Development and characterization of various osteoarthritis models for tissue engineering

Evaluating the protective effect of dapsone on experimental osteoarthritis models induced by MIA in male rats

OBJECTIVES

Osteoarthritis, a degenerative condition that results in significant morbidity, is typically managed with treatments aimed at symptom relief rather than addressing the underlying degeneration. Dapsone, recognized for its anti-inflammatory, antioxidant, antiexcitotoxic, and antiapoptotic properties, has demonstrated promising effects in various neurodegenerative diseases. This study explores the potential of dapsone to mitigate articular destruction, inflammation, and pain in rat models of osteoarthritis.

METHODS

Osteoarthritis was induced in rats by injecting MIA into the right knee joint. Dapsone was then administered intraperitoneally at 5, 10, or 20 mg/kg every 2 days for 2 weeks. Behavioural tests were done on days 0, 7, and 14. On day 14, the articular cartilage was histologically analysed using H&E staining. Serum levels of NF-kB, IL-1β, and TNF-α were evaluated by ELISA.

RESULTS

Dapsone effectively reduces pain, inflammation, and articular cartilage damage in osteoarthritis. Specifically, it improves mechanical allodynia and thermal hyperalgesia, reduces inflammatory markers (TNF-α, IL-1β, and NF-κB), and protects against cartilage destruction and chondrocyte loss, with the most significant effects at 20 mg/kg.

CONCLUSIONS

Dapsone effectively prevents pain, inflammation, and cartilage damage in osteoarthritis rats, suggesting its potential as a therapeutic option for managing osteoarthritis.

On-demand release of a selective MMP-13 blocker from an enzyme-responsive injectable hydrogel protects cartilage from degenerative progression in osteoarthritis

In osteoarthritis (OA), the degradation of cartilage is primarily driven by matrix metalloprotease-13 (MMP-13). Hence, the inhibition of MMP-13 has emerged as an attractive target for OA treatment. Among the various approaches that are being explored for MMP-13 regulation, blocking of the enzyme with specific binding molecules appears to be a more promising strategy for preventing cartilage degeneration. To enhance effectiveness and ensure patient compliance, it is preferable for the binding molecule to exhibit sustained activity when administered directly into the joint. Herein, we present an enzyme-responsive hydrogel that was designed to exhibit on-demand, the sustained release of BI-4394, a potent and highly selective MMP-13 blocker. The stable and compatible hydrogel was prepared using triglycerol monostearate. The efficacy of the hydrogel to prevent cartilage damage was assessed in a rat model of OA induced by anterior cruciate ligament transection (ACLT). The results revealed that in comparison to the rats administrated weekly with intra-articular BI-4394, the hydrogel implanted rats had reduced levels of inflammation and bone erosion. In comparison to untreated control, the cartilage in animals administered with BI-4394/hydrogel exhibited significant levels of collagen-2 and aggrecan along with reduced MMP-13. Overall, this study confirmed the potential of BI-4394 delivery using an enzyme-responsive hydrogel as a promising treatment option to treat the early stages of OA by preventing further cartilage degradation.

Opsonization Inveigles Macrophages Engulfing Carrier-Free Bilirubin/JPH203 Nanoparticles to Suppress Inflammation for Osteoarthritis Therapy

Osteoarthritis (OA) is a chronic inflammatory disease characterized by cartilage destruction, synovitis, and osteophyte formation. Disease-modifying treatments for OA are currently lacking. Because inflammation mediated by an imbalance of M1/M2 macrophages in the synovial cavities contributes to OA progression, regulating the M1 to M2 polarization of macrophages can be a potential therapeutic strategy. Basing on the inherent immune mechanism and pathological environment of OA, an immunoglobulin G-conjugated bilirubin/JPH203 self-assembled nanoparticle (IgG/BRJ) is developed, and its therapeutic potential for OA is evaluated. After intra-articular administration, IgG conjugation facilitates the recognition and engulfment of nanoparticles by the M1 macrophages. The internalized nanoparticles disassemble in response to the increased oxidative stress, and the released bilirubin (BR) and JPH203 scavenge reactive oxygen species (ROS), inhibit the nuclear factor kappa-B pathway, and suppress the activated mammalian target of rapamycin pathway, result in the repolarization of macrophages and enhance M2/M1 ratios. Suppression of the inflammatory environment by IgG/BRJ promotes cartilage protection and repair in an OA rat model, thereby improving therapeutic outcomes. This strategy of opsonization involving M1 macrophages to engulf carrier-free BR/JPH203 nanoparticles to suppress inflammation for OA therapy holds great potential for OA intervention and treatment.

Animal Models of Osteoarthritis: Updated Models and Outcome Measures 2016-2023

Purpose

Osteoarthritis (OA) is a global musculoskeletal disorder that affects primarily the knee and hip joints without any FDA-approved disease-modifying therapies. Animal models are essential research tools in developing therapies for OA; many animal studies have provided data for the initiation of human clinical trials. Despite this, there is still a need for strategies to recapitulate the human experience using animal models to better develop treatments and understand pathogenesis. Since our last review on animal models of osteoarthritis in 2016, there have been exciting updates in OA research and models. The main purpose of this review is to update the latest animal models and key features of studies in OA research.

Method

We used our existing classification method and screened articles in PubMed and bibliographic search for animal OA models between 2016 and 2023. Relevant and high-cited articles were chosen for inclusion in this narrative review.

Results

Recent studies were analyzed and classified. We also identified ex vivo models as an area of ongoing research. Each animal model offers its own benefit in the study of OA and there are a full range of outcome measures that can be assessed. Despite the vast number of models, each has its drawbacks that have limited translating approved therapies for human use.

Conclusion

Depending on the outcome measures and objective of the study, researchers should pick the best model for their work. There have been several exciting studies since 2016 that have taken advantage of regenerative engineering techniques to develop therapies and better understand OA.

Lay Summary

Osteoarthritis (OA) is a chronic debilitating disease without any cure that affects mostly the knee and hip joints and often results in surgical joint replacement. Cartilage protects the joint from mechanical forces and degrades with age or in response to injury. The many contributing causes of OA are still being investigated, and animals are used for preclinical research and to test potential new treatments. A single consensus OA animal model for preclinical studies is non-existent. In this article, we review the many animal models for OA and provide a much-needed update on studies and model development since 2016.

An alkaloid from Menispermum dauricum, dauricine mediates Ca2+ influx and inhibits NF-κB pathway to protect chondrocytes from IL-1β-induced inflammation and catabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Dauricine (DA) is a natural plant-derived alkaloid extracted from Menispermum dauricum. Menispermum dauricum has been used in traditional Chinese medicine as a classic remedy for rheumatoid arthropathy and is believed to be effective in alleviating swelling and pain in the limbs.

AIM OF THE STUDY

Osteoarthritis (OA) is a classic degenerative disease involving chondrocyte death, and there is still a lack of effective therapeutic agents that can reverse the progression of the disease. Here we explored the therapeutic effects of DA against OA and further explored the mechanism.

MATERIALS AND METHODS

The effect of DA on cell viability was assessed by CCK-8. IL-1β-treated mouse chondrocytes were used as an in vitro model of OA, and apoptosis was detected by flow cytometry. QRT-PCR, western blotting, cell staining, and immunofluorescence were used to detect relevant inflammatory factors and cartilage-specific expression. RNA sequencing was used to identify pertinent signaling pathways. The therapeutic effect of DA was verified by micro-CT, histological analysis and immunohistochemical analysis in a mouse OA model.

RESULTS

DA demonstrated a high safety profile on chondrocytes, significantly reversing the inflammatory response induced by IL-1β, and promoting factors associated with cartilage regeneration. Moreover, DA exhibited a significant protective effect on the knee joints of mice undergoing ACLT-DMM, effectively preventing cartilage degeneration and subchondral bone tissue destruction. These positive therapeutic effects were achieved through the modulation of the NF-κB pathway and the Ca2+ signaling pathway by DA.

CONCLUSION

Being derived from a traditional herb, DA exhibits remarkable therapeutic potential and safety in OA treatment, presenting a promising option for patients dealing with osteoarthritis.

Casticin ameliorates osteoarthritic cartilage damage in rats through PI3K/AKT/HIF-1α signaling

Knee osteoarthritis (KOA) is a chronic, disabling knee joint lesion in which degeneration and defects in articular cartilage are the most important features. Casticin (CAS) is a flavonoid extracted from the Chinese herb Vitex species that has anti-inflammatory and antitumor effects. The aim of this study was to investigate the therapeutic and mechanistic effects of CAS on cartilage damage in KOA. A KOA rat model was established by anterior cruciate ligament transection (ACLT), and cartilage morphological changes were assessed by histological analysis and micro-CT scans. Subsequently, chondrocytes were treated with 10 ng/mL IL-1β to establish an OA model. CCK-8 assays and EdU assays were performed to assess the viability of CAS-treated chondrocytes. Western blotting, flow cytometry and Hoechst 33342/PI Double Stain were used to detect chondrocyte apoptosis. Western blotting, qRT‒PCR and ELISA were used to detect changes in inflammatory mediators. In addition, cartilage matrix-related indices were detected by Western blotting, qRT‒PCR and immunofluorescence (IF) analysis. Immunohistochemistry (IHC) and Western blotting were performed to detect the expression of p-PI3K, p-AKT and HIF-1α in vivo and in vitro. Micro-CT, pathological sections and related scores showed that CAS improved the alterations in bony structures and reduced cartilage damage and osteophyte formation in the ACLT model. In vivo, CAS attenuated IL-1β-induced cartilage matrix degradation, apoptosis and the inflammatory response. In addition, CAS inhibited the expression of the PI3K/AKT/HIF-1α signaling pathway in the ACLT animal model and IL-1β cell model. CAS may ameliorate cartilage damage in OA by inhibiting the PI3K/AKT/HIF-1α signaling pathway, suggesting that CAS is a potential strategy for the treatment of OA.

