Orthosilicic Acid Accelerates Bone Formation in Human Osteoblast-Like Cells Through the PI3K-Akt-mTOR Pathway

The potential therapeutic role of curcumin in osteoporosis treatment: based on multiple signaling pathways

Osteoporosis is a common chronic metabolic bone disease caused by disturbances in normal bone metabolism and an imbalance between osteoblasts and osteoclasts. Osteoporosis is characterized by a decrease in bone mass and bone density, leading to increased bone fragility. Osteoporosis is usually treated with medications and surgical methods, but these methods often produce certain side effects. Therefore, the use of traditional herbal ingredients for the treatment of osteoporosis has become a focus of attention and a hot topic in recent years. Curcumin, widely distributed among herbs such as turmeric, tulip, and curcuma longa, contains phenolic, terpenoid, and flavonoid components. Modern pharmacological studies have confirmed that curcumin has a variety of functions including antioxidant and anti-inflammatory properties. In addition, curcumin positively regulates the differentiation and promotes the proliferation of osteoblasts, which play a crucial role in bone formation. Multiple studies have shown that curcumin is effective in the treatment of osteoporosis as it interacts with a variety of signaling pathway targets, thereby interfering with the formation of osteoblasts and osteoclasts and regulating the development of osteoporosis. This review summarized the key signaling pathways and their mechanisms of action of curcumin in the prevention and treatment of osteoporosis and analyzed their characteristics and their relationship with osteoporosis and curcumin. This not only proves the medicinal value of curcumin as a traditional herbal ingredient but also further elucidates the molecular mechanism of curcumin's anti-osteoporosis effect, providing new perspectives for the prevention and treatment of osteoporosis through multiple pathways.

PI3K/AKT/mTOR signaling regulates BCP ceramic-induced osteogenesis

An increasing number of studies demonstrate that biphasic calcium phosphate (BCP) ceramics can induce bone regeneration. However, the underlying molecular mechanisms involved are still poorly understood. This work was proposed to investigate how PI3K/AKT/mTOR signaling influenced the osteogenesis mediated by BCP ceramics. The results showed that incubation with BCP ceramics promoted the proliferation of murine bone marrow-derived mesenchymal stem cells (BMSCs) in a time-dependent manner. The resulting cell proliferation was then suppressed by the selective inhibition of either PI3K, AKT, or mTOR signaling activation. Next, we confirmed that BCP ceramics up-regulated the phosphorylation levels of AKT and mTOR in BMSCs, suggesting the ability of BCP ceramics to drive the activation of PI3K/AKT/mTOR signaling in BMSCs. Furthermore, the blockade of PI3K/AKT/mTOR signaling prevented BCP ceramics-induced osteogenic differentiation and pro-angiogenesis of BMSCs by down-regulating the expression of genes encoding OPN, RUNX2 or VEGF. Moreover, the PI3K/AKT/mTOR signaling blockade suppressed stem cell infiltration and new bone formation in the implants following intra-muscular implantation of BCP ceramics in mice. Therefore, our results suggested that PI3K/AKT/mTOR signaling played a critical regulatory role in BCP ceramic-induced osteogenesis.

Delivery of miRNAs Using Porous Silicon Nanoparticles Incorporated into 3D Hydrogels Enhances MSC Osteogenesis by Modulation of Fatty Acid Signaling and Silicon Degradation

