Quercetin promotes osteogenic differentiation and antioxidant responses of mouse bone mesenchymal stem cells through activation of the AMPK/SIRT1 signaling pathway

Capsaicin counteracts dexamethasone-induced osteoporosis and metabolic disturbances in rats: role of AMPK/SIRT1/β-catenin/RUNX2 pathway

Given their potent immunosuppressive and anti-inflammatory effects, long-term glucocorticoid therapy (GCs) is a common cause of bone fractures and secondary osteoporosis. Transient receptor potential vanilloid 1 (TRPV1) has been shown to play a role in preserving bone homeostasis and preventing bone disorders. The chili pepper is a naturally occurring source of capsaicin, a TRPV1 agonist. For this reason, this study compared the anti-resorptive properties of capsaicin with alendronate, the conventional treatment for osteoporosis, using a rat model of osteoporosis induced by dexamethasone (Dexa). Over six weeks, five groups of rats received the vehicle, Dexa alone (0.1 mg/kg, Sc), or Dexa plus either alendronate (1 mg/kg, orally) or capsaicin (1 or 2.5 mg/kg, orally). After the experiment, osteocalcin, RANKL, phosphorus, calcium, alkaline phosphatase (ALP), and metabolic parameters were measured. Furthermore, AMPK levels and the relative expression of Bax, Bcl-2, SIRT1, β-catenin, and RUNX2 were assessed in bone, and tissues from the femur were evaluated histologically. Capsaicin's effectiveness in alleviating the bone-damaging effect of dexamethasone was evident through a dose-dependent reduction in ALP, RANKL, and Bax, a rise in osteocalcin and Bcl-2, and a higher expression of AMPK, SIRT1, β-catenin, and RUNX2. Additionally, capsaicin improved bone architecture and effectively mitigated Dexa's detrimental metabolic impact on blood glucose and lipid profile. By upregulating the AMPK/SIRT1/β-catenin/RUNX2 pathway, capsaicin exhibits dose-dependent bone-stimulant effects in a dexamethasone-induced osteoporosis model in rats.

Emerging Technologies to Enhance Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells: Focus on Nanomaterials and Bioactive Compounds

Bone tissue damage and associated disorders significantly compromise the quality of life of affected patients, and existing therapeutic options remain limited. Bone marrow mesenchymal stem cells (BMSCs) play a crucial role in bone regenerative medicine, owing to their ability to differentiate into osteoblasts. Utilizing cutting-edge technologies, nanomaterials, and bioactive compounds can emulate the natural bone tissue microenvironment, offer a three-dimensional scaffold that facilitates the osteogenic differentiation of BMSCs, and modulate signals at the molecular level, thereby showing promise for applications in bone regeneration and repair. This review seeks to discuss the latest research advancements, elucidate the underlying mechanisms, and highlight the potential benefits of these technologies in augmenting the osteogenic capacity of BMSCs. Furthermore, the challenges and future directions for integrating these technologies in practical settings are discussed to pioneer new vistas in bone regenerative medicine.

Quercetin-calcium hydroxide scaffolds modulate dental pulp stem cell response in vitro under a simulated inflammatory environment

AIM

Tissue engineering can be applied to dentine regeneration, stimulating tissue repair by promoting mesenchymal cell migration and differentiation into odontoblast-like cells while modulating inflammation. This study aimed to investigate the effect of quercetin (QU) and calcium hydroxide (CH) incorporated into polycaprolactone (PCL)/polyethylene oxide (PEO) scaffolds on the differentiation of dental pulp stem cells (DPSCs) in a simulated inflammatory environment in vitro.

METHODOLOGY

Dental pulp stem cells (DPSCs) were cultured and treated with different concentrations of quercetin (QU) to assess cell viability, mineralized matrix production and responses under inflammatory stimuli. Reactive oxygen and nitrogen species, as well as TNF-α synthesis, were quantified using fluorescence and ELISA methods. Scaffolds of PCL/PEO with calcium hydroxide and QU were fabricated via electrospinning, characterized and analysed for cell adhesion, viability, inflammatory and mineralisation-related genes in an artificial pulp chamber model. Statistical analysis was performed using anova, Kruskal-Wallis and confidence intervals with a significance level of 5%.

RESULTS

Polycaprolactone/polyethylene oxide scaffolds incorporated with CH and QU showed cytocompatibility and support for DPSC differentiation at concentrations of up to 5 M diluted in the culture medium. After 14 days of treatment, the scaffolds upregulated ALPL gene expression under the inflammatory stimulus, with no differences between the control group and the nonincorporated scaffold. The expression of osteocalcin (OCN) and dentine sialophosphoprotein (DSPP) genes was significantly upregulated for the scaffold-treated group when stimulated with LPS.

CONCLUSIONS

Incorporating QU and CH into PCL/PEO scaffolds modulated the inflammatory-related response and upregulated mineralisation-related genes of LPS-challenged dental pulp stem cells.

Osteogenic Effects of Bioactive Compounds Found in Fruits on Mesenchymal Stem Cells: A Review

Phytochemicals, which are bioactive compounds contained in fruits, vegetables, and teas, have a positive effect on human health by having anti-inflammatory, antioxidant, and anticarcinogenic effects. Several studies have highlighted the ability of bioactive compounds to activate key cellular enzymes associated with important signaling pathways related to cell division and proliferation, as well as their role in inflammatory and immunological responses. Some phytochemicals are associated with increased proliferation, differentiation, and expression of markers related to osteogenesis, bone formation, and mineralization by activating various signaling pathways. The objective of this study was to clarify which bioactive compounds present in fruits have osteogenic effects on mesenchymal stem cells and the possible associated mechanisms. A literature search was conducted in the LILACS, MEDLINE, and PubMed databases for pertinent articles published between 2014 and 2024. This review included 34 articles that report the osteogenic effects of various bioactive compounds found in different fruits. All the articles reported that phytochemicals play a role in enhancing the regenerative properties of mesenchymal cells, such as proliferation, osteogenic differentiation, secretion of angiogenic factors, and extracellular matrix formation. This review highlights the potential of these phytochemicals in the prevention and treatment of bone diseases. However, more studies are recommended to identify and quantify the therapeutic dose of phytochemicals, investigate their mechanisms in humans, and ensure their safety and effectiveness for health, particularly for bone health.

Chitosan-based biomaterials for bone tissue engineering

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

Network pharmacology and in silico study of quercetin and structurally similar flavonoids as osteogenesis inducers that interact with oestrogen receptors

Background: Osteoporosis poses a global health challenge, particularly with an ageing population. Quercetin, isorhamnetin, avicularin, isoquercetin, quercitrin, and taxifolin are natural flavonoids with similar structure that induce ontogenesis.

Methods: In the present study, proteins in oestrogen signalling and bone morphogenesis were analysed, and hub genes were identified with Cytoscape, followed by pathway analysis. Then, molecular targets of flavonoids and osteoporosis-related targets were identified, and overlaps were detected. Molecular docking and dynamics simulations assessed flavonoid interactions with ERs.

Results: The study identified 14 gene products linked to osteoporosis, including ESR1 and ESR2. Enrichment analyses confirmed ESR involvement in various biological processes. SwissTargetPrediction highlighted quercetin and isorhamnetin as favourable targets for ESR1 and ESR2. Molecular docking and dynamics revealed favourable and stable binding of flavonoids to ERα and ERβ.

Conclusion: These interactions suggest therapeutic potential of natural flavonoids for osteoporosis treatment by targeting ERs, laying a foundation for future research in preclinical and clinical settings.

Creatine promotes osteogenic differentiation of dental pulp stem cells via the AMPK-ULK1-autophagy axis

OBJECTIVE

We aimed to demonstrate the effects of creatine (Cr) on osteogenic differentiation (OD) in HDPSCs.

MATERIALS AND METHODS

HDPSCs were treated with Cr and an inhibitor of Cr transporter. The OD capacity was evaluated by detecting ALP staining and activity, alizarin red staining (ARS), as well as osteogenesis-related protein levels. Transcriptomic sequencing, western blotting, transmission electron microscopy, immunofluorescence staining, and autophagy-related protein marker detection were applied to illustrate the underlying mechanism. Furthermore, the impact of Cr on bone regeneration was investigated in vivo.

RESULTS

We found that 1 mm of Cr effectively enhanced the OD of HDPSCs. The creatine group displayed significantly increased AMPK phosphorylation, overexpressed autophagy-related proteins, enhanced OD, and mineralization capabilities. We also found that ULK1 is the downstream molecule through which AMPK induces cellular autophagy. In vivo results demonstrated that Cr could increase the new bone formation of periodontitis.

CONCLUSION

Our research discovered a new AMPK-ULK1-autophagy pathway through which Cr enhances OD in HDPSCs. Cr enhanced HDPSCs-mediated periodontal tissue regeneration in a periodontitis mouse model, providing a theoretical foundation for the study of bone repair in periodontitis.

