Icariin Reduces Cartilage Degeneration in a Mouse Model of Osteoarthritis and is Associated with the Changes in Expression of Indian Hedgehog and Parathyroid Hormone-Related Protein

Targeting Chondrocyte Hypertrophy as Strategies for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a common joint disease characterized by pain and functional impairment, which severely impacts the quality of life of middle-aged and elderly individuals. During normal bone development, chondrocyte hypertrophy is a natural physiological process. However, in the progression of OA, chondrocyte hypertrophy becomes one of its key pathological features. Although there is no definitive evidence to date confirming that chondrocyte hypertrophy is the direct cause of OA, substantial experimental data indicate that it plays an important role in the disease's pathogenesis. In this review, we first explore the mechanisms underlying chondrocyte hypertrophy in OA and offer new insights. We then propose strategies for inhibiting chondrocyte hypertrophy from the perspectives of targeting signaling pathways and tissue engineering, ultimately envisioning the future prospects of OA treatment.

A Randomized, Double-Blind, Placebo-Controlled Study Investigating the Safety and Efficacy of a Herbal Formulation on Knee Joint Function in Adults with Knee Osteoarthritis

Background: Current treatments for osteoarthritis (OA) pain and stiffness have limitations, including adverse effects. Therefore, effective and safe complementary or alternative therapies are needed. Dietary supplement GJ 191, comprising Epimedium, Dioscorea, and Salvia miltiorrhiza extracts, may address this need. Methods: This randomized, double-blind, placebo-controlled study investigated GJ 191 supplementation on knee OA symptoms. Seventy-two adults (40-75 years) with mild to moderate knee OA and mild to moderate knee pain were enrolled. The Knee Injury and Osteoarthritis Outcome Score (KOOS), Pain Visual Analog Scale (VAS), Quality of Life questionnaire, knee joint range of motion, serum C-reactive protein, and rescue medication use were assessed. The Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) pain and stiffness scores were computed using KOOS scores. Results: Decreases in WOMAC pain scores were reported by both GJ 191 and placebo groups after 6 (-1.78 ± 2.71 and -1.34 ± 1.93, respectively; p < 0.01) and 12 (-2.31 ± 2.83 and -1.59 ± 2.69, respectively; p < 0.01) weeks, with no significant difference between groups. There were decreases in WOMAC stiffness scores for participants supplemented with GJ 191 by 0.53 ± 1.22 and 0.72 ± 1.46 (p ≤0.02) after 6 and 12 weeks, respectively, with respective decreases of 0.81 ± 1.51 and 0.75 ± 1.85 (p ≤0.03) for those on placebo. Significant improvements in current pain, as assessed by the Pain VAS, and bodily pain were reported by the GJ 191 group after 6 and 12 weeks, while the placebo group only reported significant improvements in these measures after 12 weeks. GJ 191 supplementation was safe and well tolerated. Conclusion: There was no significant difference in pain and stiffness scores between GJ 191 and placebo over the 12 weeks. While both groups reported improvements in WOMAC pain from baseline, improvements in current and bodily pain were experienced sooner with GJ 191 than placebo and were sustained over the study period. GJ 191 supplementation was safe and well tolerated. (CTR#: NCT04395547).

Treatment of bone-cartilage defects with dual-layer tissue-engineered scaffolds loaded with icariin and quercetin

Over the past few decades, significant research has been conducted on tissue-engineered constructs for cartilage repair. However, there is a growing interest in addressing subchondral bone repair along with cartilage regeneration. This study focuses on a bilayer tissue engineering scaffold loaded with icariin (ICA) and quercetin (QU) for simultaneous treatment of knee joint cartilage and subchondral bone defects. The cytotoxicity of dual-layer scaffolds loaded with ICA and QU was assessed through live/dead cell staining. Subsequently, these dual-layer scaffolds loaded with ICA and QU were implanted into cartilage and subchondral bone defects in Sprague-Dawley (SD) rats. The repair effects were evaluated through macroscopic observation, computed tomography, and immunohistochemistry. After 12 weeks of implantation of dual-layer scaffolds loaded with ICA and QU into the cartilage and bone defects of SD rats, better repair effects were observed in both cartilage and bone defects compared to the blank control group. We found that the dual-layer tissue-engineered scaffold loaded with ICA and QU had excellent biocompatibility and could effectively repair articular cartilage and subchondral bone injuries, showing promising prospects for clinical applications.

