Search Results (48)

Background: Osteoarthritis (OA) is a degenerative joint disease characterized by inflammation and cartilage destruction, partly mediated by interleukin (IL)-1β-induced nucle factor (NF)-κB activation. Ectoine (Ec) is a natural osmoprotectant with anti-inflammatory properties; however, its effects on NF-κB signaling in OA remain unclear. This study investigated whether ectoine attenuates IL-1β-induced inflammation in chondrocytes by suppressing NF-κB activation and mitigates OA progression in a rat model. Methods: Primary rat chondrocytes were pretreated with ectoine (0–3.0% w/v) and then stimulated with IL-1β (10 ng/mL). Cell viability was evaluated. RT-qPCR and Western blotting were used to determine the expression of inflammatory markers (inducible nitric oxide synthase [iNOS], cyclooxygenase [COX]-2, tumor necrosis factor [TNF]-α, and matrix metalloproteinase [MMP]-3/13), and NF-κB pathway activity was assessed through p65 phosphorylation and inhibitor of NF-κB alpha (IκBα) degradation. In vivo, OA was induced using the modified Hulth method, followed by intra-articular injection of ectoine alone or combined with hyaluronic acid (HA). Cartilage integrity was assessed using Osteoarthritis Research Society International (OARSI) scoring at 8 weeks. Results: Ectoine at 1.5% significantly inhibited IL-1β-induced NF-κB activation, reducing p65 phosphorylation by 59% and IκBα degradation by 41%. This inhibition decreased proinflammatory mediators (iNOS 43%, COX-2 35%, TNF-α 41%) and matrix-degrading enzymes (MMP-3 23%, MMP-13 31%), while increasing type II collagen by 84%. In vivo, ectoine reduced cartilage erosion (OARSI score: 7.0 vs. 10.2 in OA group). The Ec–HA combination improved cartilage retention by 43% compared with ectoine alone. Conclusions: These preclinical findings suggest that ectoine was associated with reduced NF-κB activation markers and attenuated OA-like changes in rat models. The enhanced effect observed with HA supports further investigation of combined therapeutic strategies for OA management. Full article

Osteoarthritis (OA) is a chronic, debilitating degenerative joint disease whose prevalence is rising markedly with the rapid aging of the global population. In this study, we investigated the chondroprotective efficacy of NP-2007, an enzymatically hydrolyzed low-molecular-weight collagen from Cervi cornu, using IL-1β-stimulated SW1353 human chondrocyte cells and a medial meniscal transection (MMT)-induced OA rat model. In SW1353 cells, NP-2007 considerably suppressed the expression of inflammatory mediators (iNOS, COX-2) and cytokines (TNF-α, IL-6) without cytotoxicity. Crucially, it restored matrix homeostasis by downregulating catabolic enzymes (MMP-3, MMP-13, and ADAMTS-5) and upregulating anabolic markers (COL2A1, aggrecan), a process associated with the modulation of the Wnt/β-catenin and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathways and the recovery of the master chondrogenic factor SOX9. These in vitro findings were consistent with the in vivo results from the MMT model, where oral administration of NP-2007 (50 and 200 mg/kg) for 8 weeks effectively preserved articular cartilage structure and proteoglycan content while markedly reducing serum levels of catabolic biomarkers, including MMP-13 and COMP. Collectively, our findings demonstrate that NP-2007 exerts potent chondroprotective effects by modulating the balance between cartilage degradation and synthesis, suggesting its potential as a therapeutic candidate for the management of OA. Full article

