Icariin inhibits osteoclast differentiation and bone resorption by suppression of MAPKs/NF-κB regulated HIF-1α and PGE(2) synthesis

Nutraceuticals in osteoporosis prevention

Nutraceuticals are gaining popularity as they can contribute to bone health by delaying the onset or slowing down the progression of pathological bone loss. Osteoporosis's bone loss is a concern for older adults and a crucial aspect of aging. Maintaining healthy bones is the key to living a full and active life. Our review explores the current knowledge on the role of nutraceuticals in preventing osteoporosis by focusing on three main aspects. First, we provide an overview of osteoporosis. Second, we discuss the latest findings on natural nutraceuticals and their efficacy in reducing bone loss, emphasizing clinical trials. Third, we conduct a structured analysis to evaluate nutraceuticals' pros and cons and identify translational gaps. In conclusion, we must address several challenges to consolidate our knowledge, better support clinicians in their prescriptions, and provide people with more reliable nutritional recommendations to help them lead healthier lives.

Icariin promotes cell adhesion for osteogenesis in bone marrow stromal cells via binding to integrin α5β1

BACKGROUND AND PURPOSE

Icariin, an 8-prenylated flavonoid glycoside, is an anabolic agent that could exert rapid estrogenic actions via ligand-independent activation of estrogen receptor alpha (ERα) in osteoblastic cells to promote osteogenesis. However, relatively little is known about its direct cellular target, its protective effects, and cell adhesion activities in bone marrow stromal cells (BMSCs) against microgravity. In the present study, the effects of icariin on osteogenesis and cell adhesion under microgravity were examined with the involvement of integrin receptor α5β1, connexin 43, and CAMs.

STUDY DESIGN AND METHODS

Icariin was orally administered to 6-month-old ovariectomized (OVX) Sprague-Dawley (SD) rats for 3 months through daily intake of phytoestrogen-free rodent diets containing icariin at 2 different dosages (50 and 500 ppm). BMSCs were harvested for experiments and RNA-sequencing analysis to examine the mechanism of action of icariin and its direct cellular target in stimulating osteogenesis.

RESULTS

The results revealed that icariin induced the expression of cell adhesion molecules (CAMs) and protected against microgravity-induced disruption of actin cytoskeleton and the loss of osteogenic activities in BMSCs through the activation of connexin-43 (Cx43) and Ras homolog family member A (RhoA) and Rac family small GTPase 1 (Rac1)-mediated signaling pathways. Computerized molecular docking techniques and the competitive solid-phase binding ELISA assay confirmed that icariin could be a direct ligand of integrin alpha 5 beta 1 (α5β1), and it could also increase the protein expression of integrin α5β1 for mechanosensing.

CONCLUSION

Our findings suggest that icariin could directly activate cell adhesion signaling by binding to integrin α5β1, which opens up new avenues for the development of integrin α5β1 ligand as an agent to protect against unloading-induced bone loss.

Investigating the anti-inflammatory effects of icariin: A combined meta-analysis and machine learning study

Objective

The objectives of this study were to define the superiority of icariin and its derivatives' anti-inflammatory activities and to create a reference framework for evaluating preclinical evidence. This method combines machine learning and meta-analysis to identify underlying biological pathways.

Methods

Data came from PubMed, Embase, Web of Science, and the Cochrane Library. SYRCLE was used to evaluate the risk of bias in a subset of research. Meta-analysis and detailed subgroup analyses, categorized by species, genders, disease type, dosage, and treatment duration, were performed using R and STATA 15.0 software to derive nuanced insights. Employing R software (version 4.2.3) and the tidymodels package, the analysis focused on constructing a model and selecting features, with TNF-α as the dependent variable. This approach aims to identify significant predictors of drug efficacy. An in-depth literature facilitated the synthesis of anti-inflammatory mechanisms attributed to icariin and its constituent compounds.

Results

Following a meticulous search and selection process, 19 studies, involving 370 and 260 animals were included in the meta-analysis and machine-learning assessment, respectively. The findings revealed that icariin and its derivatives markedly reduced inflammation markers, including TNF-α and IL-1β. Additionally, machine-learning outcomes, with TNF-α as the target variable, indicated enhanced anti-inflammatory effects of icariin across respiratory, urological, neurological, and digestive disease types. These effects were more pronounced at doses exceeding 27.52 mg/kg/day and treatment durations beyond 31.22 days.

Conclusion

Strong anti-inflammatory effects are exhibited by icariiin and its derivatives, which are especially beneficial in the management of digestive, neurological, pulmonary, and urinary conditions. Effective for periods longer than 31.22 days and at dosages more than 27.52 mg/kg/day. Subsequent research will involve more targeted animal experiments and safety assessments to obtain more comprehensive preclinical evidence.

Anti-osteoporosis effect of bioactives in edible medicinal plants: a comprehensive review

Current treatments for osteoporosis include a calcium-rich diet, adequate exercise, and medication. Many synthetic drugs, although fast-acting, can cause a range of side effects for patients when taken over a long period, such as irritation of the digestive tract and a burden on the kidneys. As the world's population ages, the prevalence of osteoporosis is increasing, and the development of safe and effective treatments is urgently needed. Active compounds in edible and medicinal homologous plants have been used for centuries to improve bone quality. It is possible to employ them as dietary supplements to prevent osteoporosis. In this review, we analyze the influencing factors of osteoporosis and systematically summarize the research progress on the anti-osteoporosis effects of active compounds in edible and medicinal homologous plants. The literature suggests that some naturally occurring active compounds in edible and medicinal homologous plants can inhibit bone loss, prevent the degeneration of bone cell microstructure, and reduce bone fragility through alleviating oxidative stress, regulating autophagy, anti-inflammation, improving gut flora, and regulating estrogen level with little side effects. Our review provides useful guidance for the use of edible and medicinal homologous plants and the development of safer novel anti-osteoporosis dietary supplements.

Synergistic Effects of Icariin and Extracellular Vesicles Derived from Rabbit Synovial Membrane-Derived Mesenchymal Stem Cells on Osteochondral Repair via the Wnt/β-Catenin Pathway

Objectives

Osteochondral defects (OCDs) are localized areas of damaged cartilage and underlying subchondral bone that can produce pain and seriously impair joint function. Literature reports indicated that icariin (ICA) has the effect of promoting cartilage repair. However, its mechanism remains unclear. Here, we explored the effects of icariin and extracellular vesicles (EVs) from rabbit synovial-derived mesenchymal stem cells (rSMSCs) on repairing of OCDs.

Materials and Methods

Rabbit primary genicular chondrocytes (rPGCs), knee skeletal muscle cells (rSMCKs), and rSMSCs, and extracellular vesicles derived from the latter two cells (rSMCK-EVs and rSMSC-EVs) were isolated and identified. The rPGCs were stimulated with ICA, rSMSC-EVs either separately or in combination. The rSMCK-EVs were used as a control. After stimulation, chondrogenic-related markers were analyzed by quantitative RT-PCR and western blotting. Cell proliferation was determined by the CCK-8 assay. The preventative effects of ICA and SMSC-EVs in vivo were determined by H&E and toluidine blue staining. Immunohistochemical analyses were performed to evaluate the levels of COL2A1 and β-catenin in vivo. Results. In vitro, the proliferation of rPGCs was markedly increased by ICA treatment in a dose-dependent manner. When compared with ICA or rSMSC-EVs treatment alone, combined treatment with ICA and SMSC-EVs produced stronger stimulative effects on cell proliferation. Moreover, combined treatment with ICA and rSMSC-EVs promoted the expression of chondrogenic-related gene, including COL2A1, SOX-9, and RUNX2, which may be via the activation of the Wnt/β-catenin pathway. In vivo, combined treatment with rSMSC-EVs and ICA promoted cartilage repair in joint bone defects. Results also showed that ICA or rSMSC-EVs both promoted the COL2A1 and β-catenin protein accumulation in articular cartilage, and that was further enhanced by combined treatment with rSMSC-EVs and ICA.

Conclusion

Our findings highlight the promising potential of using combined treatment with ICA and rSMSC-EVs for promoting osteochondral repair.

Exploring the molecular mechanism of Epimedium for the treatment of ankylosing spondylitis based on network pharmacology, molecular docking, and molecular dynamics simulations

Ankylosing spondylitis (AS) is a rheumatic disease that causes inflammation and bone formation in the spine. Despite significant advances in treatment, adverse side effects have triggered research into natural compounds. Epimedium (EP) is a traditional Chinese herb with a variety of pharmacological activities, including antirheumatic, anti-inflammatory, and immunomodulatory activities; however, its direct effects on AS treatment and the underlying molecular mechanisms have not been systematically studied. Thus, here, we used network pharmacology, molecular docking, and molecular dynamics simulations to explore the targets of EP for treating AS. We constructed an interaction network to elucidate the complex relationship between EP and AS. Sixteen active ingredients in EP were screened; 80 potential targets were identified. In particular, 8-(3-methylbut-2-enyl)-2-phenylchromone, anhydroicaritin, and luteolin were the core components and TNF, IL-6, IL-1β, MMP9, and PTGS2 were the core targets. The GO and KEGG analyses indicated that EP may modulate multiple biological processes and pathways, including the AGE-RAGE, TNF, NF-κB/MAPK, and TLR signaling pathways, for AS treatment. Molecular docking and molecular dynamics simulations showed good affinity between the active components and core targets of EP, with stable binding within 100 nanoseconds. In particular, 8-(3-methylbut-2-enyl)-2-phenylchromone possessed the highest free energy of binding to PTGS2 and TNF (-115.575 and - 87.676 kcal/mol, respectively). Thus, EP may affect AS through multiple pathways, including the alleviation of inflammation, oxidative stress, and immune responses. In summary, we identified the active components and potential targets of EP, highlighting new strategies for the further experimental validation and exploration of lead compounds for treating AS.