Collagen type II solution extracted from supercritical carbon dioxide decellularized porcine cartilage: regenerative efficacy on post-traumatic osteoarthritis model

Osteoarthritis (OA) of the knee is a common degenerative articular disorder and is one of the main causes of pain and functional disability. Cartilage damage is frequently linked to elevated osteoarthritis incidence. Supercritical carbon dioxide (scCO2) decellularized cartilage graft produced from the porcine cartilage is an ideal candidate for cartilage tissue engineering. In the present study, we derived collagen type II (Col II) solution from the scCO2 decellularized porcine cartilage graft (dPCG) and compared its efficacy with hyaluronic acid (HA) in the surgical medial meniscectomy (MNX) induced post-traumatic osteoarthritis (PTOA) model. Dose-dependent attenuation of the OA (12.3 ± 0.8) progression was observed in the intra-articular administration of Col II solution (7.3 ± 1.2) which significantly decreased the MNX-induced OA symptoms similar to HA. The pain of the OA group (37.4 ± 2.7) was attenuated dose-dependently by Col II solution (45.9 ± 4.1) similar to HA (43.1 ± 3.5) as evaluated by a capacitance meter. Micro-CT depicted a dose-dependent attenuation of articular cartilage damage by the Col II solution similar to HA treatment. A significant (p < 0.001) dose-dependent elevation in the bone volume was also observed in Col II solution-treated OA animals. The protective competence of Col II solution on articular cartilage damage is due to its significant (p < 0.001) increase in the expression of type II collagen, aggrecan and SOX-9 similar to HA. To conclude, intra-articular administration of type II collagen solution and HA reestablished the injured cartilage and decreased osteoarthritis progression in the experimental PTOA model.

Integrated Analysis of DNA Methylation and Gene Expression Profiles in a Rat Model of Osteoarthritis

Osteoarthritis (OA) is common and affected by several factors, such as age, weight, sex, and genetics. The pathogenesis of OA remains unclear. Therefore, using a rat model of monosodium iodoacetate (MIA)-induced OA, we examined genomic-wide DNA methylation using methyl-seq and characterized the transcriptome using RNA-seq in the articular cartilage tissue from a negative control (NC) and MIA-induced rats. We identified 170 genes (100 hypomethylated and upregulated genes and 70 hypermethylated and downregulated genes) regulated by DNA methylation in OA. DNA methylation-regulated genes were enriched in functions related to focal adhesion, extracellular matrix (ECM)-receptor interaction and the PI3K-Akt and Hippo signaling pathways. Functions related to extracellular matrix organization, extracellular matrix proteoglycans, and collagen formation were involved in OA. A molecular and protein-protein network was constructed using methylated expression-correlated genes. Erk1/2 was a downstream target of OA-induced changes in DNA methylation and RNA expression. We found that the integrin subunit alpha 2 (ITGA2) gene is important in focal adhesion, alpha6-beta4 integrin signaling, and the inflammatory response pathway in OA. Overall, gene expression changes because DNA methylation influences OA pathogenesis. ITGA2, whose gene expression changes are regulated by DNA methylation during OA onset, is a candidate gene. Our findings provide insights into the epigenetic targets of OA processes in rats.

Drug-Releasing Thermogel for Osteoarthritis Induction in an Animal Model

The induction of disease states in animal models is an essential step in new drug discovery procedures. In this study, osteoarthritis (OA) was induced in a mouse model using a polypeptide thermogel-based sustained drug release system. Hydrophilic lactobionic acids and hydrophobic n-butyric acids were grafted onto ε-poly(l-lysine) to prepare a thermogelling polymer of ε-poly(l-lysine) grafted with lactobionic acid and butyric acid (PLLB). The gel modulus of PLLB is about 1000 Pa at 37 °C. Collagenase, which causes OA, was slowly released from the PLLB thermogel over two weeks. The PLLB formulation containing collagenases ranging from 1-10 units was intra-articularly injected into the knee of mice. OA mouse models with Osteoarthritis Research Society International (OARSI) grades of 3-6 were developed depending on the amounts of collagenase incorporated in the PLLB thermogel formulation. This study suggests that thermogel-based drug release formulations can be a precise tool for developing animal disease models in a dose-dependent manner.

Targeting regulated chondrocyte death in osteoarthritis therapy

In vivo articular cartilage degeneration is an essential hallmark of osteoarthritis (OA), involving chondrocyte senescence, extracellular matrix degradation, chondrocyte death, cartilage loss, and bone erosion. Among them, chondrocyte death is one of the major factors leading to cartilage degeneration. Many studies have reported that various cell death modes, including apoptosis, ferroptosis, and autophagy, play a key role in OA chondrocyte death. Currently, there is insufficient understanding of OA pathogenesis, and there remains a lack of treatment methods to prevent OA and inhibit its progression. Studies suggest that OA prevention and treatment are mainly directed to arrest premature or excessive chondrocyte death. In this review, we a) discuss the forms of death of chondrocytes and the associations between them, b) summarize the critical factors in chondrocyte death, c) discuss the vital role of chondrocyte death in OA, d) and, explore new approaches for targeting the regulation of chondrocyte death in OA treatment.

Tongbi Huoluo Decoction alleviates cartilage degeneration in knee osteoarthritis by inhibiting degradation of extracellular matrix

BACKGROUND

Knee osteoarthritis (KOA) is an age-related degenerative disease characterized by abrasion of articular cartilage. Tongbi Huoluo Decoction (TBHLD) has been transformed from the famous traditional Chinese medicine Duhuo Jisheng Decoction, which can effectively alleviate pain symptoms in KOA. However, the active components and mechanisms of TBHLD in treating KOA have not yet been elucidated. The purpose of the study was to demonstrate the molecular mechanism of TBHLD in treating KOA.

METHODS

The components and targets of TBHLD and KOA were collected from multiple databases, and the protein to protein interaction (PPI) network was constructed. Next, we performed topological calculation and enrichment analysis. Besides, we performed virtual screening for molecular docking and molecular dynamics simulation (MDS). Furthermore, the vitro and vivo experiments were performed to evaluate the validity and mechanism of TBHLD.

RESULTS

206 active components and 187 potential targets were screened from Tongbi Huoluo Decoction. A total of 50 intersecting genes were identified between TBHLD and KOA, 20 core targets were calculated by network topology analysis. The core targets were enriched in the ECM interaction pathways. The results of virtual screening for molecular docking and MDS showed that the active components of TBHLD had steady binding conformations with core genes. Moreover, we identified 32 differential serum components in TBHLD-containing serum using LC-MS, including 22 upregulated and 10 downregulated serum components. TBHLD improved the proliferation activity of OA chondrocytes, decreased the expression of Col1a1, Col1a2, Mmp2, Mmp13 in OA chondrocytes, ameliorated the cartilage lesions and restored the cartilage abrasion.

CONCLUSION

TBHLD inhibited degradation of cartilage ECM by regulating the expression of type I collagens and Mmps to ameliorate cartilage degeneration in KOA.

Self-assembled peptide-substance P hydrogels alleviate inflammation and ameliorate the cartilage regeneration in knee osteoarthritis

BACKGROUND

Self-assembled peptide (SAP)-substance P (SP) hydrogels can be retained in the joint cavity longer than SP alone, and they can alleviate inflammation and ameliorate cartilage regeneration in knee osteoarthritis (OA). We conducted a preclinical study using diverse animal models of OA and an in vitro study using human synoviocytes and patient-derived synovial fluids to demonstrate the effect of SAP-SP complex on the inflammation and cartilage regeneration.

METHODS

Surgical induction OA model was prepared with New Zealand white female rabbits and chemical induction, and naturally occurring OA models were prepared using Dunkin Hartely female guinea pigs. The SAP-SP complex or control (SAP, SP, or saline) was injected into the joint cavities in each model. We performed micro-computed tomography (Micro-CT) analysis, histological evaluation, immunofluorescent analysis, and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling (TUNEL) assay and analyzed the recruitment of intrinsic mesenchymal stem cells (MSCs), macrophage activity, and inflammatory cytokine in each OA model. Human synoviocytes were cultured in synovial fluid extracted from human OA knee joints injected with SAP-SP complexes or other controls. Proliferative capacity and inflammatory cytokine levels were analyzed.

RESULTS

Alleviation of inflammation, inhibition of apoptosis, and enhancement of intrinsic MSCs have been established in the SAP-SP group in diverse animal models. Furthermore, the inflammatory effects on human samples were examined in synoviocytes and synovial fluid from patients with OA. In this study, we observed that SAP-SP showed anti-inflammatory action in OA conditions and increased cartilage regeneration by recruiting intrinsic MSCs, inhibiting progression of OA.