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease characterized by progressive cartilage destruction, and chondrocyte apoptosis plays a critical role in TMJOA progression. As chondrocytes reside in an avascular microenvironment inside the cartilage matrix, energy production via glycolysis is crucial for their survival. This study investigated the role of the key glycolytic enzyme Hexokinase 2 (HK2) in TMJOA pathogenesis and the therapeutic potential of dental pulp stem cell-derived extracellular vesicles (DPSC-EVs). In a rat experimental TMJOA model induced by monosodium iodoacetate (MIA) intra-articular injection, we observed a significantly decreased expression of HK2 along with cartilage matrix degradation. In the in vitro study, MIA induced chondrocyte apoptosis with caspase-3 activation, accompanied by impaired glycolytic function. Intervention with DPSC-EVs effectively rescued the expression of HK2 within chondrocytes, leading to a notable restoration of cellular glycolysis. Consequently, DPSC-EV treatment markedly attenuated the progression of TMJOA by reducing chondrocyte apoptosis and improved cartilage integrity. Our findings demonstrated that DPSC-EVs represent a promising cell-free therapeutic strategy for TMJOA, exerting their protective effects by targeting HK2, thereby preserving chondrocyte viability and attenuating osteoarthritis development. Full article

Osteoarthritis (OA), a degenerative joint disease primarily affecting the hips and knees, is characterized by multifactorial dysregulation of chondrocyte homeostasis and currently lacks curative treatment options. Intra-articular hyaluronic acid (HA) injections have clinically provided symptomatic relief for three decades; however, HA’s rapid in vivo degradation by free radicals and hyaluronidases limits its efficacy. We hypothesized that adding niacinamide (vitamin B3) to linear HA hydrogels would provide ancillary anti-inflammatory and anti-catabolic properties, thereby improving HA-based viscosupplementation therapy. This preliminary preclinical mechanistic study investigated the functional effects of incorporating niacinamide into linear HA-based hydrogels using in vitro cellular models. Initially, Raw 264.7 macrophages and C28/I2 or SW1353 human chondrocytes were pre-treated with varying concentrations of HA/B3, with or without lipopolysaccharide (LPS) or interleukin-1β (IL-1β), respectively. Subsequently, pro-inflammatory and pro-catabolic markers were quantified biochemically. Results demonstrated that HA/B3 hydrogels exhibited enhanced functional stability compared to HA alone and possessed significant anti-inflammatory and anti-catabolic properties, without inducing cytotoxicity in either cell line. In Raw 264.7 macrophages, HA/B3 inhibited LPS-induced tumor necrosis factor-α (TNF-α) release and suppressed cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) protein expression. In vitro, HA/B3 hydrogels reduced IL-1β-induced IL-6 production in primary chondrocytes by 16% and suppressed PGE₂ concentration in both macrophages and chondrocytes by 60%, effects superior to HA alone. Finally, a rat primary articular chondrocyte model suggested slight anti-hypertrophic effects of HA/B3 in vitro. Collectively, these findings suggest that HA/B3 hydrogels possess anti-arthritic potential, highlighting a novel strategy for next-generation viscosupplement systems. Full article

Cartilage regeneration has long been a major challenge in the treatment of osteoarthritis (OA). Aiming to develop a simple outpatient treatment for knee OA, we have demonstrated the potential of combining Nomura’s jellyfish mucin (JM) and hyaluronic acid (HA) to contribute to cartilage repair and regeneration in chondrocytes. In this study, we examined the effects of moon jellyfish JM and jellyfish collagen (JC) on chondrocytes. Polydactyly-derived chondrocytes (PDs), obtained from polydactyly surgery, were used. PDs were cultured in media supplemented with JM or JC, harvested, and evaluated by RT-qPCR. The effects of simultaneous addition of the inflammatory cytokine IL-1β were also examined. Furthermore, the effects on rat articular cartilage were investigated. A mono-iodoacetate (MIA) model was created by intra-articular injection in 6-week-old rats, followed by four intra-articular injections. Evaluations were performed using macroscopic observation and histological assessment with the OARSI scoring system. In vitro, the addition of JM or JC significantly affected the expression of ACAN, MMP3, and ADAMTS5. However, in vivo, intra-articular injection of JM alone did not significantly suppress cartilage degeneration in MIA-induced OA model rats. Both JM and JC may contribute to the suppression of cartilage degeneration as well as to cartilage repair and regeneration, even in the absence of HA. However, further studies are needed to clarify the optimal conditions, such as dosage, timing, and delivery method, that are required to achieve these effects in articular cartilage. Full article