Natural anti-inflammatory products for osteoarthritis: From molecular mechanism to drug delivery systems and clinical trials

Osteoarthritis (OA) is a degenerative joint disease that affects millions globally. The present nonsteroidal anti-inflammatory drug treatments have different side effects, leading researchers to focus on natural anti-inflammatory products (NAIPs). To review the effectiveness and mechanisms of NAIPs in the cellular microenvironment, examining their impact on OA cell phenotype and organelles levels. Additionally, we summarize relevant research on drug delivery systems and clinical randomized controlled trials (RCTs), to promote clinical studies and explore natural product delivery options. English-language articles were searched on PubMed using the search terms "natural products," "OA," and so forth. We categorized search results based on PubChem and excluded "natural products" which are mix of ingredients or compounds without the structure message. Then further review was separately conducted for molecular mechanisms, drug delivery systems, and RCTs later. At present, it cannot be considered that NAIPs can thoroughly prevent or cure OA. Further high-quality studies on the anti-inflammatory mechanism and drug delivery systems of NAIPs are needed, to determine the appropriate drug types and regimens for clinical application, and to explore the combined effects of different NAIPs to prevent and treat OA.

Effects of genus Epimedium in the treatment of osteoarthritis and relevant signaling pathways

Osteoarthritis (OA) is a common chronic degenerative joint disease in clinical practice with a high prevalence, especially in the elderly. Traditional Chinese Medicine (TCM) believes that OA belongs to the category of "Bi syndrome" and the "bone Bi syndrome". The etiology and pathogenesis lie in the deficiency of the liver and kidney, the deficiency of Qi and blood, and external exposure to wind, cold, and dampness. Epimedium is a yang-reinforcing herb in TCM, which can tonify the liver and kidney, strengthen muscles and bones, dispel wind, cold and dampness, and can treat both the symptoms and the root cause of "bone Bi syndrome". In addition, Epimedium contains a large number of ingredients. Through modern science and technology, more than 270 compounds have been found in Epimedium, among which flavonoids are the main active ingredients. Therefore, our study will review the effects and mechanisms of genus Epimedium in treating OA from two aspects: (1) Introduction of Epimedium and its main active ingredients; (2) Effects of Epimedium and its active ingredients in treating OA and relevant signaling pathways, in order to provide more ideas for OA treatment.

Network pharmacology of the Yigu Decoction empirical formula on the treatment of knee osteoarthritis

OBJECTIVE

To investigate the mechanism of the Yigu Decoction empirical formula in the treatment of knee osteoarthritis (KOA) using network pharmacology and molecular docking methods.

METHODS

The active ingredients and targets of Yigu Decoction were screened using the TCMSP database. Relevant targets were predicted using several databases. A "drug-component-target-disease" network was constructed using Cytoscape software. A protein-protein interaction network was constructed using the STRING database. Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes signalling pathways of the target genes were analysed.