Strategies incorporating mesenchymal stromal cells (MSC), hydrogels and osteoinductive signals offer promise for bone repair. Osteoinductive signals such as growth factors face challenges in clinical translation due to their high cost, low stability and immunogenicity leading to interest in microRNAs as a simple, inexpensive and powerful alternative. The selection of appropriate miRNA candidates and their efficient delivery must be optimised to make this a reality. This study evaluated pro-osteogenic miRNAs and used porous silicon nanoparticles modified with polyamidoamine dendrimers (PAMAM-pSiNP) to deliver these to MSC encapsulated within gelatin-PEG hydrogels. miR-29b-3p, miR-101-3p and miR-125b-5p are strongly pro-osteogenic and are shown to target FASN and ELOVL4 in the fatty acid biosynthesis pathway to modulate MSC osteogenesis. Hydrogel delivery of miRNA:PAMAM-pSiNP complexes enhanced transfection compared to 2D. The osteogenic potential of hBMSC in hydrogels with miR125b:PAMAM-pSiNP complexes is evaluated. Importantly, a dual-effect on osteogenesis occurred, with miRNAs increasing expression of alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2) whilst the pSiNPs enhanced mineralisation, likely via degradation into silicic acid. Overall, this work presents insights into the role of miRNAs and fatty acid signalling in osteogenesis, providing future targets to improve bone formation and a promising system to enhance bone tissue engineering.

Engineering Large-Scale Self-Mineralizing Bone Organoids with Bone Matrix-Inspired Hydroxyapatite Hybrid Bioinks

Addressing large bone defects remains a significant challenge owing to the inherent limitations in self-healing capabilities, resulting in prolonged recovery and suboptimal regeneration. Although current clinical solutions are available, they have notable shortcomings, necessitating more efficacious approaches to bone regeneration. Organoids derived from stem cells show great potential in this field; however, the development of bone organoids has been hindered by specific demands, including the need for robust mechanical support provided by scaffolds and hybrid extracellular matrices (ECM). In this context, bioprinting technologies have emerged as powerful means of replicating the complex architecture of bone tissue. The research focused on the fabrication of a highly intricate bone ECM analog using a novel bioink composed of gelatin methacrylate/alginate methacrylate/hydroxyapatite (GelMA/AlgMA/HAP). Bioprinted scaffolds facilitate the long-term cultivation and progressive maturation of extensive bioprinted bone organoids, foster multicellular differentiation, and offer valuable insights into the initial stages of bone formation. The intrinsic self-mineralizing quality of the bioink closely emulates the properties of natural bone, empowering organoids with enhanced bone repair for both in vitro and in vivo applications. This trailblazing investigation propels the field of bone tissue engineering and holds significant promise for its translation into practical applications.

Evaluation of layer-by-layer assembly systems for drug delivery and antimicrobial properties in orthopaedic application

Layer-by-layer self-assembly systems were developed using monolayer and multilayer carriers to prevent infections and improve bone regeneration of porous Ti-6Al-4V scaffolds. These polymeric carriers incorporated (Gel/Alg-IGF-1 + Chi-Cef) and (4Gel/Alg-IGF-1 + Chi-Cef) on the surface of porous implants produced via electron beam melting (EBM). The results showed that the drug release from multilayer carriers was higher than that of monolayers after 14 days. However, the carrier containing Gel/Alg-IGF-1 + Chi-Cef exhibited more sustained behavior. Cell morphology was characterized, revealing that multilayer carriers had higher cell adhesion than monolayers. Additionally, cell differentiation was significantly greater for (Gel/Alg-IGF-1) + Chi-Cef, and (4Gel/Alg-IGF-1) + Chi-Cef multilayer carriers than for the monolayer groups after 7 days. Notably, the drug dosage was effective and did not interfere, and the cell viability assay showed safe results. Antibacterial evaluations demonstrated that both multilayer carriers had a greater effect on Staphylococcus aureus during treatment. The carriers containing lower alginate had notably less effect than the other studied carriers. This study aimed to test systems for controlling drug release, which will be applied to improve MG63 cell behavior and prevent bacterial accumulation during orthopaedic applications.

