Rat Osteoarthritis Research Articles

Additive effects of curcumin and glucosamine on knee function, cartilage protection, and subchondral bone preservation in a post-traumatic osteoarthritis rat model

Background: Osteoarthritis (OA) increasingly become a global public health concern. Curcumin and glucosamine, both widely used as dietary supplements for OA, have shown distinct therapeutic effects. However, curcumin’s low bioavailability and the debated efficacy of glucosamine limit their broader clinical use. Objective: Investigate the combined effects of curcumin and glucosamine on knee function, subchondral bone preservation, and cartilage protection in post-traumatic OA rat. Methods: Post-traumatic OA was induced in Lewis rats through medial meniscus transection (MMT) surgery. Rats were treated for 8 weeks with curcumin phospholipid liposome (C, 120 mg/kg/day), glucosamine (G, 190 mg/kg/day), or a combination of both (CG, C: G=1:3, 63/190 mg/kg/day). Knee width was measured weekly, and weight-bearing was assessed twice weekly. Subchondral bone and cartilage changes were analyzed using micro-CT, toluidine blue staining, and the OARSI (Osteoarthritis Research Society International) score. Collagen II expression in cartilage was evaluated by immunohistochemistry. Results: Curcumin phospholipid liposomes significantly reduced joint swelling by up to 4.1% (P<0.001) and improved weight-bearing force by 24.2% at week 2 (P<0.01) and 14.9% at week 8 (P<0.05) in comparison with the MMT group. Analysis of Micro-CT indicated an increase in bone volume (11.6%) and bone mineral content (13.0%) (P<0.05). Histological analysis showed a 28.8% reduction in OARSI scores (P<0.01) and a 53.1% increase in collagen II expression (P<0.005). Glucosamine treatment reduced joint swelling by up to 5.7% (P<0.0001), improved weight-bearing by 31.6% (P<0.001) at week 2, and significantly increased bone volume (30.4%) and bone mineral content (29.9%) (P<0.05). The combined treatment further reduced swelling by up to 6.6% (P<0.0001) and improved the R/L weight-bearing ratio by 24.7% (P<0.0001) at week 8. It also enhanced bone volume (28.6%), bone mineral content (29.7%, and anisotropy degree (59.3%) (P< 0.05). Additionally, the combination therapy decreased OARSI scores by 27.1% (P<0.01) and enhanced the expression of collagen II by 54.2% (P<0.005), indicating enhanced cartilage and subchondral bone protection. Conclusion: Curcumin showed superior protection for cartilage, while glucosamine mainly benefited subchondral bone. Combined treatment demonstrated additive effects, improving both knee structure and physical function in OA, offering enhanced pain relief, anti-inflammatory action, and joint preservation.

Anti-arthritic Effects of Undifferentiated and Chondrogenic Differentiated MSCs in MIA-induced Osteoarthritis in Wistar Rats: Involvement of Oxidative Stress and Immune Modulation.