CONCLUSIONS

These therapeutic effects have been validated in diverse OA models, including rabbits, Dunkin Hartley guinea pigs, and human synoviocytes. Therefore, we propose that SAP-SP may be an effective injectable therapeutic agent for treating OA. In this manuscript, we report a preclinical study of novel self-assembled peptide (SAP)-substance P (SP) hydrogels with diverse animal models and human synoviocytes and it displays anti-inflammatory effects, apoptosis inhibition, intrinsic mesenchymal stem cells recruitments and cartilage regeneration.

Ceria Nanoparticles Alleviated Osteoarthritis through Attenuating Senescence and Senescence-Associated Secretory Phenotype in Synoviocytes

Accumulation of senescent cells is the prominent risk factor for osteoarthritis (OA), accelerating the progression of OA through a senescence-associated secretory phenotype (SASP). Recent studies emphasized the existence of senescent synoviocytes in OA and the therapeutic effect of removing senescent synoviocytes. Ceria nanoparticles (CeNP) have exhibited therapeutic effects in multiple age-related diseases due to their unique capability of ROS scavenging. However, the role of CeNP in OA remains unknown. Our results revealed that CeNP could inhibit the expression of senescence and SASP biomarkers in multiple passaged and hydrogen-peroxide-treated synoviocytes by removing ROS. In vivo, the concentration of ROS in the synovial tissue was remarkably suppressed after the intra-articular injection of CeNP. Likewise, CeNP reduced the expression of senescence and SASP biomarkers as determined by immunohistochemistry analysis. The mechanistic study showed that CeNP inactivated the NFκB pathway in senescent synoviocytes. Finally, safranin O-fast green staining showed milder destruction of articular cartilage in the CeNP-treated group compared with the OA group. Overall, our study suggested that CeNP attenuated senescence and protected cartilage from degeneration via scavenging ROS and inactivating the NFκB signaling pathway. This study has potentially significant implications in the field of OA as it provides a novel strategy for OA treatment.

Achyranthoside D attenuates chondrocyte loss and inflammation in osteoarthritis via targeted regulation of Wnt3a

BACKGROUND

Achyranthes bidentata Blume (A. bidentata) is a common Chinese herb used to treat osteoarthritis (OA). Achyranthoside D (Ach-D) is a glucuronide saponin isolated from A. bidentata.

PURPOSE

To assess the mechanisms of action of Ach-D and its effects on OA.

METHODS

The effects of Ach-D were evaluated in rats underwent anterior cruciate ligament transection (ACLT) with medial meniscectomy (MMx) and in interleukin (IL)-1β-induced chondrocytes. Histological changes in rat cartilage tissues were detected using Safranin O-Fast green and haematoxylin-eosin staining. Immunohistochemical staining, qRT-PCR, ELISA, immunoblotting, and immunofluorescence were conducted to examine cartilage degeneration-related and inflammation-related factor expression. CCK-8, LDH assay, and EdU staining were performed to detect chondrocyte death.

RESULTS

Ach-D dose-dependently reduced the Osteoarthritis Research Society International (OARSI) scores, alleviated cartilage injury, and decreased the serum concentrations of CTX-II and COMP in ACLT-MMx models. Ach-D increased the expression levels of collagen II and aggrecan and decreased the levels of cartilage degeneration-related proteins, ADAMTS-5, MMP13, and MMP3, in rat cartilage tissues. Additionally, nod-like receptor protein 3 (NLRP3)-related inflammation was reduced by Ach-D, as shown by the significantly inhibited expression levels of NLRP3, ASC, GSDMD, IL-6, TNF-α, IL-1β, and IL-18 in rat cartilage tissues. In primary rat chondrocytes, Ach-D protected against IL-1β-induced viability loss and LDH release. Wnt3a is the target protein of Ach-D. Mechanistically, Ach-D alleviated OA by inhibiting Wnt signalling.

CONCLUSION

ACH-D may reduce inflammation and cartilage degeneration by inhibiting the Wnt signalling pathway, thereby reducing OA.

Silencing of circ-NT5C2 retards the progression of IL-1β-induced osteoarthritis in an in vitro cell model by targeting the miR-142-5p/NAMPT axis

Osteoarthritis (OA) is a degenerative disease that occurs mostly in the elderly, and its specific pathogenesis is still unknown, but recent studies have found that circular RNA generally display aberrant expression in OA. Our study explored the expression characteristics and mechanism of action of circ-NT5C2 in OA. Circ-NT5C2, microRNA-142-5p (miR-142-5p), and nicotinamide phosphoribosyltransferase (NAMPT) mRNA levels were measured using RT-qPCR. Western blot was employed to assess the protein level of NAMPT and extracellular matrix (ECM) production-related markers. The viability, proliferation, apoptosis and inflammation were examined using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, and enzyme-linked immunosorbent assay, respectively. Relationship between miR-142-5p and circ-NT5C2 or NAMPT was demonstrated by dual-luciferase reporter system and RNA immunoprecipitation assay. We reported that circ-NT5C2 and NAMPT were greatly upregulated, and miR-142-5p level was constrained in OA tissues and in a cell model. Circ-NT5C2 silencing alleviated IL-1β-induced inhibitory effects on chondrocyte proliferation and ECM generation, meanwhile the promotional role of IL-1β on chondrocyte apoptosis and inflammation was also weakened. The targeting relationship of miR-142-5p with either circ-NT5C2 or NAMPT was confirmed. Knockdown of miR-142-5p reversed the suppressive effects of circ-NT5C2 silencing on the OA progression in vitro, and NAMPT overexpression also attenuated the effects of miR-142-5p upregulation in an OA cell model. Collectively, circ-NT5C2 accelerated the OA process by targeting the miR-142-5p/NAMPT axis. This study provides valuable information to find a better treatment for OA.

Transglutaminase 2 inhibitors attenuate osteoarthritic degeneration of TMJ-osteoarthritis by suppressing NF-κB activation

BACKGROUND

The temporomandibular joint osteoarthritis (TMJ-OA) is characterized by progressive cartilage degradation, subchondral bone erosion, and chronic pain, leading to articular damage and chewing dysfunction. Studies have shown that interleukin-1β (IL-1β) plays a critical role in the development of TMJ-OA. Transglutaminase 2 (TG2) has been identified as a marker of chondrocyte hypertrophy and IL-1β was able to increase TG2 expression in chondrocytes. Therefore, the aim of this study was to explore the ability of TG2 inhibitors to suppress TMJ-OA progression.

METHODS

Firstly, toluidine blue staining, cell counting kit-8 assay, immunocytofluorescent staining and western blot were used to investigate the anti-inflammatory effects of TG2 inhibitors in IL-1β-stimulated murine chondrocytes and the underlying mechanisms. Afterwards, micro-CT analysis, histological staining, immunohistochemical and immunohistofluorescent staining were used to evaluate the therapeutic efficacy of TG2 inhibitors in monosodium iodoacetate (MIA)-induced TMJ-OA in rats.

RESULTS

TG2 inhibitors suppressed the IL-1β-induced upregulation of COX-2, iNOS, MMP-13, and MMP-3 and reversed the IL-1β-induced proteoglycan loss in chondrocytes through inhibiting NF-κB activation. Consistently, the MIA-induced upregulation of MMP-13 and MMP-3, and loss of structural integrity of the articular cartilage and subchondral bone were markedly reversed by TG2 inhibitors via inhibiting NF-κB activation.

CONCLUSIONS

TG2 inhibitors demonstrated a potent therapeutic efficacy on cartilage and subchondral bone structures of TMJ-OA by reducing inflammation and cartilage degradation through suppressing NF-κB activation.

Microstructural changes of cartilage and subchondral bone in a guinea pig model of early- and middle-stage patellofemoral arthritis

OBJECTIVE

Patellofemoral arthritis is a common type of knee osteoarthritis and a prime cause of anterior knee pain and disability. Most of the existing research on knee osteoarthritis focuses on tibial-femoral arthritis, while studies on patellofemoral arthritis are relatively rare. This study aims to observe changes in osteochondral and subchondral bone structure over time in the patella and femoral trochlea in an animal model of spontaneous patellofemoral arthritis.

METHODS

A total of 24 1-, 3- or 5-month-old healthy female Hartley guinea pigs were used for experiments. No intervention was applied, and the mechanical pain threshold was assessed prior to euthanasia. Bilateral knee joints were collected in the animals at the different ages, and the patellofemoral joints were taken to evaluate the bone microstructure of patellofemoral articular cartilage and subchondral bone by macroscopy, histopathology and micro-computed tomography (micro-CT).

RESULTS

There was a significant difference in the severity of femoral trochlea injury assessed by the Macro score between 5- and 1-month-old groups (P<0.01), as well as in patellar cartilage damage (P<0.05). The mechanical pain threshold of lower extremities in each group was statistically different between different age groups (P<0.05). The OARSI articular cartilage histopathological scores, including patella and femoral trochlea, were significantly different among 1-, 3- and 5-month-old groups. The 5-month-old group exhibited statistically lower values of bone volume/trabecular volume, trabecular number and trabecular thickness in the femoral subchondral bone and evidently higher structure model index than the 1-month-old group.