Nodakenin alleviates ovariectomy-induced osteoporosis by modulating osteoblastogenesis and osteoclastogenesis

Osteoporosis, a systemic bone disease defined by decreased bone mass and deterioration of bone microarchitecture, is becoming a global concern. Nodakenin (NK) is a furanocoumarin-like compound isolated from the traditional Chinese medicine Radix Angelicae biseratae (RAB). NK has been reported to have various pharmacological activities, but osteoporosis has not been reported to be affected by NK. In this study, we used network pharmacology, molecular docking and molecular dynamics simulation techniques to identify potential targets and pathways of NK in osteoporosis. We found that NK treatment significantly promoted osteogenic differentiation of BMSCs while activating the PI3K/AKT/mTOR signalling pathway by measuring alkaline phosphatase activity and the expression of various osteogenic markers. In contrast, LY294002, an inhibitor of PI3K, reversed these changes and inhibited the osteogenic differentiation-enabling effect of NK. Meanwhile, prevent the Akt and NFκB signalling pathways by down-regulating c-Src and TRAF6 thereby effectively inhibiting RANKL-induced osteoclastogenesis. In addition, oral administration of NK to mice significantly elevated bone mass and ameliorated ovariectomized (OVX)-mediated bone microarchitectural disorders. In conclusion, these data suggest that NK attenuates OVX-induced bone loss by enhancing osteogenesis and inhibiting osteoclastogenesis.

Recent advances in the application and biological mechanism of silicon nitride osteogenic properties: a review

Silicon nitride, an emerging bioceramic material, is highly sought after in the biomedical industry due to its osteogenesis-promoting properties, which are a result of its unique surface chemistry and excellent mechanical properties. Currently, it is used in clinics as an orthopedic implant material. The osteogenesis-promoting properties of silicon nitride are manifested in its contribution to the formation of a local osteogenic microenvironment, wherein silicon nitride and its hydrolysis products influence osteogenesis by modulating the biological behaviors of the constituents of the osteogenic microenvironment. In particular, silicon nitride regulates redox signaling, cellular autophagy, glycolysis, and bone mineralization in cells involved in bone formation via several mechanisms. Moreover, it may also promote osteogenesis by influencing immune regulation and angiogenesis. In addition, the wettability, surface morphology, and charge of silicon nitride play crucial roles in regulating its osteogenesis-promoting properties. However, as a bioceramic material, the molding process of silicon nitride needs to be optimized, and its osteogenic mechanism must be further investigated. Herein, we summarize the impact of the molding process of silicon nitride on its osteogenic properties and clinical applications. In addition, the mechanisms of silicon nitride in promoting osteogenesis are discussed, followed by a summary of the current gaps in silicon nitride mechanism research. This review, therefore, aims to provide novel ideas for the future development and applications of silicon nitride.

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

mTOR Signaling Pathway in Bone Diseases Associated with Hyperglycemia

The interplay between bone and glucose metabolism has highlighted hyperglycemia as a potential risk factor for bone diseases. With the increasing prevalence of diabetes mellitus worldwide and its subsequent socioeconomic burden, there is a pressing need to develop a better understanding of the molecular mechanisms involved in hyperglycemia-mediated bone metabolism. The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that senses extracellular and intracellular signals to regulate numerous biological processes, including cell growth, proliferation, and differentiation. As mounting evidence suggests the involvement of mTOR in diabetic bone disease, we provide a comprehensive review of its effects on bone diseases associated with hyperglycemia. This review summarizes key findings from basic and clinical studies regarding mTOR's roles in regulating bone formation, bone resorption, inflammatory responses, and bone vascularity in hyperglycemia. It also provides valuable insights into future research directions aimed at developing mTOR-targeted therapies for combating diabetic bone diseases.

Pro-Osteogenic and Anti-Inflammatory Synergistic Effect of Orthosilicic Acid, Vitamin K2, Curcumin, Polydatin and Quercetin Combination in Young and Senescent Bone Marrow-Derived Mesenchymal Stromal Cells