Osteoarthritis (OA) is a degenerative joint disease that can affect the many tissues of the joint. There are no officially recognized disease-modifying therapies for clinical use at this time probably due to a lack of complete comprehension of the pathogenesis of the disease. In recent years, emerging regenerative therapy and treatments with stem cells both undifferentiated and differentiated cells have gained much attention as they can efficiently promote tissue repair and regeneration. To determine how bone marrow-derived mesenchymal stem cells (BM-MSCs) and chondrogenic differentiated MSCs (CD-MSCs) can treat OA in rats, OA was induced in Wistar rats by injecting three doses of 100 μL physiological saline containing 1 mg of MIA into rat ankle joint of the right hind leg for three consecutive days. Following the induction, the osteoarthritic rats were injected weekly with BM-MSCs or CD-MSCs at a dose of 1x106 cells/rat/dose for three weeks. In addition to morphological and histological investigations of the ankle, spectrophotometric, ELISA, and Western blot analyses were applied to detect various immunological and molecular parameters in serum and ankle. The results of the study showed that in osteoarthritic rats, BM-MSCs and CD-MSCs significantly reduced right hind paw circumference, total leucocyte count (TLC), differential leukocyte count (DLC) of neutrophils, monocytes, lymphocytes, and eosinophils, serum rheumatoid factor (RF), prostaglandin E2 (PGE2) and interleukin (IL-) 1β levels, while they elevated serum IL-10 level. Additionally, BM-MSCs and CD-MSCs markedly reduced lipid peroxides (LPO) levels while they elevated superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities. The monocyte chemoattractant protein-1 (MCP-1) level was significantly downregulated in ankle joint articular tissues by treatment with BM-MSCs or CD-MSCs while nuclear factor erythroid 2-related factor 2 (Nrf2) was upregulated; CD-MSCs treatment was more effective. According to these findings, it can be inferred that BM-MSCs and CD-MSCs have anti-arthritic potential in MIA-induced OA; CD-MSCs therapy is more effective than MSCs. The ameliorative anti-arthritic effects may be mediated by suppressing inflammation and oxidative stress through the downregulation of MCP-1 and upregulation of Nrf2. Based on the obtained results, BM-MSCs and CD-MSCs therapies are promising new options that can be associated with other clinical treatments to improve cartilage regeneration and joint healing. However, more preclinical and clinical research is required to assess the benefits and safety of treating osteoarthritic patients with BM-MSCs and CD-MSCs.

Remodeling the Proinflammatory Microenvironment in Osteoarthritis through Interleukin-1 Beta Tailored Exosome Cargo for Inflammatory Regulation and Cartilage Regeneration.

Osteoarthritis (OA) presents a significant therapeutic challenge, with few options for preserving joint cartilage and repairing associated tissue damage. Inflammation is a pivotal factor in OA-induced cartilage deterioration and synovial inflammation. Recently, exosomes derived from human umbilical cord mesenchymal stem cells (HucMSCs) have gained recognition as a promising noncellular therapeutic modality, but their use is hindered by the challenge of harvesting a sufficient number of exosomes with effective therapeutic efficacy. Given that HucMSCs are highly sensitive to microenvironmental signals, we hypothesized that priming HucMSCs within a proinflammatory environment would increase the number of exosomes secreted with enhanced anti-inflammatory properties. Subsequent miRNA profiling and pathway analysis confirmed that interleukin-1 beta (IL-1β)-induced exosomes (C-Exos) exert positive effects through miRNA regulation and signaling pathway modulation. In vitro experiments revealed that C-Exos enhance chondrocyte functionality and cartilage matrix production, as well as macrophage polarization, thereby enhancing cartilage repair. C-Exos were encapsulated in hyaluronic acid hydrogel microspheres (HMs) to ensure sustained release, leading to substantial improvements in the inflammatory microenvironment and cartilage regeneration in a rat OA model. This study outlines a strategy to tailor exosome cargo for anti-inflammatory and cartilage regenerative purposes, with the functionalized HMs demonstrating potential for OA treatment.

Danggui niantong decoction attenuates synovial fibrosis through regulating PI3k/AKT signaling pathway.