Icariin regulates RANKL-induced osteoclast differentiation via the ERα/c-Src/RANK signaling

Osteoporosis (OP) is a common metabolic bone disease. Excessive osteoclastic activity significantly contributes to the development of OP. Icariin (ICA) is a flavonol glycoside derived from herbal plants and possesses curative effects on postmenopausal OP and bone fracture. This study aimed to investigate the effects of ICA on osteoclast differentiation induced by receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) and the involvement of estrogen receptorα(ERα) and RANK signaling cascade in this process. RANKL was used to induce the differentiation of RAW264.7 cells to into osteoclasts. Small interfering RNA technique was used to knockdown ERαin cells. Cell counting kit-8 assay was performed to determine the cytotoxicity of ICA. The number of tartrate-resistant acid phosphatase (TRAP)-positive cells was quantified by TRAP staining. RANKL induced the differentiation of RAW264.7 cells into osteoclasts, while ICA abolished the pro-osteoporotic effect of RANKL. Moreover, ERαknockdown abolished the effects of ICA on RANKL-induced osteoclastogenesis. Further exploration revealed that ICA inhibited the phosphorylation ofc-Src in osteoclasts via regulating ERα, while inactivation ofc-Src reversed ERαknockdown-promoted osteoclastogenesis. Lastly, ICA inhibited the activation of the mitogen-activated protein kinase signaling pathway and downregulated the expressions of target osteoclastogenic proteins in RANKL-treated RAW 264.7 cells, while ERαknockdown almost completely diminished the effects of ICA. ICA inhibited RANKL-induced osteoclast differentiation via regulating the ERα/c-Src/RANK signaling. These findings elucidated a novel mechanism by which ICA exerts an anti-osteoporotic effect.

Effect of icariin surface treatment on the resorption of denuded roots after replantation in rat

AIM

Limiting the incidence of resorption associated with delayed replantation of avulsed teeth is critical for long-term tooth survival. In this study, we assessed whether icariin, a natural product with anti-osteoclastic properties, could reduce root resorption in a rat model of tooth replantation.

METHODOLOGY

Cytocompatibility of icariin (10, 20, 40 and 80 μM) was evaluated by CCK-8 proliferation assay in vitro, and an osteoclastogenesis assay was performed to evaluate the effect of icariin on the differentiation of rat bone marrow macrophages and human peripheral blood monocytes into tartrate-resistant acid phosphatase-stained (TRAP+ ) multinucleated giant cells (MNGCs). Differentiation of human periodontal ligament stem cells (hPDLSCs) treated with icariin (10 μM) was also evaluated at 5, 10 and 21 days of osteogenic induction. The first maxillary molars of five-week-old male Sprague-Dawley rats were extracted, denuded of PDL, then treated either with neutralized collagen solution (Carrier control) or icariin in collagen (3 μg/μL) before replantation into their sockets. The animals were euthanized 2 weeks post-surgery for micro-computed tomography (micro-CT) imaging and histological analyses.

RESULTS

Icariin was cytocompatible and significantly reduced the differentiation of TRAP+ MNGCs in a dose-dependent manner compared to the control. Moreover, icariin enhanced alkaline phosphatase activity, expression of osteogenic marker genes and proteins, and calcium deposition in hPDLSCs. Micro-CT imaging of the replanted samples demonstrated a significantly higher volume of remaining roots in the icariin-treated group than in the control group. Histological analysis revealed a marked number of resorptive lacunae with TRAP activity in the control group, whereas icariin-treated samples showed signs of functional healing and reduced osteoclastic activity.

CONCLUSIONS

Icariin was biocompatible and demonstrated potent anti-osteoclastic and pro-osteogenic properties that reduced resorption and promoted functional healing of denuded roots in a rat maxillary first molar model of replantation. These findings indicate that root surface treatment with icariin may be a clinically relevant and practical method for improving the retention and survival of teeth with compromised PDL after delayed replantation following traumatic avulsion.

A review on therapeutic mechanism of medicinal plants against osteoporosis: effects of phytoconstituents

Osteoporosis is a metabolic bone disorder that over time results in bone loss and raises the risk of fracture. The condition is frequently silent and only becomes apparent when fractures develop. Osteoporosis is treated with pharmacotherapy as well as non-pharmacological therapies such as mineral supplements, lifestyle changes, and exercise routines. Herbal medicine is frequently used in clinical procedures because of its low risk of adverse effects and cost-effective therapeutic results. In the current review, we have used a thorough strategy to identify some known medicinal plants with anti-osteoporosis capabilities, their origin, active ingredients, and pharmacological information. Furthermore, several signaling pathways, such as the apoptotic pathway, transcription factors, the Wnt/-catenin signaling pathway, and others, are regulated by bioactive components and help to improve bone homeostasis. This review will provide a better understanding of the anti-osteoporotic effects of bioactive components and the concomitant modulations of signaling pathways.

Icariin inhibits prostate cancer bone metastasis and destruction via suppressing TAM/CCL5-mediated osteoclastogenesis

BACKGROUND

Bone metastasis occurs in nearly 70% of patients with metastatic prostate cancer (PCa), and represents the leading cause of death in patients with PCa. Emerging evidence has demonstrated the potential activities of icariin in modulating bone metabolism and remodelling the tumor microenvironment (TME). However, whether icariin could inhibit PCa bone metastasis and destruction by modulating the TME as well as the underlying mechanisms remains unclear.

PURPOSE

This study investigated whether icariin could inhibit PCa bone metastasis and destruction by modulating the bone TME as well as the underlying mechanisms.

METHODS

Osteoclasts were induced from mouse bone marrow-derived macrophages (BMMs) or Raw264.7 cells. PCa cells were cultured in the conditional medium (CM) of macrophages in vitro or co-injected with macrophages in vivo to simulate their coexistence in the TME. Multiple molecular biology experiments and the mouse RM1-Luc PCa bone metastasis model were used to explore the inhibitory activity and mechanism of icariin on PCa metastasis and bone destruction.

RESULTS

Icariin treatment significantly suppressed PCa growth, bone metastasis and destruction as well as osteoclastogenesis in vivo. Furthermore, icariin remarkably inhibited osteoclast differentiation, even in the presence of the CM of tumor-associated macrophages (TAMs), while exhibiting no obvious effect on osteoblasts. Moreover, icariin suppressed the M2 phenotype polarization of Raw264.7-derived TAMs and transcriptionally attenuated their CC motif chemokine ligand 5 (CCL5) expression and secretion via inhibiting SPI1. Additionally, CCL5 induced the differentiation and chemotaxis of osteoclast precursor cells by binding with its receptor CCR5. The clinicopathological analysis further verified the positive correlation between the TAM/CCL5/CCR5 axis and osteoclastogenesis within the TME of PCa patients. More importantly, icariin remarkably suppressed PCa metastasis-induced bone destruction in vivo by inhibiting osteoclastogenesis via downregulating the TAM/CCL5 pathway.

CONCLUSION

Altogether, these results not only implicate icariin as a promising candidate immunomodulator for PCa bone metastasis and destruction but also shed novel insight into targeting TAM/CCL5-mediated osteoclastogenesis as a potential treatment strategy for osteolytic bone metastasis. This study helps to advance the understanding of the crosstalk between bone TME and bone homeostasis.

Synthetic Calcium-Phosphate Materials for Bone Grafting

Synthetic bone grafting materials play a significant role in various medical applications involving bone regeneration and repair. Their ability to mimic the properties of natural bone and promote the healing process has contributed to their growing relevance. While calcium-phosphates and their composites with various polymers and biopolymers are widely used in clinical and experimental research, the diverse range of available polymer-based materials poses challenges in selecting the most suitable grafts for successful bone repair. This review aims to address the fundamental issues of bone biology and regeneration while providing a clear perspective on the principles guiding the development of synthetic materials. In this study, we delve into the basic principles underlying the creation of synthetic bone composites and explore the mechanisms of formation for biologically important complexes and structures associated with the various constituent parts of these materials. Additionally, we offer comprehensive information on the application of biologically active substances to enhance the properties and bioactivity of synthetic bone grafting materials. By presenting these insights, our review enables a deeper understanding of the regeneration processes facilitated by the application of synthetic bone composites.