During aging, bone marrow mesenchymal stromal cells (MSCs)-the precursors of osteoblasts-undergo cellular senescence, losing their osteogenic potential and acquiring a pro-inflammatory secretory phenotype. These dysfunctions cause bone loss and lead to osteoporosis. Prevention and intervention at an early stage of bone loss are important, and naturally active compounds could represent a valid help in addition to diet. Here, we tested the hypothesis that the combination of two pro-osteogenic factors, namely orthosilicic acid (OA) and vitamin K2 (VK2), and three other anti-inflammatory compounds, namely curcumin (CUR), polydatin (PD) and quercetin (QCT)-that mirror the nutraceutical BlastiMin Complex^® (Mivell, Italy)-would be effective in promoting MSC osteogenesis, even of replicative senescent cells (sMSCs), and inhibiting their pro-inflammatory phenotype in vitro. Results showed that when used at non-cytotoxic doses, (i) the association of OA and VK2 promoted MSC differentiation into osteoblasts, even when cultured without other pro-differentiating factors; and (ii) CUR, PD and QCT exerted an anti-inflammatory effect on sMSCs, and also synergized with OA and VK2 in promoting the expression of the pivotal osteogenic marker ALP in these cells. Overall, these data suggest a potential role of using a combination of all of these natural compounds as a supplement to prevent or control the progression of age-related osteoporosis.

A study on the anti-osteoporosis mechanism of isopsoralen based on network pharmacology and molecular experiments

OBJECTIVE

Osteoporosis (OP) is a disease caused by multiple factors. Studies have pointed out that isopsoralen (IPRN) is one of the most effective drugs for the treatment of OP. Based on network pharmacological and molecular experimental analysis, the molecular mechanism of IPRN in osteoporosis is clarified.

METHODS

IPRN target genes and OP-related genes were predicted from the databases. Intersections were obtained and visualized. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on target genes, which was confirmed by experiments internal and external experiments. Molecular docking was used to verify the binding between IPRN and target proteins. Molecular dynamics (MD) simulates the binding affinity of protein targets and active compounds.

RESULTS

87 IPRN target genes and 242 disease-related targets were predicted. The protein-protein interaction (PPI) network identified 18 IPRN target proteins for the treatment of OP. GO analysis indicated that target genes were involved in biological processes. KEGG analysis showed that pathways such as PI3K/AKT/mTOR were associated with OP. Cell experiments (qPCR and WB) found that the expressions of PI3K, AKT, and mTOR in MC3T3-E1 cells at 10 μM, 20 μM, and 50 μM IPRN concentrations, especially at 20 μM IPRN treatment, were higher than those in the control group at 48 h. Animal experiments also showed that compared with the control group, 40 mg/kg/time IPRN could promote the expression of the PI3K gene in chondrocytes of SD rats.

CONCLUSIONS

This study predicted the target genes of IPRN in the treatment of OP and preliminarily verified that IPRN plays an anti-OP role through the PI3K/AKT/mTOR pathway, which provides a new drug for the treatment of OP.

Potential Targets and Mechanisms of Jiedu Quyu Ziyin Decoction for Treating SLE-GIOP: Based on Network Pharmacology and Molecular Docking

Background

Systemic lupus erythematosus (SLE) is characterized by poor regulation of the immune response leading to chronic inflammation and multiple organ dysfunction. Glucocorticoid (GC) is currently one of the main treatments. However, a high dose or prolonged use of GC may result in glucocorticoid-induced osteoporosis (GIOP). Jiedu Quyu Ziyin decoction (JP) is effective in treating SLE and previous clinical studies have proved that JP can prevent and treat SLE steroid osteoporosis (SLE-GIOP). We aim to examine JPs main mechanism on SLE-GIOP through network pharmacology and molecular docking.

Methods

TCMSP and TCMID databases were used to screen potential active compounds and targets of JP. The SLE-GIOP targets are collected from GeneCards, OMIM, PharmGkb, TTD, and DrugBank databases. R software was used to obtain the cross-targets of JP and SLE-GIOP and to perform GO and KEGG enrichment analysis. Cytoscape software was used to make the Chinese Medicines-Active Ingredient-Intersection Targets network diagram. STRING database construct protein-protein interaction network and obtain the core targets. Auto Dock Tools and Pymol software were used for docking.