CONCLUSIONS

This study demonstrated that 3- to 5-month-old female Hartley guinea pigs can develop early-to-mid-stage spontaneous patellofemoral arthritis that causes significant cartilage degeneration and loss of subchondral bone. In addition, the bone microarchitecture of the femur is more severely degraded.

A Combination of Surgical and Chemical Induction in a Rabbit Model for Osteoarthritis of the Knee

BACKGROUND

Appropriate animal models of osteoarthritis (OA) are essential to develop new treatment modalities for OA. A combination of surgical and chemical induction could be appropriate for OA models.

METHODS

Rabbit knee OA models developed by surgical induction (anterior cruciate ligament transection [ACLT]), chemical induction (monosodium iodoacetate [MIA] injection), and a combination of both were compared to assess compositional and structural destruction of the knee joint. Twenty-one New Zealand white rabbits were randomly divided into 3 groups to induce OA (group 1: ACLT, n = 3; group 2: MIA [3, 6, 9 mg] injection, n = 9; group 3: ACLT + MIA [3, 6, 9 mg] injection, n = 9).

RESULTS

In all groups, the Modified Mankin score was significantly higher in the osteoarthritis-induced knee than in the control. Modified Mankin scores were compared by category. The ACLT group was observed to score high in cartilage structure. In the MIA group, chondrocytes and matrix staining showed higher scores, and the ACLT+MIA group scored higher in all categories for cartilage structure, chondrocytes, matrix staining, and tidemark integrity. The ACLT + 3 mg MIA showed definite OA characteristics such as cartilage surface destruction and degeneration of cartilage layers, and the ACLT + 6 mg MIA and ACLT + 9 mg MIA showed more prominent OA characteristics such as cartilage surface destruction, matrix disorganization, and osteophyte formation.

CONCLUSION

The combination of MIA injection and ACLT could be an appropriate method for OA induction in rabbit models.

Serum periostin level is not sufficient to serve as a clinically applicable biomarker of osteoarthritis

BACKGROUND

Emerging knowledge has highlighted the role of periostin (POSTN) in osteoarthritis (OA) process; however, whether POSTN is suitable as a biomarker of OA remains unclear. This study aimed to investigate the potential value of POSTN as a biomarker of OA.

METHODS

Ten 6-month-old female Sprague-Dawley (SD) rats were used in this study. Five rats underwent ovariectomy (OVX) operation and the others were carried out sham operation. Thirty-two patients with OA and eighteen patients who had meniscus injuries or ligament injuries but with intact articular cartilages were recruited in this study from January to July 2019 at the Peking University International Hospital. We first detected the expression of POSTN in the cartilage of OVX induced OA rats and different compartments of the knee joint in patients with OA using immunohistochemistry. Besides, serum POSTN levels in patients with or without OA were examined using enzyme-linked immunosorbent assay (ELISA). The associations among serum POSTN levels, clinical symptoms, and radiological severity were assessed according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and, Kellgren-Lawrence (KL) grading, respectively. Finally, multivariable cumulative link models were established to evaluate the validity of serum POSTN level as a predictor of knee OA.

RESULTS

The significantly higher POSTN expression was found in OVX-OA rats than Sham rats, while, the expression of POSTN was significantly higher in the torn cartilage of patients with OA. However, the serum POSTN level did not differ significantly between patients with and without OA. Additionally, we found no remarkable associations between serum POSTN level and WOMAC scores and KL grading. Subsequent analysis revealed that serum POSTN was not a significant predictor of OA.

CONCLUSION

Thus, although POSTN may be involved OA process and local POSTN is valuable in disease diagnosis and distinguishing of the severity of disease, its serum level is not sufficient to serve as a candidate biomarker of OA given the current analysis technology.

Surgical Classification for Preclinical Rat Femoral Bone Defect Model: Standardization Based on Systematic Review, Anatomical Analysis and Virtual Surgery

Though surgical techniques profoundly influence in vivo experiments, significant heterogeneity exists in current surgeries for inducing rat femoral bone defects. Such variations reduce the reproducibility and comparability of preclinical studies, and are detrimental to clinical translation. The purposes of this study were: (1) to conduct a systematic review of rat femoral defect models, summarizing and analyzing the surgical techniques; (2) to analyze surgical design and potential pitfalls via 3D anatomy and virtual surgeries for fostering future precision research; and (3) to establish a surgical classification system, for improving the reproducibility and comparability among studies, avoiding unnecessary repetitive experiments. The online database PubMed was searched to identify studies from January 2000 to June 2022 using keywords, including rat, femur, bone defect. Eligible publications were included for a review of surgical methods. Anatomical analysis and virtual surgeries were conducted based on micro-CT reconstruction of the rat femur for further investigation and establishment of a classification system. A total of 545 publications were included, revealing marked heterogeneity in surgical methods. Four major surgical designs were reported for inducing defects from the proximal to distal femur: bone tunnel, cortical window, segmental defect, and wedge-shaped defect. Anatomical analysis revealed potential pitfalls hindering efficient clinical translation. A classification system was established according to the anatomical region, surgical design, and fixation devices. This systematic review in combination with 3D analysis and virtual surgery provides a general overview of current surgical approaches to inducing femoral defects in rats, and establishes a surgical classification facilitating preclinical research of quality and translational value.

A Novel Hypoxia Related Marker in Blood Link to Aid Diagnosis and Therapy in Osteoarthritis

Osteoarthritis (OA) is a common chronic degenerative arthritis. Its treatment options are very limited. At present, hypoxia is a prominent factor in OA. This study aimed to re-explore the mechanism between hypoxia and OA, which provides new insights into the diagnosis and therapy of OA. We acquired the OA-related expression profiles of GSE48556, GSE55235, and GSE55457 for our analysis. Using gene set variation analysis (GSVA), we found significant differences in hypoxia. These differences result from multiple pathways, such as the p53 signaling pathway, cell senescence, the NF-kappa B signaling pathway, Ubiquitin-mediated proteolysis, and apoptosis. Meanwhile, the single-sample gene set enrichment analysis (ssGSEA) showed that hypoxia was significantly associated with the level of immune cell infiltration in the immune microenvironment. Thus, we believe that hypoxia is useful for the diagnosis and treatment of OA. We successfully constructed a novel hypoxia-related index (HRI) based on seven hypoxia-related genes (ADM, CDKN3, ENO1, NDRG1, PGAM1, SLC2A1, VEGFA) by least absolute shrinkage and binary logistic regression of the generalized linear regression. HRI showed potential for improving OA diagnosis through receiver operation characteristic (ROC) analysis (AUC training cohort = 0.919, AUC testing cohort = 0.985). Moreover, we found that celastrol, droxinostat, torin-2, and narciclasine may be potential therapeutic compounds for OA based on the Connectivity Map (CMap). In conclusion, hypoxia is involved in the development and progression of OA. HRI can improve diagnosis and show great potential in clinical application. Celastrol, droxinostat, torin-2, and narciclasine may be potential compounds for the treatment of OA patients.

Naturally Occurring Osteoarthritis Features and Treatments: Systematic Review on the Aged Guinea Pig Model

To date, several in vivo models have been used to reproduce the onset and monitor the progression of osteoarthritis (OA), and guinea pigs represent a standard model for studying naturally occurring, age-related OA. This systematic review aims to characterize the guinea pig for its employment in in vivo, naturally occurring OA studies and for the evaluation of specific disease-modifying agents. The search was performed in PubMed, Scopus, and Web of Knowledge in the last 10 years. Of the 233 records screened, 49 studies were included. Results showed that within a relatively short period of time, this model develops specific OA aspects, including cartilage degeneration, marginal osteophytes formation, and subchondral bone alterations. Disease severity increases with age, beginning at 3 months with mild OA and reaching moderate–severe OA at 18 months. Among the different strains, Dunkin Hartley develops OA at a relatively early age. Thus, disease-modifying agents have mainly been evaluated for this strain. As summarized herein, spontaneous development of OA in guinea pigs represents an excellent model for studying disease pathogenesis and for evaluating therapeutic interventions. In an ongoing effort at standardization, a detailed characterization of specific OA models is necessary, even considering the main purpose of these models, i.e., translatability to human OA.

Progress in osteoarthritis research by the National Natural Science Foundation of China

Osteoarthritis (OA) in China is gradually becoming an important scientific research area that has had a significant impact on research and development (R&D) activities in the OA field worldwide. This article summarizes the R&D progress related to OA in China in recent years. The National Natural Science Foundation of China (NSFC) is a national funding institution for basic research and plays a critical role in promoting and supporting Chinese scholars' R&D activities. We collected and analyzed information on NSFC funding in the field of OA from 2010 to 2019, including the amount, the level and the program categories of the funded projects. The data fully demonstrate the important and positive role of the NSFC in supporting free exploration, cultivating research teams and young talent, and boosting OA R&D. In this article, we outline and discuss hot topics in focused areas, key advances in this field and the prospects for progress in OA research in China.