Icariin promotes osteogenic differentiation by upregulating alpha-enolase expression

Osteogenic differentiation is a crucial biological process for maintaining bone remodelling. Aerobic glycolysis is the main source of energy for osteogenic differentiation. Alpha-enolase (Eno1), a glycolytic enzyme, is a therapeutic target for numerous diseases. Icariin, a principal active component of the traditional Chinese medicine Epimedium grandiflorum, can stimulate osteogenic differentiation. Here, we aimed to determine if icariin promotes osteogenic differentiation via Eno1. Icariin (1 μM) significantly promoted osteogenic differentiation of MC3T3-E1 cells. Icariin upregulated Eno1 protein and gene expressions during osteogenic differentiation. Moreover, ENOblock, a specific inhibitor of Eno1, markedly inhibited icariin-induced osteogenic differentiation. Futhermore, western blot assay showed that Eno1 might mediate osteogenic differentiation through the BMP/Smad4 signalling pathway. Collectively, Eno1 could be a promising drug target for icariin to regulate osteogenic differentiation.

Anti-inflammatory and antioxidant traditional Chinese Medicine in treatment and prevention of osteoporosis

A metabolic bone disorder called osteoporosis is characterized by decreased bone mass and compromised microarchitecture. This condition can deteriorate bones and raise the risk of fractures. The two main causes of osteoporosis are an increase in osteoclast activity or quantity and a decrease in osteoblast viability. Numerous mechanisms, including estrogen shortage, aging, chemical agents, and decreased mechanical loads, have been linked to osteoporosis. Inflammation and oxidative stress have recently been linked to osteoporosis, according to an increasing number of studies. The two primary medications used to treat osteoporosis at the moment are bisphosphonates and selective estrogen receptor modulators (SERMs). These medications work well for osteoporosis brought on by aging and estrogen deprivation, however, they do not target inflammation and oxidative stress-induced osteoporosis. In addition, these drugs have some limitations that are attributed to various side effects that have not been overcome. Traditional Chinese medicine (TCM) has been applied in osteoporosis for many years and has a high safety profile. Therefore, in this review, literature related to botanical drugs that have an effect on inflammation and oxidative stress-induced osteoporosis was searched for. Moreover, the pharmacologically active ingredients of these herbs and the pathways were discussed and may contribute to the discovery of more safe and effective drugs for the treatment of osteoporosis.

Molecules Inducing Dental Stem Cells Differentiation and Bone Regeneration: State of the Art

Teeth include mesenchymal stem cells (MSCs), which are multipotent cells that promote tooth growth and repair. Dental tissues, specifically the dental pulp and the dental bud, constitute a relevant source of multipotent stem cells, known as dental-derived stem cells (d-DSCs): dental pulp stem cells (DPSCs) and dental bud stem cells (DBSCs). Cell treatment with bone-associated factors and stimulation with small molecule compounds are, among the available methods, the ones who show excellent advantages promoting stem cell differentiation and osteogenesis. Recently, attention has been paid to studies on natural and non-natural compounds. Many fruits, vegetables, and some drugs contain molecules that can enhance MSC osteogenic differentiation and therefore bone formation. The purpose of this review is to examine research work over the past 10 years that has investigated two different types of MSCs from dental tissues that are attractive targets for bone tissue engineering: DPSCs and DBSCs. The reconstruction of bone defects, in fact, is still a challenge and therefore more research is needed; the articles reviewed are meant to identify compounds useful to stimulate d-DSC proliferation and osteogenic differentiation. We only consider the results of the research which is encouraging, assuming that the mentioned compounds are of some importance for bone regeneration.

Understanding the mechanistic potential of plant based phytochemicals in management of postmenopausal osteoporosis

Postmenopausal osteoporosis, an epidemic disorder is defined as a loss in bone mineral density and a greater possibility of fractures in older women. It is a multifactorial disease under the control of various genetic, hormonal, and environmental factors. Insufficiency of estrogen hormone, leads to postmenopausal osteoporosis. Hormone replacement therapy (HRT), despite being the most effective treatment, it is associated with the risk of breast cancer and cardiovascular disorders. This review seeks to compile the most recent information on medicinal plants and natural compounds used to treat and prevent postmenopausal osteoporosis. Furthermore, the origin, chemical constituents and the molecular mechanisms responsible for this therapeutic and preventive effect are also discussed. Literature research was conducted using PubMed, Science direct, Scopus, Web of Science, and Google Scholar. Different plant extracts and pure compounds exerts their antiosteoporotic activity by inhibition of RANKL and upregulation of OPG. RANKL signaling regulates osteoclast formation, characterized by increased bone turnover and osteoprotegrin is a decoy receptor for RANKL thereby preventing bone loss from excessive resorption. In addition, this review also includes the chemical structure of bioactive compounds acting on NFκB, TNF α, RUNX2. In conclusion, we propose that postmenopausal osteoporosis could be prevented or treated with herbal products.

Phytochemistry and pharmacology of natural prenylated flavonoids

Prenylated flavonoids are a special kind of flavonoid derivative possessing one or more prenyl groups in the parent nucleus of the flavonoid. The presence of the prenyl side chain enriched the structural diversity of flavonoids and increased their bioactivity and bioavailability. Prenylated flavonoids show a wide range of biological activities, such as anti-cancer, anti-inflammatory, neuroprotective, anti-diabetic, anti-obesity, cardioprotective effects, and anti-osteoclastogenic activities. In recent years, many compounds with significant activity have been discovered with the continuous excavation of the medicinal value of prenylated flavonoids, and have attracted the extensive attention of pharmacologists. This review summarizes recent progress on research into natural active prenylated flavonoids to promote new discoveries of their medicinal value.

Anticancer and bone-enhanced nano-hydroxyapatite/gelatin/polylactic acid fibrous membrane with dual drug delivery and sequential release for osteosarcoma

Surgical resection of osteosarcoma is always accompanied by residual metastasis of tumor cells and bone tissue defects. In this work, a novel kind of gelatin/polylactic acid (PLA) coaxial fiber membrane with a shell layer containing doxorubicin-loaded hydroxyapatite (DOX@nHAp) nanoparticles and a core layer containing Icariin (ICA) was developed for antitumor and bone enhancement at the defect site. Physical evaluation displayed that the composite membrane provided moderate hydrophilicity, enhanced tensile strength (Dry: 2-3 MPa, wet: 1-2 MPa) and elasticity (70-100 %), as well as increased specific surface area and pore volume (19.39 m²/g and 0.16 cm³/g). In SBF, DOX@nHAp in the fibers promoted biomineralization on the fiber surface. In in vitro evaluation, approximately 80 % of DOX had a short-term release during the first 8 days, followed by long-term release behavior of ICA for up to 40 days. CCK-8 results confirmed that the membrane could actively support MC3T3-E1 cells proliferation and was conductive to high alkaline phosphatase expression, while the viability of MG-63 cells was effectively inhibited to 50 %. Thus, the dual-loaded fibrous membrane with a coaxial structure and nHAp is a promising system for anticancer and defects reconstruction after osteosarcoma surgery.

Icariin-conditioned serum combined with chitosan attenuates cartilage injury in rabbit knees with osteochondral defect

BACKGROUND

Knee osteoarthritis (KOA) is one of the most common degenerative diseases. Its development is closely related to cartilage injury and subchondral bone remodeling homeostasis. In the present study, we combined icariin-conditioned serum (ICS) with thiolated chitosan (CSSH), a material widely used in tissue engineering for cartilage repair, to demonstrate its effect on the repair of cartilage damage and abnormal subchondral remodeling.

METHODS

New Zealand rabbits were undergoing surgery for cartilage defect, and joint cavity injection was performed in each group with 0.5 mL normal saline (NS), ICS, CSSH and ICS-CSSH in the right joint every week for five times. Positioning performance was observed using VICON motion capture system. Glycosaminoglycans (GAG) secretion of articular fluid was assessed. Osteoarthritis Research Society International (OARSI) score and immunohistochemical (IHC) analysis including H&E, Safranin O and collagen II staining were employed to evaluate the morphologic repair of cartilage and subchondral bone. mRNA expression of COL2A1, MMP13 and ADAMTS5 was detected in chondrocytes from injury area.

RESULTS

ICS combined with CSSH attenuated cartilage injury and abnormal subchondral remodeling in rabbits with KOA. ICS and CSSH groups showed slight improvement in positioning performance, while ICS-CSSH group exhibited better positioning performance. ICS-CSSH group showed increased GAG secretion of articular fluid and expression of COL2A1 in articular chondrocytes. Furthermore, both macroscopic observation and IHC analysis showed femoral condyle in ICS-CSSH rabbits were repaired with more native cartilage and subchondral bone regeneration.

CONCLUSIONS

ICS combined with CSSH could promote the repair of osteochondral defect and stabilize subchondral bone remodeling in rabbit knees.

