (p < 0.01, p < 0.05). qPCR results showed upregulation of key bone-related genes (sp7, runx2a, bmp2a, bmp4, and col2a1a), indicating enhanced bone and cartilage structure. Metabolomics analysis revealed alterations in over 300 metabolites, with changes in anti-inflammatory and energy pathways. Gut microbiota analysis demonstrated an increase in beneficial bacteria and a decrease in pathogenic genera.

Conclusions

LC86 significantly improved bone health, cartilage structure, and gut microbiota composition in a Dexamethasone-induced zebrafish model, supporting its potential as a therapeutic strategy for osteoporosis and cartilage injury via modulation of the gut-bone axis.

Pim1 promotes the maintenance of bone homeostasis by regulating osteoclast function

The Pim1 (proviral integration site for Moloney leukemia virus 1) protein is a serine/threonine kinase that is essential for cell proliferation, apoptosis and innate immune responses. Here we show that Pim1 promotes osteoclast resorptive function without affecting osteoclast numbers. Specifically, we found that mice lacking Pim1 (Pim1-/-) developed increased trabecular bone mass and indices such as trabecular bone-mass density. This was due to the direct phosphorylation of TRAF6 by Pim1 in mature osteoclasts, which activated the Akt-GSK3β signaling pathway. This, in turn, promoted the acetylation and consequent stabilization of microtubules, which permitted the formation of the osteoclast sealing zone. In vivo experiments then showed that, when mice with lipopolysaccharide-induced bone loss or tumor-induced osteolysis were treated with SGI-1776, a Pim1 inhibitor that is more selective for Pim1, the bone loss was significantly ameliorated. Thus, Pim1 plays an important role in osteoclast function and may be a therapeutic target for bone-related diseases.

Yak milk inhibits osteoclast differentiation by suppressing TRPV5 expression

Yak milk is a potential nutrient for improving osteoporosis. However, the effect of yak milk on the expression of Ca2+ion channel TRPV5 during osteoclast differentiation is still unclear. This study used ruthenium red as a control to investigate the effect of yak milk on osteoclast differentiation and activity. Tartrate-resistant acid phosphatase staining and bone resorption pit experiments showed that yak milk inhibited osteoclast differentiation and bone resorption activity in a dose-dependent manner. In addition, yak milk can inhibit osteoclast activity by inhibiting the expression of TRPV5. Quantitative real-time PCR and western blot results also exhibited that yak milk significantly decreased the expression of TRPV5 and calbindin-D28k mRNA and protein in osteoclasts. These results suggest that yak milk inhibits nuclear factor-κβ ligand-receptor activator-induced osteoclast differentiation and bone resorption activity in RAW 264.7 cells by suppressing the expression level of TRPV5 and calbindin-D28k mRNA and protein.

Advances in copper-containing biomaterials for managing bone-related diseases

Bone-related diseases pose a major challenge in contemporary society, with significant implications for both health and economy. Copper, a vital trace metal in the human body, facilitates a wide range of physiological processes by being crucial for the function of proteins and enzymes. Numerous studies have validated copper's role in bone regeneration and protection, particularly in the development and expansion of bone collagen. Owing to copper's numerous biological advantages, an increasing number of scientists are endeavoring to fabricate novel, multifunctional copper-containing biomaterials as an effective treatment strategy for bone disorders. This review integrates the current understanding regarding the biological functions of copper from the molecular and cellular levels, highlighting its potential for bone regeneration and protection. It also reviews the novel fabrication techniques for developing copper-containing biomaterials, including copper-modified metals, calcium phosphate bioceramics, bioactive glasses, bone cements, hydrogels and biocomposites. The fabrication strategies and various applications of these biomaterials in addressing conditions such as fractures, bone tumors, osteomyelitis, osteoporosis, osteoarthritis and osteonecrosis are carefully elaborated. Moreover, the long-term safety and toxicity assessments of these biomaterials are also presented. Finally, the review addresses current challenges and future prospects, in particular the regulatory challenges and safety issues faced in clinical implementation, with the aim of guiding the strategic design of multifunctional copper-based biomaterials to effectively manage bone-related diseases.

Developmental Endothelial Locus-1 Promotes Osteoclast Differentiation and Activation

Developmental endothelial locus-1 (DEL-1) has traditionally been characterized within the scientific community as having anti-inflammatory properties with potential inhibitory effects on osteoclast formation. Our investigation challenges this paradigm by examining Del-1 expression in RAW264.7 cells and bone marrow-derived macrophages (BMMs) during osteoclastogenesis, as well as its functional impact on osteoclast development and activity. Our experimental findings revealed that Del-1 mRNA levels were markedly elevated in cells stimulated by the receptor activator of the nuclear factor κB ligand compared to unstimulated precursors. When cultured with varying concentrations of recombinant DEL-1, osteoclast differentiation increased in a dose-dependent manner. Furthermore, BMMs isolated from ovariectomized mice exhibited significantly higher Del-1 mRNA expression than those from control animals. To confirm DEL-1's role, we employed RNA interference techniques, demonstrating that DEL-1 silencing in RAW264.7 cells substantially reduced osteoclast formation. These results suggest that DEL-1 plays a previously unrecognized role in promoting osteoclastogenesis and may contribute to bone metabolism imbalances in conditions like osteoporosis, highlighting its complex role in skeletal homeostasis and its potential as a therapeutic target.

Enhanced Bone Targeting of Poly(l-glutamic acid)s through Cationic or Aromatic Substitution

Poly(l-glutamic acid)s (PLGs) are promising bone-targeting ligands due to their high molecular weight and facile preparation. Nevertheless, the bone-targeting efficiency of PLGs is still relatively low, validating the necessity to further enhance targeting through structural optimization. Herein, we report the use of a heteropolypeptide strategy to improve the bone targeting of PLGs through the incorporation of another side-chain functionality for enhanced affinity with bone tissues. Specifically, the introduction of cationic amino or aromatic phenolic side-chain residues resulted in a ∼2.3-fold or ∼1.6-fold increase in the in vivo bone targeting, respectively. Cationic modification not only improved the affinity with bone minerals but also exhibited prolonged retention in the bone tissues for more than 60 days. This work highlights the use of a heteropolypeptide library to screen and optimize the performance of polypeptide materials, offering promising bone-targeting polymeric materials for the design of bone-related nanomedicine.

Mongolian medicine Sugemule-7 decoction prevents osteoporosis via Erk1/2 and p38 MAPK signaling pathways according to network pharmacology analysis

Osteoporosis (OP) is a significant global public health concern that requires the development of safe and effective drugs for prevention and treatment. Sugemule-7 (SGML-7) decoction, a traditional Mongolian herbal prescription, has long been used for treating OP, but its components and mechanisms of action remain unclear. The study identified the main compounds of SGML-7 using UHPLC-Q Exactive MS and explored the multi-target mechanisms of SGML-7 in OP through network pharmacology and molecular docking. A retinoic acid (RA)-induced mouse OP model was utilized to confirm the therapeutic effects and potential mechanism of SGML-7. Additionally, mouse pre-osteoblastic (MC3T3-E1) cells treated with SGML-7 medicated serum were employed to delve deeper into the molecular mechanisms. The UHPLC-Q Exactive MS analysis, network pharmacology, and molecular docking suggested that the synergistic effect of multiple active compounds could be the main contributor to SGML-7 for its anti-OP activities. Moreover, MAPK1, JUN, ESR1, TP53, AKT1, NCOA1, FOS, and NR3C1 were identified as potential key targets, and the MAPK signaling pathway was among the signaling pathways possibly involved in the anti-OP activities of SGML-7. Consistent with these findings, experimental studies confirmed that SGML-7 prevented bone loss, enhanced bone quality in OP mice, and promoted osteoblastic activity and bone formation in MC3T3-E1 cells by modulating MAPK-associated targets. Taken together, SGML-7 shows promise as an effective and appealing anti-OP drug candidate.