The tissue covering the bones in synovial joints is called articular cartilage. Chondrocytes produce and maintain the extracellular matrix and, based on their shape and the orientation of the collagen fibers, articular cartilage is separated into four histological zones: superficial, middle, deep, and calcified zones. Osteoarthritis is a degenerative joint disorder in which mechanical, biochemical, and inflammatory factors contribute to the disruption of the balance between extracellular matrix synthesis and degradation. This article aims to review the literature published to date by identifying the techniques most used in immunohistochemistry and histology for the detection and grading of knee osteoarthritis in rabbit/rat models. A systematic review was carried out using databases to find publications that assessed osteoarthritis in rabbit/rat knee models using histological and immunohistochemical methods. Out of 766 initial articles, 56 met the criteria. Hematoxylin–Eosin and Safranin O demonstrated clear distinctions between healthy and osteoarthritis cartilage. Immunohistochemical findings showed decreased expression of type II collagen and increased expression of matrix metalloproteinases and caspase-3 in osteoarthritis cartilage. Although both have limitations, histology stains are useful for evaluating cartilage structure and osteoarthritis progression. On the other hand, immunohistochemistry techniques support established osteoarthritis processes, including apoptosis, metalloproteinases activity, and collagen degradation. Future research should explore additional pathways to improve osteoarthritis understanding. Full article

Background/Objectives: Osteoarthritis (OA) is a progressive joint disease characterized by inflammation, cartilage degradation, and subchondral bone changes, for which effective disease-modifying therapies are lacking. Messenger RNA (mRNA)-based therapeutics offer a versatile approach to modulate joint pathology, but their application to OA remains limited. Methods: We evaluated intra-articular delivery of therapeutic mRNAs using polyplex nanomicelles, a non-inflammatory and minimally invasive carrier system, in a rat model of inflammation-driven OA induced by monosodium iodoacetate (MIA). Results: IL-1 receptor antagonist (IL-1Ra) mRNA reduced synovial inflammation and alleviated pain and swelling. RUNX1 mRNA, a transcription factor critical for chondrogenesis, supported chondrocyte viability, type II collagen expression, and cartilage structure. Under conditions of pronounced inflammation, however, the protective effects of RUNX1 mRNA alone were modest. Notably, combined administration of IL-1Ra and RUNX1 mRNAs produced synergistic therapeutic benefits, with enhanced chondroprotection and preservation of subchondral bone integrity. Conclusions: These findings suggest that while RUNX1 is essential for maintaining cartilage homeostasis, effective control of joint inflammation is required for its therapeutic activity. Dual mRNA therapy delivered by polyplex nanomicelles therefore represents a promising strategy to address the multifactorial pathology of OA. Full article