The Application of Extracellular Vesicles Mediated miRNAs in Osteoarthritis: Current Knowledge and Perspective

Osteoarthritis (OA) is a whole joint disease characterized by synovitis, cartilage destruction, and subchondral bone sclerosis and cyst. Despite decades’ study, effective treatment is rare for this chronic disease. Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptosis bodies, are nano-sized vesicles with a cargo containing biologically active agents, such as nucleic acids, lipids, and proteins. As a group of short non-coding RNAs, microRNAs (miRNAs) can be delivered by parental cells secreted EVs. Negatively regulate the target mRNAs at the posttranscriptional level and regulate gene expression in recipient cells without modifying gene sequence. Recently, most studies focused on the function of EVs mediated miRNAs in the pathophysiological process of OA. However, all kinds of EVs specific and OA specific factors might influence the administration of EVs-miRNAs, especially the precise quantitative management. As a result, the flourishing of current research about EVs in the laboratory might not promote the relevant clinical transformation in OA treatment. In this review, we reviewed the present application of EVs-miRNAs in the therapeutic of OA and further analyzed the potential factors that might influence its application. Further progress in the quantitative management of EVs-miRNAs would accelerate the clinical transformation of miRNAs enriched EVs in the OA field.

The protective effect of mangiferin on osteoarthritis: An in vitro and in vivo study

Mangiferin is a kind of polyphenol chemical compound separated from these herbal medicines of Mangifera indica L., Anemarrhena asphodeloides Bge. and Belamcanda chinensis L., which has anti-inflammatory, anti-virus, and other physiological activities without toxic effects. Osteoarthritis (OA) is a chronic disease that is also a kind of arthritis disease in which articular cartilage or bones under the joint is damaged. In addition, artificial replacements are required in severe cases. At present, there are not too much researches on the potential biological activities of mangiferin that plays a protective role in the treatment of OA. In this study, we evaluated the protective effect of mangiferin on osteoarthritis (OA) in vitro and in vivo. First, the effect of different concentrations of mangiferin on rat chondrocytes was determined by MTT assay. Second, the effects of mangiferin on the expression levels of matrix metalloproteinase (MMP)-13, TNF alpha, Collagen II, Caspase-3, and cystatin-C in interleukin-1beta (IL-1beta)-induced rat chondrocytes were examined by the real-time polymerase chain reaction in vitro, meanwhile the effects of mangiferin on the nuclear factor kappa-B (NF-kappaB) signaling pathway were also investigated by Western Blot. Finally, the anti-osteoarthritic protective effect of mangiferin was evaluated in the rat model by anterior cruciate ligament transection (ACLT) combined with bilateral ovariectomy-induced OA in vivo. The results showed that the mangiferin was found to inhibit the expression of MMP-13, TNF-alpha, and Caspase-3 which also increased the expression of Collagen II and cystatin-C in IL 1beta induced rat chondrocytes. In addition, IL-1beta-induced activation of nuclear factor kappa-B (NF-kappaB) and the degradation of inhibitor of kappaB (IkappaB)-alpha were suppressed by mangiferin. For the in vivo study in a rat model of OA, 100 microl of mangiferin was administered by intra-articular injections for rats, the results showed that the cartilage degradation was suppressed by mangiferin through Micro CT and Histological Examination. According to both in vitro and in vivo results, mangiferin has a protective effect in the treatment of OA which may be a promising therapeutic agent for OA.

Intra-articular ozone slows down the process of degeneration of articular cartilage in the knees of rats with osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a joint disease of multifactorial etiology, affecting mainly the knees. We aimed to evaluate the effects of two different doses of gaseous ozone intra-articularly on the knee cartilage morphology of rats with osteoarthritis (OA).

METHODS

The articular lesion was induced by sodium monoiodoacetate (MIA). 40 Wistar rats were divided into 4 groups: G1 control (without lesion and without treatment), G2 articular lesion (AL) (only lesion MIA-induced), G3 AL + treatment with 5 μg/mL of ozone intra-articular, and G4 AL + treatment with 10 μg/mL of ozone intra-articular. The experiment was carried out for 60 days.

RESULTS

Both doses of ozone intra-articular demonstrated less reduction in joint space (G3 and G4) compared to the G2, formation of osteophytes, but without subchondral sclerosis. Ozone decreased the volumetric density of the articular lesion (VV(AL)) of tibial. The treatments recovered VV(AL) of the femur similar to G1. Ozone lower dose (G3) showed lower tibia and femur macroscopic scores.

CONCLUSION

Intra-articular gaseous ozone can delay the degeneration of articular cartilage and can represents an integrative therapy in the OA treatment of knee after 60 days of treatment. For the first time the role of ozone in articular cartilage degeneration was evaluated helping to understand this therapy.

Chitosan/Pluronic F127 Thermosensitive Hydrogel as an Injectable Dexamethasone Delivery Carrier

Intra-articular administration of anti-inflammatory drugs is a strategy that allows localized action on damaged articular cartilage and reduces the side effects associated with systemic drug administration. The objective of this work is to prepare injectable thermosensitive hydrogels for the long-term application of dexamethasone. The hydrogels were prepared by mixing chitosan (CS) and Pluronic-F127 (PF) physically. In addition, tripolyphosphate (TPP) was used as a crosslinking agent. Chitosan added to the mix increased the gel time compared to the pluronic gel alone. The incorporation of TPP into the material modified the morphology of the hydrogels formed. Subsequently, MTS and Live/Dead® experiments were performed to investigate the toxicity of hydrogels against human chondrocytes. The in vitro releases of dexamethasone (DMT) from CS-PF and CS-PF-TPP gels had an initial burst and took more time than that from the PF hydrogel. In vivo studies showed that hydrogels retained the fluorescent compound longer in the joint than when administered in PBS alone. These results suggest that the CS-PF and CS-PF-TPP hydrogels loaded with DMT could be a promising drug delivery platform for the treatment of osteoarthritis.

Role of WNT Agonists, BMP and VEGF Antagonists in Rescuing Osteoarthritic Knee Cartilage in a Rat Model

INTRODUCTION

The superficial zone of articular cartilage (AC) is vital for its function and biomechanics. The damaged AC gets vascularized and undergoes hypertrophy and ossification. Studies have highlighted these two as the major causative factors in osteoarthritis (OA). We aimed at preventing the OA progression in a rat knee instability model by inhibiting the vascular ingrowth and ossification using VEGF and BMP antagonist. A WNT agonist was also used to promote AC regeneration because of its protective effect on the superficial layer.

METHODS

Rat knee OA was created by surgical excision of the medial meniscus and medial collateral ligament. Forty rats were divided into two groups of twenty each for surgical control and tests (surgery + intra-articular injection of drugs every two weeks). Ten animals from each group were sacrificed at four and eight weeks. Histology was mainly used to evaluate the outcome.

RESULTS

A surgical OA model was successfully created with higher histological scores for operated knees, both in short- (P = 0.0001) and long-term (P = 0.001). Modified Mankin score was lesser in the test animals as compared to control (P = 0.17) in the short-term, but the trend was reversed in the long-term (P = 0.13). Subgroup analysis revealed that repeated injections in the anterolateral compartment contributed to higher scores in the lateral (P = 0.03) and anterior (P = 0.03) compartment of the knee in the long-term.

CONCLUSION

The combinatorial approach was effective in controlling the OA in short-term. Further studies are needed to test the sustained drug delivery system to improve the outcome.

miR-144-3p ameliorates the progression of osteoarthritis by targeting IL-1β: Potential therapeutic implications

The pro-inflammatory cytokine interleukin 1 beta (IL-1β) plays a critical role in osteoarthritis (OA) disease pathogenesis. MicroRNA (miRNA) activity is related to inflammation in OA and some miRNAs specifically regulate IL-mediated degradation of cartilage type II collagen. Previous studies have indicated that miR-144-3p is a useful target in the regulation of pro-inflammatory cytokines in different diseases. However, the role of miR-144-3p in OA is unclear. In this study, we observed a negative correlation between miR-144-3p and IL-1β expression in OA. miR-144-3p mimic transfection of OA synovial fibroblasts downregulated levels of IL-1β expression, while blocking the MAPK, PI3K/Akt, and NF-κB signaling pathways relating to IL-1β production, and effectively increased miR-144-3p expression in OASFs. Findings from an anterior cruciate ligament transection rat model revealed that administration of miR-144-3p mimic effectively ameliorated OA progression and reduced the numbers of IL-1β-positive cells in synovial tissue. This study suggests that miR-144-3p is a useful therapeutic target in OA disease.

Supercritical carbon dioxide decellularized porcine cartilage graft with PRP attenuated OA progression and regenerated articular cartilage in ACLT-induced OA rats

Knee osteoarthritis (OA) is a common degenerative articular disorder and considered one of the primary causes of pain and functional disability. Knee OA is prevalent in 10% of men and 13% of women aged 60 years above. The study aims to use cartilage tissue engineering that combines the triads of decellularized porcine cartilage graft as "scaffold," plasma rich platelet (PRP) as "signal" and chondrocytes from rat as "cell" to attenuate ACLT-induced OA progression and regenerate the knee cartilage in rats. Decellularization of the porcine cartilage was characterized by hematoxylin and eosin, 4,6-Diamidino-2-phenylindole staining, scanning electron microscopy and residual DNA quantification. The protective effect of decellularized porcine cartilage graft (dPCG) was evaluated by intra-articular administration in surgically induced anterior cruciate ligament transection (ACLT) rat osteoarthritis (OA) model. Supercritical carbon dioxide technology completely decellularized the porcine cartilage. Intra-articular administration of dPCG with or without PRP significantly reduced the ACLT-induced OA symptoms and attenuated the OA progression. Pain-relief by dPCG with or without PRP was assessed by capacitance meter and improved articular cartilage damage in the rat knee was characterized by X-ray and micro-CT. Besides, the histological analysis depicted cartilage protection by dPCG with or without PRP. The repairation and attenuation effect by dPCG with or without PRP in the articular knee cartilage damage were also explored by safranin-O, type II collagen, aggrecan and SOX-9 immuno-staining. To conclude, intra-articular administration of dPCG with or without PRP is efficient in repairing the damaged cartilage in the experimental OA model.