Danggui Niantong Decoction (DGNTD) is a traditional Chinese medicine compound formula that has been demonstrated to possess efficacy in the treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), as well as for dispelling moisture and relieving pain. As mentioned before, DGNTD is essential for synovial inflammation in RA. The primary features of the OA synovial membrane are low-grade inflammation, hyperplasia with enhanced fibroblast-like synoviocytes (FLS) proliferation, and fibrosis, which can cause pain and stiffness. However, it is still unknown how DGNTD functions in the OA synovium. Clarify the influence of DGNTD on OA synovium and investigate potential mechanisms of action. The principal constituents of DGNTD were detected using liquid chromatography-mass spectrometry (LC-MS) analysis. To evaluate the effect of DGNTD on synovial inflammation and fibrosis, a transforming growth factor beta (TGF-β)-stimulated rat FLS cell model and a rat OA animal model based on anterior cruciate ligament transection (ACLT) and partial medial meniscectomy (MMx) were employed. Our results showed that 322 components were detected using LC-MS. In vivo, DGNTD therapy reduced pain, synovial inflammation, and fibrosis. The therapy significantly reduced levels of pain-related molecules, specifically calcitonin gene-related peptide (CGRP) and inducible nitric oxide synthase (iNOS), as well as fibrotic markers, including alpha smooth muscle actin (α-SMA) and type III collagen alpha-1 (Col3a1), in the synovium. A proteomics study demonstrated that DGNTD decreased the fibrotic protein Col3a1. DGNTD reduced the mRNA expression of pro-inflammatory and fibrotic markers (tumor necrosis factor alpha (TNF-α), interleukin-1 beta(IL-1β), interleukin-6(IL-6), α-SMA, Col3a1and TGF-β) in TGF-β-induced FLS. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and validation results revealed that DGNTD inhibits synovial fibrosis via the phosphatidylinositol 3-kinase (PI3K)/protein Kinase B (AKT) signaling pathway. DGNTD partially relieves pain, synovitis, and synovial fibrosis by regulating the PI3K/AKT pathway. These findings provide fresh information about the underlying mechanisms and successful therapy of OA, as well as a theoretical and experimental foundation for the clinical management of OA using DGNTD.

Intra-articular injection of MOF-based nanomaterials for the treatment of osteoarthritis by modulating the bone microenvironment

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation, subchondral bone remodeling, and chronic inflammation. Current therapeutic strategies often fail to address the underlying mechanisms of OA. This study investigates the efficacy of ZIF-8 composite molybdenum (Mo) nanozymes coated by CaCO3 layer (CaCO3@ZIF@Mo-TA) as a novel therapeutic approach for OA. The nanozymes were characterized using various techniques, including transmission electron microscopy (TEM) and X-ray diffraction (XRD). In vivo studies demonstrated that administration of CaCO3@ZIF-8@Mo-TA at a dose of 100 mg/kg significantly improved joint health, reduced inflammation, and enhanced cartilage preservation in an OA rat model. Mechanistic studies revealed that the nanozymes exerted antioxidant and anti-inflammatory effects by modulating key signaling pathways, including the NLRP3 inflammasome. These findings suggest that ZIF-8@Mo-TA nanozymes represent a promising therapeutic strategy for OA management.

Coixol-Loaded Hydrogels Promote Osteochondral Defect Repair via Modulation of Ferroptosis and Autophagy in Chondrocytes.

Osteoarthritis (OA) is a chronic multifactorial disease characterized by cartilage degeneration, pain, and reduced mobility. Current therapies primarily aim to relieve pain and restore function, but they often have limited effectiveness and side effects. Coixol, a bioactive compound from Coix lacryma-jobi L., exhibits anti-inflammatory and analgesic properties, suggesting potential benefits in OA treatment. This study explored the effects of coixol on OA chondrocytes. Primary chondrocytes from OA rats were isolated and treated with varying concentrations of coixol. Cell viability and proliferation were assessed by using CCK-8 assays. The expression of genes related to ferroptosis and autophagy was analyzed through RT-qPCR, Western blot, and immunofluorescence. Moreover, the study investigated the characteristics and performance of coixol-loaded PDLLA-PEG-PDLLA (PLEL)/gelatin sponge (GS) hydrogels (Coixol@PLEL/GS) for enhancing osteochondral defect repair by specifically targeting chondrocyte ferroptosis and autophagy. The characteristics of coixol-loaded PDLLA-PEG-PDLLA/gelatin sponge (Coixol@PLEL/GS) hydrogels were evaluated using cryo-scanning electron microscopy (SEM) or SEM, and coixol release kinetics were determined. In vivo, a rat osteochondral defect model was used to assess the efficacy of Coixol@PLEL/GS in osteochondral defect repair using International Cartilage Repair Society (ICRS) scores, Safranin O/Fast green staining, Toluidine blue staining, and immunofluorescence. Coixol significantly increased the viability and proliferation of OA chondrocytes in a dose-dependent manner. Furthermore, coixol inhibited ferroptosis and stimulated autophagy, as evidenced by the upregulation of related genes. In vivo, Coixol@PLEL/GS remarkably enhanced the repair of osteochondral defects compared to that of control groups. In conclusion, coixol protects OA chondrocytes by improving survival, inhibiting ferroptosis, and activating autophagy, highlighting its potential as a therapeutic strategy for OA treatment.