RESULTS

We identified 18 components of Rhizoma drynariae (Gusuibu), 23 components of Yinyanghuo (Herba Epimedii Brevicornus), 16 components of Yam, 65 components of Danshen, 8 components of Sheng Di Huang (Rehmannia glutinosa), 29 components of Buguzhi (Psoralea corylifolia fruit), neoeriocitrin, and protocatechuic aldehyde. The targets were predicted using SwissTargetPrediction software. In total, 653 targets were screened, including 168 potential targets of Rhizoma drynariae (Gusuibu), 192 potential targets of Yinyanghuo (Herba Epimedii Brevicornus), 14 potential targets of Yam, 123 potential targets of Danshen, 216 potential targets of Sheng Di Huang (Rehmannia glutinosa), and 274 potential targets of Buguzhi (Psoralea corylifolia). Intersection analysis of a total of 2,292 targets related to KOA obtained from the GeneCard database, 30 targets from the OMIM database, 12 targets from the DrugBank database, and 368 targets from the DisGeNET database resulted in 2,316 target genes.

CONCLUSIONS

Yigu Decoction can improve KOA through multiple targets and mechanisms. Yigu Decoction may be a useful alternative therapy for treating KOA.

Potential of Icariin–Glucosamine Combination in the Treatment of Osteoarthritis by Topical Application: Development of Topical Formulation and In Vitro Permeation Study

The aim of this study was to develop a topically applied formulation with the potential to alleviate arthritis ailments. A combination of two active ingredients, icariin from Epimedium L. (Species: Epimedium Koreanum) extract as a potential promoter of chondrogenesis and glucosamine sulfate as a precursor of cartilage tissues, was tested. In permeation studies, the potential for skin permeation of both substances was confirmed; however, the in vitro release test did not accurately reflect the degree of skin permeation. The in vitro release of icariin was at a level of 15.0–19.0% for the plant-extract-derived icariin and 29.0–35.0% for the pure substance. The level of glucosamine sulfate release was 38.4% (on average). For icariin of both origins, the release results were higher than those obtained via oral administration (about 12.0%), which shows the potential superiority of topical application. In addition, the physicochemical parameters that affect the in vitro release and performance of topical formulations were addressed. This preliminary research and permeation analysis of the formulation produced a promising picture of its prospects regarding arthritis treatment, although further investigation is needed.

Natural Compounds: Potential Therapeutics for the Inhibition of Cartilage Matrix Degradation in Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease characterized by enzymatic degradation of the cartilage extracellular matrix (ECM) causing joint pain and disability. There is no disease-modifying drug available for the treatment of OA. An ideal drug is expected to stop cartilage ECM degradation and restore the degenerated ECM. The ECM primarily contains type II collagen and aggrecan but also has minor quantities of other collagen fibers and proteoglycans. In OA joints, the components of the cartilage ECM are degraded by matrix-degrading proteases and hydrolases which are produced by chondrocytes and synoviocytes. Matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS5) are the major collagenase and aggrecanase, respectively, which are highly expressed in OA cartilage and promote cartilage ECM degradation. Current studies using various in vitro and in vivo approaches show that natural compounds inhibit the expression and activity of MMP-13, ADAMTS4, and ADAMTS5 and increase the expression of ECM components. In this review, we have summarized recent advancements in OA research with a focus on natural compounds as potential therapeutics for the treatment of OA with emphasis on the prevention of cartilage ECM degradation and improvement of joint health.

Icariin alleviates osteoarthritis through PI3K/Akt/mTOR/ULK1 signaling pathway

OBJECTIVES

This study aims to investigate the effects of Icariin (ICA) on interleukin-1β (IL-1β)-induced osteoarthritis (OA) and its potential mechanism of action.

METHODS

SW1353 chondrocytes were pretreated with ICA for 2 h, followed by stimulation with IL-1β to mimic OA. Expression levels of matrix metalloproteinases (MMP-3) and collagen II were determined using real-time PCR and Western blot assays. Autophagy activation (by ICA) or inhibition (by shRNA) was determined based on the expression levels of ULK1, Beclin-1, LC3-II/I, and p62, using Western blot analysis. The phosphorylation levels of PI3K, Akt, mTOR, and ULK1 were also detected using Western blot analysis.