Results

Fifty eight targets overlapped between JP and SLE-GIOP were suggested as potential targets of JP in the treatment of SLE-GIOP. Network topology analysis identified five core targets. GO enrichment analysis was obtained 1,968 items, and the top 10 biological process, closeness centrality, and molecular function were displayed. A total of 154 signaling pathways were obtained by KEGG enrichment analysis, and the top 30 signaling pathways were displayed. JP was well bound by MAPK1, TP53, and MYC according to the molecular docking results.

Conclusion

We investigated the potential targets and signaling pathways of JP against SLE-GIOP in this study. It shows that JP is most likely to achieve the purpose of treating SLE-GIOP by promoting the proliferation and differentiation of osteoblasts. A solid theoretical foundation will be provided for the future study of clinical and experimental topics.

Ortho-silicic Acid Plays a Protective Role in Glucocorticoid-Induced Osteoporosis via the Akt/Bad Signal Pathway In Vitro and In Vivo

Glucocorticoid-induced osteoporosis (GIOP) has been the most common form of secondary osteoporosis. Glucocorticoids (GCs) can induce osteocyte and osteoblast apoptosis. Plenty of research has verified that silicon intake would positively affect bone. However, the effects of silicon on GIOP are not investigated. In this study, we assessed the impact of ortho-silicic acid (OSA) on Dex-induced apoptosis of osteocytes by cell apoptosis assays. The apoptosis-related genes, cleaved-caspase-3, Bcl-2, and Bax, were detected by western blotting. Then, we evaluated the possible role of OSA on osteogenesis and osteoclastogenesis with Dex using Alizarin red staining and tartrate-resistant acid phosphatase (TRAP) staining. We also detected the related genes by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and western blotting. We then established the GIOP mouse model to evaluate the potential role of OSA in vivo. We found that OSA showed no cytotoxic on osteocytes below 50 μM and prevented MLO-Y4 from Dex-induced apoptosis. We also found that OSA promoted osteogenesis and inhibited osteoclastogenesis with Dex. OSA had a protective effect on GIOP mice via the Akt signal pathway in vivo. In the end, we verified the Akt/Bad signal pathway in vitro, which showed the same results. Our finding demonstrated that OSA could protect osteocytes from apoptosis induced by GCs both in vitro and in vivo. Also, it promoted osteogenesis and inhibited osteoclastogenesis with the exitance of Dex. In conclusion, OSA has the potential value as a therapeutic agent for GIOP.

MicroRNA-7a-5p ameliorates diabetic peripheral neuropathy by regulating VDAC1/JNK/c-JUN pathway

AIMS

The pathogenesis of diabetic peripheral neuropathy (DPN) is complex, and its treatment is extremely challenging. MicroRNA-7a-5p (miR-7a-5p) has been widely reported to alleviate apoptosis and oxidative stress in various diseases. This study aimed to investigate the mechanism of miR-7a-5p in DPN.

METHODS

DPN cell model was constructed with high-glucose-induced RSC96 cells. Cell apoptosis and viability were detected by flow cytometry analysis and cell counting kit-8 (CCK-8) assay respectively. The apoptosis and Jun N-terminal kinase (JNK)/c-JUN signalling pathway-related proteins expression were detected by Western blotting. The intracellular calcium content and oxidative stress levels were detected by flow cytometry and reagent kits. Mitochondrial membrane potential was evaluated by tetrechloro-tetraethylbenzimidazol carbocyanine iodide (JC-1) staining. The targeting relationship between miR-7a-5p and voltage-dependent anion-selective channel protein 1 (VDAC1) was determined by RNA pull-down assay and dual-luciferase reporter gene assay. The streptozotocin (STZ) rat model was constructed to simulate DPN in vivo. The paw withdrawal mechanical threshold (PTW) was measured by Frey capillary line, and the motor nerve conduction velocity (MNCV) was measured by electromyography.