Treatment with Lactobacillus paracasei L30 extract induces osteogenic differentiation of human bone marrow mesenchymal stem cells in vitro

Bone-related diseases such as osteoporosis pose a significant health economic burden to countries around the world and, because current treatments are insufficient, more effective therapies are desperately needed. This study explored the potential of Lactobacillus paracasei L30 extract to influence the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs). Our results showed that L30 extract significantly enhanced the expression of osteogenic markers in hBM-MSCs, including alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), and collagen type I alpha 1 (COL1A1). Mechanistic studies revealed that L30 extract activated the p38 MAPK and AKT signaling pathways, leading to phosphorylation of Glycogen synthase kinase-3 beta (GSK3β) and subsequent nuclear translocation of β-catenin. Conversely, inhibition of p38 MAPK, AKT, or knockdown of β-catenin significantly attenuated the osteogenic effects of L30 extract on hBM-MSCs. Furthermore, we found that L30 extract promoted osteogenic differentiation in primary osteoblast precursors isolated from mouse calvaria and enhances bone formation in ex vivo calvarial organ cultures. Therefore, the application of Lactobacillus paracasei L30 extract in such contexts could serve as a therapeutic approach for promoting bone formation. Collectively, our findings suggest a novel approach for the clinical management of bone-related disorders, with possible applications for treating diseases such as osteoporosis.

Inhibiting autophagy further promotes Ginkgolide B's anti-osteoclastogenesis ability

Excessive osteoclast activity could cause skeletal diseases including osteoporosis. Additionally, autophagy plays an initial role in osteoclast differentiation and function. Ginkgolide B (GB), a key compound in Ginkgo biloba, improves bone mass and suppresses mature osteoclast formation in vitro. This study examines the role of GB role in regulating osteoclast formation via autophagy. Using murine bone marrow-derived macrophages in vitro, we explored GB's effects on autophagy and osteoclast formation. We also assessed bone loss prevention in an ovariectomized (OVX) mouse model using GB combined with an autophagy inhibitor. Tartrate-resistant acid phosphatase staining was used to observe osteoclast formation. Autophagy-related proteins and intracellular microtubule associated protein 1 light chain 3 beta puncta were observed using western blotting and immunofluorescence. The impact of GB on OVX mice was evaluated using micro-computed tomography and hematoxylin and eosin staining. GB directly promoted autophagy in osteoclast precursors (OCPs), but inhibited osteoclast differentiation by reducing receptor activator of nuclear factor kappa B ligand (RANKL)-induced autophagy. GB inhibits the phosphorylation of RANKL downstream signaling pathways, such as Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK). Anisomycin (ANI), a JNK activator, reversed GB's inhibitory effects on RANKL-induced autophagy and osteoclastogenesis. Inhibiting autophagy using 3-Methyladenine (3-MA) or small interfering RNA significantly suppressed osteoclast differentiation both in vitro and in vivo. Our findings suggested that GB inhibits osteoclast formation by decreasing JNK phosphorylation and autophagy under RANKL stimulation. Interestingly, GB also directly promotes autophagy in OCPs. Thus, GB markedly reduces osteoclast differentiation and prevents bone loss, with its anti-osteoclastogenesis effect being enhanced by 3-MA. Accordingly, inhibiting GB-induced direct autophagy could further increase its therapeutic effect on bone disease resulting from excessive osteoclast activity.

Rapid and relaying deleterious effects of a gastrointestinal pathogen, Citrobacter rodentium, on bone, an extra-intestinal organ

Enteropathogenic infections cause pathophysiological changes in the host but their effects beyond the gastrointestinal tract are undefined. Here, using Citrobacter rodentium infection in mouse, which mimics human diarrheal enteropathogenic Escherichia coli, we show that gastrointestinal infection negatively affects bone remodeling, leading to compromised bone architecture. Transmission of infection through fecal-oral route from Citrobacter rodentium-infected to non-infected mice caused bone loss in non-infected cage mates. Mice with B cell deficiency (Igh6-/- mice) failed to clear C. rodentium infection and exhibited more severe and long-term bone loss compared to WT mice. Unbiased cytokine profiling showed an increase in circulating tumor necrosis factor α (TNFα) levels following Citrobacter rodentium infection, and immunoneutralization of TNFα prevented infection-induced bone loss completely in WT and immunocompromised mice. These findings reveal rapid, relaying, and modifiable effects of enteropathogenic infections on an extraintestinal organ-bone, and provide insights into the mechanism(s) through which these infections affect extraintestinal organ homeostasis.

Shark chondroitin sulfate gold nanoparticles: A biocompatible apoptotic agent for osteosarcoma

Osteosarcoma is a highly aggressive tumor that originates in the bone and often infiltrates nearby bone cells. It is the most prevalent type of primary bone cancer among the various bone malignancies. Traditional cancer treatment methods such as surgery, chemotherapy, immunotherapy, and radiotherapy have had restricted success. However, the integration of nanotechnology into cancer research has led to notable progress. One promising area is the use of marine-derived polysaccharide-based nano formulations for treating various human diseases, including cancer. This study presents a straightforward method for synthesizing biocompatible gold nanoparticles (AuNPs), utilizing sodium borohydride as a reducing agent and a cost-effective, water-soluble chondroitin sulfate (CS) derived from shark cartilage as a stabilizing agent. The synthesized CS-Au NPs appeared purple and were mainly spherical, with 40.768 nm of average size. Cytotoxicity assays (MTT) indicated that CS-Au NPs significantly reduced the viability of human osteosarcoma cells (MG63) at 100 μg/mL, while it showed no cytotoxic effects on mouse embryonic fibroblast cells (NIH3T3) at the same concentration. The observed toxicity of the CS-Au NPs was linked to a rise in the production of reactive oxygen species (ROS) within damaged mitochondria. ROS generation and changes in mitochondrial membrane potential were detected in MG63 cells treated with CS-Au NPs. Furthermore, apoptotic analysis through ethidium bromide dual staining and flow cytometry demonstrated that CS-Au NPs at higher concentrations significantly increased the amount of apoptotic cells, as demonstrated by acridine orange/ethidium bromide staining. Flow cytometry also confirmed that CS-Au NPs activated the apoptotic pathway in MG63 cells.

Piperazine-Derived Bisphosphonate-Based Ionizable Lipid Nanoparticles Enhance mRNA Delivery to the Bone Microenvironment

Nucleic acid delivery with mRNA lipid nanoparticles are being developed for targeting a wide array of tissues and cell types. However, targeted delivery to the bone microenvironment remains a significant challenge in the field, due in part to low local blood flow and poor interactions between drug carriers and bone material. Here we report bone-targeting ionizable lipids incorporating a piperazine backbone and bisphosphate moieties, which bind tightly with hydroxyapatite ([Ca5(PO4)3OH]), a key component of mineralized tissues. These lipids demonstrate biocompatibility and low toxicity in both vitro and in vivo studies. LNP formulated with these lipids facilitated efficient cellular transfection and improved binding to hydroxyapatite in vitro, and targeted delivery to the bone microenvironment in vivo following systemic administration. Overall, our findings demonstrate the critical role of the piperazine backbone in a novel ionizable lipid, which incorporates a bisphosphonate group to enable efficient bone-targeted delivery, highlighting the potential of rational design of ionizable lipids for next-generation bone-targeting delivery systems.