Hypoxia Pathway in Osteoporosis: Laboratory Data for Clinical Prospects

The hypoxia pathway not only regulates the organism to adapt to the special environment, such as short-term hypoxia in the plateau under normal physiological conditions, but also plays an important role in the occurrence and development of various diseases such as cancer, cardiovascular diseases, osteoporosis. Bone, as a special organ of the body, is in a relatively low oxygen environment, in which the expression of hypoxia-inducible factor (HIF)-related molecules maintains the necessary conditions for bone development. Osteoporosis disease with iron overload endangers individuals, families and society, and bone homeostasis disorder is linked to some extent with hypoxia pathway abnormality, so it is urgent to clarify the hypoxia pathway in osteoporosis to guide clinical medication efficiently. Based on this background, using the keywords "hypoxia/HIF, osteoporosis, osteoblasts, osteoclasts, osteocytes, iron/iron metabolism", a matching search was carried out through the Pubmed and Web Of Science databases, then the papers related to this review were screened, summarized and sorted. This review summarizes the relationship and regulation between the hypoxia pathway and osteoporosis (also including osteoblasts, osteoclasts, osteocytes) by arranging the references on the latest research progress, introduces briefly the application of hyperbaric oxygen therapy in osteoporosis symptoms (mechanical stimulation induces skeletal response to hypoxic signal activation), hypoxic-related drugs used in iron accumulation/osteoporosis model study, and also puts forward the prospects of future research.

Mechanisms by which kidney-tonifying Chinese herbs inhibit osteoclastogenesis: Emphasis on immune cells

The immune system plays a crucial role in regulating osteoclast formation and function and has significance for the occurrence and development of immune-mediated bone diseases. Kidney-tonifying Chinese herbs, based on the theory of traditional Chinese medicine (TCM) to unify the kidney and strengthen the bone, have been widely used in the prevention and treatment of bone diseases. The common botanical drugs are tonifying kidney-yang and nourishing kidney-yin herbs, which are divided into two parts: one is the compound prescription of TCM, and the other is the single preparation of TCM and its active ingredients. These botanical drugs regulate osteoclastogenesis directly and indirectly by immune cells, however, we have limited information on the differences between the two botanical drugs in osteoimmunology. In this review, the mechanism by which kidney-tonifying Chinese herbs inhibiting osteoclastogenesis was investigated, emphasizing the immune response. The differences in the mechanism of action between tonifying kidney-yang herbs and nourishing kidney-yin herbs were analysed, and the therapeutic value for immune-mediated bone diseases was evaluated.

Periplaneta Americana extract inhibits osteoclastic differentiation in vitro

OBJECTIVES

Periplaneta americana extract (PAE) is proven to be promising in treating fever, wound healing, liver fibrosis, and cardiovascular disease. However, the role of PAE in skeletal disorders remains unclear. This study investigated whether PAE regulates osteoclastic differentiation in vitro via the culture using RAW264.7 cells and bone marrow derived macrophages (BMDMs).

MATERIALS AND METHODS

RAW264.7 cells and BMDMs were cultured and induced for osteoclastic differentiation supplementing with different concentrations of PAE (0, 0.1, 1, and 10 mg/mL). Cell counting kit-8 (CCK-8) assay was used to detect the cytotoxicity and cell proliferation. TRAP staining, actin ring staining, real-time quantitative PCR (RT-qPCR), and bone resorption activity test were performed to detect osteoclastic differentiation. RT-qPCR and enzyme-linked immunosorbent assay (ELISA) were conducted to assay the expression and secretion of inflammatory factors. RNA sequencing (RNA-seq) and western blot analysis were carried out to uncover the underlying mechanism.

RESULTS

CCK-8 results showed that 10 mg/mL and a lower concentration of PAE did not affect cell proliferation. RT-qPCR analysis verified that PAE down-regulated the osteoclastic genes Nfatc1, Ctsk, and Acp5 in macrophages. Moreover, PAE restrained the differentiation, formation, and function of osteoclasts. Besides, RT-qPCR and ELISA assays showed that PAE decreased inflammatory genes expression and reduced the secretion of inflammatory factors, including IL1β, IL6, and TNFα. Subsequent RNA-seq analysis identified possible genes and signaling pathways of PAE-mediated osteoclastogenesis suppression.

CONCLUSIONS

Our study indicates that PAE has inhibitive effects on osteoclastogenesis and may be a potential therapeutic alternative for bone diseases.

Kidney tonifying traditional Chinese medicine: Potential implications for the prevention and treatment of osteoporosis

The aging global population is increasingly affected by osteoporosis (OP), which is one of the most significant threats to the elderly. Moreover, its prevention and treatment situations have become increasingly severe. Therefore, it is imperative to develop alternatives or complementary drugs for preventing and treating osteoporosis. Kidney tonifying traditional Chinese medicine (KTTCM) has been used for the treatment of osteoporosis for a long time. Pharmacological studies have shown that kidney tonifying traditional Chinese medicine can promote osteoblasts, inhibit osteoclasts, and regulate the level of estrogen and plays vital roles in stimulating osteogenesis, restraining adipogenesis of marrow mesenchymal stem cells (MSCs), regulating the metabolism of calcium and phosphorus, and inhibiting oxidative stress. These effects are mediated by OPG/RANKL/RANK, BMP/Smads, MAPKs, and Wnt/β-catenin systems. To develop a safe, synergistic, effective, and homogenized TCM formula with robust scientific evidence to provide faster and more economical alternatives, the anti-osteoporosis ingredients and pharmacological mechanisms of kidney tonifying traditional Chinese medicine are recapitulated from the perspective of molecular and cell biology, and the safety and toxicity of kidney tonifying traditional Chinese medicine have also been reviewed in this paper.

A mechanistic review of chinese medicine polyphenols on bone formation and resorption

Bone reconstruction includes a steady state system of bone formation and bone absorption. This tight coupling requires subtle coordination between osteoblasts and osteoclasts. If this balance is broken, it will lead to bone mass loss, bone density reduction, and bone metabolic diseases, such as osteoporosis. Polyphenols in Chinese herbal medicines are active ingredients in plant extracts with high safety and few side effects, and they can play a role in affecting bone formation and bone resorption. Some of these have estrogen-like effects and can better target bone health in postmenopausal women. The purpose of this review is to provide comprehensive information on the mechanisms underlying the relationship between traditional Chinese medicine polyphenols and bone formation or bone resorption.

Progress in Composite Hydrogels and Scaffolds Enriched with Icariin for Osteochondral Defect Healing

Osteochondral structure reconstruction by tissue engineering, a challenge in regenerative medicine, requires a scaffold that ensures both articular cartilage and subchondral bone remodeling. Functional hydrogels and scaffolds present a strategy for the controlled delivery of signaling molecules (growth factors and therapeutic drugs) and are considered a promising therapeutic approach. Icariin is a pharmacologically-active small molecule of prenylated flavonol glycoside and the main bioactive flavonoid isolated from Epimedium spp. The in vitro and in vivo testing of icariin showed chondrogenic and ostseoinductive effects, comparable to bone morphogenetic proteins, and suggested its use as an alternative to growth factors, representing a low-cost, promising approach for osteochondral regeneration. This paper reviews the complex structure of the osteochondral tissue, underlining the main aspects of osteochondral defects and those specifically occurring in osteoarthritis. The significance of icariin's structure and the extraction methods were emphasized. Studies revealing the valuable chondrogenic and osteogenic effects of icariin for osteochondral restoration were also reviewed. The review highlighted th recent state-of-the-art related to hydrogels and scaffolds enriched with icariin developed as biocompatible materials for osteochondral regeneration strategies.

Study on the Protective Effect and Mechanism of the Rhizoma Drynariae-Epimedium Formula on Osteoarthritis in Rats

Purpose

The aim of the study was to study the protective effect of the Rhizoma Drynariae-Epimedium formula on osteoarthritis in rats and to explore its mechanism.

Methods

Fifty SD rats were randomly divided into 5 groups, namely, the control group, model group, Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group, with 10 rats in each group. Knee arthritis models were established by injecting papain solution (10% papain + 0.03 mol/L L-cysteine mixture) into the knee joint cavity of SD rats on the 0th, 3rd, and 6th days of the experiment, respectively. The model group, Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group were given modeling treatment, while the control group was not given modeling treatment. The Rhizoma Drynariae group, Epimedium group, and the Rhizoma Drynariae-Epimedium group were, respectively, given corresponding solvent gavage treatment. Both the model group and the control group were given an equal volume of normal saline. Once a day, a total of 4 w were administered. The general conditions of the rats were observed and recorded, and the knee joint width and the knee joint swelling degree of the affected side were measured and compared. HE staining and Safranin O-fast green staining were used to compare the structural changes of cartilage. The concentrations of inflammatory factors IL-1β, IL-6, and TNF-α in the joint cavity lavage fluid were determined by using ELISA. The expression of key proteins of the MAPK signaling pathway (p38, p-p38, ERK, p-ERK, JNK, and p-JNK) in joint synovial tissue was determined by western blotting.