RESULTS

IL-1β increased MMP-3 overproduction, induced collagen II degradation, and reduced the level of autophagy-associated proteins, including ULK1, Beclin-1, and LC3-II/I. In contrast, ICA pretreatment attenuated IL-1β-induced MMP-3 overproduction, increased collagen II expression, and induced expression of autophagy-related proteins. ICA also decreased PI3K, Akt, and mTOR phosphorylation, increased the production of ULK1, and induced autophagy. Short hairpin RNA-mediated knockdown of ULK1 led to activation of the PI3K/Akt/mTOR pathway, which reversed the protective effects of ICA.

CONCLUSIONS

Our findings indicate that ICA can induce autophagy by regulating the PI3K/AKT/mTOR/ULK1 signaling pathway. This study suggests that ICA may be effective for treating OA.

Medicinal plants and their secondary metabolites in alleviating knee osteoarthritis: A systematic review

BACKGROUND

With the increasing ages of the general population, the incidence of knee osteoarthritis (KOA) is also rising, and KOA has become a major health problem worldwide. Recently, medicinal plants and their secondary metabolites have gained interest due to their activity in treating KOA. In this paper, a comprehensive systematic review of the literature was performed concerning the effects of medicinal plant extracts and natural compounds against KOA in recent years. The related molecular pathways of natural compounds against KOA were summarized, and the possible crosstalk among components in chondrocytes was discussed to propose possible solutions for the current situation of treating KOA.

PURPOSE

This review focused on the molecular mechanisms by which medicinal plants and their secondary metabolites act against KOA.

METHODS

Literature searches were performed in the PUBMED, Embase, Science Direct, and Web of Science databases for a 10-year period from 2011 to 2022 with the search terms "medicinal plants," "bioactive compounds," "natural products," "phytochemical," "knee osteoarthritis," "knee joint osteoarthritis," "knee osteoarthritis," "osteoarthritis of the knee," and "osteoarthritis of knee joint."

RESULTS

According to the results, substantial plant extracts and secondary metabolites show a positive effect in fighting KOA. Plant extracts and their secondary metabolites can affect the diagnostic and prognostic biomarkers of KOA. Natural products inhibit the expression of MMP1, MMP3, MMP19, syndecan IV, ADAMTS-4, ADAMTS-5, iNOS, COX-2, collagenases, IL-6, IL-1β, and TNF-α in vitro and in vivo and . Cytokines also upregulate the expression of collagen II and aggrecan. The main signaling pathways affected by the extracts and isolated compounds include AMPK, SIRT, NLRP3, MAPKs, PI3K/AKT, mTOR, NF-κB, WNT/β-catenin, JAK/STAT3, and NRF2, as well as the cell death modes apoptosis, autophagy, pyroptosis, and ferroptosis.

CONCLUSION

The role of secondary metabolites in different signaling pathways supplies a better understanding of their potential to develop further curative options for KOA.

Primary Cilia: A Cellular Regulator of Articular Cartilage Degeneration

Osteoarthritis (OA) is the most common joint disease that can cause pain and disability in adults. The main pathological characteristic of OA is cartilage degeneration, which is caused by chondrocyte apoptosis, cartilage matrix degradation, and inflammatory factor destruction. The current treatment for patients with OA focuses on delaying its progression, such as oral anti-inflammatory analgesics or injection of sodium gluconate into the joint cavity. Primary cilia are an important structure involved in cellular signal transduction. Thus, they are very sensitive to mechanical and physicochemical stimuli. It is reported that the primary cilia may play an important role in the development of OA. Here, we review the correlation between the morphology (location, length, incidence, and orientation) of chondrocyte primary cilia and OA and summarize the relevant signaling pathways in chondrocytes that could regulate the OA process through primary cilia, including Hedgehog, Wnt, and inflammation-related signaling pathways. These data provide new ideas for OA treatment.