Effect of Luteolin on cadmium-inhibited bone growth via suppressing osteoclastogenesis in laying chickens

Luteolin (Lut) is a flavonoid derived from several plant sources. Cadmium (Cd) is a widespread environmental contaminant and potential toxin with detrimental effects on animal health. However, the effect of Lut on Cd-induced inhibition of bone growth in laying chickens remains unclear. This study investigates the effects of Lut on Cd-induced inhibition of bone growth in the femur and tibia of laying chickens. A total of sixty 1-d-old green-eggshell yellow feather laying chickens were randomly assigned to 4 groups after a 5-d acclimation period: basal diet (Con), cadmium chloride (CdCl2, Cd), Lut, and Lut + Cd. Bone microstructure, serum biomarkers of bone remodeling, the levels of Cd, calcium (Ca), phosphorus (P), and trace metal elements were assessed using the micro-computed tomography (Micro-CT), enzyme-linked immunosorbent assay (ELISA), and microwave digestion, respectively. Bone remodeling biomarkers, late endosomal/lysosomal adaptor and MAPK and mTOR activator 1 (LAMTOR1), as well as the phosphorylation of AMP-activated protein kinase α (AMPKα) and protein kinase B (Akt), were quantified using the qRT-PCR and western blot. The results indicated that Lut effectively mitigated Cd-induced bone mass loss compared to the Cd group, resulting in increased bone volume (BV), bone surface/BV (BS/BV), connectivity density (Conn.Dn), and the length and weight of the femur and tibia in laying chickens. Mechanistically, compared to the Cd group, Lut restored the ratio of osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) in serum and bone tissue, enhanced the expression of bone morphogenetic protein-2 (BMP-2), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and Osterix (OSX), while reducing the levels of Ca, Cd, and alkaline phosphatase (ALP) activity, as well as the expression of osteopontin (OPN), c-Fos, osteoclast stimulatory-transmembrane protein (OC-STAMP), tartrate-resistant acid phosphatase, cathepsin K (CTSK), matrix metalloprotein-9 (MMP-9), LAMTOR1, and the phosphorylation of AMPKα and Akt. Therefore, Lut alleviates Cd-induced damage to the femur and tibia of chickens by promoting osteogenesis and inhibiting osteoclastogenesis, positioning Lut as a potential therapeutic plant extract for enhancing bone growth in laying chickens.

Osteoporosis in Adrenal Insufficiency: Could Metformin be Protective?

Adrenal insufficiency (AI) is a serious disorder characterized by the adrenal glucocorticoid deficiency. Regardless of the etiology, AI patients need long-term replacement therapy for glucocorticoids and, in some cases, for mineralocorticoids. The replacement therapy cannot completely mirror the physiological secretion patterns, and therefore, glucocorticoid excess is a common sequela in AI patients. Moreover, due to the absence of the reliable clinical markers to monitor the adequacy of the replacement therapy, clinicians often over-treat the AI patients to avoid adrenal crisis. Long-term glucocorticoid use is associated with the loss of bone density and osteoporosis, increasing the risk of fractures. Moreover, glucocorticoid-induced hyperglycemia and type 2 diabetes mellitus further aggravates the bone disorders. In the recent years, ameliorating effects of metformin on glucocorticoid-induced bone disorders, as well as hyperglycemia, have been reported by a multitude of studies; and here, we reviewed and discussed the most recent findings regarding the positive effects of metformin on alleviating the bone disorders, and their implications in the AI patients.

Transcriptomic Characterization Reveals Mitochondrial Involvement in Nrf2/Keap1-Mediated Osteoclastogenesis

Although osteoclasts play crucial roles in the skeletal system, the mechanisms that underlie oxidative stress during osteoclastogenesis remain unclear. The transcription factor Nrf2 and its suppressor, Keap1, function as central mediators of oxidative stress. To further elucidate the function of Nrf2/Keap1-mediated oxidative stress regulation in osteoclastogenesis, DNA microarray analysis was conducted in this study using wild-type (WT), Keap1 knockout (Keap1 KO), and Nrf2 knockout (Nrf2 KO) osteoclasts. Principal component analysis showed that 403 genes, including Nqo1, Il1f9, and Mmp12, were upregulated in Keap1 KO compared with WT osteoclasts, whereas 24 genes, including Snhg6, Ccdc109b, and Wfdc17, were upregulated in Nrf2 KO compared with WT osteoclasts. Moreover, 683 genes, including Car2, Calcr, and Pate4, were upregulated in Nrf2 KO cells compared to Keap1 KO cells. Functional analysis by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis showed upregulated genes in Nrf2 KO osteoclasts were mostly enriched in oxidative phosphorylation. Furthermore, GeneMANIA predicted the protein-protein interaction network of novel molecules such as Rufy4 from genes upregulated in Nrf2 KO osteoclasts. Understanding the complex interactions between these molecules may pave the way for developing promising therapeutic strategies against bone metabolic diseases caused by increased osteoclast differentiation under oxidative stress.

Fabrication and X-ray microtomography of sandwich-structured PEEK implants for skull defect repair

Bone defects pose a significant risk to human health. Medical polyetheretherketone (PEEK) is an excellent implant material for bone defect repair, but it faces the challenge of bone osteoconduction and osseointegration. Osteoconduction describes the process by which bone grows on the surface of the implant, while osseointegration is the stable anchoring of the implant achieved by direct contact between the bone and the implant. Bone defects repair depends on the implant's three-dimensional spatial structure, including pore size, porosity, and interconnections to a great extent. However, it is challenging to fabricate the porous structures to meet specific requirements and to characterize them without causing damage. In this study, we designed and fabricated sandwich-like PEEK implants mimicking the three-layer structures of the skull, whose defects imposes a significant burden on young adulthood and paediatric populations, and performed in-line phase-contrast synchrotron X-ray microtomography to non-destructively investigate the internal porous microstructures. The sandwich-like three-layer microstructure, comprising a dense layer, a loose layer and a dense layer in succession, exhibits structural similarity to that in a natural skull. This work demonstrated the fabrication of the sandwich-like PEEK implant that could potentially enhance osteoconduction and osseointegration. Furthermore, the interior structures and residual porogen sodium chloride particles were observed within the PEEK implant, which cannot be realized by other microscopic methods without destroying the sample. It highlights the advantages and potential of using synchrotron X-ray microtomography to analyze the structure of biomedical materials. This study provides theoretical guidance for the further design and fabrication of PEEK bone repair materials and will advance the clinical application of innovative bioactive bone repair materials.

Design and Applications of Supramolecular Peptide Hydrogel as Artificial Extracellular Matrix

Supramolecular peptide hydrogels (SPHs) consist of peptides containing hydrogelators and functional epitopes, which can first self-assemble into nanofibers and then physically entangle together to form dynamic three-dimensional networks. Their porous structures, excellent bioactivity, and high dynamicity, similar to an extracellular matrix (ECM), have great potential in artificial ECM. The properties of the hydrogel are largely dependent on peptides. The noncovalent interactions among hydrogelators drive the formation of assemblies and further transition into hydrogels, while bioactive epitopes modulate cell-cell and cell-ECM interactions. Therefore, SPHs can support cell growth, making them ideal biomaterials for ECM mimics. This Review outlines the classical molecular design of SPHs from hydrogelators to functional epitopes and summarizes the recent advancements of SPHs as artificial ECMs in nervous system repair, wound healing, bone and cartilage regeneration, and organoid culture. This emerging SPH platform could provide an alternative strategy for developing more effective biomaterials for tissue engineering.