Porcine-Derived Chondroitin Sulfate Sodium Alleviates Osteoarthritis in HTB-94 Cells and MIA-Induced SD Rat Models.

Osteoarthritis (OA) is a chronic disease characterized by cartilage degradation, leading to bone friction, inflammation, stiffness, pain, and reduced mobility. This study investigates the therapeutic effects of porcine-derived chondroitin sulfate sodium (CS) on OA symptoms at both cellular and animal levels. In vitro study, HTB-94 chondrocytes were treated with inflammatory stimuli and CS (10, 50, 100, and 200 μg/mL) to assess the release of inflammatory mediators and the expression of genes and proteins related to cartilage synthesis and degradation. In vivo study, an MIA-induced OA rat model was used, and CS (62, 124, and 248 mg/kg b.w.) was orally administered for 4 weeks. Key parameters, such as exercise capacity, micro-CT, histological evaluation of joint tissues, serum inflammatory markers, and the expression of mRNA and proteins (inflammatory, cartilage synthesis and degradation, and apoptosis markers), were analyzed. Porcine-derived CS significantly reduced PGE2, NO, and extracellular matrix degradation marker (COMP and CTX-II) levels and increased the expression of cartilage synthesis-related genes and proteins in both HTB-94 cells and the MIA-induced rats. Additionally, CS modulated cartilage degradation pathways and notably inhibited apoptosis in vivo. The effects of porcine CS were comparable to the NSAID ibuprofen, demonstrating its potential as an anti-inflammatory and chondroprotective agent for OA management and dietary supplementation.

Identification of a novel disulfidptosis-related gene signature in osteoarthritis using bioinformatics analysis and experimental validation

Osteoarthritis (OA) is a degenerative bone disease characterized by the destruction of joint cartilage and synovial inflammation, involving intricate immune regulation processes. Disulfidptosis, a novel form of programmed cell death, has recently been identified; however, the effects and roles of disulfidptosis-related genes (DR-DEGs) in OA remain unclear. We obtained six OA datasets from the GEO database, using four as training sets and two as validation sets. Differential expression analysis was employed to identify DR-DEGs, and unique molecular subtypes of OA were constructed based on these DR-DEGs. Subsequently, the immune microenvironment of OA patients was comprehensively analyzed using the “CIBERSORT” algorithm for immune infiltration. Various machine learning algorithms were utilized to screen characteristic DR-DEGs, and nomogram models and ROC curves were built based on these genes. The scRNA dataset (GSE169454) was used to classify chondrocytes in OA samples into distinct cell types, further exploring the gene distribution and correlation of characteristic DR-DEGs with specific cell subpopulations. Moreover, the expression levels of four characteristic DR-DEGs were validated through OA cell models and rat models. In our study, we identified 10 DR-DEGs with significant differences in expression within OA samples. Based on these DR-DEGs, two distinct molecular subtypes were recognized (cluster 1 and 2). ZNF484 and NDUFS1 were found to be significantly overexpressed in subtype 1, while the infiltration abundance of activated mast cells was markedly elevated in subtype 2. Moreover, significant differences were observed in the infiltration proportions of 11 immune cell types between OA and control samples, with 9 DR-DEGs demonstrating substantial correlations with immune cell infiltration levels. Further analysis of the scRNA dataset revealed that SLC3A2 and NDUFC1 were predominantly expressed in the preHTC subpopulation. All 10 DR-DEGs exhibited notably higher expression in the EC subpopulation across various cell types. The proportion of EC subgroups with high SLC3A2 expression increased, mainly enriching pathways related to inflammation, such as the IL-17 signaling pathway and TGF-beta signaling pathway. Using machine learning, we identified four characteristic DR-DEGs, which, in combination with the nomogram and ROC models, demonstrated promising performance in the diagnosis of OA. Additionally, in vivo validation confirmed a significant elevation of PPM1F expression in OA models. This study identified DR-DEGs as potential biomarkers for the diagnosis and classification of OA and provided a preliminary understanding of their role in the immune microenvironment. However, further experimental and clinical studies are required to validate their diagnostic value and therapeutic potential.