Senolytic elimination of senescent cells improved periodontal ligament stem cell-based bone regeneration partially through inhibiting YAP

Periodontal ligament stem cell (PDLSC)-based tissue engineering is an important method to promote periodontal tissue regeneration. However, PDLSCs are susceptible to the effects of replicative senescence, leading to reduced proliferation and differentiation abilities and weakened tissue regeneration potential. Senolytics (the combination of dasatinib and quercetin) are drugs that inhibit cellular aging through inducing the apoptosis of senescent cells, but whether they have positive effects during the senescence of PDLSCs is unknown. The present study established a long-term in vitro culture model of PDLSCs and then analyzed the effects of senolytics on the senescence, apoptosis, and osteogenic differentiation of PDLSCs in vitro and PDLSC-based tissue regeneration in vivo. The results showed that senolytics delayed the process of aging in prolonged-cultured PDLSCs and promoted the elimination and apoptosis of senescent cells. Moreover, senolytics improved the osteogenic differentiation ability of both young and senescent PDLSCs in vitro and promoted PDLSC-based alveolar bone regeneration in vivo. Furthermore, senolytics inhibited the expression of YAP in senescent PDLSCs. Their antiaging effects were enhanced when combined with the YAP inhibitor verteporfin, but were inhibited when combined with the YAP activator NIBR-LTSi. Taken together, these findings suggest that senolytics promoted the elimination of senescent PDLSCs and enhanced senescent PDLSC-based bone regeneration, partially through the inhibition of YAP expression.

Molecular mechanism of mitochondrial autophagy mediating impaired energy metabolism leading to osteoporosis

Osteoporosis (OP) is a bone metabolic disease caused by decreased bone mass leading to destruction of bone microstructure. Treatment of OP is characterized by a lifelong nature, causing extreme financial and psychological burdens to patients. Hormonal abnormalities, cellular autophagy, Ferroptosis, and oxidative stress are all part of the intricate and varied pathophysiology of OP. Recent research has revealed that mitochondrial dysfunction is a significant factor in the onset and progression of OP. By regulating bone marrow mesenchymal stem cell differentiation through various signaling pathways and cytokines, abnormal mitochondrial energy metabolism brought on by oxidative stress processes impacts osteoblast and osteoclast proliferation and differentiation, causing an imbalance in bone metabolism that ultimately results in OP. Therefore, one possible method to prevent and manage OP may be to use mitochondria as a carrier to trigger osteogenic differentiation of bone marrow mesenchymal stem cells from mitochondrial energy consumption, oxidative stress, autophagy, and osteoclast death. In order to offer some theoretical references and therapeutic approaches for the clinical prevention and treatment of OP, we will examine the pathophysiology of OP from mitochondrial dysfunction in this work.

Synthesis and Characterization of a Strontium-Quercetin Complex and Its In Vitro and In Vivo Potential for Application in Bone Regeneration

Progress has been made toward developing therapies to treat bone-related diseases and defects caused by trauma. However, some of these therapies, such as administering strontium ranelate to treat osteoporosis, have significant side effects. In this context, designing new and safer strontium-based materials constitutes an important current challenge. Here, we have used quercetin as a platform to synthesize a new complex based on strontium and evaluate its activity in vitro and in vivo. First, we carried out strontium complexation with quercetin. Then, we employed Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermal gravimetric analysis to determine the chemical composition of the resulting complex as [(C15H7O7)Sr2]·6(H2O), which was also supported by theoretical calculations. This complex enhanced osteogenic differentiation of a preosteoblastic cell line in vitro, which increased alkaline phosphatase activity and extracellular matrix mineralization. By using a periapical lesion model in mice, we tested whether treatment with this complex could regenerate bone defects in vivo and found that the lesions decreased after 7 days. Together, our data showed that the strontium-quercetin complex synthesized herein is a potential candidate for developing new bone regeneration therapies.

Role of sirtuins in obesity and osteoporosis: molecular mechanisms and therapeutic targets

The prevalence of obesity and osteoporosis (OP) represents a significant public health concern on a global scale. A substantial body of evidence indicates that there is a complex relationship between obesity and OP, with a correlation between the occurrence of OP and obesity. In recent years, sirtuins have emerged as a prominent area of interest in the fields of aging and endocrine metabolism. Among the various research avenues exploring the potential of sirtuins, the effects of these proteins on obesity and OP have garnered significant attention from numerous researchers. Sirtuins regulate energy balance and lipid balance, which in turn inhibit the process of adipogenesis. Additionally, sirtuins regulate the balance between osteogenic and osteoblastic activity, which protects against the development of OP. However, no study has yet provided a comprehensive discussion of the relationship between the three: sirtuins, obesity, and OP. This paper will therefore describe the relationship between sirtuins and obesity, the relationship between sirtuins and OP, and a discussion focusing on the possibility of treating OP caused by obesity by targeting sirtuins. This will be based on the common influences on the occurrence of obesity and OP (such as mesenchymal stem cells, gut microbiota, and insulin). Finally, the potential of SIRT1, an important member of sirtuins, in polyphenolic natural products for the treatment of obesity and OP will be presented. This will contribute to a better understanding of the interactions between sirtuins and obesity and bone, which will facilitate the development of new therapeutic strategies for obesity and OP in the future.

Repair of Osteoporotic Bone Defects in Rats via the Sirtuin 1-Wnt/β-catenin Signaling Pathway by Novel Icariin/Porous Magnesium Alloy Scaffolds

The slow rate of bone regeneration and repair in osteoporotic defects is one of the difficulties of clinical work. To prepare a novel icariin (ICA)/porous magnesium alloy scaffold and to investigate its effectiveness and possible mechanism in repairing osteoporotic bone defects, bilateral ovariectomy was performed on Sprague-Dawley rats. Then, a cylindrical bone defect was created in the model, and a novel ICA/porous magnesium alloy scaffold was prepared and implanted into the defect. Eight or 12 weeks after repairing, specimens and micro-computed tomography (CT) data were collected. Microscopic observation was fulfilled through hematoxylin and eosin, Goldner, Masson, periodic acid-Schiff, and Sirius red staining. The expression of proteins was detected by immunohistochemical staining. The novel ICA/porous magnesium alloy scaffold was noncytotoxic and biologically safe. After it was implanted into the defect for 8 or 12 weeks, the surface color and smoothness, depth, and area of the defect were better than those in the control group. Besides, there was sufficient osteoid tissue, more mineralized bones, more collagen fibers, and more polysaccharide components in the defect repaired with the ICA/porous magnesium alloy scaffold. These conditions are closer to those of real bones. Moreover, the repair effect improved with the repair time. Compared with those in the control group, the expression levels of Sirtuin 1(SIRT1), Wnt5a, β-catenin, glycogen synthase kinase 3β, alkaline phosphatase, runt-related transcription factor 2, bone morphogenetic protein-2, and osteocalcin proteins were elevated in bone tissue after the scaffold was implanted into the defect for 8 weeks (all P < 0.05). The novel ICA/porous magnesium alloy scaffold promotes the repair of osteoporotic bone defects in rats, a process that may be achieved through activation of the SIRT1-Wnt/β-catenin signaling pathway.

Flavonoids modulate regenerative-related cellular events in LPS-challenged dental pulp cells

OBJECTIVE

To investigate the effects of quercetin (QU), hesperetin (HT), and taxifolin (TX) on human dental pulp cells (hDPCs) chronically exposed to lipopolysaccharide (LPS).

METHODS

First, the cytotoxicity (alamarBlue) and bioactivity (biomineralization, Alizarin Red) of QU, HT, and TX concentrations were evaluated on healthy hDPCs. Then, the effects of non-cytotoxic and bioactive concentrations were investigated on hDPCs after previous stimulation with E. coli LPS (10 µg/mL) for 7 days. Cell culture media with and without LPS were used as positive and negative controls, respectively. Cell viability (alamarBlue), NF-κB activation (immunofluorescence), reactive oxygen species production (ROS, H2DCFDA probe), cell migration (Transwell), inflammation-related gene expression (RT-qPCR), and odontogenic differentiation (RT-qPCR and alizarin red) were evaluated (n = 8). Data were analyzed using confidence intervals and ANOVA (α = 5 %).

RESULTS

The concentrations of 20 µM QU, 20 µM HT, and 200 µM TX reduced cell viability by more than 30 %. The 5 µM QU, 10 µM HT, and 100 µM TX concentrations were cytocompatible and stimulated biomineralization by healthy hDPCs. These concentrations were tested under the LPS challenge, and cell viability and odontogenic differentiation were significantly increased, while ROS production and inflammatory response were significantly decreased. In addition, the flavonoids significantly stimulated cell migration, reduced NF-κB activation, and increased biomineralization by LPS-challenged hDPCs compared to cells exposed to LPS alone and without any other treatment.