Icariin accelerates cartilage defect repair by promoting chondrogenic differentiation of BMSCs under conditions of oxygen-glucose deprivation

This study explored the role played by combined ICA and bone mesenchymal stem cells (BMSCs) in repairing rabbit knee cartilage defects. Firstly, rabbit BMSCs were isolated and used to construct an in vitro cellular model of oxygen‐glucose deprivation/reoxygenation (OGD/R). Subsequently, ICA processing, Alcian blue staining, immunofluorescence and Western blot studies were performed to evaluate the ability of BMSCs to display signs of chondrogenic differentiation. Furthermore, a rabbit knee cartilage injury model was established in vivo. International Cartilage Repair Society (ICRS) macroscopic evaluations, H&E, Alcian blue and EdU staining, as well as immunohistochemistry, were analysed cartilage repair and pathological condition of the knee cartilage tissue. Our in vitro results showed that ICA promoted the chondrogenic differentiation of BMSCs, as well as aggrecan (AGR), bone morphogenetic protein 2 (BMP2) and COL2A1 protein expression in BMSCs. In vivo experiments showed that rabbits in the BMSCs or ICA treatment group had higher ICRS scores and displayed a better restoration of cartilage‐like tissue and chondrocyte expression on the surface of their cartilage defects. In conclusion, ICA or BMSCs alone could repair rabbit knee cartilage damage, and combined treatment with ICA and BMSCs showed a better ability to repair rabbit knee cartilage damage.

Verification of pain-related neuromodulation mechanisms of icariin in knee osteoarthritis

Knee osteoarthritis (KOA) is a common disease with no specific treatment. Icariin (ICA) is considered an agent for KOA. This study aimed to confirm the pain-related neuromodulation mechanisms of ICA on KOA. Three experiments were designed: (1) verifying the therapeutic effects of ICA in vivo and in vitro, (2) exploring the potential pain-related neuromodulation pathways involved in ICA treatment by functional magnetic resonance imaging (fMRI) and virus retrograde tracing (VRT) and (3) confirming the pain-related targets by tandem mass tag (TMT)-based quantitative proteomics and bioinformatic analyses. Experiment 1 verified the efficacy of ICA in OA animal and cell models. Experiment 2 found a series of brain regions associated with KOA reversed by ICA treatment, indicating that a pain-related hypothalamic-mediated neuromodulation pathway and an endocannabinoid (EC)-related pathway contribute to ICA mechanisms. Experiment 3 explored and confirmed four pain-related genes involved in KOA and ICA treatment. We confirmed the key role of pain-related neuromodulation mechanisms in ICA treatment associated with its analgesic effect. Our findings contribute to considering ICA as a novel therapy for KOA.

Functional Duality of Chondrocyte Hypertrophy and Biomedical Application Trends in Osteoarthritis

Chondrocyte hypertrophy is one of the key indicators in the progression of osteoarthritis (OA). However, compared with other OA indications, such as cartilage collapse, sclerosis, inflammation, and protease activation, the mechanisms by which chondrocyte hypertrophy contributes to OA remain elusive. As the pathological processes in the OA cartilage microenvironment, such as the alterations in the extracellular matrix, are initiated and dictated by the physiological state of the chondrocytes, in-depth knowledge of chondrocyte hypertrophy is necessary to enhance our understanding of the disease pathology and develop therapeutic agents. Chondrocyte hypertrophy is a factor that induces OA progression; it is also a crucial factor in the endochondral ossification. This review elaborates on this dual functionality of chondrocyte hypertrophy in OA progression and endochondral ossification through a description of the characteristics of various genes and signaling, their mechanism, and their distinguishable physiological effects. Chondrocyte hypertrophy in OA progression leads to a decrease in chondrogenic genes and destruction of cartilage tissue. However, in endochondral ossification, it represents an intermediate stage at the process of differentiation of chondrocytes into osteogenic cells. In addition, this review describes the current therapeutic strategies and their mechanisms, involving genes, proteins, cytokines, small molecules, three-dimensional environments, or exosomes, against the OA induced by chondrocyte hypertrophy. Finally, this review proposes that the contrasting roles of chondrocyte hypertrophy are essential for both OA progression and endochondral ossification, and that this cellular process may be targeted to develop OA therapeutics.