Unraveling Macrophage Polarization: Functions, Mechanisms, and "Double-Edged Sword" Roles in Host Antiviral Immune Responses

Numerous viruses that propagate through the respiratory tract may be initially engulfed by macrophages (Mφs) within the alveoli, where they complete their first replication cycle and subsequently infect the adjacent epithelial cells. This process can lead to significant pathological damage to tissues and organs, leading to various diseases. As essential components in host antiviral immune systems, Mφs can be polarized into pro-inflammatory M1 Mφs or anti-inflammatory M2 Mφs, a process involving multiple signaling pathways and molecular mechanisms that yield diverse phenotypic and functional features in response to various stimuli. In general, when infected by a virus, M1 macrophages secrete pro-inflammatory cytokines to play an antiviral role, while M2 macrophages play an anti-inflammatory role to promote the replication of the virus. However, recent studies have shown that some viruses may exhibit the opposite trend. Viruses have evolved various strategies to disrupt Mφ polarization for efficient replication and transmission. Notably, various factors, such as mechanical softness, the altered pH value of the endolysosomal system, and the homeostasis between M1/M2 Mφs populations, contribute to crucial events in the viral replication cycle. Here, we summarize the regulation of Mφ polarization, virus-induced alterations in Mφ polarization, and the antiviral mechanisms associated with these changes. Collectively, this review provides insights into recent advances regarding Mφ polarization in host antiviral immune responses, which will contribute to the development of precise prevention strategies as well as management approaches to disease incidence and transmission.

Irilin D suppresses RANKL-induced osteoclastogenesis and prevents inflammation-induced bone loss by disrupting the NF-κB and MAPK signaling pathways

Excessive activity of osteoclasts(OCs) lead to bone resorption in chronic inflammatory conditions. The use of natural compounds to target OCs offers significant promise in the treatment or prevention of OC-associated diseases. Irilin D (IRD), a natural isoflavone derived from Belamcanda chinensis (L.) DC., has potential effects on OC differentiation both in vitro and in vivo that have yet to be thoroughly explored. In our study, we found that IRD inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced OC differentiation, actin ring formation, and bone resorption in vitro without compromising cell viability. However, IRD did not exhibit anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated macrophages. Furthermore, IRD reduced LPS-induced inflammatory bone loss by blocking osteoclastogenesis in a mouse model. Mechanistically, IRD disrupted RANKL-induced activation of mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB), leading to the inhibition of c-Fos and nuclear factor of activated T cells cytoplasmic 1 (NFATc1) activation. We also demonstrated that IRD inhibited RANKL-induced osteoclastic NFATc1 target genes, including DC-STAMP, ACP5, and CtsK. Our results indicate that IRD mitigates LPS-induced inflammatory bone resorption in mice by inhibiting RANKL-activated MAPKs and NF-κB signaling pathways, suggesting its potential as a natural isoflavone for preventing or treating OC-associated diseases.

Zoledronic acid relieves steroid-induced avascular necrosis of femoral head via inhibiting FOXD3 mediated ANXA2 transcriptional activation

BACKGROUND

Zoledronic acid (ZOL) is a type of bisphosphonate with good therapeutic effects on orthopaedic diseases. However, the pharmacological functions of ZOL on steroid-induced avascular necrosis of femoral head (SANFH) and the underlying mechanism remain unclear, which deserve further research.

METHODS

SANFH models both in vivo and in vitro were established by dexamethasone (Dex) stimulation. Osteoclastogenesis was examined by TRAP staining. Immunofluorescence was employed to examine autophagy marker (LC3) level. Cell apoptosis was analyzed by TUNEL staining. The interaction between Foxhead box D3 protein (FOXD3) and Annexin A2 (ANXA2) promoter was analyzed using ChIP and dual luciferase reporter gene assays.

RESULTS

Dex aggravated osteoclastogenesis and induced osteoclast differentiation and autophagy in vitro, which was abrogated by ZOL treatment. PI3K inhibitor LY294002 abolished the inhibitory effect of ZOL on Dex-induced osteoclast differentiation and autophagy. FOXD3 overexpression neutralized the downregulation effects of ZOL on Dex-induced osteoclasts by transcriptionally activating ANXA2. ANXA2 knockdown reversed the effect of FOXD3 overexpression on ZOL-mediated biological effects in Dex-treated osteoclasts. In addition, ZOL improved SANFH symptoms in rats.

CONCLUSION

ZOL alleviated SANFH through regulating FOXD3 mediated ANXA2 transcriptional activity and then promoting PI3K/AKT/mTOR pathway, revealing that FOXD3 might be a target for ZOL in SANFH treatment.

Bone Destruction-Chemotactic Osteoprogenitor Cells Deliver Liposome Nanomedicines for the Treatment of Osteosarcoma and Osteoporosis

Therapeutic efficacy of skeletal diseases is usually limited by unfavorable drug delivery due to incapable bone targeting and low bone affinity of conventional drug carriers, as well as relatively reduced vascularization and dense structure of bone tissues. Due to CXC chemokine receptor 4 (CXCR4)/CXC chemokine ligand 12 (CXCL12) signal axis-guided recruitment, osteoprogenitor cells (OPCs) can actively migrate to bone disease nidus. Here, drugs-loaded nanoliposomes are prepared and decorated onto OPCs by biotin-streptavidin linkage for precise bone disease targeting and effective drug delivery. In mouse models of tibia defect and orthotopic osteosarcoma, superior targeting property of OPCs-based drug delivery systems toward diseased bone niduses is verified. By encapsulating antitumor and antiosteoporosis drugs into nanoliposomes, OPCs-based drug delivery systems effectively inhibit disease development and restore bone destruction in mouse models of orthotopic osteosarcoma and ovariectomized osteoporosis. This study reveals a cell-based drug delivery system for precise bone disease targeting and highly effective drug delivery, which will find great potential as a universal drug delivery platform for targeting treatment of various bone diseases.

Autophagy Regulator Rufy 4 Promotes Osteoclastic Bone Resorption by Orchestrating Cytoskeletal Organization via Its RUN Domain

Rufy4, a protein belonging to the RUN and FYVE domain-containing protein family, participates in various cellular processes such as autophagy and intracellular trafficking. However, its role in osteoclast-mediated bone resorption remains uncertain. In this study, we investigated the expression and role of the Rufy4 gene in osteoclasts using small interfering RNA (siRNA) transfection and gene overexpression systems. Our findings revealed a significant increase in Rufy4 expression during osteoclast differentiation. Silencing Rufy4 enhanced osteoclast differentiation, intracellular cathepsin K levels, and formation of axial protrusive structures but suppressed bone resorption. Conversely, overexpressing wild-type Rufy4 in osteoclasts hindered differentiation while promoting podosome formation and bone resorption. Similarly, overexpression of a Rufy4 variant lacking the RUN domain mimics the effects of Rufy4 knockdown, significantly increasing intracellular cathepsin K levels, promoting osteoclastogenesis, and elongated axial protrusions formation, yet inhibiting bone resorption. These findings indicate that Rufy4 plays a critical role in osteoclast differentiation and bone resorption by regulating the cytoskeletal organization through its RUN domain. Our study provides new insights into the molecular mechanisms governing osteoclast activity and underscores Rufy4's potential as a novel therapeutic target for bone disorders characterized by excessive bone resorption.