CONCLUSION

Flavonoids can modulate the metabolism of hDPCs chronically exposed to LPS in vitro, stimulating cellular events compatible with stem cell-based regenerative processes.

CLINICAL SIGNIFICANCE

Flavonoids may be explored as adjuvant therapeutic agents during pulp capping to counteract chronic inflammatory conditions and stimulate regeneration of the dentin-pulp complex in caries-affected teeth, thereby preserving tooth vitality.

Flavonoids attenuate inflammation of HGF and HBMSC while modulating the osteogenic differentiation based on microfluidic chip

BACKGROUND

When inflammation occurs in periodontal tissues, a dynamic cellular crosstalk interacts between gingival fibroblasts and bone marrow mesenchymal stem cells (BMSCs), which plays a crucial role in the biological behaviour and differentiation of the cells. Recently, flavonoids are increasingly recognized for their therapeutic potential in modulating inflammation and osteogenic differentiation. Owing to their varied molecular structures and mechanisms, there are more needs that flavonoid compounds should be identified by extensive screening. However, current drug research mostly relies on static, single-type cell cultures. In this study, an innovative bionic microfluidic chip system tailored for both soft and hard tissues was developed to screen for flavonoids suitable for treating periodontitis.

METHODS

This study developed a microfluidic system that bionically simulates the soft and hard structures of periodontal tissues. Live/dead staining, reactive oxygen species (ROS) staining, and RT-qPCR analysis were employed. These techniques evaluated the effects of flavonoid compounds on the levels of inflammatory factors and ROS contents in HGF and HBMSC under LPS stimulation. Additionally, the impact of these compounds on osteogenic induction in HBMSC and the exploration of the underlying mechanisms were assessed.

RESULTS

The microfluidic chip used in this study features dual chambers separated by a porous membrane, allowing cellular signal communication via bioactive factors secreted by cells in both layers under perfusion. The inflammatory response within the chip under LPS stimulation was lower compared to individual static cultures of HGF and HBMSC. The selected flavonoids-myricetin, catechin, and quercetin-significantly reduced cellular inflammation, decreased ROS levels, and enhanced osteogenic differentiation of BMSCs. Additionally, fisetin, silybin, and icariside II also demonstrated favorable outcomes in reducing inflammation, lowering ROS levels, and promoting osteogenic differentiation through the Wnt/β-catenin pathway.

CONCLUSIONS

The bionic microfluidic chip system provides enhanced capabilities for drug screening and evaluation, delivering a more precise assessment of drug efficacy and safety compared to traditional in vitro methods. This study demonstrates the efficacy of flavonoids in influencing osteogenic processes in BMSCs primarily through the Wnt/β-catenin pathway. These results uncover the potential of flavonoids as therapeutic medicine for treating periodontitis, meriting further research and development.

The release behavior and in vitro osteogenesis of quercetin-loaded bioactive glass/hyaluronic acid/sodium alginate nanocomposite paste

Injectable pastes based on bioactive compounds and natural polymers are of interest in non-invasive bone surgeries. Several quantities of quercetin (100, 150, and 200 μM) were added to a sol-gel derived mesoporous bioactive glass. Injectable pastes based on quercetin-loaded bioactive glass, sodium alginate, and hyaluronic acid were prepared. Aggregated nanoparticles of bioactive glass and quercetin-loaded bioactive glass with mesoporous morphologies were confirmed by TEM and BET techniques. The quercetin release study was assessed in phosphate-buffered solution medium over 200 h and the obtained data were fitted by different eqs. A sustained release of quercetin was found, in which a better regression coefficient was achieved using Weibull equation. Human-derived mesenchymal stem cells were utilized to determine alkaline phosphatase activity and bone-related protein expression by western blotting and real-time PCR evaluations. Quercetin-loaded pastes increased the levels of alkaline phosphatase activity and the expression of Collagen-1, Osteopontin, Osteocalcin, and Runx2 proteins in a concentration-dependent manner. Due to the mesoporous architecture and high specific surface area of bioactive glass, the paste made of these particles and sodium alginate/hyaluronic acid macromolecules is appropriate matrix for quercetin release, resulting in promoted osteogenesis. The further in vivo studies can support the osteogenesis capacity of the quercetin-loaded paste.

NOX4-reactive oxygen species axis: critical regulators of bone health and metabolism

Bone marrow stromal cells (BMSCs) play a significant role in bone metabolism as they can differentiate into osteoblasts, bone marrow adipocytes (BMAds), and chondrocytes. BMSCs chronically exposed to nutrient overload undergo adipogenic programming, resulting in bone marrow adipose tissue (BMAT) formation. BMAT is a fat depot transcriptionally, metabolically, and morphologically distinct from peripheral adipose depots. Reactive oxygen species (ROS) are elevated in obesity and serve as important signals directing BMSC fate. ROS produced by the NADPH oxidase (NOX) family of enzymes, such as NOX4, may be responsible for driving BMSC adipogenesis at the expense of osteogenic differentiation. The dual nature of ROS as both cellular signaling mediators and contributors to oxidative stress complicates their effects on bone metabolism. This review discusses the complex interplay between ROS and BMSC differentiation in the context of metabolic bone diseases.Special attention is paid to the role of NOX4-ROS in regulating cellular processes within the bone marrow microenvironment and potential target in metabolic bone diseases.

Role of oxidative stress in the concurrent development of osteoporosis and tendinopathy: Emerging challenges and prospects for treatment modalities

Both osteoporosis and tendinopathy are widely prevalent disorders, encountered in diverse medical contexts. Whilst each condition has distinct pathophysiological characteristics, they share several risk factors and underlying causes. Notably, oxidative stress emerges as a crucial intersecting factor, playing a pivotal role in the onset and progression of both diseases. This imbalance arises from a dysregulation in generating and neutralising reactive oxygen species (ROS), leading to an abnormal oxidative environment. Elevated levels of ROS can induce multiple cellular disruptions, such as cytotoxicity, apoptosis activation and reduced cell function, contributing to tissue deterioration and weakening the structural integrity of bones and tendons. Antioxidants are substances that can prevent or slow down the oxidation process, including Vitamin C, melatonin, resveratrol, anthocyanins and so on, demonstrating potential in treating these overlapping disorders. This comprehensive review aims to elucidate the complex role of oxidative stress within the interlinked pathways of these comorbid conditions. By integrating contemporary research and empirical findings, our objective is to outline new conceptual models and innovative treatment strategies for effectively managing these prevalent diseases. This review underscores the importance of further in-depth research to validate the efficacy of antioxidants and traditional Chinese medicine in treatment plans, as well as to explore targeted interventions focused on oxidative stress as promising areas for future medical advancements.

Quercetin in Osteoporosis Treatment: A Comprehensive Review of Its Mechanisms and Therapeutic Potential

PURPOSE OF REVIEW

This review aims to provide a theoretical basis and insights for quercetin's clinical application in the prevention and treatment of osteoporosis (OP), analyzing its roles in bone formation promotion, bone resorption inhibition, anti-inflammation, antioxidant effects, and potential mechanisms.

RECENT FINDINGS

OP, a prevalent bone disorder, is marked by reduced bone mineral density and impaired bone architecture, elevating the risk of fractures in patients. The primary approach to OP management is pharmacotherapy, with quercetin, a phytochemical compound, emerging as a focus of recent interest. This natural flavonoid exerts regulatory effects on bone marrow mesenchymal stem cells, osteoblasts, and osteoclasts and promotes bone health and metabolic equilibrium via anti-inflammatory and antioxidative pathways. Although quercetin has demonstrated significant potential in regulating bone metabolism, there is a need for further high-quality clinical studies focused on medicinal quercetin.

Effect of polydimethylsiloxane surface morphology on osteogenic differentiation of mesenchymal stem cells through SIRT1 signalling pathway

Constructing surface topography with a certain roughness is a widely used, non-toxic, cost-effective and effective method for improving the microenvironment of cells, promoting the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs), and promoting the osseointegration of grafts and further improving their biocompatibility under clinical environmental conditions. SIRT1 plays an important regulatory role in the osteogenic differentiation of bone marrow-derived MSCs (BM-MSCs). However, it remains unknown whether SIRT1 plays an important regulatory role in the osteogenic differentiation of BM-MSCs with regard to surface morphology. Polydimethylsiloxane (PDMS) with different surface morphologies were prepared using different grits of sandpaper. The value for BMSCs added on different surfaces was detected by cell proliferation assays. RT-qPCR and Western blotting were performed to detect SIRT1 activation and osteogenic differentiation of MSCs. Osteogenesis of MSCs was detected by alkaline phosphatase (ALP) and alizarin red S staining. SIRT1 inhibition experiments were performed to investigate the role of SIRT1 in the osteogenic differentiation of MSCs induced by surface morphology. We found that BM-MSCs have better value and osteogenic differentiation ability on a surface with roughness of PDMS-1000M. SIRT1 showed higher gene and protein expression on a PDMS-1000M surface with a roughness of 13.741 ± 1.388 µm. The promotion of the osteogenic differentiation of MSCs on the PDMS-1000M surface was significantly decreased after inhibiting SIRT1 expression. Our study demonstrated that a surface morphology with certain roughness can activate the SIRT1 pathway of MSCs and promote the osteogenic differentiation of BMSCs via the SIRT1 pathway.