Results

After modeling, except for the normal activities of the SD rats in the control group, the rest of the groups showed lack of energy and a slight limp in the knee joints. The SD rats in the model group, Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group had local swelling of the knee joint, and the knee joint width was greater than those in the control group (p < 0.05). Compared with the model group, the knee joint swelling of SD rats in the Rhizoma Drynariae group, the Epimedium group, and the Rhizoma Drynariae-Epimedium group was significantly reduced. The knee joint swelling degree of SD rats in the Rhizoma Drynariae-Epimedium group was significantly lower than that in the Rhizoma Drynariae and Epimedium groups. HE staining and Safranin O-fast green staining showed that the cartilage structure of SD rats was severely damaged and eroded, and the subchondral bone mass was reduced. Compared with the model group, the damage of cartilage tissue in the Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group was less severe. In the Rhizoma Drynariae-Epimedium group, cartilage tissue structure damage and erosion were lighter than those of the Rhizoma Drynariae group and the Epimedium group. The concentrations of inflammatory factors IL-1β, IL-6, and TNF-α in the articular cavity lavage fluid of SD rats in the model group, Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group were higher than those in the control group. Compared with the model group, the concentrations of IL-1β, IL-6, and TNF-α in the joint cavity lavage fluid of the Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group were significantly decreased. In the Rhizoma Drynariae-Epimedium group, IL-1β, IL-6, and TNF-α concentrations were lower than those of the Rhizoma Drynariae and Epimedium groups. Compared with the control group, the expression levels of p-p38, p-ERK, and p-JNK proteins in the model group, Rhizoma Drynariae group, Epimedium group, and Rhizoma Drynariae-Epimedium group were significantly increased. The expression levels of p-ERK, p-p38 and p-JNK in the Drynariae group, Epimedium group, and Drynariae-Epimedium group were significantly lower than those in the model group. The expression levels of p-ERK, p-p38, and p-JNK in the Rhizoma Drynariae-Epimedium group were significantly lower than those in the Rhizoma Drynariae and Epimedium groups.

Conclusion

The Rhizoma Drynariae-Epimedium formula can play a protective role in the process of osteoarthritis by inhibiting the phosphorylation levels of p38, ERK, and JNK-related proteins in the cartilage tissue MAPK signaling pathway, reducing the inflammatory response.

Impact of Icariin and its derivatives on inflammatory diseases and relevant signaling pathways

Herba Epimedii is a famous herb collected from China and Korea. It has been used for impotency, osteoporosis, and amnestic treatment for thousands of years. Icariin, a typical flavonoid compound isolated from Herba Epimedii, was reported as a potential anti-inflammatory drug. Icariside and icaritin are the two metabolites of icariin. Icariin and its metabolites have been used to treat a wide range of inflammatory diseases, such as atherosclerosis, Alzheimer's disease, depression, osteoarthritis, and asthma. They exert powerful suppression of proinflammatory signaling, such as NF-κB and MAPKs. More importantly, they can upregulate anti-inflammatory signaling, such as GR and Nrf2. In this study, we review the therapeutic effects and mechanisms of icariin and its metabolites in inflammatory diseases and provide novel insights into these potential anti-inflammatory drugs.

Effects of Type 2 Diabetes Mellitus on Osteoclast Differentiation, Activity, and Cortical Bone Formation in POSTmenopausal MRONJ Patients

Osteoporosis is a common metabolic bone disease in patients with diabetes, which can develop simultaneously with type 2 diabetes (T2D) in postmenopausal women. Bisphosphonate (BP) is administered to patients with both conditions and may cause medication-related osteonecrosis of the jaw (MRONJ). It affects the differentiation and function of osteoclasts as well as the thickness of the cortical bone through bone mineralization. Therefore, this study aimed to investigate the effects of T2D on osteoclast differentiation and activity as well as cortical bone formation in postmenopausal patients with MRONJ. Tissue samples were collected from 10 patients diagnosed with T2D and stage III MRONJ in the experimental group and from 10 patients without T2D in the control group. A histological examination was conducted, and the expression of dendritic cell-specific transmembrane protein (DC-STAMP) and tartrate-resistant acid phosphatase (TRAP) was assessed. Cortical bone formation was analyzed using CBCT images. The number of TRAP-positive osteoclasts and DC-STAMP-positive mononuclear cells was significantly less in the experimental group (p < 0.05). Furthermore, the thickness and ratio of cortical bone were significantly greater in the experimental group (p < 0.05). In conclusion, T2D decreased the differentiation and function of osteoclasts and increased cortical bone formation in postmenopausal patients with MRONJ.

TiO2 Nanotubes Functionalized with Icariin for an Attenuated In Vitro Immune Response and Improved In Vivo Osseointegration

Due to their superior mechanical and chemical properties, titanium (Ti) and its alloys have been widely used as orthopedic implantable devices. However, their bioinertness represents a limitation, which can be overcome by employing various surface modifications, such as TiO₂ nanotube (TNT) fabrication via electrochemical anodization. Anodic TNTs present tunable dimensions and unique structures, turning them into feasible drug delivery platforms. In the present work, TNTs were loaded with icariin (Ica) through an adhesive intermediate layer of polydopamine (DP), and their in vitro and in vivo biological performance was evaluated. The successful fabrication of the modified surfaces was verified by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements (CA), while the in vitro release of Ica was evaluated via UV-VIS spectrophotometry. In terms of in vitro behaviour, comparative studies on RAW 264.7 macrophages demonstrated that the TNT substrates, especially TNT-DP-Ica, elicited a lower inflammatory response compared to the Ti support. Moreover, the in vivo implantation studies evinced generation of a reduced fibrotic capsule around this implant and increased thickness of the newly formed bone tissue at 1 month and 3 months post-implantation, respectively. Overall, our results indicate that the controlled release of Ica from TNT surfaces could result in an improved osseointegration process.

Traditional Chinese Medicine Compound-Loaded Materials in Bone Regeneration

Bone is a dynamic organ that has the ability to repair minor injuries via regeneration. However, large bone defects with limited regeneration are debilitating conditions in patients and cause a substantial clinical burden. Bone tissue engineering (BTE) is an alternative method that mainly involves three factors: scaffolds, biologically active factors, and cells with osteogenic potential. However, active factors such as bone morphogenetic protein-2 (BMP-2) are costly and show an unstable release. Previous studies have shown that compounds of traditional Chinese medicines (TCMs) can effectively promote regeneration of bone defects when administered locally and systemically. However, due to the low bioavailability of these compounds, many recent studies have combined TCM compounds with materials to enhance drug bioavailability and bone regeneration. Hence, the article comprehensively reviewed the local application of TCM compounds to the materials in the bone regeneration in vitro and in vivo. The compounds included icariin, naringin, quercetin, curcumin, berberine, resveratrol, ginsenosides, and salvianolic acids. These findings will contribute to the potential use of TCM compound-loaded materials in BTE.

Re-appraising the role of flavonols, flavones and flavonones on osteoblasts and osteoclasts- A review on its molecular mode of action

Bone disorders have become a global concern illustrated with decreased bone mineral density and disruption in microarchitecture of natural bone tissue organization. Natural compounds that promote bone health by augmenting osteoblast functions and suppressing osteoclast functions has gained much attention and offer greater therapeutic value compared to conventional therapies. Amongst several plant-based molecules, flavonoids act as a major combatant in promoting bone health through their multi-faceted biological activities such as antioxidant, anti-inflammatory, and osteogenic properties. They protect bone loss by regulating the signalling cascades involved in osteoblast and osteoclast functions. Flavonoids augment osteoblastogenesis and inhibits osteoclastogenesis through their modulation of various signalling pathways. This review discusses the role of various flavonoids and their molecular mechanisms involved in maintaining bone health by regulating osteoblast and osteoclast functions.

Roles of Altered Macrophages and Cytokines: Implications for Pathological Mechanisms of Postmenopausal Osteoporosis, Rheumatoid Arthritis, and Alzheimer's Disease

Postmenopausal osteoporosis (PMOP) is characterized by the uncoupling of bone resorption and bone formation induced by estrogen deficiency, which is a complex outcome related to estrogen and the immune system. The interaction between bone and immune cells is regarded as the context of PMOP. Macrophages act differently on bone cells, depending on their polarization profile and secreted paracrine factors, which may have implications for the development of PMOP. PMOP, rheumatoid arthritis (RA), and Alzheimer's disease (AD) might have pathophysiological links, and the similarity of their pathological mechanisms is partially visible in altered macrophages and cytokines in the immune system. This review focuses on exploring the pathological mechanisms of PMOP, RA, and AD through the roles of altered macrophages and cytokines secretion. First, the multiple effects on cytokines secretion by bone-bone marrow (BM) macrophages in the pathological mechanism of PMOP are reviewed. Then, based on the thought of "different tissue-same cell type-common pathological molecules-disease pathological links-drug targets" and the methodologies of "molecular network" in bioinformatics, highlight that multiple cytokines overlap in the pathological molecules associated with PMOP vs. RA and PMOP vs. AD, and propose that these overlaps may lead to a pathological synergy in PMOP, RA, and AD. It provides a novel strategy for understanding the pathogenesis of PMOP and potential drug targets for the treatment of PMOP.