An LC-MS/MS method for simultaneous quantification of 11 components of Xian-Xiong-Gu-Kang in the plasma of osteoarthritic rats and pharmacokinetic analysis

Xian-Xiong-Gu-Kang is composed of Epimedium brevicornu, Ligusticum chuanxiong, Radix clematidis, Cinnamomum cassia, and Fructus xanthii. It is used to treat numbness and pain of limbs. In this study, we developed a method to simultaneously quantify 11 components of Xian-Xiong-Gu-Kang (icarrin, epimedin A, epimedin B, epimedin C, icariside II, chlorogenic acid, ligustilide, senkyunolide A, senkyunolide I, ferulic acid, and cinnamic acid) in rat plasma using ultra-performance liquid chromatography coupled with quadrupole linear ion trap mass spectrometry. Chromatographic separation was performed on an ACQUITY UPLC BEH C18 column using gradient elution with a mobile phase comprising acetonitrile and 0.05% (v/v) formic acid aqueous solution. Mass spectrometry detection was performed using positive and negative electrospray ionization in the multiple reaction monitoring mode. The calibration curves of the 11 constituents were linear, with correlation coefficients > 0.99. The intra- and interday accuracy and precision values were within ±15.0%. The extraction recoveries of the 11 constituents and two internal standards were between 66.05 and 105.40%, and the matrix effects were between 86.74 and 112.86%. Using this method, the pharmacokinetic features of the 11 constituents were elucidated in the plasma of osteoarthritic rats after oral administration of the Xian-Xiong-Gu-Kang extract.

Icariin alleviates osteoarthritis by regulating autophagy of chondrocytes by mediating PI3K/AKT/mTOR signaling

Osteoarthritis (OA) is a chronic degenerative disease that significantly impacts the quality of life of the elderly population. Recently, the pathogenesis of OA has been reported to involve autophagy in chondrocytes. Intriguingly, icariin, one of the main components of epimedium, exerts multiple pharmacological effects, including a protective effect against chondrocyte damage. Thus, we aimed to investigate the therapeutic effect of icariin on OA and its potential underlying mechanism by using a rat model of OA. After treatment with icariin or an autophagy activator (rapamycin) or inhibitor (3-methyladenine), OA chondrocyte viability was measured using the CCK-8 assay, apoptosis in the chondrocytes was evaluated using the acridine orange-propidium iodide assay and flow cytometry, and OA tissue pathological state was assessed using micro-CT scanning and safranin O staining. Furthermore, immunohistochemical staining was used to measure the expression level of Beclin-1 and immunofluorescence labeling was used to visualize LC3 expression, and western blotting was used to determine the expression levels of autophagy proteins and key proteins in the PI3K signaling pathway. The apoptotic rate of OA chondrocytes was markedly elevated by 3-methyladenine and suppressed by rapamycin and icariin; autophagy genes were drastically downregulated in the 3-methyladenine group and upregulated in the rapamycin and icariin groups; and the PI3K/AKT/mTOR signaling pathway was activated by 3-methyladenine and inhibited by rapamycin and icariin. Notably, following treatment with rapamycin and icariin, the severe pathological state in OA cartilage tissues was substantially alleviated, and this was accompanied by activated autophagy and inhibited PI3K signaling in the cartilage tissues. Taken together, these findings indicate that icariin alleviates OA by regulating the autophagy of chondrocytes by mediating PI3K/AKT/mTOR signaling.