A novel framework for elucidating the effect of mechanical loading on the geometry of ovariectomized mouse tibiae using principal component analysis

Introduction

Murine models are used to test the effect of anti-osteoporosis treatments as they replicate some of the bone phenotypes observed in osteoporotic (OP) patients. The effect of disease and treatment is typically described as changes in bone geometry and microstructure over time. Conventional assessment of geometric changes relies on morphometric scalar parameters. However, being correlated with each other, these parameters do not describe separate fractions of variations and offer only a moderate insight into temporal changes.

Methods

The current study proposes a novel image-based framework that employs deformable image registration on in vivo longitudinal images of bones and Principal Component Analysis (PCA) for improved quantification of geometric effects of OP treatments. This PCA-based model and a novel post-processing of score changes provide orthogonal modes of shape variations temporally induced by a course of treatment (specifically in vivo mechanical loading).

Results and Discussion

Errors associated with the proposed framework are rigorously quantified and it is shown that the accuracy of deformable image registration in capturing the bone shapes (∼1 voxel = 10.4 μm) is of the same order of magnitude as the relevant state-of-the-art evaluation studies. Applying the framework to longitudinal image data from the midshaft section of ovariectomized mouse tibia, two mutually orthogonal mode shapes are reliably identified to be an effect of treatment. The mode shapes captured changes of the tibia geometry due to the treatment at the anterior crest (maximum of 0.103 mm) and across the tibia midshaft section and the posterior (0.030 mm) and medial (0.024 mm) aspects. These changes agree with those reported previously but are now described in a compact fashion, as a vector field of displacements on the bone surface. The proposed framework enables a more detailed investigation of the effect of disease and treatment on bones in preclinical studies and boosts the precision of such assessments.

Modulation of NRF2/KEAP1 Signaling by Phytotherapeutics in Periodontitis

Periodontitis affects up to 40% of adults over 60 years old and is a consequence of gingivitis. Periodontitis is characterized by a chronic inflammation, periodontal damage, and alveolar bone resorption. The nuclear factor erythroid 2-related factor 2 (NFE2L2 or NRF2)/Kelch-like ECH-Associated Protein 1 (KEAP1) (NRF2/KEAP1) signaling pathway plays a key role in periodontitis by modulating redox balance and inflammation of the periodontium. However, NRF2 expression is decreased in gingival tissues of patients with periodontitis while oxidative stress is significantly increased in this pathology. Oxidative stress and lipopolysaccharide (LPS) produced by gram-negative bacteria favor the production of inflammatory causing periodontal inflammation and favoring alveolar bone. In this review, we analyzed the current literature regarding the role of natural and synthetic compounds in modulating the NRF2/KEAP1 pathway in in vitro and in vivo models of periodontitis in order to evaluate new potential treatments of periodontitis that can improve the outcome of this disease.

Synthesis and Antiosteoporotic Characterization of Diselenyl Maleimides: Discovery of a Potent Agent for the Treatment of Osteoporosis by Targeting RANKL

To discover new osteoclast-targeting antiosteoporosis agents, we identified forty-six diselenyl maleimides, which were efficiently prepared using a novel, simple, and metal-free method at room temperature in a short reaction time. Among them, 3k showed the most marked inhibition of osteoclast differentiation with an IC50 value of 0.36 ± 0.03 μM. Moreover, 3k significantly suppressed RANKL-induced osteoclast formation, bone resorption, and osteoclast-specific genes expression in vitro. Mechanistic studies revealed that 3k remarkably blocked the RANKL-induced mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways. In ovariectomized mice, intragastric administration of 3k significantly alleviated bone loss, exhibiting an effect similar to that of alendronate. Surface plasmon resonance assay and microscale thermophoresis assay results suggested that RANKL might be a potential molecular target for 3k. Collectively, the findings presented above provided a novel candidate for further development of bone antiresorptive drugs that target RANKL.

Melatonin's protective role against Bisphenol F and S-induced skeletal damage: A morphometric and histological study in rat

This study aimed to evaluate the potential effects of Bisphenol F and S exposure on the skeletal structures of Sprague-Dawley rats. Given the increasing concern about the potential endocrine-disrupting effects of Bisphenol analogs on bone health, this research sought to elucidate their impact in conjunction with Melatonin. Using 80 male Sprague Dawley rats, bones were subjected to a 3-point bending test to assess mechanical properties, and histopathological evaluation was conducted after fixation and decalcification. Statistical analysis was performed using SPSS. The results of the mechanical tests revealed significant differences in deformation and elastic modulus values between groups treated with Bisphenol F+Melatonin and Bisphenol S+Melatonin compared to the control groups. However, the histological images showed no significant differences between the groups. In the discussion, it was noted that the injection of Bisphenol F and Melatonin together increased bone hardness, suggesting that Bisphenol F and Bisphenol S may mitigate the negative effects of melatonin on bone. We attributed the absence of histological differences to the male gender of the studied rats and previous exposure considerations. This study shows that Melatonin can reduce Bisphenol F and Bisphenol S' rapid adjustment effects and increase bone elasticity. The side effects of Bisphenol F and S, as well as the prophylactic effects of Melatonin, can be observed and improved by carefully adjusting the duration, dose, and gender selection.

IGF signaling pathway in bone and cartilage development, homeostasis, and disease

The skeleton plays a fundamental role in the maintenance of organ function and daily activities. The insulin-like growth factor (IGF) family is a group of polypeptide substances with a pronounced role in osteoblast differentiation, bone development, and metabolism. Disturbance of the IGFs and the IGF signaling pathway is inextricably linked with assorted developmental defects, growth irregularities, and jeopardized skeletal structure. Recent findings have illustrated the significance of the action of the IGF signaling pathway via growth factors and receptors and its interactions with dissimilar signaling pathways (Wnt/β-catenin, BMP, TGF-β, and Hh/PTH signaling pathways) in promoting the growth, survival, and differentiation of osteoblasts. IGF signaling also exhibits profound influences on cartilage and bone development and skeletal homeostasis via versatile cell-cell interactions in an autocrine, paracrine, and endocrine manner systemically and locally. Our review summarizes the role and regulatory function as well as a potentially integrated gene network of the IGF signaling pathway with other signaling pathways in bone and cartilage development and skeletal homeostasis, which in turn provides an enlightening insight into visualizing bright molecular targets to be eligible for designing effective drugs to handle bone diseases and maladies, such as osteoporosis, osteoarthritis, and dwarfism.

Bone targeted nano-drug and nano-delivery

There are currently no targeted delivery systems to satisfactorily treat bone-related disorders. Many clinical drugs consisting of small organic molecules have a short circulation half-life and do not effectively reach the diseased tissue site. This coupled with repeatedly high dose usage that leads to severe side effects. With the advance in nanotechnology, drugs contained within a nano-delivery device or drugs aggregated into nanoparticles (nano-drugs) have shown promises in targeted drug delivery. The ability to design nanoparticles to target bone has attracted many researchers to develop new systems for treating bone related diseases and even repurposing current drug therapies. In this review, we shall summarise the latest progress in this area and present a perspective for future development in the field. We will focus on calcium-based nanoparticle systems that modulate calcium metabolism and consequently, the bone microenvironment to inhibit disease progression (including cancer). We shall also review the bone affinity drug family, bisphosphonates, as both a nano-drug and nano-delivery system for bone targeted therapy. The ability to target and release the drug in a controlled manner at the disease site represents a promising safe therapy to treat bone diseases in the future.