Flavonoids: Classification, Function, and Molecular Mechanisms Involved in Bone Remodelling

Flavonoids are polyphenolic compounds spotted in various fruits, vegetables, barks, tea plants, and stems and many more natural commodities. They have a multitude of applications through their anti-inflammatory, anti-oxidative, anti-carcinogenic properties, along with the ability to assist in the stimulation of bone formation. Bone, a rigid connective body tissue made up of cells embedded in a mineralised matrix is maintained by an assemblage of pathways assisting osteoblastogenesis and osteoclastogenesis. These have a significant impact on a plethora of bone diseases. The homeostasis between osteoblast and osteoclast formation decides the integrity and structure of the bone. The flavonoids discussed here are quercetin, kaempferol, icariin, myricetin, naringin, daidzein, luteolin, genistein, hesperidin, apigenin and several other flavonoids. The effects these flavonoids have on the mitogen activated protein kinase (MAPK), nuclear factor kappa β (NF-kβ), Wnt/β-catenin and bone morphogenetic protein 2/SMAD (BMP2/SMAD) signalling pathways, and apoptotic pathways lead to impacts on bone remodelling. In addition, these polyphenols regulate angiogenesis, decrease the levels of inflammatory cytokines and play a crucial role in scavenging reactive oxygen species (ROS). Considering these important effects of flavonoids, they may be regarded as a promising agent in treating bone-related ailments in the future.

Insights into the Effects of Dietary Omega-6/Omega-3 Polyunsaturated Fatty Acid (PUFA) Ratio on Oxidative Metabolic Pathways of Oncological Bone Disease and Global Health

Various nutrients have been designated as antioxidants, with a possible effect on diseases like cancer. This is partly due to their effect on prostaglandins, thereby affecting local pathological metabolic acidosis. This paper aims to summarize the culprit pathophysiological mechanisms involved, with a focus on the bone microenvironment. The omega- 6/omega-3 PUFA ratio is particularly investigated for its antioxidative effects, countering these pathways to fight the disease. This feature is looked at concerning its impact on health in general, with a particular focus on malignant bone metastasis.

Fabrication of Chinese Traditional Medicines incorporated collagen biomaterials for human bone marrow mesenchymal stem cells

Chinese Traditional Medicines (CTMs) are very popular for therapeutic applications to cure several chronic diseases. Many researchers are trying to discover the potential application and actual mechanism of CTMs in order to scientifically prove their effects for commercial use. One of the main functions of CTMs is to aid stem cell regeneration. Since, this study was focused to fabricate CTMs incorporated fish collagen film, which has good biocompatibility in mammalian cell growth and thus investigated the effect on human Mesenchymal stem cells (hMSCs) proliferation and differentiation. In this study, three types of CTMs such as Genistein, Icariin, and Naringin were used for film fabrication. Mechanical properties of collagen films were improved by the addition of CTMs, especially in Collagen-Naringin films. Solubility and In-vitro biodegradation of collagen films were enhanced by the hydrophobicity and chemical interaction of CTMs with collagen. The proliferation rate was accelerated in hMSCs cultured on CTMs incorporated collagen films in a dose- and time-dependent manner. Proliferation biomarkers such as Ki-67 and BrdU levels were higher in hMSCs cultured on CTMs incorporated collagen films. The proliferative and differentiation effect of CTMs was further confirmed by higher gene expression of Collagen I, Runx2, c-Fos, SMAD3 and TGF-β1 in hMSCs. Overall, this study provides a new insight on novel biomaterial fabrication using CTMs and fish collagen for making a compatible platform for in-vitro stem cell culture.

Chrysin induces osteogenic differentiation of human dental pulp stem cells

OBJECTIVES

As an ideal cell source for tissue engineering and bone defect repair, dental pulp stem cells (DPSCs) have good osteogenic differentiation potential. Chrysin, a flavonoid extracted from oroxylum seeds, has been proven to promote bone formation of bone marrow stem cells. However, the effect of chrysin on osteogenic differentiation of DPSCs remains unclear. This study aimed to investigate the role of Chrysin in promoting osteogenic differentiation of DPSCs and in DPSC-based bone formation.

MATERIAL AND METHODS

We investigated the effects of chrysin on DPSCs from patients by CCK-8 assay, Alizarin Red S staining, qPCR and Western blotting. The effects of chrysin on DPSC-based bone formation in a heterotopic osteogenesis model in nude mice and a rat calvarial defect model were also performed. Finally, we investigated the mechanism of chrysin-treated DPSCs by proteomics.

RESULTS

Chrysin upregulated the expression of osteogenic proteins and induced osteogenic differentiation of DPSCs. Moreover, chrysin induced abundant β-TCP-induced formation of mineralized bone tissue and promoted DPSC-based bone formation in a heterotopic osteogenesis model in nude mice and a rat calvarial defect model. Proteomics showed that upregulation of the Smad3 was closely related to osteogenic differentiation. Inhibiting of Smad3 activation by a Smad3 inhibitor could reverse the chrysin-mediated increases in the expression levels of osteogenic genes and osteogenic induction of DPSCs.

CONCLUSIONS

Our study implies the intriguing potential of chrysin-treated DPSCs in bone regeneration and bone defect repair.

The Use of Herbal Medicines for the Prevention of Glucocorticoid-Induced Osteoporosis

Glucocorticoids are drugs that are widely used to suppress inflammation and the activation of the immune system. However, the prolonged use or at high doses of glucocorticoid can result in adverse side effects including osteoporosis, bone loss, and an increased risk of fracture. A number of compounds derived from natural plant sources have been reported to exert anti-inflammatory activity by interacting with the glucocorticoid receptor (GR), likely owing to their chemical similarity to glucocorticoids, or by regulating GR, without a concomitant risk of treatment-related side effects such as osteoporosis. Other herbal compounds can counteract the pathogenic processes underlying glucocorticoid-induced osteoporosis (GIOP) by regulating homeostatic bone metabolic processes. Herein, we systematically searched the PubMed, Embase, and Cochrane library databases to identify articles discussing such compounds published as of May 01, 2021. Compounds reported to exert anti-inflammatory glucocorticoid-like activity without inducing GIOP include escin, ginsenosides, and glycyrrhizic acid, while compounds reported to alleviate GIOP by improving osteoblast function or modulating steroid hormone synthesis include tanshinol and icariin.

Icariin alleviates MSU-induced rat GA models through NF-κB/NALP3 pathway

Icariin (ICA) has anti-inflammatory effects in some diseases, but its role in gouty arthritis (GA) is not clear. This study investigated the effects of ICA in monosodium urate (MSU)-induced GA rat models. GA rat models were induced by MSU, and co-treated with ICA of low-dose (20 mg/kg), medium-dose (40 mg/kg), and high-dose (80 mg/kg), respectively. The ankle swelling rates, haematoxylin-eosin (HE) staining changes, inflammatory factors (interleukin (IL)-1β, IL-6, tumour necrosis factor-α (TNF-α)) and prostaglandin E2 (PGE₂ ) levels in synovial tissues were detected. The antioxidants levels in rat serum, and NF-κB pathway-related proteins and NALP3 inflammasome expressions in synovial tissues were also analysed. In cell experiments, chondrocytes were co-treated with different concentrations of ICA (1, 5, 10 μmol/L) on the basis of MSU. The activities and inflammatory cytokines, hydroxyproline (Hyp) and glycosaminogly (GAG) expressions in chondrocytes were measured. In rat experiments, MUS increased the ankle swelling rates, promoted inflammatory cells infiltration, and increased IL-1β, IL-6, TNF-α, PGE₂ levels in synovial tissues, which were all alleviated by ICA. Moreover, ICA also suppressed nuclear translocation of NF-κB pathway-related proteins and reduced the expression of NALP3 inflammasome in rat models. As for cell experiments, ICA decreased the activity, inflammatory cytokines and GAG levels, and suppressed nuclear translocation of NF-κB pathway-related proteins of MSU-treated chondrocytes. In general, medium and high concentrations of ICA showed good effects. ICA has an inhibitory effect in MSU-induced rat GA models through NF-κB/NALP3 pathway, which may provide a direction for the treatment of GA. SIGNIFICANCE: Icariin (ICA) has anti-inflammatory effects in some diseases, but its role in gouty arthritis (GA) is not clear. This study excogitated that monosodium urate (MSU) increased the ankle swelling rates of rats, promoted inflammatory cells infiltration, and increased cytokines levels in synovial tissues, which were all alleviated by ICA. In related mechanism, we found that ICA might exert the catabatic functions through the NF-κB/NALP3 pathway. The findings of this study clarified that ICA may provide a direction for the treatment of patients with GA and illustrated the relevant underlying mechanism of its role.