1,25(OH)2D3 induces chondrocyte autophagy and reduces the loss of proteoglycans in osteoarthritis through inhibiting the NF-κB pathway.

Nuclear transcription factor-κB (NF-κB) activation is a pivotal event in the pathogenesis of osteoarthritis (OA). OA patients frequently exhibit vitamin D (VD) deficiency, which is commonly associated with NF-κB activation. Our study aimed to investigate whether VD could protect against OA by modulating NF-κB pathway and to explore the underlying mechanisms. Proteins levels were assessed by western blot analysis, gene expression was quantified by quantitative real-time polymerase chain reaction (qRT‒PCR) in vivo and in vitro. The expression of phosphorylated-p65 (p-p65) in knee OA rats was detected by immunohistochemistry, and an NF-κB nuclear translocation assay was validated in chondrocytes. Immunoprecipitation was employed to detect the interaction between NF-κB and vitamin D receptor (VDR) in vivo and in vitro. Small interfering RNA (Si-NF-κB and Si-VDR) transfection was used to investigate the role of NF-κB and VDR signaling pathway in knee OA rats under VD influence. Cartilage changes were visualized of knee OA rats using hematoxylin and eosin as well as safranin-O/fast green of staining. Our findings indicated that VD alleviates OA by inhibiting NF-κBpathway, which in turn reduces chondrocyte apoptosis and extracellular matrix (ECM) degradation. Further analysis revealed that VD primarily stabilizes NF-κB through the interaction of VDR and NF-κB, modulating the AMPK/mTOR signaling pathway to enhance autophagy and delay the progression of OA. This study highlights the protective role of VD in OA by stabilization of NF-κB, mainly through the interaction between VDR and NF-κB. This interaction regulates the AMPK/mTOR signaling pathway, promoting autophagy and suggesting a potential therapeutic strategy for OA management. Key Points • VD confers a protective effect on OA by primarily stabilizing NF-κB through the interaction between VDR and NF-κB, which in turn inhibits NF-κB phosphorylation and nuclear translocation. • In chondrocytes, VD helps shield against OA by blocking NF-κB's entry into the nucleus, subsequently regulating autophagy via the AMPK/mTOR signaling pathway.

Slide-Ring Structured Stress-Electric Coupling Hydrogel Microspheres for Low-Loss Transduction Between Tissues.

High transductive loss at tissue injury sites impedes repair. The high dissipation characteristics in the electromechanical conversion of piezoelectric biomaterials pose a challenge. Therefore, supramolecular engineering and microfluidic technology is utilized to introduce slide-ring polyrotaxane and conductive polypyrrole to construct stress-electric coupling hydrogel microspheres. The molecular slippage mechanism of slide-ring structure stores and releases mechanical energy, reducing mechanical loss, the piezoelectric barium titanate enables stress-electricity conversion, and conjugated π-electron movement in conductive network improves the internal electron transfer efficiency of microspheres, thereby reducing the loss in stress-electricity conversion for the first time. Compared to traditional piezoelectric hydrogel microspheres, the stress-electric coupling efficiency of low-dissipation microspheres increased by 2.3 times, and the energy dissipation decreased to 43%. At cellular level, electrical signals generated by the microspheres triggered Ca2+ influx into stem cells and upregulated the cAMP signaling pathways, promoting chondrogenic differentiation. Enhanced electrical signals induced macrophage polarization to the M2 phenotype, reshaping inflammation and promoting tissue repair. In vivo, the low-dissipation microspheres restored low-loss transduction between tissues, alleviated cartilage damage, improved behavioral outcomes, and promoted the treatment of osteoarthritis in rats. Therefore, this study proposes a new strategy for restoring low-loss transduction between tissues, particularly in mechanically sensitive tissues.