Efficient three-dimensional (3D) human bone differentiation on quercetin-functionalized isotropic nano-architecture chitinous patterns of cockroach wings

Developing cost-effective, biocompatible scaffolds with nano-structured surface that truthfully replicate the physico-(bio)chemical and structural properties of bone tissue's extracellular matrix (ECM) is still challenging. In this regard, surface functionalization of natural scaffolds to enhance capability of mimicking 3D niches of the bone tissue has been suggested as a solution. In the current study, we aimed to investigate the potential of chitin-based cockroach wings (CW) as a natural scaffold for bone tissue engineering. To raise the osteogenic differentiation capacity of such a scaffold, a quercetin coating was also applied (hereafter this scaffold is referred as QCW). Moreover, the QCW scaffold exhibited effective antibacterial properties against gram-positive S. aureus bacteria. With respect to bone regeneration, the QCW scaffold optimally induced the differentiation of adipose-derived human mesenchymal stem cells (AD-hMSCs) into osteoblasts, as validated by mineralization assays, alkaline phosphatase (ALP) activity measurements, expression of pre-osteocyte marker genes, and immunocytochemical staining. Confirmation of the potent biocompatibility and physicochemical characteristics of the QCW scaffold through a series of in vitro and in vivo analysis revealed that surface modification had significant effect on multi-purpose features of obtained scaffold. Altogether, surface modification of QCW made it as an affordable bioinspired scaffold for bone tissue engineering.

Quercetin induces its chemoprotective effects via hormesis

Quercetin is a polyphenol present in numerous fruits and vegetables and therefore widely consumed by humans with average daily dietary intakes of 10-20 mg/day. It is also a popular dietary supplement of 250-1000 mg/day. However, despite the widespread consumer interest in quercetin, due to its possible chemopreventive properties, the extensively studied quercetin presents a highly diverse and complex array of biological effects. Consequently, the present paper provides the first assessment of quercetin-induced hormetic concentration/dose responses, their quantitative features and mechanistic foundations, and their biological, biomedical, clinical, and public health implications. The findings indicate that quercetin-induced hormetic dose responses are widespread, being independent of biological model, cell type, and endpoint. These findings have the potential to enlighten future experimental studies with quercetin especially with respect to study design parameters and may also affect the appraisal of possible public health benefits and risks associated with highly diverse consumer consumption practices.

A multifunctional quercetin/polycaprolactone electrospun fibrous membrane for periodontal bone regeneration

Image 1.

Pharmacological and mechanistic aspects of quercetin in osteoporosis

Osteoporosis (OP) is a bone disease associated with increasing age. Currently, the most common medications used to treat OP are anabolic agents, anti-resorptive agents, and medications with other mechanisms of action. However, many of these medications have unfavorable adverse effects or are not intended for long-term use, potentially exerting a severe negative impact on a patient's life and career and placing a heavy burden on families and society. There is an urgent need to find new drugs that can replace these and have fewer adverse effects. Quercetin (Que) is a common flavonol in nature. Numerous studies have examined the therapeutic applications of Que. However, a comprehensive review of the anti-osteoporotic effects of Que has not yet been conducted. This review aimed to describe the recent studies on the anti-osteoporotic effects of Que, including its biological, pharmacological, pharmacokinetic, and toxicological properties. The outcomes demonstrated that Que could enhance OP by increasing osteoblast differentiation and activity and reducing osteoclast differentiation and activity via the pathways of Wnt/β-catenin, BMP/SMAD/RUNX2, OPG/RANKL/RANK, ERK/JNK, oxidative stress, apoptosis, and transcription factors. Thus, Que is a promising novel drug for the treatment of OP.

Sirtuins mediate mitochondrial quality control mechanisms: a novel therapeutic target for osteoporosis

Mitochondria plays a role in cell differentiation and apoptosis processes. Maintaining mitochondrial function is critical, and this involves various aspects of mitochondrial quality control such as protein homeostasis, biogenesis, dynamics, and mitophagy. Osteoporosis, a metabolic bone disorder, primarily arises from two factors: the dysregulation between lipogenic and osteogenic differentiation of aging bone marrow mesenchymal stem cells, and the imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Mitochondrial quality control has the potential to mitigate or even reverse the effects. Among the Sirtuin family, consisting of seven Sirtuins (SIRT1-7), SIRT1-SIRT6 play a crucial role in maintaining mitochondrial quality control. Additionally, SIRT1, SIRT3, SIRT6, and SIRT7 are directly involved in normal bone development and homeostasis by modulating bone cells. However, the precise mechanism by which these Sirtuins exert their effects remains unclear. This article reviews the impact of various aspects of mitochondrial quality control on osteoporosis, focusing on how SIRT1, SIRT3, and SIRT6 can improve osteoporosis by regulating mitochondrial protein homeostasis, biogenesis, and mitophagy. Furthermore, we provide an overview of the current state of clinical and preclinical drugs that can activate Sirtuins to improve osteoporosis. Specific Sirtuin-activating compounds are effective, but further studies are needed. The findings of this study may offer valuable insights for future research on osteoporosis and the development of clinical prevention and therapeutic target strategies.

Manganese Enhances the Osteogenic Effect of Silicon-Hydroxyapatite Nanowires by Targeting T Lymphocyte Polarization

Biomaterials encounter considerable challenges in extensive bone defect regeneration. The amelioration of outcomes may be attainable through the orchestrated modulation of both innate and adaptive immunity. Silicon-hydroxyapatite, for instance, which solely focuses on regulating innate immunity, is inadequate for long-term bone regeneration. Herein, extra manganese (Mn)-doping is utilized for enhancing the osteogenic ability by mediating adaptive immunity. Intriguingly, Mn-doping engenders heightened recruitment of CD4+ T cells to the bone defect site, concurrently manifesting escalated T helper (Th) 2 polarization and an abatement in Th1 cell polarization. This consequential immune milieu yields a collaborative elevation of interleukin 4, secreted by Th2 cells, coupled with attenuated interferon gamma, secreted by Th1 cells. This orchestrated interplay distinctly fosters the osteogenesis of bone marrow stromal cells and effectuates consequential regeneration of the mandibular bone defect. The modulatory mechanism of Th1/Th2 balance lies primarily in the indispensable role of manganese superoxide dismutase (MnSOD) and the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK). In conclusion, this study highlights the transformative potential of Mn-doping in amplifying the osteogenic efficacy of silicon-hydroxyapatite nanowires by regulating T cell-mediated adaptive immunity via the MnSOD/AMPK pathway, thereby creating an anti-inflammatory milieu favorable for bone regeneration.

Mechanism of Action of NvZhen ErXian HeJi in Ovariectomized Rats with Myocardial Infarction based on Network Pharmacology

OBJECTIVE

NvZhen ErXian HeJi (NZEXHJ) is used to treat perimenopausal syndrome (PS), but its effect on perimenopausal coronary heart disease is unclear. Furthermore, the aim of this research is to study the effect of NZEXHJ on perimenopausal coronary heart disease (PMCHD) in a rat model based on a network pharmacology approach.

MATERIALS AND METHODS

Based on network pharmacological analysis combined with molecular docking, we predicted the potential therapeutic target and pharmacological mechanism of NZEXHJ in the treatment of PMCHD. We used an ovariectomized rat (OVR) model to understand the effect of NZEXHJ on myocardial injury and further verified the target of NZEXHJ in the intervention of PMCHD.

RESULTS

We selected 52 active components of NZEXHJ against PMCHD and an intersection of their targets on network pharmacology, to which SCN5A, SER1, AR, and PGR were significantly correlated. The protein- protein interaction network revealed CASP3, CXCL8, IL6, MAPK1, TNF, TP53, and VEGFA in the treatment of PMCHD with NZEXHJ. Kaempferol, luteolin, and mistletoe presented good affinity towards the aforementioned targets by Molecular docking NZEXHJ exerted protecting cardiomyocytes for OVR. The mechanism was related to a reduction in the expression levels of the CXCL8, TNF, and regulating PI3K-Akt signaling pathways.