Icariin alleviates rheumatoid arthritis via regulating miR-223-3p/NLRP3 signalling axis

Rheumatoid arthritis (RA) is considered to be a chronic autoimmune disease, pathogenesis of RA is complex and effective treatments for RA is still lacking. Previous studies found that microRNAs (miRNAs) play important roles in the pathogenesis of RA, and miR-223-3p is considered to be one of the possible biomarkers of RA. Recent studies have revealed that icariin alleviates RA in murine models, but the underlying mechanism needs to be further investigated. MiR-223-3p expression levels in fibroblast-like synoviocyte (RA-FLS) and patients with RA were quantified by qRT-PCR, cell proliferation was analyzed by CCK-8 and BrdU assay. Cell apoptosis was assessed by flow cytometry and western blotting. TNF-α, IL-1β and IL-6 concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Dual luminescence-based reporter gene assay was conducted to confirm the possible interaction between miR-223-3p and NLRP3. Icariin inhibits proliferation and inflammation cytokines secretion, promotes apoptosis of RA-FLS cells and upregulated the expression of miR-223-3p. MiR-223-3p targets to 3'-UTR of NRLP3 and regulates its expression. MiR-223-3p inhibitor reversed the effect of icariin on RA-FLS cells function. Additionally, anti-RA activity of icariin was restored by NLRP3 inhibitor MCC950 in miR-223-3p knockdown RA-FLS cells. Icariin inhibits proliferation and inflammation, promotes apoptosis of RA-FLS cells by regulating miR-223-3p/NLRP3 signalling, which may serve as a potential therapeutic target to alleviate RA.

Glutathione-S-transferase A3 protein suppresses thiram-induced tibial dyschondroplasia by regulating prostaglandin-related genes expression

Tibial dyschondroplasia (TD) is an intractable avian cartilage disease in which proximal growth plates of tibia lack blood vessels and contain nonviable cells, and it leads to the inflammatory response. Prostaglandins (PGs) genes have not been studied yet in TD chicken, and they might play role in skeletal metabolism, therefore we planned to explore the role of recombinant glutathione-S-transferase A3 (rGSTA3) protein and PG-related genes. In this study, qRT-PCR, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) analysis were used to identify the expression patterns of eight PG-related genes in the tibial growth plate of broiler chicken. The results showed that the expression of PG-related genes glutathione-S-transferase A3 (GSTA3), cyclooxygenase 2 (COX-2), prostaglandin D2 synthase (PTGDS), prostaglandin E synthase (PTGES), prostaglandin E2 receptor (PTGER) 3, PTGER4, prostaglandin reductase 1 (PTGR1) and hematopoietic prostaglandin D synthases (HPGDS) expression were identified and could significantly respond to thiram-induced TD chicken. Interestingly, the expression of rate-limiting enzyme COX-2 and PGE₂ were induced after the treatment of rGSTA3 protein. These findings demonstrated that the occurrence of TD is closely related to the inhibition of PGs. Moreover, rGSTA3 protein participated in the recovery of TD by strengthening the expression of PG-related genes.

Potential Advantages of Bioactive Compounds Extracted From Traditional Chinese Medicine to Inhibit Bone Destructions in Rheumatoid Arthritis

Bone destruction is an important pathological feature of rheumatoid arthritis (RA), which finally leads to the serious decline of life quality in RA patients. Bone metabolism imbalance is the principal factor of bone destruction in RA, which is manifested by excessive osteoclast-mediated bone resorption and inadequate osteoblast-mediated bone formation. Although current drugs alleviate the process of bone destruction to a certain extent, there are still many deficiencies. Recent studies have shown that traditional Chinese medicine (TCM) could effectively suppress bone destruction of RA. Some bioactive compounds from TCM have shown good effect on inhibiting osteoclast differentiation and promoting osteoblast proliferation. This article reviews the research progress of bioactive compounds exacted from TCM in inhibiting bone destruction of RA, so as to provide references for further clinical and scientific research.

Repair of osteochondral defect using icariin-conditioned serum combined with chitosan in rabbit knees

BACKGROUND

Osteochondral defects caused by an acute traumatic injury or articular degeneration remains difficult to be manipulated. Repair of articular defects is still a great challenge for both tissue engineers and orthopedic surgeons. Therefore, combination of biomaterials with cartilage promotive drugs is well worth being developed to support the regeneration of both cartilage and subchondral bone.

METHODS

Rabbits undergoing osteochondral defect surgery were intrarticularly injected with icariin-conditioned serum (ICS), chitosan (CSSH) and combination of ICS with CSSH, respectively. Gait analysis was performed using VICON motion capture system. ICRS score and immunohistochemical (IHC) analysis including H&E, Safranin O, toluidine blue and collagen II staining was employed to evaluate macroscopic cartilage regeneration and determine the morphologic repair of cartilage.

RESULTS

Rabbits with the treatment of ICS or CSSH alone showed mild improvement in hopping time and range of joint angles while ICS-CSSH group exhibited longer jumping time and larger range of joint angles. In addition, femoral condyle in ICS-CSSH rabbits could be seen with more native cartilage and subchondral bone regeneration in both macroscopic observation and IHC analysis.

CONCLUSION

ICS combined with CSSH could promote the repair of osteochondral defect in rabbit knees. Combination of biomaterials with cartilage promotive drugs may ultimately have profound implications in the management of cartilage defect.

Sweroside promotes osteoblastic differentiation and mineralization via interaction of membrane estrogen receptor-α and GPR30 mediated p38 signalling pathway on MC3T3-E1 cells

BACKGROUND

Dipsaci Radix has been clinically used for thousands of years in China for strengthening muscles and bones. Sweroside is the major active iridoid glycoside isolated from Dipsaci Radix. It has been reported that sweroside can promote alkaline phosphatase (ALP) activity in both the human osteosarcoma cell line MG-63 and rat osteoblasts. However, the underlying mechanism involved in these osteoblastic processes is poorly understood.

PURPOSE

This study aimed to characterize the bone protective effects of sweroside and to investigate the signaling pathway that is involved in its actions in MC3T3-E1 cells.

METHODS

Cell proliferation, differentiation and mineralization were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, ALP test and Alizarin Red S staining, respectively. The concentration of sweroside in intracellular and extracellular fluids was determined by ultra-performance liquid chromatography coupled to triple quadrupole xevo-mass spectrometry (UPLC/TQ-XS-MS). Proteins associated with the osteoblastic signaling pathway were analysed by western blot and immunofluorescence methods.

RESULTS

Sweroside did not obviously affect the proliferation but significantly promoted the ALP activity and mineralization of MC3T3-E1 cells. The maximal absorption amount 0.465 ng/ml (1.3 × 10^-9 M) of sweroside was extremely lower than the tested concentration of 358.340 ng/ml (10^-6 M), indicating an extremely low absorption rate by MC3T3-E1 cells. Moreover, the ALP activity, the protein expression of ER-α and G protein-coupled receptor 30 (GPR30) induced by sweroside were markedly blocked by both the ER antagonist ICI 182780 and the GPR30 antagonist G15. In addition, sweroside also activated the phosphorylation of p38 kinase (p-p38), while the phosphorylation effects together with ALP and mineralization activities were completely blocked by a p38 antagonist, SB203580. Additionally, the phosphorylation of p38 induced by sweroside were markedly blocked by both the ER antagonist ICI 182780 and the GPR30 antagonist G15.

CONCLUSIONS

The present study indicated that sweroside, as a potential agent in treatment of osteoporosis, might exert beneficial effects on MC3T3-E1 cells by interaction with the membrane estrogen receptor-α and GPR30 that then activates the p38 signaling pathway. This is the first study to report the specific mechanism of the effects of sweroside on osteoblastic differentiation and mineralization of MC3T3-E1 cells.

Pharmacological effects of icariin

Icariin (ICA) is a principal active component from traditional Chinese medicine Epimedium grandiflorum. To explain its traditional medical usages by modern science, a variety of pharmacological effects have been studied for ICA. In this review, we summarized the pharmacokinetics of ICA as well as its pharmacological mechanisms in neurodegenerative disease, cardiovascular disease, anti-osteoporosis, anti-inflammation, anti-oxidative stress, anti-depression and anti-tumors.

Icariin alleviates hypoxia-induced damage in MC3T3-E1 cells by downregulating TALNEC2

Osteonecrosis is a harmful musculoskeletal disease. We aim to detect the effects of icariin (ICA) in MC3T3-E1 cell. MC3T3-E1 cell was pretreated with ICA and was subjected to hypoxia stimuli. The tumor-associated long noncoding RNA expressed on chromosome 2 (TALNEC2) overexpression or silencing vectors (pTALNEC2 or si-TALNEC2) was utilized for MC3T3-E1 cell transfection. Viability and apoptosis rate were individually tested by cell counting kit-8 and Annexin V-fluorescein isothiocyanate/propidium iodide kit untied with flow cytometry. The alkaline phosphatase activity (ALP) activity was tested through ALP assay. The quantitative reverse transcription PCR or Western blot was performed for elements detection at the RNA or protein level. Hypoxia treatment induced viability inhibition and CyclinD1 reduction, but elevation of p53 and p16. It also promoted apoptosis by increasing apoptotic cells, Bax, and cleaved-poly ADP-ribose polymerase but decreasing Bcl-2. Also, hypoxia stimuli restrained ALP activity, and osteopontin, osteocalcin, and Runt-related transcription factor 2 expression. Those effects caused by hypoxia stimuli were all reversed by ICA. TALNEC2 was downregulated by ICA, whose impacts were subsequently abolished by pTALNEC2. Silencing TALNEC2 displayed similar effects with ICA. But the apoptosis was not affected by si-TALNEC2. ICA blocked ste20-related proline/alanine-rich kinase/c-Jun N-terminal kinase (SPAK/JNK) but triggered phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway in MC3T3-E1 cell by suppressing TALNEC2. ICA relieved hypoxia-stimulated damage by restraining TALNEC2 through blocking SPAK/JNK and triggering PI3K/AKT/mTOR in the MC3T3-E1 cell.