Identification and Validation of Pivotal Genes in Osteoarthritis Combined with WGCNA Analysis.

The prevalence of osteoarthritis (OA), the most common chronic joint condition, is increasing due to the aging population and escalating obesity rates, leading to a significant impact on human health and well-being. Thus, analyzing the key targets of OA through bioinformatics can help discover new biomarkers to improve its diagnosis. The microarray and RNA-seq results were screened from the Gene Expression Omnibus (GEO) database. Functional enrichment analyses, protein-protein interaction (PPI) analysis, and weighted gene co-expression network analysis (WGCNA) of the DEGs were performed. RT-qPCR and WB were further performed to verify the hub gene expression in OA rat. In this study, 35 key genes were identified through differential expression analysis and weighted gene co-expression network analysis (WGCNA) using the GSE169077 and GSE114007 datasets. Enrichment analysis revealed that these key genes were predominantly enriched in the HIF-1 signaling pathway, ECM-receptor interaction, and FoxO signaling pathway. Through the integration of protein-protein interaction (PPI) analysis, validation in animal models and ROC curve analysis, four pivotal genes (GADD45B, CLDN5, HILPDA and CDKN1B) were finally identified. In conclusion, these identified key genes could serve as novel targets for predicting and treating OA, offering fresh insights into its etiology and pathogenesis.

Skatole Alleviates Osteoarthritis by Reprogramming Macrophage Polarization and Protecting Chondrocytes.

Osteoarthritis (OA) is the most prevalent joint disease, yet effective disease-modifying OA drugs (DMOADs) remain elusive. Targeting macrophage polarization has emerged as a promising avenue for OA treatment. This study identified skatole through high-throughput screening as an efficient modulator of macrophage polarization. Invivo experiments demonstrated that skatole administration markedly reduced synovitis and cartilage damage in both destabilization of medial meniscus (DMM)-induced OA mice and monosodium iodoacetate (MIA)-induced OA rats. Mechanistically, skatole activated signal transducer and activator of transcription 6 (Stat6) signaling, promoting M2 macrophage polarization, while inhibiting nuclear factor-κB (NFκB) and mitogen-activated protein kinase (MAPK) signaling pathways to suppress M1 polarization. RNA-sequencing analysis, targeted metabolomics, and mitochondrial stress tests further revealed that skatole treatment shifted macrophages toward oxidative phosphorylation for energy production. Additionally, it up-regulated genes associated with glutathione metabolism and reactive oxygen species (ROS) pathways, reducing intracellular ROS production. The CUT&Tag assay results indicated that the downstream transcription factor p65 of NFκB can directly bind to gene loci related to inflammation, oxidative phosphorylation, and glutathione metabolism, thereby modulating gene expression. This regulatory process is inhibited by skatole. At the chondrocyte level, conditional medium from skatole-treated M1 macrophages balanced anabolism and catabolism in mouse chondrocytes and inhibited apoptosis. In IL1β-treated chondrocytes, skatole suppressed inflammation and catabolism without affecting apoptosis or anabolism. Overall, skatole maintains immune microenvironment homeostasis by modulating macrophage polarization in joints and preserves cartilage function by balancing chondrocyte anabolism and catabolism, effectively alleviating OA. These findings suggest skatole's potential as a DMOAD.

Transcriptomic Analysis and Experimental Verification of Ferroptosis Signature Genes in Osteoarthritis.