CONCLUSION

This study reveals the potential multi-component, multi-target, and multi-pathway pharmacological effects of NZEXHJ and predicts its protection against myocardial infarction in ovariectomized rats through the PI3K Akt pathway, providing a theoretical basis for the treatment of PMCHD.

Prevention and treatment of osteoporosis with natural products: Regulatory mechanism based on cell ferroptosis

CONTEXT

With the development of society, the number of patients with osteoporosis is increasing. The prevention and control of osteoporosis has become a serious and urgent issue. With the continuous progress of biomedical research, ferroptosis has attracted increased attention. However, the pathophysiology and mechanisms of ferroptosis and osteoporosis still need further study. Natural products are widely used in East Asian countries for osteoporosis prevention and treatment.

OBJECTIVE

In this paper, we will discuss the basic mechanisms of ferroptosis, the relationship between ferroptosis and osteoclasts and osteoblasts, and in vitro and in vivo studies of natural products to prevent osteoporosis by interfering with ferroptosis.

METHODS

This article takes ferroptosis, natural products, osteoporosis, osteoblasts and osteoclast as key words. Retrieve literature from 2012 to 2023 indexed in databases such as PubMed Central, PubMed, Web of Science, Scopus and ISI.

RESULTS

Ferroptosis has many regulatory mechanisms, including the system XC -/GSH/GPX4, p62/Keap1/Nrf2, FSP1/NAD (P) H/CoQ10, P53/SAT1/ALOX15 axes etc. Interestingly, we found that natural products, such as Artemisinin, Biochanin A and Quercetin, can play a role in treating osteoporosis by promoting ferroptosis of osteoclast and inhibiting ferroptosis of osteoblasts.

CONCLUSIONS

Natural products have great potential to regulate OBs and OCs by mediating ferroptosis to prevent and treat osteoporosis, and it is worthwhile to explore and discover more natural products that can prevent and treat osteoporosis.

Cornus officinalis: a potential herb for treatment of osteoporosis

Osteoporosis (OP) is a systemic metabolic skeletal disorder characterized by a decline in bone mass, bone mineral density, and deterioration of bone microstructure. It is prevalent among the elderly, particularly postmenopausal women, and poses a substantial burden to patients and society due to the high incidence of fragility fractures. Kidney-tonifying Traditional Chinese medicine (TCM) has long been utilized for OP prevention and treatment. In contrast to conventional approaches such as hormone replacement therapy, TCM offers distinct advantages such as minimal side effects, low toxicity, excellent tolerability, and suitability for long-term administration. Extensive experimental evidence supports the efficacy of kidney-tonifying TCM, exemplified by formulations based on the renowned herb Cornus officinalis and its bioactive constituents, including morroniside, sweroside, flavonol kaempferol, Cornuside I, in OP treatment. In this review, we provide a comprehensive elucidation of the underlying pathological principles governing OP, with particular emphasis on bone marrow mesenchymal stem cells, the homeostasis of osteogenic and osteoclastic, and the regulation of vascular and immune systems, all of which critically influence bone homeostasis. Furthermore, the therapeutic mechanisms of Cornus officinalis-based TCM formulations and Cornus officinalis-derived active constituents are discussed. In conclusion, this review aims to enhance understanding of the pharmacological mechanisms responsible for the anti-OP effects of kidney-tonifying TCM, specifically focusing on Cornus officinalis, and seeks to explore more efficacious and safer treatment strategies for OP.

Quercetin suppresses ovariectomy-induced osteoporosis in rat mandibles by regulating autophagy and the NLRP3 pathway

With the aging population and the popularity of implant prostheses, an increasing number of postmenopausal osteoporosis (PMOP) patients require implant restorations; however, poor bone condition affects the long-term stability of implant prostheses. This study aimed to investigate the therapeutic effect of quercetin (QR) compared with alendronate (ALN), the primary treatment for PMOP, on mandibular osteoporosis (OP) induced by ovariectomy (OVX) in female rats. Adult female rats were treated with QR (50 mg/kg/day), ALN (6.25 mg/kg/week) by gavage for 8 weeks, chloroquine (CQ, 10 mg/kg/twice a week), and cytokine release inhibitory drug 3 (MCC950, 10 mg/kg/three times a week) by intraperitoneal injection for 8 weeks after bilateral OVX. Blood samples were collected prior to euthanasia; the mandibles were harvested and subjected to micro-computed tomography (micro-CT) and pathological analysis. QR administration controlled weight gain and significantly improved the bone microstructure in OVX rats, increasing bone mass, and bone mineral density (BMD), reducing bone trabecular spacing, and decreasing osteoclast numbers. Western blotting, real-time quantitative PCR (RT-qPCR), and serum markers confirmed that QR inhibited interleukin- 1β (IL-1β) and interleukin-18 (IL-18) on the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) protein 3 (NLRP3) pathway thereby inhibiting osteoclast differentiation, immunofluorescence and western blotting also confirmed that QR inhibited autophagy in OVX rats and suppressed the number of tartrate-resistant acid phosphatase (TRAP)-stained positive osteoclasts. The findings suggest that QR may protect the bone structure and prevent bone loss in osteoporotic rats by inhibiting the NLRP3 pathway and autophagy in osteoclasts with comparable effects to ALN, thus QR may have the potential to be a promising alternative supplement for the preventive and therapeutic treatment of PMOP.

Protective effect of quercetin on fetal development and congenital skeletal anomalies against exposure of pregnant Wistar rats to crude oil vapor

BACKGROUND

Epidemiological evidence indicates a relationship between maternal exposure to crude oil vapors (COV) during pregnancy and adverse pregnancy outcomes. Quercetin (QUE) is a plant flavonoid with purported antioxidant and anti-inflammatory effects, which has been shown to prevent birth defects. This study was aimed to investigate the protective role of QUE on fetal development and congenital skeletal anomalies caused by exposure of pregnant rats to COV.

METHODS

Twenty-four pregnant Wistar rats were randomly categorized into four groups of control, COV, COV + QUE, and QUE (50 mg/kg). The inhalation method was used to expose pregnant rats to COV from day 0 to 20 of pregnancy, and QUE was administered orally during this period. On day 20 of gestation, the animals were anesthetized and a laparotomy was performed, and then the weight and crown rump length (CRL) of the fetuses were determined. Skeletal stereomicroscopic evaluations of fetuses were performed using Alcian blue/Alizarin red staining method, and the expression of osteogenesis-related genes (Runx2 and BMP-4) was evaluated using qPCR.

RESULTS

This study showed that prenatal exposure to COV significantly reduced fetal weight and CRL, and expression of Runx2 and BMP-4 genes. Moreover, COV significantly increased the incidence of congenital skeletal anomalies such as cleft palate, spina bifida and non-ossification of the fetal bones. However, administration of QUE with exposure to COV improved fetal bone development and reduced congenital skeletal anomalies.

CONCLUSION

QUE can ameliorate the teratogenic effects of prenatal exposure to COV by increasing the expression of osteogenesis-related genes.

Regulatory Effects of Quercetin on Bone Homeostasis: Research Updates and Future Perspectives

The imbalance of bone homeostasis has become a major public medical problem amid the background of an aging population, which is closely related to the occurrence of osteoporosis, osteoarthritis, and fractures. Presently, most drugs used in the clinical treatment of bone homeostasis imbalance are bisphosphonates, calcitonin, estrogen receptor modulators, and biological agents that inhibit bone resorption or parathyroid hormone analogs that promote bone formation. However, there are many adverse reactions. Therefore, it is necessary to explore potential drugs. Quercetin, as a flavonol compound with various biological activities, is widely distributed in plants. Studies have found that quercetin can regulate bone homeostasis through multiple pathways and targets. An in-depth exploration of the pharmacological mechanism of quercetin is of great significance for the development of new drugs. This review discusses the therapeutic mechanisms of quercetin on bone homeostasis, such as regulating the expression of long non-coding RNA, signaling pathways of bone metabolism, various types of programmed cell death, bone nutrients supply pathways, anti-oxidative stress, anti-inflammation, and activation of Sirtuins. We also summarize recent progress in improving quercetin bioavailability and propose some issues worth paying attention to, which may help guide future research efforts.

An aqueous extract of Prunella vulgaris L. ameliorates cadmium-induced bone loss by promoting osteogenic differentiation in female rats

Cadmium (Cd) causes bone loss, concerning inhibiting osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Prunella vulgaris L. (PV) has the potential for promoting osteogenic differentiation, but its influence on Cd-induced bone loss is unclear. This study investigated the effect of PV aqueous extract (PVE) on Cd-induced bone loss and its underlying mechanisms. Eight-week-old female SD rats were randomly assigned into four groups and treated for 16 weeks: Control, Cd (50 mg/L of Cd chloride), Cd + PV Low (125 mg/kg bw of PVE), and Cd + PV High (250 mg/kg bw of PVE). PV ameliorated femoral bone loss in Cd-treated rats manifested as increases in bone mineral density, bone volume, trabecular thickness, number, and area, and decreases in trabecular separation. Compared with Cd group, PV-treatment groups had higher serum levels of bone formation markers (ALP, BGP). Additionally, in PV-treatment groups, expressions of bone formation markers (Osterix, Runx2) and molecules involved in osteogenic differentiation signal pathway BMP/Smad (BMP4, Smad1/5/9) in the tibia of rats and isolated rat primary BMSCs were upregulated. These results suggest that PV alleviates Cd-induced bone loss by promoting osteogenic differentiation, which is likely associated with BMP/Smad pathway.