Therapeutic Anabolic and Anticatabolic Benefits of Natural Chinese Medicines for the Treatment of Osteoporosis

Osteoporosis is a bone disease characterized by increasing osseous fragility and fracture due to the reduced bone mass and microstructural degradation. Primary pharmacological strategies for the treatment of osteoporosis, hormone replacement treatment (HRT), and alendronate therapies may produce adverse side-effects and may not be recommended for long-term usage. Some classic and bone-specific natural Chinese medicine are very popularly used to treat osteoporosis and bone fracture effectively in clinical with their potential value in bone growth and development, but with few adverse side-effects. Current evidence suggests that the treatments appear to improve bone metabolism and attenuate the osteoporotic imbalance between bone formation and bone resorption at a cellular level by promoting osteoblast activity and inhibiting the effects of osteoclasts. The valuable therapies might, therefore, provide an effective and safer alternative to primary pharmacological strategies. Therefore, the purpose of this article is to comprehensively review these classic and bone-specific drugs in natural Chinese medicines for the treatment of osteoporosis that had been deeply and definitely studied and reported with both bone formation and antiresorption effects, including Gynochthodes officinalis (F.C.How) Razafim. & B.Bremer (syn. Morinda officinalis F.C.How), Curculigo orchioides Gaertn., Psoralea corylifolia (L.) Medik Eucommia ulmoides Oliv., Dipsacus inermis Wall. (syn. Dipsacus asperoides C.Y.Cheng & T.M.Ai), Cibotium barometz (L.) J. Sm., Velvet Antler, Cistanche deserticola Ma, Cuscuta chinensis Lam., Cnidium monnieri (L.) Cusson, Epimedium brevicornum Maxim, Pueraria montana (Lour.) Merr. and Salvia miltiorrhiza Bunge., thus providing evidence for the potential use of alternative Chinese medicine therapies to effectively treat osteoporosis.

Icariin promotes osteogenic differentiation by suppressing Notch signaling

Osteoporosis is a bone disease characterized by microarchitectural deterioration, low bone mass, and increased risk of fractures. Icariin (ICA), an active flavonoid glucoside isolated from Herba epimedii (HEF), is a potent stimulator of osteogenic differentiation and has potential applications for preventing bone loss in postmenopausal women. However, the molecular mechanism underlying the osteogenic effect of ICA has not yet been fully elucidated. In this study, we report that ICA treatment significantly elevated gene expression of osteogenic markers and increased alkaline phosphatase (ALP) activity in MC3T3-E1 and C3H10T1/2 cells. RNA sequencing revealed that the expression of several genes involved in the Notch pathway was decreased following ICA treatment. Real-time PCR further demonstrated that the mRNA levels of Notch ligands Jagged-1 (Jag1), lunatic fringe (Lfng), and Notch signaling downstream target gene Hey-1 were significantly decreased following ICA treatment. In addition, we found that constitutive activation of Notch signaling through overexpression of the intracellular domain of Notch (NICD) fully blocked ICA-induced osteoblast differentiation. Moreover, inhibiting Notch signaling with DAPT markedly enhanced osteogenic differentiation following ICA treatment. We found that the mRNA levels of Notch pathway molecules (Lfng, Notch1, Rbpjk and Nfatc1) were increased in ovariectomized (OVX) mice, and administration of ICA significantly decreased the expression of these genes. Our results suggest that ICA promotes osteogenic differentiation in vitro and alleviates osteoporosis in vivo through inhibition of the Notch signaling pathway.

Icariin Promotes the Osteogenic Action of BMP2 by Activating the cAMP Signaling Pathway

Icariin (ICA) is the main active flavonoid glucoside from herbs of the genus Epimedium; in traditional Chinese medicine, these herbs have long been prescribed for the treatment of bone fractures and osteoporosis. Several studies have shown that treatment with ICA can increase osteogenic differentiation and reduce bone loss in vivo and in vitro. However, the definite signaling pathway of this osteogenic effect remains unclear. In this study, we selected bone morphogenetic protein 2 (BMP2)-induced osteoblastic differentiation of multipotent mesenchymal progenitor C2C12 cells as a model of osteoblast differentiation. We investigated the effects of ICA on C2C12 cells osteogenic differentiation and the underlying molecular mechanisms. We found that ICA could enhance BMP2-mediated osteoblastic differentiation of C2C12 cells in a dose-dependent manner. Treatment with ICA activated the cAMP/PKA/CREB signaling axis in a time-dependent manner. Blocking cAMP signaling using the PKA selective inhibitor H89 significantly inhibited the stimulatory effect of ICA on osteogenesis. Therefore, the osteoinductive potential and the low cost of ICA indicate that it is a promising alternative treatment or promoter for enhancing the therapeutic effects of BMP2.

The naturally derived small compound Osthole inhibits osteoclastogenesis to prevent ovariectomy-induced bone loss in mice

OBJECTIVE

This study was to determine the bone protective effects and underlying mechanisms of Osthole (OT) in ovariectomized (OVX) mice. We found that the inhibitory effects of OT on receptor activator of nuclear factor kappa-B ligand (RANKL)-activated osteoclastogenesis are responsible for its bone protective effects in OVX mice.

METHODS

Eight-week-old mice were ovariectomized and OT (10 mg/kg/d) was intraperitoneally administrated to OVX mice 7 days after the surgery and were sacrificed at the end of the 3 months. Osteoclasts were generated from primary bone marrow macrophages (BMMs) to investigate the inhibitory effects of OT. The activity of RANKL-activated signaling was simultaneously analyzed in vitro and in vivo using immunohistochemistry, Western blot, and PCR assays.

RESULTS

OT dose dependently inhibited RANKL-mediated osteoclastogenesis in BMM cultures. OT administration attenuated bone loss (mg Ha/cm: 894.68 ± 33.56 vs 748.08 ± 19.51, P < 0.05) in OVX mice. OT inhibits osteoclastogenesis (Oc.N/per view area: 72 ± 4.3 vs 0.8 ± 0.4, P < 0.05) and bone resorption activity (bone resorbed percentages %, 48.56 ± 7.25 vs 3.25 ± 1.37, P < 0.05) from BMMs. Mechanistically, OT inhibited the expressions of nuclear factor of activated T-cells c1 (NFATc1) and c-Fos. Moreover, OT suppressed the expression of RANKL-induced osteoclast marker genes, including matrix metalloproteinase 9 (MMP9), Cathepsin K (Ctsk), tartrate-resistant acid phosphatase (TRAP), and carbonic anhydrase II (Car2).

CONCLUSIONS

OT inhibits RANKL-mediated osteoclastogenesis and prevents bone loss in OVX mice. Our findings revealed that OT is a potential new drug for treating postmenopausal osteoporosis.

Daphnetin attenuates LPS-induced osteolysis and RANKL mediated osteoclastogenesis through suppression of ERK and NFATc1 pathways

Aseptic prosthetic loosening and periprosthetic infection resulting in inflammatory osteolysis is a leading complication of total joint arthroplasty (TJA). Excessive bone destruction around the bone and prosthesis interface plays a key role in the loosening prostheses leading to revision surgery. The bacterial endotoxins or implant-derived wear particles-induced inflammatory response is the major cause of the elevated osteoclast formation and activity. Thus, agents or compounds that can attenuate the inflammatory response and/or inhibit the elevated osteoclastogenesis and excessive bone resorption would provide a promising therapeutic avenue to prevent aseptic prosthetic loosening in TJA. Daphnetin (DAP), a natural coumarin derivative, is clinically used in Traditional Chinese Medicine for the treatment of rheumatoid arthritis due to its anti-inflammatory properties. In this study, we report for the first time that DAP could protect against lipopolysaccharide-induced inflammatory bone destruction in a murine calvarial osteolysis model in vivo. This protective effect of DAP can in part be attributed to its direct inhibitory effect on RANKL-induced osteoclast differentiation, fusion, and bone resorption in vitro. Biochemical analysis found that DAP inhibited the activation of the ERK and NFATc1 signaling cascades. Collectively, our findings suggest that DAP as a natural compound has potential for the treatment of inflammatory osteolysis.