Melatonin Regulates Osteoblast Differentiation through the m6A Reader hnRNPA2B1 under Simulated Microgravity

Recent studies have confirmed that melatonin and N6-methyladenosine (m6A) modification can influence bone cell differentiation and bone formation. Melatonin can also regulate a variety of biological processes through m6A modification. Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1) serves as a reader of m6A modification. In this study, we used the hindlimb unloading model as an animal model of bone loss induced by simulated microgravity and used 2D clinorotation to simulate a microgravity environment for cells on the ground. We found that hnRNPA2B1 was downregulated both in vitro and in vivo during simulated microgravity. Further investigations showed that hnRNPA2B1 could promote osteoblast differentiation and that overexpression of hnRNPA2B1 attenuated the suppression of osteoblast differentiation induced by simulated microgravity. We also discovered that melatonin could promote the expression of hnRNPA2B1 under simulated microgravity. Moreover, we found that promotion of osteoblast differentiation by melatonin was partially dependent on hnRNPA2B1. Therefore, this research revealed, for the first time, the role of the melatonin/hnRNPA2B1 axis in osteoblast differentiation under simulated microgravity. Targeting this axis may be a potential protective strategy against microgravity-induced bone loss and osteoporosis.

Osteogenic differentiation of periodontal ligament fibroblasts inhibits osteoclast formation

One of the deficits of knowledge on bone remodelling, is to what extent cells that are driven towards osteogenic differentiation can contribute to osteoclast formation. The periodontal ligament fibroblast (PdLFs) is an ideal model to study this, since they play a role in osteogenesis, and can also orchestrate osteoclastogenesis.when co-cultured with a source of osteoclast-precursor such as peripheral blood mononuclear cells (PBMCs). Here, the osteogenic differentiation of PdLFs and the effects of this process on the formation of osteoclasts were investigated. PdLFs were obtained from extracted teeth and exposed to osteogenic medium for 0, 7, 14, or 21 out of 21 days. After this 21-day culturing period, the cells were co-cultured with peripheral blood mononuclear cells (PBMCs) for an additional 21 days to study osteoclast formation. Alkaline phosphatase (ALP) activity, calcium concentration, and gene expression of osteogenic markers were assessed at day 21 to evaluate the different stages of osteogenic differentiation. Alizarin red staining and scanning electron microscopy were used to visualise mineralisation. Tartrate-resistant acid phosphatase (TRAcP) activity, TRAcP staining, multinuclearity, the expression of osteoclastogenesis-related genes, and TNF-α and IL-1β protein levels were assessed to evaluate osteoclastogenesis. The osteogenesis assays revealed that PdLFs became more differentiated as they were exposed to osteogenic medium for a longer period of time. Mineralisation by these osteogenic cells increased with the progression of differentiation. Culturing PdLFs in osteogenic medium before co-culturing them with PMBCs led to a significant decrease in osteoclast formation. qPCR revealed significantly lower DCSTAMP expression in cultures that had been supplemented with osteogenic medium. Protein levels of osteoclastogenesis stimulator TNF-α were also lower in these cultures. The present study shows that the osteogenic differentiation of PdLFs reduces the osteoclastogenic potential of these cells. Immature cells of the osteoblastic lineage may facilitate osteoclastogenesis, whereas mature mineralising cells may suppress the formation of osteoclasts. Therefore, mature and immature osteogenic cells may have different roles in maintaining bone homeostasis.

Active fraction of Polyrhachis vicina (Rogers) inhibits osteoclastogenesis by targeting Trim38 mediated proteasomal degradation of TRAF6

BACKGROUND

Reactive Oxygen Species (ROS) is a key factor in the pathogenesis of osteoporosis (OP) primarily characterized by excessive osteoclast activity. Active fraction of Polyrhachis vicina Rogers (AFPR) exerts antioxidant effects and possesses extensive promising therapeutic effects in various conditions, however, its function in osteoclastogenesis and OP is unknown.

PURPOSE

The aim of this study is to elucidate the cellular and molecular mechanisms of AFPR in OP.

STUDY DESIGN AND METHODS

CCK8 assay was used to evaluate the cell viability under AFPR treatment. TRAcP staining, podosome belts staining and bone resorption were used to test the effect of AFPR on osteoclastogenesis. Immunofluorescence staining was used to observe the effect of AFPR on ROS production. si-RNA transfection, coimmunoprecipitation and Western-blot were used to clarify the underlying mechanisms. Further, an ovariectomy (OVX) -induced OP mice model was used to identify the effect of AFPR on bone loss using Micro-CT scanning and histological examination.

RESULTS

In the present study, AFPR inhibited osteoclast differentiation and bone resorption induced by nuclear factor-κB receptor activator (NF-κB) ligand (RANKL) in dose-/ time-dependent with no cytotoxicity. Meanwhile, AFPR decreased RANKL-mediated ROS levels and enhanced ROS scavenging enzymes. Mechanistically, AFPR promoted proteasomal degradation of TRAF6 by significantly upregulating its K48-linked ubiquitination, subsequently inhibiting NFATc1 activity. We further observed that tripartite motif protein 38 (TRIM38) could mediate the ubiquitination of TRAF6 in response to RANKL. Moreover, TRIM38 could negatively regulate the RANKL pathway by binding to TRAF6 and promoting K48-linked polyubiquitination. In addition, TRIM38 deficiency rescued the inhibition of AFPR on ROS and NFATc1 activity and osteoclastogenesis. In line with these results, AFPR reduced OP caused by OVX through ameliorating osteoclastogenesis.

CONCLUSION

AFPR alleviates ovariectomized-induced bone loss via suppressing ROS and NFATc1 by targeting Trim38 mediated proteasomal degradation of TRAF6. The research offers innovative perspectives on AFPR's suppressive impact in vivo OVX mouse model and in vitro, and clarifies the fundamental mechanism.

Oral microbiome, periodontal disease and systemic bone-related diseases in the era of homeostatic medicine

BACKGROUND

Homeostasis is a state of self-regulation and dynamic equilibrium, maintaining the good physiological functions of each system in living organisms. In the oral cavity, the interaction between the host and the oral microbiome forms oral microbial homeostasis. Physiological bone remodeling and renewal can occur under the maintenance of oral microbial homeostasis. The imbalance of bone homeostasis is a key mechanism leading to the occurrence of systemic bone-related diseases. Considering the importance of oral microbial homeostasis in the maintenance of bone homeostasis, it still lacks a complete understanding of the relationship between oral microbiome, periodontal disease and systemic bone-related diseases.

AIM OF REVIEW

This review focuses on the homeostatic changes, pathogenic routes and potential mechanisms in the oral microbiome in periodontal disease and systemic bone-related diseases such as rheumatoid arthritis, osteoarthritis, osteoporosis and osteomyelitis. Additionally, this review discusses oral microbiome-based diagnostic approaches and explores probiotics, mesenchymal stem cells, and oral microbiome transplantation as promising treatment strategies.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review highlights the association between oral microbial homeostasis imbalance and systemic bone-related diseases, and highlights the possibility of remodeling oral microbial homeostasis for the prevention and treatment of systemic bone-related diseases.

Identification of key genes and long non‑coding RNA expression profiles in osteoporosis with rheumatoid arthritis based on bioinformatics analysis

BACKGROUND

Although rheumatoid arthritis (RA) is a chronic systemic tissue disease often accompanied by osteoporosis (OP), the molecular mechanisms underlying this association remain unclear. This study aimed to elucidate the pathogenesis of RA and OP by identifying differentially expressed mRNAs (DEmRNAs) and long non-coding RNAs (lncRNAs) using a bioinformatics approach.