Zoledronate Promotes Peri-Implant Osteogenesis in Diabetic Osteoporosis by the AMPK Pathway

Together with diabetic osteoporosis (DOP), diabetes patients experience poor peri-implant osteogenesis following implantation for dentition defects. Zoledronate (ZOL) is widely used to treat osteoporosis clinically. To evaluate the mechanism of ZOL for the treatment of DOP, experiments with DOP rats and high glucose-grown MC3T3-E1 cells were used. The DOP rats treated with ZOL and/or ZOL implants underwent a 4-week implant-healing interval, and then microcomputed tomography, biomechanical testing, and immunohistochemical staining were performed to elucidate the mechanism. In addition, MC3T3-E1 cells were maintained in an osteogenic medium with or without ZOL to confirm the mechanism. The cell migration, cellular actin content, and osteogenic differentiation were evaluated by a cell activity assay, a cell migration assay, as well as alkaline phosphatase, alizarin red S, and immunofluorescence staining. The mRNA and protein expression of adenosine monophosphate-activated protein kinase (AMPK), phosphorylated AMPK (p-AMPK), osteoprotegerin (OPG), receptor activator of nuclear factor kappa B ligand (RANKL), bone morphogenetic protein 2 (BMP2), and collagen type I (Col-I) were detected using real-time quantitative PCRs and western blot assays, respectively. In the DOP rats, ZOL markedly improved osteogenesis, enhanced bone strength and increased the expression of AMPK, p-AMPK, and Col-I in peri-implant bones. The in vitro findings showed that ZOL reversed the high glucose-induced inhibition of osteogenesis via the AMPK signaling pathway. In conclusion, the ability of ZOL to promote osteogenesis in DOP by targeting AMPK signaling suggests that therapy with ZOL, particularly simultaneous local and systemic administration, may be a unique approach for future implant repair in diabetes patients.

Research progress on the role of lncRNA-miRNA networks in regulating adipogenic and osteogenic differentiation of bone marrow mesenchymal stem cells in osteoporosis

Osteoporosis (OP) is characterized by a decrease in osteoblasts and an increase in adipocytes in the bone marrow compartment, alongside abnormal bone/fat differentiation, which ultimately results in imbalanced bone homeostasis. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into osteoblasts and adipocytes to maintain bone homeostasis. Several studies have shown that lncRNAs are competitive endogenous RNAs that form a lncRNA-miRNA network by targeting miRNA for the regulation of bone/fat differentiation in BMSCs; this mechanism is closely related to the corresponding treatment of OP and is important in the development of novel OP-targeted therapies. However, by reviewing the current literature, it became clear that there are limited summaries discussing the effects of the lncRNA-miRNA network on osteogenic/adipogenic differentiation in BMSCs. Therefore, this article provides a review of the current literature to explore the impact of the lncRNA-miRNA network on the osteogenic/adipogenic differentiation of BMSCs, with the aim of providing a new theoretical basis for the treatment of OP.

Myricitrin promotes osteogenesis and prevents ovariectomy bone mass loss via the PI3K/AKT signalling pathway

This study aimed to explore the effect of myricitrin on osteoblast differentiation in mice immortalised bone marrow mesenchymal stem cells (imBMSCs). Additionally, ovariectomy (OVX) mice were employed to examine the effect of myricitrin on bone trabecular loss in vivo. The effect of myricitrin on the proliferation of imBMSCs was evaluated using a cell counting kit-8 assay. Alizarin red staining, alkaline phosphatase staining were performed to elucidate osteogenesis. Furthermore, qRT-PCR and western blot determined the expression of osteo-specific genes and proteins. To screen for candidate targets, mRNA transcriptome genes were sequenced using bioinformatics analyses. Western blot and molecular docking analysis were used to examine target signalling markers. Moreover, rescue experiments were used to confirm the effect of myricitrin on the osteogenic differentiation of imBMSCs. OVX mice were also used to estimate the delay capability of myricitrin on bone trabecular loss in vivo using western blot, micro-CT, tartaric acid phosphatase (Trap) staining, haematoxylin and eosin staining, Masson staining and immunochemistry. In vitro, myricitrin significantly enhanced osteo-specific genes and protein expression and calcium deposition. Moreover, mRNA transcriptome gene sequencing and molecular docking analysis revealed that this enhancement was accompanied by an upregulation of the PI3K/AKT signalling pathway. Furthermore, copanlisib, a PI3K inhibitor, partially reversed the osteogenesis promotion induced by myricitrin. In vivo, western blot, micro-CT, hematoxylin and eosin staining, Masson staining, Trap staining and immunochemistry revealed that bone trabecular loss rate was significantly alleviated in the myricitrin low- and high-dose groups, with an increased expression of osteopontin, osteoprotegerin, p-PI3K and p-AKT compared to the OVX group. Myricitrin enhances imBMSC osteoblast differentiation and attenuate bone mass loss partly through the upregulation of the PI3K/AKT signalling pathway. Thus, myricitrin has therapeutic potential as an antiosteoporosis drug.

N-acetylcysteine protects human periodontal ligament fibroblasts from pyroptosis and osteogenic differentiation dysfunction through the SIRT1/NF-κB/Caspase-1 signaling pathway

OBJECTIVE

This study was aimed to determine whether N-acetylcysteine (NAC) could inhibit lipopolysaccharides / adenosine triphosphate (ATP)-induced pyroptosis and alleviate the damage of osteogenic differentiation in human periodontal ligament fibroblasts (hPDLFs). Furthermore, this study detected whether NAC acted effectively by modulating the silent information regulator 2 homolog 1 (SIRT1)/ the nuclear factor-κB (NF-κB)/Caspase-1 signaling pathway in hPDLFs.

DESIGN

Cell Counting Kit-8 assay was employed to determine the appropriate concentration of NAC for the follow-up experiments. To explore the effect and the underlying mechanisms of NAC on pyroptosis and osteogenic differentiation in hPDLFs, intracellular reactive oxygen species levels were detected using 2',7'-Dichlorodihydrofluorescein Diacetate kits. Moreover, SIRT1 inhibitor, SIRT1 activator, NF-κB inhibitor and Caspase-1 inhibitor were applied, the incidence of pyroptosis was detected by flow cytometry, the osteogenic differentiation of hPDLFs was observed using alkaline phosphatase and alizarin red staining, Real-time quantitative polymerase chain reaction and Western Blot were used to detect the expression of relevant factors, the release of interleukin-1β, interleukin-18 and lactate dehydrogenase were detected by Enzyme-linked immunosorbent assay.

RESULTS

The results demonstrated that NAC protected hPDLFs from lipopolysaccharides/ATP-induced damage, alleviating pyroptosis and osteogenic differentiation dysfunction. Moreover, NAC abrogated the inhibition of SIRT1 activity by scavenging reactive oxygen species, thereby reduced pyroptosis and osteogenic differentiation dysfunction by inhibiting the NF-κB/Caspase-1signaling pathway.

CONCLUSION

NAC could inhibit pyroptosis and osteogenic differentiation dysfunction of hPDLFs by scavenging reactive oxygen species to regulate the SIRT1/NF-κB/Caspase-1 signaling axis.

The effect of natural polyphenols Resveratrol, Gallic acid, and Kuromanin chloride on human telomerase reverse transcriptase (hTERT) expression in HepG2 hepatocellular carcinoma: role of SIRT1/Nrf2 signaling pathway and oxidative stress

BACKGROUND

There is evidence that low doses or physiological concentrations of certain natural polyphenols enhance the activity of telomerase. However, the precise mechanism by which natural polyphenols regulate telomerase activity remains unclear. Recent research indicates that NF-E2 related factor 2 (Nrf2) and silent information regulator 1 (SIRT1) are involved in human telomerase reverse transcriptase (hTERT) regulation. Thus, in order to better comprehend the mechanism by which polyphenols regulate hTERT, the present study investigated the effects of the natural polyphenols Resveratrol, Gallic acid, and Kuromanin chloride on hTERT, Nrf2, and SIRT1 expression as well as oxidative stress in HepG2 hepatocellular carcinoma.