Histomorphometric Quantitative Evaluation of Long-Term Risedronate Use in a Knee Osteoarthritis Rabbit Model

Osteoarthritis (OA) treatment is a major orthopedic challenge given that there is no ideal drug capable to reverse or stop the progression of the OA. In that regard, bisphosphonates have been proposed as potential disease-modifying drugs due to their possible chondroprotective effect related to obtaining a greater subchondral bone quality. However, their effectiveness in OA is still controversial and additionally, there is little evidence focused on their long-term effect in preclinical studies. The aim of this study was to evaluate the risedronate quantitative effect on articular and subchondral periarticular bone by histomorphometry, in an experimental rabbit model in an advanced stage of OA. Twenty-four adult New Zealand rabbits were included in the study. OA was surgically induced in one randomly chosen knee, using the contralateral as healthy control. Animals were divided into three groups (n = 8): placebo control group, sham surgery group and risedronate-treated group. After 24 weeks of treatment, cartilage and subchondral femorotibial pathology was evaluated by micro-computed tomography (micro-CT) and undecalcified histology. The research results demonstrated that the experimental animal model induced osteoarthritic changes in the operated joints, showing an increased cartilage thickness and fibrillation associated with underlying subchondral bone thinning and decreased trabecular bone quality. These changes were especially highlighted in the medial tibial compartments as a possible response to surgical instability. Regarding the trabecular analysis, significant correlations were found between 2D histomorphometry and 3D imaging micro-CT for the trabecular bone volume, trabecular separation, and the trabecular number. However, these associations were not strongly correlated, obtaining more precise measurements in the micro-CT analysis. Concerning the long-term risedronate treatment, it did not seem to have the capacity to reduce the osteoarthritic hypertrophic cartilage response and failed to diminish the superficial cartilage damage or prevent the trabecular bone loss. This study provides novel information about the quantitative effect of long-term risedronate use on synovial joint tissues.

Effects of Dipsacus asperoides Extract on Monosodium Iodoacetate-Induced Osteoarthritis in Rats Based on Gene Expression Profiling

The root of Dipsacus asperoides C. Y. Cheng et T. M. Ai is traditionally used as an analgesic and anti-inflammatory agent to treat pain, rheumatoid arthritis, and bone fractures. However, neither its effects on osteoarthritis (OA) nor its effects on the arthritic cartilage tissue transcriptome have not been fully investigated. In this study, we used a rat model of monosodium iodoacetate- (MIA-) induced OA to investigate the therapeutic effects of a Dipsacus asperoides ethanolic extract (DAE, 200 mg/kg for 21 days). The study first assessed joint diameter, micro-CT scans, and histopathological analysis and then conducted gene expression profiling using RNA sequencing in articular cartilage tissue. We found that DAE treatment ameliorates OA disease phenotypes; it reduced the knee joint diameter and prevented changes in the structural and histological features of the joint, thereby showing that DAE has a protective effect against OA. Based on the results of gene expression profiling and subsequent pathway analysis, we found that several canonical pathways were linked to DAE treatment, including WNT/β-catenin signaling. Taken together, the present results suggest molecular mechanism, involving gene expression changes, by which DAE has a protective effect in a rat model of MIA-induced OA.

Agnuside Alleviates Synovitis and Fibrosis in Knee Osteoarthritis through the Inhibition of HIF-1α and NLRP3 Inflammasome

Increasing evidence has shown that NLRP3 inflammasome activation participates in chronic aseptic inflammation and is related to tissue fibrosis. Our last study also revealed the vital role of NLRP3 inflammasome, highly associated with tissue hypoxia, in the onset and development of knee osteoarthritis (KOA). In this study, we tried to find a possible benign intervention for that pathological process. Agnuside (AGN), a nontoxic, natural small molecule isolated from the extract of Vitex negundo L. (Verbenaceae), has been demonstrated to have antioxidation, anti-inflammatory, analgesia, and many other properties as an iridoid glycoside, although its specific target is still unclear. Therefore, we established MIA-induced KOA model rats and investigated the effects of AGN oral gavage on oxygen-containing state, NLRP3 inflammasome, synovitis, and fibrosis in KOA. Pimonidazole staining and HIF-1α immunohistochemical assay both showed that AGN at the oral dose of 6.25 mg/kg can effectively relieve local hypoxia in synovial tissue. Besides, we observed a decrease of HIF-1α, caspase-1, ASC, and NLRP3 after AGN intervention, both in the mRNA and protein levels. In addition, rats treated with the AGN showed less inflammatory reaction and fibrosis, not only in the expression of NLRP3, inflammasome downstream factors IL-1β and IL-18, and fibrosis markers TGF-β, TIMP1, and VEGF but also in the observation of HE staining, anatomical characteristics, Sirius Red staining, and type I collagen immunohistochemistry. Subsequently, we established LPS-induced models of fibroblast-like synoviocytes (FLSs) mimicking the inflammatory environment of KOA and activating NLRP3 inflammasome. FLSs treated with AGN (3 μM) resulted in a downregulation of HIF-1α and the components required for NLRP3 inflammasome activation. Meanwhile, the content of proinflammatory factors IL-1β and IL-18 in FLS supernatant was also reduced by AGN. In addition, both mRNA and protein levels of the fibrotic markers were significantly decreased after AGN management. To conclude, this study demonstrates that AGN alleviates synovitis and fibrosis in experimental KOA through the inhibition of HIF-1α accumulation and NLRP3 inflammasome activation. Additionally, not only does it reveal some novel targets for anti-inflammatory and antioxidant effects of AGN but also announces its potential value in treating KOA in humans.

Pharmacological Targeting of Heme Oxygenase-1 in Osteoarthritis

Osteoarthritis (OA) is a common aging-associated disease that clinically manifests as joint pain, mobility limitations, and compromised quality of life. Today, OA treatment is limited to pain management and joint arthroplasty at the later stages of disease progression. OA pathogenesis is predominantly mediated by oxidative damage to joint cartilage extracellular matrix and local cells such as chondrocytes, osteoclasts, osteoblasts, and synovial fibroblasts. Under normal conditions, cells prevent the accumulation of reactive oxygen species (ROS) under oxidatively stressful conditions through their adaptive cytoprotective mechanisms. Heme oxygenase-1 (HO-1) is an iron-dependent cytoprotective enzyme that functions as the inducible form of HO. HO-1 and its metabolites carbon monoxide and biliverdin contribute towards the maintenance of redox homeostasis. HO-1 expression is primarily regulated at the transcriptional level through transcriptional factor nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2), specificity protein 1 (Sp1), transcriptional repressor BTB-and-CNC homology 1 (Bach1), and epigenetic regulation. Several studies report that HO-1 expression can be regulated using various antioxidative factors and chemical compounds, suggesting therapeutic implications in OA pathogenesis as well as in the wider context of joint disease. Here, we review the protective role of HO-1 in OA with a focus on the regulatory mechanisms that mediate HO-1 activity.

Multifaceted Optimization of MSC-Based Formulation upon Sodium Iodoacetate-Induced Osteoarthritis Models by Combining Advantageous HA/PG Hydrogel and Fluorescent Tracer

Owing to the boundedness of conventional remedies upon articular cartilage for self-rehabilitation and the incrementally senior citizens, the incidence of osteoarthritis (OA) is increasing worldwide. Empirical studies have revealed the advantageous and promising potentials of mesenchymal stem/stromal cells (MSCs) on the refractory OA, whereas the deficiency of systematic and detailed exploration of MSC-based therapy largely hampers the large-scale applications in regenerative medicine. Herein, we initially utilized the monosodium iodoacetate- (MIA-) induced OA rabbit models and investigated the therapeutic effect of human umbilical cord-derived UC-MSCs at serial dose gradients with the splendid hyaluronic acid and/or propylene glycol hydrogels (HA, HA/PG), respectively. Afterwards, we turned to a dual-luciferase reporter tracing system and evaluated the spatiotemporal distribution and metabolokinetics of bifluorescence expressing UC-MSCs (BF-MSCs) in OA rats. Of the aforementioned trials, we verified that the combination of HA/PG and middle-dose MSCs ( $0.5\times {10}^7$ cells/ml) eventually manifested the optimal efficacy on OA rabbits. Furthermore, with the aid of the bioluminescence imaging (BLI) technology for dynamic in vitro and in vivo tracking, we intuitively delineated the spatiotemporal distribution and therapeutic process of BF-MSCs in OA rats, which substantially confirmed the reinforcement of HA/PG on BF-MSCs for OA treatment. Collectively, our data conformably demonstrated that the middle dose of UC-MSCs combined with HA/PG hydrogel was sufficient for optimal MSC-based formulation for blocking OA progression and promoting cartilage repair, which supplied overwhelming new references and enlightened MSC-based therapeutic strategies for cartilage defects.