METHODS

Expression profiles of individuals diagnosed with OP and RA were retrieved from the Gene Expression Omnibus database. Differential expression analysis was conducted. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) pathway enrichment analyses were performed to gain insights into the functional categories and molecular/biochemical pathways associated with DEmRNAs. We identified the intersection of common DEmRNAs and lncRNAs and constructed a protein-protein interaction (PPI) network. Correlation analysis between the common DEmRNAs and lncRNAs facilitated the construction of a coding-non-coding network. Lastly, serum peripheral blood mononuclear cells (PBMCs) from patients with RA and OP, as well as healthy controls, were obtained for TRAP staining and qRT-PCR to validate the findings obtained from the online dataset assessments.

RESULTS

A total of 28 DEmRNAs and 2 DElncRNAs were identified in individuals with both RA and OP. Chromosomal distribution analysis of the consensus DEmRNAs revealed that chromosome 1 had the highest number of differential expression genes. GO and KEGG analyses indicated that these DEmRNAs were primarily associated with " platelets (PLTs) degranulation", "platelet alpha granules", "platelet activation", "tight junctions" and "leukocyte transendothelial migration", with many genes functionally related to PLTs. In the PPI network, MT-ATP6 and PTGS1 emerged as potential hub genes, with MT-ATP6 originating from mitochondrial DNA. Co-expression analysis identified two key lncRNA-mRNA pairs: RP11 - 815J21.2 with MT - ATP6 and RP11 - 815J21.2 with PTGS1. Experimental validation confirmed significant differential expression of RP11-815J21.2, MT-ATP6 and PTGS1 between the healthy controls and the RA + OP groups. Notably, knockdown of RP11-815J21.2 attenuated TNF + IL-6-induced osteoclastogenesis.

CONCLUSIONS

This study successfully identified shared dysregulated genes and potential therapeutic targets in individuals with RA and OP, highlighting their molecular similarities. These findings provide new insights into the pathogenesis of RA and OP and suggest potential avenues for further research and targeted therapies.

Sirt1: An Increasingly Interesting Molecule with a Potential Role in Bone Metabolism and Osteoporosis

Osteoporosis (OP) is a common metabolic bone disease characterized by low bone mass, decreased bone mineral density, and degradation of bone tissue microarchitecture. However, our understanding of the mechanisms of bone remodeling and factors affecting bone mass remains incomplete. Sirtuin1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase that regulates a variety of cellular metabolisms, including inflammation, tumorigenesis, and bone metabolism. Recent studies have emphasized the important role of SIRT1 in bone homeostasis. This article reviews the role of SIRT1 in bone metabolism and OP and also discusses therapeutic strategies and future research directions for targeting SIRT1.

Zoledronic Acid and Enriched Autologous Bone Marrow Stem Cell Implantation for Femoral Head Osteonecrosis

Purpose

This study evaluated the clinical results of zoledronic acid in the treatment of early osteonecrosis of the femoral head (ONFH).

Materials and Methods

Study retrospectively analyzed 60 patients with zoledronic acid with bone marrow stem cell (BMSC) implantation (The study group) and 64 patients with BMSC implantation (The control group). The primary evaluation index included VAS, HHS, collapsed rate, and total hip replacement arthroplasty (THA) conversion rate.

Results

The study group had a lower VAS (1.12 ± 0.22 vs 1.44 ± 0.32) and higher HHS (75.07 ± 3.66 vs 68.78 ± 2.24) compared to the control group in 6 months after surgery (P < 0.05). In the study group, 12 hips (20%) collapsed, and 7 of 60 hips (11.67%) required THA surgery at the last follow-up. However, 25 hips (38.8%) collapsed in the control group, and 19 hips (29.69%) required THA surgery. The study group had a lower collapsed rate (P = 0.029) and THA conversion rate (P = 0.016) in survival analysis.

Conclusion

Zoledronic acid and BMSC implantation in the treatment of early ONFH is safe and effective, reduces pain shortens recovery time, and reduces collapsed rate and THA conversion rate in ONFH patients.

Delivering Microrobots in the Musculoskeletal System

Disorders of the musculoskeletal system are the major contributors to the global burden of disease and current treatments show limited efficacy. Patients often suffer chronic pain and might eventually have to undergo end-stage surgery. Therefore, future treatments should focus on early detection and intervention of regional lesions. Microrobots have been gradually used in organisms due to their advantages of intelligent, precise and minimally invasive targeted delivery. Through the combination of control and imaging systems, microrobots with good biosafety can be delivered to the desired area for treatment. In the musculoskeletal system, microrobots are mainly utilized to transport stem cells/drugs or to remove hazardous substances from the body. Compared to traditional biomaterial and tissue engineering strategies, active motion improves the efficiency and penetration of local targeting of cells/drugs. This review discusses the frontier applications of microrobotic systems in different tissues of the musculoskeletal system. We summarize the challenges and barriers that hinder clinical translation by evaluating the characteristics of different microrobots and finally point out the future direction of microrobots in the musculoskeletal system.

Harnessing cerium-based biomaterials for the treatment of bone diseases

Bone, an actively metabolic organ, undergoes constant remodeling throughout life. Disturbances in the bone microenvironment can be responsible for pathologically bone diseases such as periodontitis, osteoarthritis, rheumatoid arthritis and osteoporosis. Conventional bone tissue biomaterials are not adequately adapted to complex bone microenvironment. Therefore, there is an urgent clinical need to find an effective strategy to improve the status quo. In recent years, nanotechnology has caused a revolution in biomedicine. Cerium(III, IV) oxide, as an important member of metal oxide nanomaterials, has dual redox properties through reversible binding with oxygen atoms, which continuously cycle between Ce(III) and Ce(IV). Due to its special physicochemical properties, cerium(III, IV) oxide has received widespread attention as a versatile nanomaterial, especially in bone diseases. This review describes the characteristics of bone microenvironment. The enzyme-like properties and biosafety of cerium(III, IV) oxide are also emphasized. Meanwhile, we summarizes controllable synthesis of cerium(III, IV) oxide with different nanostructural morphologies. Following resolution of synthetic principles of cerium(III, IV) oxide, a variety of tailored cerium-based biomaterials have been widely developed, including bioactive glasses, scaffolds, nanomembranes, coatings, and nanocomposites. Furthermore, we highlight the latest advances in cerium-based biomaterials for inflammatory and metabolic bone diseases and bone-related tumors. Tailored cerium-based biomaterials have already demonstrated their value in disease prevention, diagnosis (imaging and biosensors) and treatment. Therefore, it is important to assist in bone disease management by clarifying tailored properties of cerium(III, IV) oxide in order to promote the use of cerium-based biomaterials in the future clinical setting. STATEMENT OF SIGNIFICANCE: In this review, we focused on the promising of cerium-based biomaterials for bone diseases. We reviewed the key role of bone microenvironment in bone diseases and the main biological activities of cerium(III, IV) oxide. By setting different synthesis conditions, cerium(III, IV) oxide nanostructures with different morphologies can be controlled. Meanwhile, tailored cerium-based biomaterials can serve as a versatile toolbox (e.g., bioactive glasses, scaffolds, nanofibrous membranes, coatings, and nanocomposites). Then, the latest research advances based on cerium-based biomaterials for the treatment of bone diseases were also highlighted. Most importantly, we analyzed the perspectives and challenges of cerium-based biomaterials. In future perspectives, this insight has given rise to a cascade of cerium-based biomaterial strategies, including disease prevention, diagnosis (imaging and biosensors) and treatment.

Bone mineral density parameters and related nutritional factors in vegans, lacto-ovo-vegetarians, and omnivores: a cross-sectional study

Introduction

The growing prevalence of vegetarianism determines the need for comprehensive study of the impact of these diets on health and particularly on bone metabolism. We hypothesized that significant dietary differences between vegans, lacto-ovo-vegetarians, and omnivores also cause significant differences in their nutrient status, which may affect bone health.