Introduction: Osteoarthritis (OA), a leading cause of disability among the elderly, is characterized by progressive joint tissue destruction. Fucoidan, a sulfated polysaccharide with known anti-inflammatory and antioxidant properties, has been investigated for its potential to protect against interleukin-1 beta (IL-1β)-induced articular tissue damage. Methods: Human primary chondrocytes and synovial fibroblasts were pre-treated with 100 μg/mL fucoidan before stimulation with 1 ng/mL of IL-1β. The protective effects of fucoidan were assessed by measuring oxidative stress markers and catabolic enzyme levels. These in vitro findings were corroborated using a rat anterior cruciate ligament transection-induced OA model. To explore the underlying mechanisms, particularly the interaction between microRNAs (miRs) and heme oxygenase-1 (HO-1), five candidate miRs were identified in silico and experimentally validated. Luciferase reporter assays were used to confirm direct interactions. Results: Fucoidan exhibited protective effects against IL-1β-induced oxidative stress and catabolic processes in both chondrocytes and synovial fibroblasts, consistent with in vivo observations. Fucoidan treatment restored HO-1 expression while reducing inducible nitric oxide synthase and matrix metalloproteinase levels in IL-1β-stimulated cells. Notably, this study revealed that fucoidan modulates the miR-22/HO-1 pathway, a previously uncharacterized mechanism in OA. Specifically, miR-22 was upregulated by IL-1β and subsequently attenuated by fucoidan. Luciferase reporter assays confirmed a direct interaction between miR-22 and HO-1. Conclusion: The results demonstrate that fucoidan mitigates OA-related oxidative stress in chondrocytes and synovial fibroblasts through the novel modulation of the miR-22/HO-1 axis. The miR-22/HO-1 pathway represents a crucial therapeutic target for OA, and fucoidan may offer a promising therapeutic intervention. Full article

Background: Articular chondrocytes are specialized cells in synovial joint cartilage, responsible for maintaining and regenerating the extracellular matrix. Inflammation disrupts the balance between matrix synthesis and degradation, leading to cartilage breakdown. This process, commonly observed in conditions such as osteoarthritis, results in chondrocyte dysfunction and accelerates joint degeneration. Since TRPA1 channels are implicated in inflammatory processes, this study investigates the expression of TRPA1 channels in freshly dissociated rat articular chondrocytes and their modulation by anti-inflammatory agents. Methods: We used the whole-cell patch-clamp method to assess TRPA1 channel expression and modulation. Results: Freshly dissociated chondrocytes exhibit ion currents attributable to TRPA1 channel expression, with higher magnitudes observed in medium-sized cells. These currents decrease over time in primary culture. Treatment with pro-inflammatory agents (IL-1α, IL-1β, and LPS) increases TRPA1′s current magnitude. IL-1β treatment directly induces transient TRPA1 currents. Several signaling components activated during inflammation contribute to the IL-1β-induced enhancement of TRPA1 current density, including IL-1 R1, the adaptor protein MyD88, and the downstream kinases IRAK1 and IRAK4. Conclusions: Our findings demonstrate that healthy rat chondrocytes express functional TRPA1 channels and that inflammatory processes modulate their expression. Full article

Background: The injection of bone mesenchymal stem cells (BMSCs) for osteoarthritis (OA) treatment fails to address the disrupted extracellular microenvironment, limiting the differentiation and paracrine functions of BMSCs and resulting in suboptimal therapeutic outcomes. Proteoglycans (PGs) promote cell differentiation, tissue repair, and microenvironment remodeling. This study investigated the potential of combining PGs with BMSCs to increase the efficacy of OA treatment. Methods: We evaluated the effects of PG on BMSC and chondrocyte functions by adding various PG concentrations to the culture media. Additionally, a Transwell system was used to assess the impact of PG on the communication between BMSCs and chondrocytes. The results of the in vitro experiment were verified by tissue staining and immunohistochemistry following the treatment of OA model rats. Results: Our findings indicate that PG effectively induces Col II expression in BMSCs and enhances the paracrine secretion of TGF-β1, thereby activating the TGF-β signaling pathway in chondrocytes and increasing PRG4 gene expression. Compared with the other groups, the BMSC/PG treatment group presented a smoother articular surface and more robust extracellular matrix than the other groups in vivo, with significantly increased expression and distribution of Smad2/3 and PRG4. Conclusions: PG enhances BMSC differentiation into chondrocytes and stimulates paracrine TGF-β1 secretion. Proteoglycans not only promote chondrocyte differentiation and paracrine TGF-β1 signaling in BMSCs but also increase the sensitivity of chondrocytes to TGF-β1 secreted from BMSCs, leading to PRG4 expression through the TGFR/Smad2/3 pathway. Proteoglycans can enhance the therapeutic effect of BMSC treatment on OA and have the potential to delay the degeneration of OA cartilage. Full article