Two-step generation of mesenchymal stem/stromal cells from human pluripotent stem cells with reinforced efficacy upon osteoarthritis rabbits by HA hydrogel

Background

Current studies have enlightened the rosy prospects of human pluripotent stem cell (hPSC)-derived mesenchymal stem/stromal cells (MSCs) in regenerative medicine. However, systematic investigation of their signatures and applications with alternative biomaterials in osteoarthritis (OA) remains indistinct.

Methods

Herein, we initially took advantage of a small molecule library-mediated programming strategy for hPSC-MSC induction. Then, with the aid of multifaceted analyses such as flow cytometry (FCM), chromosome karyocyte and cell vitality, wound healing and microtubule formation assay and coculturing with T lymphocytes, we systematically evaluated the characterizations of signatures in vitro and the in vivo efficacy of hPSC-MSCs and HA hydrogel composite on rabbit osteoarthritis model.

Results

We found the combination of LLY-507 and AZD5153 was sufficient for high-efficiency CD73⁺CD90⁺CD105⁺CD31⁻CD34⁻CD45⁻HLA-DR⁻ MSC induction from both hESCs and hiPSCs with stemness (POU5F1/SOX2/NANOG). The programmed hPSC-MSCs revealed conservative transcriptome variations and went through a heterogeneous intermediate-stage with mesenchymal-associated gene expression (NT5E, ENG, VIM and FN1) as well as displayed typical cytomorphology, immunophenotypes and normal karyotyping, multilineage differentiation potential, favorable cell vitality, proangiogenic and immunoregulatory properties in vitro. Meanwhile, the cell population exhibited preferable restorative and ameliorative function on OA rabbits with HA hydrogel in vivo.

Conclusions

Collectively, we established a rapid and convenient procedure for hPSC-MSC generation without redundant manipulations. The fundamental and clinical studies upon osteoarthritis (OA) treatment would benefit tremendously from the combination of the inexhaustible hPSC-MSCs and advantageous biomaterials.

β-ecdysterone alleviates osteoarthritis by activating autophagy in chondrocytes through regulating PI3K/AKT/mTOR signal pathway

PURPOSE

To investigate the therapeutic effects of β-ecdysterone on osteoarthritis (OA) and the underlying mechanism.

METHODS

OA model was established on rats by injecting MIA. ELSA was used to determine the concentration of IL-1β, IL-6, NO and TNF-α in the chondrocytes and cartilage tissues. Immunofluorescence assay was used to determine the expression of collagen II in the chondrocytes. The survival rate of chondrocytes was evaluated by MTT assay. The apoptosis of chondrocytes was checked by AO/PI staining and flow cytometry assay. The expression level of Atg7, PI3K and caspase-3 was evaluated by qRT-PCR. Western Blot was used determine the expression of PI3K, p-AKT1, AKT1, p-mTOR, mTOR, p70S6K, p-p70S6K, LC3I, LC3II and caspase-3. HE staining was used to check the pathological state of cartilage tissues.

RESULTS

Chondrocytes were tolerable to rapamycin, 3-methyladenine and β-ecdysterone at the concentration of 10 mM, 100 nM and 40 μM, respectively. The apoptosis of chondrocytes was inhibited by rapamycin and β-ecdysterone, and induced by 3-methyladenine. PI3K, p-AKT1, p-mTOR, p-p70S6K and caspase-3 were down-regulated by rapamycin and β-ecdysterone, and up-regulated by 3-methyladenine in both the chondrocytes and the cartilage tissues. The expression of Atg7 and LC3II/LC3I were regulated in a opposite way. The inflammation state was improved by rapamycin and β-ecdysterone both the chondrocytes and the cartilage tissues. HE staining results showed that the pathological state of cartilage tissues was alleviated by β-ecdysterone.

CONCLUSION

β-ecdysterone might alleviate osteoarthritis by activating autophagy in chondrocytes through regulating PI3K/AKT/mTOR signal pathway.

Use of the Contralateral Knee as a Control in the Destabilization of Medial Meniscus Osteoarthritis Rat Model

Destabilization of the medial meniscus (DMM) induces osteoarthritis (OA) in a rat model, but using the contralateral limb as control is unknown. We examined DMM and obesity in an OA rat model using contralateral limbs as control. Femoral condyles and tibial plateaus were evaluated. No differences were found between knees across diet groups (P=.61) or between surgery scores in diet groups (both P>.49). Thus, contralateral limbs may be a control for short-term (≤4 weeks) studies.

Physioxia Expanded Bone Marrow Derived Mesenchymal Stem Cells Have Improved Cartilage Repair in an Early Osteoarthritic Focal Defect Model

Focal early osteoarthritis (OA) or degenerative lesions account for 60% of treated cartilage defects each year. The current cell-based regenerative treatments have an increased failure rate for treating degenerative lesions compared to traumatic defects. Mesenchymal stem cells (MSCs) are an alternative cell source for treating early OA defects, due to their greater chondrogenic potential, compared to early OA chondrocytes. Low oxygen tension or physioxia has been shown to enhance MSC chondrogenic matrix content and could improve functional outcomes of regenerative therapies. The present investigation sought to develop a focal early OA animal model to evaluate cartilage regeneration and hypothesized that physioxic MSCs improve in vivo cartilage repair in both, post-trauma and focal early OA defects. Using a rabbit model, a focal defect was created, that developed signs of focal early OA after six weeks. MSCs cultured under physioxia had significantly enhanced in vitro MSC chondrogenic GAG content under hyperoxia with or without the presence of interleukin-1β (IL-1β). In both post-traumatic and focal early OA defect models, physioxic MSC treatment demonstrated a significant improvement in cartilage repair score, compared to hyperoxic MSCs and respective control defects. Future investigations will seek to understand whether these results are replicated in large animal models and the underlying mechanisms involved in in vivo cartilage regeneration.

Resistin enhances IL-1β and TNF-α expression in human osteoarthritis synovial fibroblasts by inhibiting miR-149 expression via the MEK and ERK pathways

Resistin is a cysteine-rich adipokine that promotes the release of inflammatory cytokines, particularly interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α), which are critical pro-inflammatory mediators in osteoarthritis (OA) pathogenesis. We describe evidence of significantly higher levels of resistin, IL-1β, and TNF-α expression in OA knee synovial tissue compared with that from non-OA knees. Resistin-induced enhancement of IL-1β and TNF-α expression in human OA synovial fibroblasts (OASFs) were attenuated by MEK and ERK inhibitors, as well as their respective siRNAs. Our data reveal that resistin enhances the expression of TNF-α and IL-1β in OASFs by inhibiting miR-149 expression via MEK and ERK signaling. Our findings elucidate the inter-relationships between resistin and pro-inflammatory mediators during OA pathogenesis and could help to facilitate the development of synovium-targeted therapy in OA.

Effect of whole body vibration on HIF-2α expression in SD rats with early knee osteoarthritis

INTRODUCTION

To investigate the effect of different frequencies of whole body vibration (WBV) on articular cartilage of early knee osteoarthritis (OA) rats and determine whether WBV would influence the pathway of hypoxia-inducible factor-2α (HIF-2α) regulation-related genes after 8 weeks of treatment.

MATERIALS AND METHODS

Forty 8-week-old OA rats were divided into five groups: sham control (SC); high frequency 60 Hz (HV₁); high frequency 40 Hz (HV₂); middle frequency 20 Hz (MV) and low frequency 10 Hz (LV). WBV (0.3 g) treatment was given 40 min/day and 5 days/week. After 8 weeks, rats were killed and knees were harvested. OA grading score: Osteoarthritis Research Society International (OARSI), and the expression of related genes: interleukin-1β (IL-1β), HIF-2α, matrix metalloproteinases-13 (MMP-13), and collagen type II alpha 1 (COL2A1), at both mRNA and protein levels were analyzed.

RESULTS

After 8 weeks of WBV, our data showed that lower frequency (10 Hz) was more effective than the higher ones, yet they all suggested that WBV alleviates the erosion of knee articular cartilage in early OA. The expression of IL-1β, HIF-2α and MMP-13 decreased with frequency and reached the lowest level at 10 Hz, the expression of COL2A1 increased with frequency and reached the highest level at 10 Hz.

CONCLUSIONS

This study demonstrates that WBV could alleviate the degeneration of knee joints in an early OA rat model. WBV regulates related gene expression at both mRNA and protein levels. HIF-2α could be a therapeutic target. The effect of WBV is frequency dependent; the lower frequency shows better effects.