Methods

The study assessed dual-energy X-ray absorptiometry parameters in lumbar spine and femoral neck, average nutrient intake, serum nutrient concentrations, serum PTH levels, and urinary pH among 46 vegans, 38 lacto-ovo-vegetarians, and 44 omnivores.

Results

There were no differences in bone mineral density (BMD) between the groups. However, the parathyroid hormone (PTH) levels were still higher in vegans compared to omnivores, despite the same prevalence of hyperparathyroidism in all groups. These findings may probably be explained by the fact that each group had its own "strengths and weaknesses." Thus, vegans and, to a lesser extent, lacto-ovo-vegetarians consumed much more potassium, magnesium, copper, manganese, and vitamins B6, B9, and C. At the same time, the diet of omnivores contained more protein and vitamins D and B12. All the subjects consumed less vitamin D than recommended. More than half of vegans and omnivores had insufficiency or even deficiency of vitamin D in the blood. Low serum concentrations of manganese with its quite adequate intake are also noteworthy: its deficiency was observed in 57% of vegans, 79% of lacto-ovo-vegetarians, and 63% of omnivores.

Discussion

Currently, it is no longer possible to conclude that lacto-ovo-vegetarians have lower BMD than omnivores, as our research supported. Vegans in our study also did not demonstrate lower BMD values, only higher PTH blood concentrations, compared to omnivores, however, a large number of studies, including recent, show the opposite view. In this regard, further large-scale research is required. Vegans and lacto-ovo-vegetarians now have a variety of foods fortified with vitamins D and B12, as well as calcium. There is also a great diversity of ethically sourced dietary supplements. The found low concentrations of manganese require further investigation.

New evidence on the controversy over the correlation between vertebral osteoporosis and intervertebral disc degeneration: a systematic review of relevant animal studies

OBJECTIVE

The effect of vertebral osteoporosis on disc degeneration remains controversial. The aim of this study was to conduct a systematic review and meta-analysis of relevant animal studies to shed more light on the effects and mechanisms of vertebral osteoporosis on disc degeneration and to promote the resolution of the controversy.

METHODS

The PubMed, Cochrane Library, and Embase databases were searched for studies that met the inclusion criteria. Basic information and data were extracted from the included studies and data were analyzed using STATA 15.1 software. This study was registered on INPLASY with the registration number INPLASY202370099 and https://doi.org/10.37766/inplasy2023.7.0099 .

RESULTS

A total of 13 studies were included in our study. Both animals, rats and mice, were covered. Meta-analysis results showed in disc height index (DHI) (P < 0.001), histological score (P < 0.001), number of osteoblasts in the endplate (P = 0.043), number of osteoclasts in the endplate (P < 0.001), type I collagen (P < 0.001), type II collagen (P < 0.001), aggrecan (P < 0.001), recombinant a disintegrin and metalloproteinase with thrombospondin-4 (ADAMTS-4) (P < 0.001), matrix metalloproteinase-1 (MMP-1) (P < 0.001), MMP-3 (P < 0.001), MMP-13 (P < 0.001), the difference between the osteoporosis group and the control group was statistically significant. In terms of disc volume, the difference between the osteoporosis group and the control group was not statistically significant (P = 0.459).

CONCLUSION

Our study shows that vertebral osteoporosis may exacerbate disc degeneration. Abnormal bone remodeling caused by vertebral osteoporosis disrupts the structural integrity of the endplate, leading to impaired nutrient supply to the disc, increased expression of catabolic factors, and decreased levels of type II collagen and aggrecan may be one of the potential mechanisms.

Isobavachin attenuates osteoclastogenesis and periodontitis-induced bone loss by inhibiting cellular iron accumulation and mitochondrial biogenesis

As bone-resorbing cells rich in mitochondria, osteoclasts require high iron uptake to promote mitochondrial biogenesis and maintain a high-energy metabolic state for active bone resorption. Given that abnormal osteoclast formation and activation leads to imbalanced bone remodeling and osteolytic bone loss, osteoclasts may be crucial targets for treating osteolytic diseases such as periodontitis. Isobavachin (IBA), a natural flavonoid compound, has been confirmed to be an inhibitor of receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs). However, its effects on periodontitis-induced bone loss and the potential mechanism of its anti-osteoclastogenesis effect remain unclear. Our study demonstrated that IBA suppressed RANKL-induced osteoclastogenesis in BMMs and RAW264.7 cells and inhibited osteoclast-mediated bone resorption in vitro. Transcriptomic analysis indicated that iron homeostasis and reactive oxygen species (ROS) metabolic process were enriched among the differentially expressed genes following IBA treatment. IBA exerted its anti-osteoclastogenesis effect by inhibiting iron accumulation in osteoclasts. Mechanistically, IBA attenuated iron accumulation in RANKL-induced osteoclasts by inhibiting the mitogen-activated protein kinase (MAPK) pathway to upregulate ferroportin1 (Fpn1) expression and promote Fpn1-mediated intracellular iron efflux. We also found that IBA inhibited mitochondrial biogenesis and function, and reduced RANKL-induced ROS generation in osteoclasts. Furthermore, IBA attenuated periodontitis-induced bone loss by reducing osteoclastogenesis in vivo. Overall, these results suggest that IBA may serve as a promising therapeutic strategy for bone diseases characterized by osteoclastic bone resorption.

Engineering approaches to manipulate osteoclast behavior for bone regeneration

Extensive research has delved into the multifaceted roles of osteoclasts beyond their traditional function in bone resorption in recent years, uncovering their significant influence on bone formation. This shift in understanding has spurred investigations into engineering strategies aimed at leveraging osteoclasts to not only inhibit bone resorption but also facilitate bone regeneration. This review seeks to comprehensively examine the mechanisms by which osteoclasts impact bone metabolism. Additionally, it explores various engineering methodologies, including the modification of bioactive material properties, localized drug delivery, and the introduction of exogenous cells, assessing their potential and mechanisms in aiding bone repair by targeting osteoclasts. Finally, the review proposes current limitations and future routes for manipulating osteoclasts through biological and material cues to facilitate bone repair.

RUFY4 deletion prevents pathological bone loss by blocking endo-lysosomal trafficking of osteoclasts

Mature osteoclasts degrade bone matrix by exocytosis of active proteases from secretory lysosomes through a ruffled border. However, the molecular mechanisms underlying lysosomal trafficking and secretion in osteoclasts remain largely unknown. Here, we show with GeneChip analysis that RUN and FYVE domain-containing protein 4 (RUFY4) is strongly upregulated during osteoclastogenesis. Mice lacking Rufy4 exhibited a high trabecular bone mass phenotype with abnormalities in osteoclast function in vivo. Furthermore, deleting Rufy4 did not affect osteoclast differentiation, but inhibited bone-resorbing activity due to disruption in the acidic maturation of secondary lysosomes, their trafficking to the membrane, and their secretion of cathepsin K into the extracellular space. Mechanistically, RUFY4 promotes late endosome-lysosome fusion by acting as an adaptor protein between Rab7 on late endosomes and LAMP2 on primary lysosomes. Consequently, Rufy4-deficient mice were highly protected from lipopolysaccharide- and ovariectomy-induced bone loss. Thus, RUFY4 plays as a new regulator in osteoclast activity by mediating endo-lysosomal trafficking and have a potential to be specific target for therapies against bone-loss diseases such as osteoporosis.