The limited capacity of articular cartilage for self-repair is a critical challenge in orthopedic medicine. Here, we aimed to develop a simplified method of generating chondrocyte particles from human-induced pluripotent stem cell-derived expandable limb-bud mesenchymal cells (ExpLBM) using a cell self-aggregation technique (CAT). ExpLBM cells were induced to form chondrocyte particles through a stepwise differentiation protocol performed on a CAT plate (prevelex-CAT^®), which enables efficient and consistent production of an arbitrary number of uniformly sized particles. Histological and immunohistochemical analyses confirmed that the generated chondrocyte particles expressed key cartilage markers, such as type II collagen and aggrecan, but not hypertrophic markers, such as type X collagen. Additionally, when these particles were transplanted into osteochondral defects in rats with X-linked severe combined immunodeficiency, they demonstrated successful engraftment and extracellular matrix production, as evidenced by Safranin O and Toluidine Blue staining. These data suggest that the plate-based CAT system offers a robust and scalable approach to produce a large number of chondrocyte particles in a simplified and efficient manner, with potential application to cartilage regeneration. Future studies will focus on refining the system and exploring its clinical applications to the treatment of cartilage defects. Full article

Background: Hesperetin, a flavonoid derived from citrus fruits, exhibits potent antioxidant and anti-inflammatory activities and has been implicated in cartilage protection. However, its effectiveness against T-2 toxin-induced knee cartilage damage remains unclear. Methods: In this study, high-throughput sequencing analysis was employed to identify the key signaling pathways involved in T-2 toxin-induced articular cartilage damage in rats. Animal models were divided into the following groups: control, low-dose T-2 toxin, high-dose T-2 toxin, T-2 toxin + hesperetin, hesperetin, and vehicle. Pathological staining and immunohistochemistry were used to assess pathological changes, as well as the expression levels of the cartilage matrix-related proteins MMP13 and collagen II, along with the activation of the p38 MAPK signaling pathway. Additionally, primary rat chondrocytes were cultured to establish an in vitro model for investigating the underlying mechanism. Results: High-throughput sequencing analysis revealed the involvement of the MAPK signaling pathway in T-2 toxin-induced articular cartilage damage in rats. Hesperetin intervention in T-2 toxin-exposed rats attenuated pathological cartilage damage. Immunohistochemistry results demonstrated a significant reduction in collagen II protein expression in the high-dose T-2 toxin group (p < 0.01), accompanied by a significant increase in MMP13 protein expression (p < 0.01). In both the articular cartilage and the epiphyseal plate, the T-2 toxin + hesperetin group exhibited significantly higher collagen II protein expression than the high-dose T-2 toxin group (p < 0.05), along with significantly lower MMP13 protein expression (p < 0.05). Hesperetin inhibited the over-activation of the p38/MEF2C signaling axis induced by T-2 toxin in primary rat chondrocytes. Compared to the T-2 toxin group, the T-2 toxin + hesperetin group showed significantly reduced phosphorylation levels of p38 and protein expression levels of MEF2C (p < 0.001 or p < 0.05). Moreover, the T-2 toxin + hesperetin group exhibited a significant decrease in MMP13 protein expression (p < 0.05) and a significant increase in collagen II protein expression (p < 0.01) compared to the T-2 toxin group. Conclusions: T-2 toxin activates the p38 MAPK signaling pathway, causing knee cartilage damage in rats. Treatment with hesperetin inhibits the p38/MEF2C signaling axis, regulates collagen II and MMP13 protein expression, and reduces cartilage injury significantly. Full article