Small molecule compounds promote the proliferation of chondrocytes and chondrogenic differentiation of stem cells in cartilage tissue engineering

The application of tissue engineering to generate cartilage is limited because of low proliferative ability and unstable phenotype of chondrocytes. The sources of cartilage seed cells are mainly chondrocytes and stem cells. A variety of methods have been used to obtain large numbers of chondrocytes, including increasing chondrocyte proliferation and stem cell chondrogenic differentiation via cytokines, genes, and proteins. Natural or synthetic small molecule compounds can provide a simple and effective method to promote chondrocyte proliferation, maintain a stable chondrocyte phenotype, and promote stem cell chondrogenic differentiation. Therefore, the study of small molecule compounds is of great importance for cartilage tissue engineering. Herein, we review a series of small molecule compounds and their mechanisms that can promote chondrocyte proliferation, maintain chondrocyte phenotype, or induce stem cell chondrogenesis. The studies in this field represent significant contributions to the research in cartilage tissue engineering and regenerative medicine.

Recent advance in treatment of osteoarthritis by bioactive components from herbal medicine

Osteoarthritis (OA) is a common chronic articular degenerative disease, and characterized by articular cartilage degradation, synovial inflammation/immunity, and subchondral bone lesion, etc. The disease affects 2-6% of the population around the world, and its prevalence rises with age and exceeds 40% in people over 70. Recently, increasing interest has been devoted to the treatment or prevention of OA by herbal medicines. In this paper, the herbal compounds with anti-OA activities were reviewed, and the cheminformatics tools were used to predict their drug-likeness properties and pharmacokinetic parameters. A total of 43 herbal compounds were analyzed, which mainly target the damaged joints (e.g. cartilage, subchondral bone, and synovium, etc.) and circulatory system to improve the pathogenesis of OA. Through cheminformatics analysis, over half of these compounds have good drug-likeness properties, and the pharmacokinetic behavior of these components still needs to be further optimized, which is conducive to the enhancement in their drug-likeness properties. Most of the compounds can be an alternative and valuable source for anti-OA drug discovery, which may be worthy of further investigation and development.

Herbal Remedies as Potential in Cartilage Tissue Engineering: An Overview of New Therapeutic Approaches and Strategies

It is estimated that by 2023, approximately 20% of the population of Western Europe and North America will suffer from a degenerative joint disease commonly known as osteoarthritis (OA). During the development of OA, pro-inflammatory cytokines are one of the major causes that drive the production of inflammatory mediators and thus of matrix-degrading enzymes. OA is a challenging disease for doctors due to the limitation of the joint cartilage's capacity to repair itself. Though new treatment approaches, in particular with mesenchymal stem cells (MSCs) that integrate the tissue engineering (TE) of cartilage tissue, are promising, they are not only expensive but more often do not lead to the regeneration of joint cartilage. Therefore, there is an increasing need for novel, safe, and more effective alternatives to promote cartilage joint regeneration and TE. Indeed, naturally occurring phytochemical compounds (herbal remedies) have a great anti-inflammatory, anti-oxidant, and anabolic potential, and they have received much attention for the development of new therapeutic strategies for the treatment of inflammatory diseases, including the prevention of age-related OA and cartilage TE. This paper summarizes recent research on herbal remedies and their chondroinductive and chondroprotective effects on cartilage and progenitor cells, and it also emphasizes the possibilities that exist in this research area, especially with regard to the nutritional support of cartilage regeneration and TE, which may not benefit from non-steroidal anti-inflammatory drugs (NSAIDs).

The shared KEGG pathways between icariin-targeted genes and osteoporosis

Osteoporosis is a common metabolic bone disease that affects about 40% of postmenopausal women. Treatment options for osteoporosis are limited, however. Icariin is an herbal substance that has been shown to improve bone mass, but the mechanisms are largely unknown. Using bioinformatics analysis, we have identified the hub genes and KEGG pathways shared between icariin-targeted genes and osteoporosis. The top five shared KEGG pathways were the Toll-like receptor signaling pathway, adipocytokine pathway, neurotrophin signaling pathway, NOD-like receptor signaling, and B cell receptor signaling pathway; the hub genes were RELA, NFKBIA, and IKBKB, belonging to the NF-κB family. The identified icariin-targeted genes are involved in inflammation, insulin resistance, apoptosis, and immune responses, and regulate the PI3K-Akt, NF-κB, MAPK, and JNK signaling pathways. Our in vitro data show that icariin inhibits apoptosis in human mesenchymal stem cells by suppressing JNK/c-Jun signaling pathway. Together, these findings indicate that icariin exerts its anti-osteoporotic function by inhibiting JNK/c-Jun signaling pathway, and suggest that icariin may be a promising treatment option for osteoporosis.