RESULTS

MiR-7a-5p expression was decreased, while VDAC1 expression was increased in HG-induced RSC96 cells and STZ rats. In HG-induced RSC96 cells, miR-7a-5p overexpression promoted cell proliferation, inhibited apoptosis, down-regulated calcium release, improved mitochondrial membrane potential and repressed oxidative stress response. MiR-7a-5p negatively regulated VDAC1 expression. VDAC1 knockdown improved cell proliferation activity, suppressed cell apoptosis and mitochondrial dysfunction by inhibiting JNK/c-JUN pathway activation. MiR-7a-5p overexpression raised PTW, restored MNCV and reduced oxidative stress levels and nerve cell apoptosis in STZ rats.

CONCLUSION

MiR-7a-5p overexpression ameliorated mitochondrial dysfunction and inhibited apoptosis in DPN by regulating VDAC1/JNK/c-JUN pathway.

The Osteocyte Stimulated by Wnt Agonist SKL2001 Is a Safe Osteogenic Niche Improving Bioactivities in a Polycaprolactone and Cell Integrated 3D Module

Finding and constructing an osteogenic microenvironment similar to natural bone tissue has always been a frontier topic in orthopedics. We found that osteocytes are targeting cells controlling bone anabolism produced by PTH (JBMR 2017, PMID: 27704638), and osteocytes with activated Wnt signaling orchestrate bone formation and resorption (PNAS 2015, PMID: 25605937). However, methods for taking advantage of the leading role of osteocytes in bone regeneration remain unexplored. Herein, we found that the osteocytes with SKL2001-activated Wnt signaling could be an osteogenic microenvironment (SOOME) which upregulates the expression of bone transcription factor Runx2 and Bglap and promotes the differentiation of bone marrow stromal cell ST2 into osteoblasts. Interestingly, 60 μM SKL2001 treatment of osteocytic MLO-Y4 for 24 h maintained Wnt signaling activation for three days after removal, which was sufficient to induce osteoblast differentiation. Triptonide, a Wnt inhibitor, could eliminate this differentiation. Moreover, on day 5, the Wnt signaling naturally decreased to the level of the control group, indicating that this method of Wnt-signaling induction is safe to use. We quickly verified in vivo function of SOOME to a good proximation in 3D bioprinted modules composed of reciprocally printed polycaprolactone bundles (for support) and cell bundles (for bioactivity). In the cell bundles, SOOME stably supported the growth and development of ST2 cells, the 7-day survival rate was as high as 91.6%, and proliferation ability increased linearly. Similarly, SOOME greatly promoted ST2 differentiation and mineralization for 28 days. In addition, SOOME upregulated the expression of angiopoietin 1, promoted endothelial cell migration and angiogenesis, and increased node number and total length of tubes and branches. Finally, we found that the function of SOOME could be realized through the paracrine pathway. This study reveals that osteocytes with Wnt signaling activated by SKL2001 are a safe osteogenic microenvironment. Both SOOME itself and its cell-free culture supernatant can improve bioactivity for osteoblast differentiation, with composite scaffolds especially bearing application value.

Ortho-silicic Acid Inhibits RANKL-Induced Osteoclastogenesis and Reverses Ovariectomy-Induced Bone Loss In Vivo

Numerous experiments in vitro and in vivo have shown that an appropriate increase intake of silicon can facilitate the synthesis of collagen and its stabilization and promote the differentiation and mineralization of osteoblasts. In this study, we examined whether ortho-silicic acid restrains the differentiation of osteoclast through the receptor activator of nuclear factor κB ligand (RANKL)/receptor activator of nuclear factor κB (RANK)/osteoprotegerin (OPG) signaling pathway by investigating its effect in vitro and in vivo. Bone marrow macrophage (BMM) cells were isolated and cultured with or without ortho-silicic acid, and then TRAP staining and immunofluorescence were performed to detect the differentiation of osteoclast. The RANKL-induced osteoclast marker gene and protein expression including c-Fos, nuclear factor of activated T cells cl (NFATcl), tumor necrosis factor receptor-associated factor 6 (TRAF6), nuclear factor kappa B P50 (NF-κB P50), NF-κB P52, RANK, integrin β3, cathepsin K (CTSK), DC-STAMP, and TRAP were quantitatively detected by western blot and RT-PCR. Ovariectomized (OVX) rats were injected with ortho-silicic acid (OVX+Si group) and normal saline (OVX group), and sham-operated rats were injected with normal saline (Sham group). And micro-CT, H&E, and TRAP staining, ELISA, and western blot were performed. Ortho-silicic acid could inhibit the differentiation of osteoclast, and the marker genes and proteins were decreased. The OVX-induced bone loss could be reversed by ortho-silicic acid. Our finding demonstrated that ortho-silicic acid suppresses RANKL-induced osteoclastogenesis and has potential value as a therapeutic agent for OVX-induced bone loss.