Articular chondrocytes are the primary cells responsible for maintaining the integrity and functionality of articular cartilage, which is essential for smooth joint movement. A key aspect of their role involves mechanosensitive ion channels, which allow chondrocytes to detect and respond to mechanical forces encountered during joint activity; nonetheless, the variety of mechanosensitive ion channels involved in this process has not been fully resolved so far. Because some members of the two-pore domain potassium (K2P) channel family have been described as mechanosensors in other cell types, in this study, we investigate whether articular chondrocytes express such channels. RT-PCR analysis reveals the presence of TREK-1 and TREK-2 channels in these cells. Subsequent protein expression assessments, including Western blotting and immunohistochemistry, confirm the presence of TREK-1 in articular cartilage samples. Furthermore, whole-cell patch clamp assays demonstrate that freshly isolated chondrocytes exhibit currents attributable to TREK-1 channels, as evidenced by activation by arachidonic acid (AA) and ml335 and further inhibition by spadin. Additionally, exposure to hypo-osmolar shock activates currents, which can be attributed to the presence of TREK-1 channels, as indicated by their inhibition with spadin. Therefore, these findings highlight the expression of TREK channels in rat articular chondrocytes and suggest their potential involvement in regulating the integrity of cartilage extracellular matrix. Full article

Osteoarthritis (OA) is the most common joint disease, causing symptoms such as joint pain, swelling, and deformity, which severely affect patients’ quality of life. Despite advances in medical treatment, OA management remains challenging, necessitating the development of safe and effective drugs. Quercetin (QUE), a natural flavonoid widely found in fruits and vegetables, shows promise due to its broad range of pharmacological effects, particularly in various degenerative diseases. However, its role in preventing OA progression and its underlying mechanisms remain unclear. In this study, we demonstrated that QUE has a protective effect against OA development both in vivo and in vitro, and we elucidated the underlying molecular mechanisms. In vitro, QUE inhibited the expression of IL−1β-induced chondrocyte matrix metalloproteinases (MMP3 and MMP13) and inflammatory mediators such as INOS and COX−2. It also promoted the expression of collagen II, thereby preventing the extracellular matrix (ECM). Mechanistically, QUE exerts its protective effect on chondrocytes by activating the SIRT1/Nrf−2/HO−1 and inhibiting chondrocyte ferroptosis. Similarly, in an OA rat model induced by anterior cruciate ligament transection (ACLT), QUE treatment improved articular cartilage damage, reduced joint pain, and normalized abnormal subchondral bone remodeling. QUE also reduced serum IL−1β, TNF−α, MMP3, CTX−II, and COMP, thereby slowing the progression of OA. QUE exerts chondroprotective effects by inhibiting chondrocyte oxidative damage and ferroptosis through the SIRT1/Nrf−2/HO−1 pathway, effectively alleviating OA progression in rats. Full article

Although the moderate thermal stimulation of articular cartilage exerts chondroprotective effects, it is difficult to effectively heat deep articular cartilage with conventional methods. Photosensitizers increase the ambient temperature using near-infrared (NIR) radiation, which has high tissue permeability. We hypothesized that the intra-articular administration of photosensitizers and NIR irradiation would exert a greater heating effect on articular cartilage. We aimed to evaluate the heating effect of this method on cultured chondrocytes and rat knee cartilage. In vitro, we irradiated a photosensitizer-containing medium with NIR and measured changes in the medium temperature, cytotoxicity, and gene expression of heat shock protein (HSP) 70 and aggrecan (ACAN). In vivo, the knee joints of rats treated with photosensitizers were irradiated with NIR, and changes in intra-articular temperature and gene expression were measured, alongside histological analysis. The results showed that the medium and intra-articular temperature were raised to approximately 40 °C with no apparent disruption to articular cartilage or the immunohistochemically enhanced staining of HSP70 in chondrocytes. The gene expression of HSP70 and ACAN was increased in both cultured and articular cartilage. In summary, this method can safely heat joints and enhance cartilage metabolism by inducing HSP70 expression in articular cartilage. It presents a new hyperthermia therapy with effective cartilage protection. Full article