METHODS

The trypan blue dye exclusion assay was used to assess cell viability. The level of mRNA for hTERT, Nrf2, and SIRT1 was then determined using real-time PCR. A spectrophotometric analysis was conducted to quantify oxidative stress markers.

RESULTS

The results demonstrated that Resveratrol induces the expression of hTERT and the SIRT1/Nrf2 pathway in a dose-dependent manner. Gallic acid at concentrations of 10 and 20 μM also increased the expression of the hTERT and SIRT1/Nrf2 pathway. Furthermore, dose-dependent overexpression of hTERT and Nrf2 was induced by Kuromanin chloride at 10 and 20 µM. Moreover, we found that Resveratrol and Kuromanin chloride ameliorated oxidative stress, whereas Gallic acid exacerbated it.

CONCLUSIONS

This study demonstrates that low doses of polyphenols (Resveratrol, Gallic acid, and Kuromanin chloride) upregulate the expression of the hTERT gene in the HepG2 hepatocellular carcinoma cell line, possibly via induction of the SIRT1/Nrf2 signaling pathway. Therefore, by targeting this pathway or hTERT, the anti-cancer effect of polyphenols can be enhanced.

Adenosine monophosphate activated protein kinase contributes to skeletal muscle health through the control of mitochondrial function

Skeletal muscle is one of the largest organs in the body and the largest protein repository. Mitochondria are the main energy-producing organelles in cells and play an important role in skeletal muscle health and function. They participate in several biological processes related to skeletal muscle metabolism, growth, and regeneration. Adenosine monophosphate-activated protein kinase (AMPK) is a metabolic sensor and regulator of systemic energy balance. AMPK is involved in the control of energy metabolism by regulating many downstream targets. In this review, we propose that AMPK directly controls several facets of mitochondrial function, which in turn controls skeletal muscle metabolism and health. This review is divided into four parts. First, we summarize the properties of AMPK signal transduction and its upstream activators. Second, we discuss the role of mitochondria in myogenesis, muscle atrophy, regeneration post-injury of skeletal muscle cells. Third, we elaborate the effects of AMPK on mitochondrial biogenesis, fusion, fission and mitochondrial autophagy, and discuss how AMPK regulates the metabolism of skeletal muscle by regulating mitochondrial function. Finally, we discuss the effects of AMPK activators on muscle disease status. This review thus represents a foundation for understanding this biological process of mitochondrial dynamics regulated by AMPK in the metabolism of skeletal muscle. A better understanding of the role of AMPK on mitochondrial dynamic is essential to improve mitochondrial function, and hence promote skeletal muscle health and function.

Botanicals and Oral Stem Cell Mediated Regeneration: A Paradigm Shift from Artificial to Biological Replacement

Stem cells are a well-known autologous pluripotent cell source, having excellent potential to develop into specialized cells, such as brain, skin, and bone marrow cells. The oral cavity is reported to be a rich source of multiple types of oral stem cells, including the dental pulp, mucosal soft tissues, periodontal ligament, and apical papilla. Oral stem cells were useful for both the regeneration of soft tissue components in the dental pulp and mineralized structure regeneration, such as bone or dentin, and can be a viable substitute for traditionally used bone marrow stem cells. In recent years, several studies have reported that plant extracts or compounds promoted the proliferation, differentiation, and survival of different oral stem cells. This review is carried out by following the PRISMA guidelines and focusing mainly on the effects of bioactive compounds on oral stem cell-mediated dental, bone, and neural regeneration. It is observed that in recent years studies were mainly focused on the utilization of oral stem cell-mediated regeneration of bone or dental mesenchymal cells, however, the utility of bioactive compounds on oral stem cell-mediated regeneration requires additional assessment beyond in vitro and in vivo studies, and requires more randomized clinical trials and case studies.

Therapeutic application of quercetin in aging-related diseases: SIRT1 as a potential mechanism

Quercetin, a naturally non-toxic flavonoid within the safe dose range with antioxidant, anti-apoptotic and anti-inflammatory properties, plays an important role in the treatment of aging-related diseases. Sirtuin 1 (SIRT1), a member of NAD+-dependent deacetylase enzyme family, is extensively explored as a potential therapeutic target for attenuating aging-induced disorders. SIRT1 possess beneficial effects against aging-related diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), Depression, Osteoporosis, Myocardial ischemia (M/I) and reperfusion (MI/R), Atherosclerosis (AS), and Diabetes. Previous studies have reported that aging increases tissue susceptibility, whereas, SIRT1 regulates cellular senescence and multiple aging-related cellular processes, including SIRT1/Keap1/Nrf2/HO-1 and SIRTI/PI3K/Akt/GSK-3β mediated oxidative stress, SIRT1/NF-κB and SIRT1/NLRP3 regulated inflammatory response, SIRT1/PGC1α/eIF2α/ATF4/CHOP and SIRT1/PKD1/CREB controlled phosphorylation, SIRT1-PINK1-Parkin mediated mitochondrial damage, SIRT1/FoxO mediated autophagy, and SIRT1/FoxG1/CREB/BDNF/Trkβ-catenin mediated neuroprotective effects. In this review, we summarized the role of SIRT1 in the improvement of the attenuation effect of quercetin on aging-related diseases and the relationship between relevant signaling pathways regulated by SIRT1. Moreover, the functional regulation of quercetin in aging-related markers such as oxidative stress, inflammatory response, mitochondrial function, autophagy and apoptosis through SIRT1 was discussed. Finally, the prospects of an extracellular vesicles (EVs) as quercetin loading and delivery, and SIRT1-mediated EVs as signal carriers for treating aging-related diseases, as well as discussed the ferroptosis alleviation effects of quercetin to protect against aging-related disease via activating SIRT1. Generally, SIRT1 may serve as a promising therapeutic target in the treatment of aging-related diseases via inhibiting oxidative stress, reducing inflammatory responses, and restoring mitochondrial dysfunction.

miRNA-Gene Interaction Network Construction Strategy to Discern Promising Traditional Chinese Medicine against Osteoporosis

Osteoporosis is a widespread bone disease that affects million cases annually. The underlying mechanisms behind the progress of osteoporosis remain enigmatic, which limits detections of biomarkers and therapeutic targets. Hence, this study was aimed at exploring hub molecules to better understand the mechanism of osteoporosis development and discover the traditional Chinese medicine potential drugs for osteoporosis. miRNA and gene expression profiles were downloaded from Gene Expression Omnibus (GEO). Weighted correlation network analysis (WGCNA) was used to identify the key modules for osteoporosis. DIANA Tools was applied to perform pathway enrichment. A miRNA-gene interaction network was constructed, and hub miRNAs and genes were distinguished using Cytoscape software. Receiver operating characteristic (ROC) curves of hub miRNAs and genes were plotted, and correlations with hub genes and osteoporosis-associated factors were evaluated. Potential drugs for osteoporosis in Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) were screened, and molecular docking models between these drugs and target genes were showed by AutoDock tools. Two hub modules, 1 miRNA module and 1 gene module, were identified to be the most strongly correlated with osteoporosis by using WGCNA. Then, 3 KEGG pathways including focal adhesion, PI3K-Akt signaling pathway, and gap junction were shared pathways enriched with the miRNAs and genes screened out by WGCNA and differential expression analyses. Finally, after constructing a miRNA-gene interaction network, 6 hub miRNAs (hsa-miR-18b-3p, hsa-miR-361-3p, hsa-miR-484, hsa-miR-519e-5p, hsa-miR-940, and hsa-miR-1275) and 6 hub genes (THBS1, IFNAR2, ARHGAP5, TUBB2B, FLNC, and NTF3) were detected. ROC curves showed good performances of miRNAs and genes for osteoporosis. Correlations with hub genes and osteoporosis-associated factors suggested implicational roles of them for osteoporosis. Based on these hub genes, 3 natural compounds (kainic acid, uridine, and quercetin), which were the active ingredients of 192 herbs, were screened out, and a target-compound-herb network was extracted using TCMSP. Molecular docking models of kainic acid-NTF3, uridine-IFNAR2, and quercetin-THBS1 were exhibited with AutoDock tools. Our study sheds light on the pathogenesis of osteoporosis and provides promising therapeutic targets and traditional Chinese medicine drugs for osteoporosis.

Anti-osteoporosis effects and regulatory mechanism of Lindera aggregata based on network pharmacology and experimental validation

Osteoporosis (OP) is characterized by the flaccidity of bones or bone bi-disease caused by kidney deficiency. Lindera aggregate has been used to strengthen kidney function in China for thousands of years. It has been approved by Chinese Pharmacopoeia that the root of Lindera aggregata (RLA) can replenish and tonify the kidney, which is thought to be an effective way to alleviate OP. In this study, a network pharmacology approach was applied to explore the active components and potential mechanisms of RLA in osteoporosis treatment. Then, the ethanolic extract of the root of L. aggregata (EERL) was prepared and these predicted results were validated by prednisone-induced zebrafish embryos model. Moreover, the candidate compounds were identified by UPLC-ESI-MS/MS. The anti-OP results showed that EERL could significantly reverse the bone loss of zebrafish induced by prednisone. The mRNA expressions results showed that EERL decreased osteoclast bone resorption by regulating the RANK/RANKL/OPG system. Also, it increased bone formation by regulating the gene expressions of spp1, mmp2, mmp9, runx2b, alp, and entpd5a. Our results demonstrated the reliability of the network pharmacology method, and also revealed the anti-OP effect and potential mechanism of RLA.