Morroniside promotes the osteogenesis by activating PI3K/Akt/mTOR signaling

Morroniside exerts a proosteogenic effect, which can prevent bone loss. However, the detailed mechanism underlying Morroniside-regulated bone formation is unclear. Morroniside can maintain cell homeostasis by promoting PI3K/Akt/mTOR signaling. The purpose of this study is to explore the significance of PI3K/Akt/mTOR signaling in Morroniside-regulated osteogenesis. The results showed that Morroniside promoted the activities of PI3K, Akt, and mTOR in osteoblast precursor MC3T3-E1. The differentiation of MC3T3-E1 to mature osteoblasts promoted by Morroniside can be reversed by the pharmacological inhibition of PI3K or mTOR. Importantly, in the presence of Morroniside, the osteoblast differentiation suppressed by PI3K inhibitor was reversed by mTOR overexpression. In vivo assays showed that in bone tissue of ovariectomized mice, Morroniside-enhanced osteoblast formation was reversed by the pharmacological inhibition of PI3K or mTOR. In conclusion, Morroniside can promote the osteogenesis through PI3K/Akt/mTOR signaling, which provides a novel clue for the strategy of Morroniside in treating osteoporosis.

Biological Roles and Delivery Strategies for Ions to Promote Osteogenic Induction

Bone is the most studied tissue in the field of tissue regeneration. Even though it has intrinsic capability to regenerate upon injury, several pathologies and injuries could hamper the highly orchestrated bone formation and resorption process. Bone tissue engineering seeks to mimic the extracellular matrix of the tissue and the different biochemical pathways that lead to successful regeneration. For many years, the use of extrinsic factors (i.e., growth factors and drugs) to modulate these biological processes have been the preferred choice in the field. Even though it has been successful in some instances, this approach presents several drawbacks, such as safety-concerns, short release profile and half-time life of the compounds. On the other hand, the use of inorganic ions has attracted significant attention due to their therapeutic effects, stability and lower biological risks. Biomaterials play a key role in such strategies where they serve as a substrate for the incorporation and release of the ions. In this review, the methodologies used to incorporate ions in biomaterials is presented, highlighting the osteogenic properties of such ions and the roles of biomaterials in controlling their release.

Exploration of the Molecular Mechanism of Polygonati Rhizoma in the Treatment of Osteoporosis Based on Network Pharmacology and Molecular Docking

OBJECTIVE

To explore the effective components and mechanism of Polygonati Rhizoma (PR) in the treatment of osteoporosis (OP) based on network pharmacology and molecular docking methods.

METHODS

The effective components and predicted targets of PR were obtained through the Traditional Chinese Medicine Systems Pharmacology and Analysis Platform (TCMSP) database. The disease database was used to screen the disease targets of OP. The obtained key targets were uploaded to the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database for protein-protein interaction (PPI) network analysis. The Database for Annotation, Visualization, and Integrated Discovery (DAVID) was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of key targets. Analysis and docking verification of chemical effective drug components and key targets were performed with IGEMDOCK software.

RESULTS

A total of 12 chemically active components, 84 drug target proteins and 84 common targets related to drugs and OP were obtained. Key targets such as JUN, TP53, AKT1, ESR1, MAPK14, AR and CASP3 were identified through PPI network analysis. The results of enrichment analysis showed that the potential core drug components regulate the HIF-1 signaling pathway, PI3K-Akt signaling pathway, estrogen signaling pathway and other pathways by intervening in biological processes such as cell proliferation and apoptosis and estrogen response regulation, with an anti-OP pharmacological role. The results of molecular docking showed that the key targets in the regulatory network have high binding activity to related active components.