Resistin Enhances VCAM-1 Expression and Monocyte Adhesion in Human Osteoarthritis Synovial Fibroblasts by Inhibiting MiR-381 Expression through the PKC, p38, and JNK Signaling Pathways

The development of osteoarthritis (OA) is characterized by synovial inflammation and the upregulation of vascular cell adhesion molecule type 1 (VCAM-1) in human osteoarthritis synovial fibroblasts (OASFs). This increase in VCAM-1 expression promotes monocyte adhesion to OASFs. The adipokine resistin is known to promote the release of inflammatory cytokines during OA progression. In this study, we identified significantly higher levels of resistin and CD68 (a monocyte surface marker) expression in human OA tissue compared with in healthy control tissue. We also found that resistin enhances VCAM-1 expression in human OASFs and facilitates the adhesion of monocytes to OASFs. These effects were attenuated by inhibitors of PKCα, p38, and JNK; their respective siRNAs; and by a microRNA-381 (miR-381) mimic. In our anterior cruciate ligament transection (ACLT) rat model of OA, the inhibition of resistin activity prevented ACLT-induced damage to the OA rat cartilage and pathological changes in resistin and monocyte expression. We also found that resistin affects VCAM-1 expression and monocyte adhesion in human OASFs by inhibiting miR-381 synthesis via the PKCα, p38, and JNK signaling pathways. Our clarification of the crucial role played by resistin in the pathogenesis of OA may lead to more effective therapy that reduces OA inflammation.

Total Knee Arthroplasty with a Ti6Al4V/PEEK Prosthesis on an Osteoarthritis Rat Model: Behavioral and Neurophysiological Analysis

Arthroplasty is a surgical procedure to restore the function of the joint of patient suffering from knee osteoarthritis. However, postoperative functional deficits are reported even after a rehabilitation program. In order to determine the origin of functional deficits of patient suffering from knee osteoarthritis and total knee arthroplasty, we developed a rodent model including a chemically-induced-osteoarthritis and designed a knee prosthesis (Ti6Al4V/PEEK) biomechanically and anatomically adapted to rat knee joint. Dynamic Weight-Bearing, gait kinematics, H-reflex from vastus medialis muscle and activities from metabosensitive III and IV afferent fibers in femoral nerve were assessed at 1 and 3 months post-surgery. Results indicate that knee osteoarthritis altered considerably the responses of afferent fibers to their known activators (i.e., lactic acid and potassium chloride) and consequently their ability to modulate the spinal sensorimotor loop, although, paradoxically, motor deficits seemed relatively light. On the contrary, results indicate that, after the total knee arthroplasty, the afferent responses and the sensorimotor function were slightly altered but that motor deficits were more severe. We conclude that neural changes attested by the recovery of the metabosensitive afferent activity and the sensorimotor loop were induced when a total knee replacement was performed and that these changes may disrupt or delay the locomotor recovery.

Celastrol ameliorates endoplasmic stress-mediated apoptosis of osteoarthritis via regulating ATF-6/CHOP signalling pathway

Objectives

Osteoarthritis (OA) is a common degenerative joint disease with the pathological features of the reduced cartilage cellularity. Celastrol, a compound from Tripterygium wilfordii, exerted therapeutic effects on arthritis, but the potential mechanism remains unclear.

Methods

Tunicamycin was used to establish a model of OA in vitro, and ACLT surgery model in rats was applied to verify the mechanism. Chondrocytes were isolated from the knee articular cartilage of rabbit. MTT and flow cytometry assay were used to detect cell viability and apoptosis rate. Haematoxylin–eosin staining was used to assess for the histopathological changes. The activity and expression of apoptosis-related factors and ERs (endoplasmic reticulum stress)-related factors were detected by ELISA, WB, PCR and IHC, respectively.

Key findings

Celastrol exhibited significant enhancement on cell viability and reduced the rate of apoptosis in Tm-exposed chondrocytes. Celastrol reduced enzyme activity and protein expression of caspase-3, caspase-6 and caspase-9, decreased Bip, Atf6, Chop and Xbp-1 expression both at protein and mRNA levels. Celastrol showed a more significant effect on cell apoptosis rate and mRNA expression in the combination with 4-PBA.

Conclusions

This study reveals that celastrol may prevent OA by inhibiting the ERs-mediated apoptosis. All these might supply beneficial hints for celastrol on OA treatment.

Understanding the Molecular Mechanisms Underlying the Pathogenesis of Arthritis Pain Using Animal Models

Arthritis, including osteoarthritis (OA) and rheumatoid arthritis (RA), is the leading cause of years lived with disability (YLD) worldwide. Although pain is the cardinal symptom of arthritis, which is directly related to function and quality of life, the elucidation of the mechanism underlying the pathogenesis of pain in arthritis has lagged behind other areas, such as inflammation control and regulation of autoimmunity. The lack of therapeutics for optimal pain management is partially responsible for the current epidemic of opioid and narcotic abuse. Recent advances in animal experimentation and molecular biology have led to significant progress in our understanding of arthritis pain. Despite the inherent problems in the extrapolation of data gained from animal pain studies to arthritis in human patients, the critical assessment of molecular mediators and translational studies would help to define the relevance of novel therapeutic targets for the treatment of arthritis pain. This review discusses biological and molecular mechanisms underlying the pathogenesis of arthritis pain determined in animal models of OA and RA, along with the methodologies used.

Inhibition of cartilage degeneration and subchondral bone deterioration by Spinacia oleracea in human mimic of ACLT-induced osteoarthritis

Osteoarthritic conditions in ACLT model in rats were attenuated by SOE administration.

Effect of high molecular weight hyaluronic acid in treatment of osteoarthritic temporomandibular joints of rats

OBJECTIVE

The aim of this study was to determine the histological and biochemical effects of high molecular weight hyaluronic acid on experimentally induced osteoarthritic changes in male rat temporomandibular joint (TMJ).

DESIGN

In this in-vivo study, 36 male albino rats were divided into 3 groups; control non-injected, disease and treatment group. Osteoarthritis was induced using a single intra-articular injection of Complete Freund's adjuvant (CFA) (50 μl). High molecular weight hyaluronic acid (HMWHA) was injected intra-articularly once a week, for a total of 3 injections. TMJ tissue samples were dissected from control, disease and treatment groups for biochemical analysis using ELISA test to detect the levels of matrix metalloproteinase-3 (MMP-3) on day 28. Histological examination was done using Hematoxylin &eosin, Mallory's trichrome and Alcian blue stains. Data was analyzed using Kruskal-Wallis test followed by Dunn-Sidek method, with a 5 % significance level.

RESULTS

Treatment group showed regaining of the normal histological features of the TMJ and decreased levels of MMP-3 when compared to disease group.

CONCLUSIONS

These findings may suggest that HMWHA plays a role in the management of CFA-induced osteoarthritic cartilage lesions.

Inhibition of Synovial Macrophage Pyroptosis Alleviates Synovitis and Fibrosis in Knee Osteoarthritis

Increasing evidence has shown that macrophage pyroptosis in different tissues participates in chronic aseptic inflammation and is related to tissue fibrosis. Our last studies also revealed the vital role of synovial fibroblast pyroptosis in the onset and development of knee osteoarthritis (KOA). In this study, we aimed to investigate whether synovial macrophage pyroptosis did occur and whether this form of cell death should be related to synovitis and fibrosis of KOA. In the synovial tissue of KOA model rats, we observed a decrease of caspase1, NLRP3, ASC, and GSDMD caused by macrophage depletion in both the mRNA and protein expressions. Besides, rats treated with the specific caspase1 inhibitor Ac-YVAD-CMK showed less inflammatory reaction and fibrosis, not only in the expression of proinflammatory factors IL-1β, IL-18, and HMGB1 and fibrosis markers TGF-β, PLOD2, COL1A1, and TIMP1 but also in the observation of HE staining, Sirius Red staining, and the transverse diameters of the right knees. Subsequently, we established an LPS+ATP-induced model in macrophages mimicking the inflammatory environment of KOA and inducing macrophage pyroptosis. Macrophages transfected with caspase1 siRNA showed reduced cell death; meanwhile, the relative expression of pyroptosis-related proteins were also downregulated. In addition, the level of fibrotic markers in synovial fibroblasts were significantly decreased after coculture with siRNA GSDMD-transfected macrophages. To conclude, synovial macrophage pyroptosis may occur in the pathological processes of KOA and inhibition of synovial macrophage pyroptosis alleviates synovitis and fibrosis in KOA model rats.

αB-crystallin (CRYAB) regulates the proliferation, apoptosis, synthesis and degradation of extracellular matrix of chondrocytes in osteoarthritis

Osteoarthritis (OA) is a chronic joint disease and hard to cure at present. Alpha B-crystallin (CRYAB) has been identified as a downregulated gene in OA cartilage. However, the precise roles and underlying molecular mechanisms of CRYAB in OA progression have not been elucidated. In the present study, we found that the expression of CRYAB in cartilages from patients with OA was significantly lower than that in the cartilages from patients with no prior medical history of OA. We established mouse models with OA by destabilization of the medial meniscus (DMM) surgery and found that the expression of CRYAB in OA cartilage was lower than that in the normal cartilages, too. Moreover, we demonstrated that the expression of CRYAB was increased during chondrogenic differentiation and cartilage development. Functional assays revealed that overexpression of CRYAB promoted the proliferation of chondrocytes and inhibited apoptosis, while knockdown of CRYAB presented opposite results. In addition, overexpression of CRYAB upregulated the expression of anabolic markers, Col2a1 and ACAN, and reduced the expression of catabolic markers, MMP13 and ADAMTS5. Conversely, knockdown of CRYAB blocked the expression of the anabolic markers and increased the expression of catabolic markers. Collectively, the results suggest that CRYAB promoted the proliferation and extracellular matrix production of chondrocytes, and inhibited chondrocytes apoptosis and cartilage degradation simultaneously. Thus, CRYAB might be a potential therapeutic target for OA treatment.