Activation of MT1/MT2 to Protect Testes and Leydig Cells against Cisplatin-Induced Oxidative Stress through the SIRT1/Nrf2 Signaling Pathway

There is growing concern that chemotherapy drugs can damage Leydig cells and inhibit the production of testosterone. Increasing evidence shows that melatonin benefits the reproductive process. This study mainly explores the protective effect and possible molecular mechanism of melatonin regarding cisplatin-induced oxidative stress in testicular tissue and Leydig cells. We found that there were only Leydig and Sertoli cells in the testes of gastrointestinal tumor patients with azoospermia caused by platinum chemotherapeutic drugs. Melatonin (Mel) receptor 1/melatonin receptor 2 (MT1/MT2) was mainly expressed in human and mouse Leydig cells of the testes. We also observed that the melatonin level in the peripheral blood decreased and oxidative stress occurred in mice treated with cisplatin or gastrointestinal tumor patients treated with platinum-based chemotherapeutic drugs. iTRAQ proteomics showed that SIRT1/Nrf2 signaling and MT1 proteins were downregulated in cisplatin-treated mouse testes. The STRING database predicted that MT1 might be able to regulate the SIRT1/Nrf2 signaling pathway. Melatonin reduced oxidative stress and upregulated SIRT1/Nrf2 signaling in cisplatin-treated mouse testes and Leydig cells. Most importantly, after inhibiting MT1/MT2, melatonin could not upregulate SIRT1/Nrf2 signaling in cisplatin-treated Leydig cells. The MT1/MT2 inhibitor aggravated the cisplatin-induced downregulation of SIRT1/Nrf2 signaling and increased the apoptosis of Leydig cells. We believe that melatonin stimulates SIRT1/Nrf2 signaling by activating MT1/MT2 to prevent the cisplatin-induced apoptosis of Leydig cells.

The potential biological effects of quercetin based on pharmacokinetics and multi-targeted mechanism in vivo

Quercetin is a plant-derived polyphenol flavonoid that has been proven to be effective for many diseases. However, the mechanism and in vivo metabolism of quercetin remains to be clarified. It achieves a wide range of biological effects through various metabolites, gut microbiota and its metabolites, systemic mediators produced by inflammation and oxidation, as well as by multiple mechanisms. The all-round disease treatment of quercetin is achieved through the organic combination of multiple channels. Therefore, this article clarifies the metabolic process of quercetin in the body, and explores the new pattern of action of quercetin in the treatment of diseases.

lncRNA MALAT1 mediates osteogenic differentiation of bone mesenchymal stem cells by sponging miR-129-5p

Background

Bone mesenchymal stem cells (BMSCs) have good osteogenic differentiation potential and have become ideal seed cells in bone tissue engineering. However, the osteogenic differentiation ability of BMSCs gradually weakens with age, and the regulatory mechanism is unclear.

Method

We conducted a bioinformatics analysis, dual-luciferase reporter (DLR) experiment, and RNA binding protein immunoprecipitation (RIP) to explore the hub genes that may affect BMSC functions.

Results

The expression level of long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (Malat1) was significantly higher in the BMSCs from elderly than younger mice, while miR-129-5p showed the opposite trend. The results of alkaline phosphatase staining, quantitative reverse transcription PCR and western blot experiments indicated that inhibiting the expression of Malat1 inhibits the osteogenic differentiation of BMSCs. This effect can be reversed by reducing the expression of miR-129-5p. Additionally, DLR and RIP experiments confirmed that Malat1 acts as a sponge for miR-129-5p.

Conclusion

Overall, our study findings indicated that lncRNA Malat1 may play a critical role in maintaining the osteoblast differentiation potential of BMSCs by sponging miR-129-5p.

Network Pharmacology and Molecular Docking Elucidate the Pharmacological Mechanism of the OSTEOWONDER Capsule for Treating Osteoporosis

Background: Osteoporosis (OP) is a serious and common bone metabolic disease with bone mass loss and bone microarchitectural deterioration. The OSTEOWONDER capsule is clinically used to treat OP. However, the potential regulatory mechanism of the OSTEOWONDER capsule in treatment of OP remains largely unknown.

Methods: The bioactive compounds of herbs and their targets were identified using the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) database. The speculative targets of OP were screened out based on GeneCards, DisGeNET, and Online Mendelian Inheritance in Man (OMIM) databases. The gene modules and hub genes of OP were identified using a weighted gene co-expression network analysis (WGCNA). Then, an herb-compound-target network was constructed based on the above analyses. The biological function of targets was subsequently investigated, and a protein–protein interaction (PPI) network was constructed to identify hub targets of OP. Finally, molecular docking was performed to explore the interaction between compounds and targets.

Results: A total of 148 compounds of eight herbs and the corresponding 273 targets were identified based on the TCMSP database. A total of 4,929 targets of OP were obtained based on GeneCards, DisGeNET, and OMIM databases. In addition, six gene modules and 4,235 hub genes of OP were screened out based on WGCNA. Generally, an herb-compound-target network, including eight herbs, 84 compounds, and 58 targets, was constructed to investigate the therapeutic mechanism of the OSTEOWONDER capsule for OP. The biofunction analysis indicated 58 targets mainly associated with the bone metabolism, stimulation response, and immune response. EGFR, HIF1A, MAPK8, IL6, and PPARG were identified as the hub therapeutic targets in OP. Moreover, the interaction between EGFR, HIF1A, MAPK8, IL6, PPARG, and the corresponding compounds (quercetin and nobiletin) was analyzed using molecular docking.

Conclusion: Our finding discovered the possible therapeutic mechanisms of the OSTEOWONDER capsule and supplied the potential therapeutic targets for OP.

Local Elimination of Senescent Cells Promotes Bone Defect Repair during Aging

Due to the declined function of bone marrow mesenchymal stem cells (BMSCs), the repair of bone defects in the elderly is retarded. Elimination of senescent cells emerges as a promising strategy for treating age-related diseases. However, whether the local elimination of senescent BMSCs can promote bone regeneration in the elderly remains elusive. To tackle the above issue, we first screened out the specific senolytics for BMSCs and confirmed their effect of eliminating senescent BMSCs in vitro. Treatment with quercetin, which is determined the best senolytics for senescent BMSCs, efficiently removed senescent cells in the population. Moreover, the self-renewal capacity was restored as well as osteogenic ability of BMSCs after treatment. We then designed a microenvironment-responsive hydrogel based on the MMPs secreted by senescent cells. This quercetin-encapsulated hydrogel exhibited a stable microstructure and responsively released quercetin in the presence of senescence in vitro. In vivo, the quercetin-loaded hydrogel effectively cleared the local senescent cells and reduced the secretion of MMPs in the bone. Due to the removal of local senescent cells, the hydrogel significantly accelerated the repair of bone defects in the femur and skull of old rats. Taken together, our study revealed the role of removing senescent cells in bone regeneration and provided a novel therapeutic approach for bone defects in aged individuals.

The Role of Macronutrients, Micronutrients and Flavonoid Polyphenols in the Prevention and Treatment of Osteoporosis

Osteoporosis is considered an age-related disorder of the skeletal system, characterized primarily by decreased bone mineral density (BMD), microstructural quality and an elevated risk of fragility fractures. This silent disease is increasingly becoming a global epidemic due to an aging population and longer life expectancy. It is known that nutrition and physical activity play an important role in skeletal health, both in achieving the highest BMD and in maintaining bone health. In this review, the role of macronutrients (proteins, lipids, carbohydrates), micronutrients (minerals—calcium, phosphorus, magnesium, as well as vitamins—D, C, K) and flavonoid polyphenols (quercetin, rutin, luteolin, kaempferol, naringin) which appear to be essential for the prevention and treatment of osteoporosis, are characterized. Moreover, the importance of various naturally available nutrients, whether in the diet or in food supplements, is emphasized. In addition to pharmacotherapy, the basis of osteoporosis prevention is a healthy diet rich mainly in fruits, vegetables, seafood and fish oil supplements, specific dairy products, containing a sufficient amount of all aforementioned nutritional substances along with regular physical activity. The effect of diet alone in this context may depend on an individual’s genotype, gene-diet interactions or the composition and function of the gut microbiota.