CONCLUSIONS

PR may regulate OP by regulating core target genes, such as JUN, TP53, AKT1, ESR1, AR and CASP3, and acting on multiple key pathways, such as the HIF-1 signaling pathway, PI3K-Akt signaling pathway, and estrogen signaling pathway.

Ortho-silicic acid enhances osteogenesis of osteoblasts through the upregulation of miR-130b which directly targets PTEN

AIMS

Osteoporosis is considered a common skeletal disease. Ortho-silicic acid has been found to enhance the osteogenic differentiation of osteoblasts. However, the molecular mechanism of osteogenesis induced by ortho-silicic acid is still undefined totally. MicroRNAs (miRs) play a key role in osteogenesis of osteoblasts. This study investigated the role of miR-130b in promoting osteogenesis induced by ortho-silicic acid.

MAIN METHODS AND KEY FINDINGS

In this study, we found ortho-silicic acid enhanced osteogenesis of osteoblasts in vitro and promoted preventing and treating osteoporosis in vivo. Furthermore, the expression of miR-130b increased under application of ortho-silicic acid. In vitro, experiments demonstrated miR-130b overexpression or inhibition significantly promoted or suppressed osteogenic differentiation of osteoblasts under application of ortho-silicic acid, respectively. Consistently, downregulation of miR-130b in ovariectomy (OVX) rats dropped off the beneficial effect of ortho-silicic acid against bone loss. Mechanistically, we identified phosphatase and tensin homologue deleted on human chromosome 10 (PTEN) as the direct target of miR-130b during osteogenesis induced by ortho-silicic acid.

SIGNIFICANCE

In conclusion, our findings reveal that ortho-silicic acid promotes the osteogenesis of osteoblasts mediated by the miR-130b/PTEN signaling axis, which identifies a new target to prevent and treat osteoporosis.

Hydrogen sulfide is a regulator of mammary gland development in prepubescent female mice

The present study aimed to investigate the effects of exogenous H2S on mammary gland development in pubescent mice and to explore the underlying mechanism. The mouse mammary epithelial cell line HC11, along with C57BL/6J mice, were treated with different concentrations of sodium hydrosulfide (NaHS), which is a donor of H2S. The HC11 cell viability, pubescent mammary gland development, and the involvement of proliferative proteins and pathways were assessed by CCK‑8 assay, EdU assay, whole mount staining, H&E staining, western blotting and reverse transcription‑quantitative PCR. Both in vitro and in vivo, a low concentration of NaHS (100 µM in vitro; 9 mg/kg in vivo) significantly promoted the viability of HC11 cells and the development of mammary glands by increasing the expression of the proliferative markers cyclin D1/3 and proliferating cell nuclear antigen. However, a high concentration of NaHS (1,000 µM in vitro; 18 mg/kg in vivo) inhibited HC11 cell viability, mammary gland development and the expression levels of proteins involved in proliferation. Subsequent experiments revealed that NaHS regulated the phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt)‑mammalian target of rapamycin (mTOR) signaling pathway during this process. In vivo, intraperitoneal injection of low concentration NaHS (9 mg/kg) activated the PI3K/Akt‑mTOR pathway in mammary glands of pubescent mice, increased the secretion of insulin‑like growth factor 1 (IGF‑1) and estradiol (E2), and then stimulated mammary gland ductal development. Whereas a high concentration of NaHS (18 mg/kg) elicited the opposite effects to those of low‑dose NaHS. In conclusion, the present study demonstrated that exogenous H2S supplied by NaHS may exert bidirectional effects on mammary gland ductal development; promoting ductal development at a low concentration and inhibiting it at a high concentration. The effects of H2S may occur via the intracellular PI3K/Akt‑mTOR signaling pathway, or by regulation of the secretion of IGF‑1 and E2.