Functional role of hedgehog pathway in osteoarthritis

The hedgehog signalling pathway is one of the key regulators of metazoan development, and it plays an important role in the regulation of a variety of developmental and physiological processes. But it is aberrantly activated in many human diseases, including osteoarthritis (OA). In this study, we have reviewed the association of hedgehog signalling pathway in the development and progression of OA and evaluated the efforts to target this pathway for the prevention of OA. Usually in OA, activation of hedgehog induces up-regulation of the expression of hypertrophic markers, including type X collagen, increases production of nitric oxide and prostaglandin E2, several matrix-degrading enzymes including matrix metalloproteinase and a disintegrin and metalloproteinase with thrombospondin motifs in human knee joint cartilage leading to cartilage degeneration, and thus contributes in OA. Targeting hedgehog signalling might be a viable strategy to prevent or treat OA. Chemical inhibitors of hedgehog signalling is promising, but they cause severe side effects. Knockdown of HH gene is not an option for OA treatment in humans because it is not possible to delete HH in larger animals. Efficient knockdown of HH achieved by local delivery of small interfering RNA in future studies utilizing large animal OA models might be a more efficient approach for the prevention of OA. However, it remains a major problem to develop one single scaffold due to the different physiological functions of cartilage and subchondral bones possess. More studies are necessary to identify selective inhibitors for efficiently targeting the hedgehog pathway in clinical conditions.

Runx1 regulates osteogenic differentiation of BMSCs by inhibiting adipogenesis through Wnt/β-catenin pathway

OBJECTIVE

Bone marrow stem cells (BMSCs) can commit to both adipocyte and osteoblast lineages. However, the mechanism underlying how transcription factors regulate this process remains elusive. Our aims were to determine the role of runt-related transcription factor 1 (Runx1) in BMSCs lineage determination and the underlying mechanisms.

STUDY DESIGN

BMSCs from mouse femur bone marrow were harvested and cultured in osteogenic medium. Runx1 was knocked down in BMSCs using lentivirus. Alkaline phosphatase (ALP), Von Kossa and Oil Red O staining were performed on the Runx1-transduced BMSCs and control cells to see the differences of osteogenic and adipogenic differentiation in these groups. Real-time quantitative PCR and Western blot were performed to analyse the expression levels of osteogenic and adipogenic factors regulated by Runx1 at gene and protein levels.

RESULTS

In BMSCs with Runx1 knockdown, the expression levels of osteogenic-related genes decreased significantly while the adipogenic genes C/EBPα, PPARγ and Fabp4 increased by 12-fold, 10-fold, and 30-fold, respectively, compared with the control cells. ALP activity and Von kossa staining were greatly decreased in Runx1-transfected cells while the Oil Red O staining was comparable to that in the control groups. Canonical Wnt signaling was investigated in the Runx1-deficient BMSCs, and a 50% decrease in the expression of active β-catenin in these cells was found. Lef1 and Tcf1, which are regulated by β-catenin were also decreased in Runx1-deficient cells compared with the levels in controls. Moreover, although there was no difference in the expression of Wnt3a among the three groups of cells, the expression of Wnt10b decreased by 80% in Runx1-deficient BMSCs compared with the levels in the other two groups.

CONCLUSIONS

Our results show Runx1 promotes the capacity of osteogenesis in BMSCs while inhibits their adipogenesis through canonical Wnt/β-catenin pathway, which provides new insights into osteoblast development.