Osteoarthritis is a systemic disease that primarily damages articular cartilage and also affects the synovium, ligaments, and bone tissues. The key mechanisms involved are chondrocyte death and degradation of the extracellular matrix. This study aims to identify differentially expressed genes (DEGs) associated with ferroptosis and investigate their roles in the development of osteoarthritis. We used several methods, such as transcriptomic data analysis, gene enrichment analysis, protein-protein interaction network construction, animal model experiments, and immune cell infiltration analysis. Our examination of the GSE114007 dataset uncovered 2614 DEGs, including 1300 that were upregulated and 1314 that were downregulated. From these, we identified eight ferroptosis-related DEGs (FRGs-DEGs). Functional enrichment analysis showed that these genes are significant for cellular migration and tissue remodeling. They are particularly involved in the HIF-1 and PPAR signaling pathways. Additionally, our immune cell infiltration analysis indicated an increase in M0 and M2 macrophages in osteoarthritis samples, while levels of eosinophils and memory B cells were notably decreased. The receiver operating characteristic curve analysis identified GJA1, TIMP Metallopeptidase Inhibitor 1 (TIMP1), and DPP4 as potential biomarkers for osteoarthritis diagnosis, with area under the curve of 0.91, 0.85, and 0.83, respectively. Moreover, RT-qPCR validation in an osteoarthritis rat model confirmed the upregulation of TIMP1, supporting our bioinformatics results. In summary, our study identifies key FRGs-DEGs and their potential roles in osteoarthritis. This research provides new insights into the disease's molecular mechanisms and suggests innovative therapeutic targets for clinical intervention. Future research should aim to include larger patient cohorts and clinical validation to improve the applicability of these findings.

Injectable Self-Assembling Procyanidin Nanospheres for Effective Osteoarthritis Treatment.

Osteoarthritis (OA), a prevalent joint disease, causes immense suffering to thousands of patients, impairing their mobility and diminishing their quality of life. Current treatment methods primarily rely on analgesics or anti-inflammatory drugs to alleviate symptoms but fail to achieve the desired therapeutic outcome. To better realize therapeutic effects of OA, procyanidins (PAs), as a type of plant flavonoids with strong antioxidant andanti-inflammatoryactivities, were designed to self-assembly with well-dispersible Pluronic F127 (PF127) through the hydrogen-bond interaction to present an injectable, biocompatibility PA nanospheres. These nanospheres significantly increased the cell viability in mouse L929 fibroblasts and ADTC5 chondrocytes compared with unassembled PAs. In addition, the self-assembling PAs/PF127 nanospheres enhanced the protein expression of collagen (COL1A1 and COL3A1) in fibroblasts, and the expression of glycosaminoglycan and COL2A1 was also higher than unassembled PAs in chondrocytes, this heralded the potential to achieve OA repair strategies at the cellular level. In an enzymolysis model of rat OA, PAs/PF127 nanospheres significantly reduce joint space swelling in the early stages of cartilage destruction and accelerate the formation of subchondral bone and cartilaginous surface. This study offers valuable insights into the preparation of novel PA nanospheres for effective repair of OA.

Biocompatible ionized air alleviates rat osteoarthritis by modulating polarization from M1 to M2 macrophages

AbstractThe imbalance in the proportion of M1/M2 macrophage polarization is a crucial contributor to the persistent progression of osteoarthritis (OA). This study aimed to evaluate the effects of low-dose biocompatible ionized air (BIA) on macrophage polarization and its subsequent chondroprotective effects, thereby validating the potential of BIA in slowing the progression of OA. In vitro experiments demonstrated that BIA modulates the polarization of M1 macrophages toward the M2 phenotype via the ROS-mediated STAT6 pathway. This shift reduces the expression of pro-inflammatory mediators while increasing the expression of anti-inflammatory mediators and pro-chondrogenic factors, leading to an improved microenvironment surrounding chondrocytes. The direct benefits of this improved microenvironment include enhanced chondrocyte viability, inhibition of apoptosis, and reduced degradation of the extracellular matrix. In vivo studies in rats showed that BIA inhibited M1 macrophage infiltration in the synovium, upregulated the proportion of M2 macrophages, alleviated cartilage degeneration, and delayed OA progression. This gas-based regulatory strategy may open new avenues for the treatment of OA.

Heat-Killed Lactobacillus delbrueckii subsp. lactis 557 Extracts Protect Chondrocytes from Osteoarthritis Damage by Reducing Inflammation: An In Vitro Study.

Osteoarthritis (OA) is a chronic condition characterized by joint pain and disability, driven by excessive oxidative stress and inflammatory cytokine production in chondrocytes, resulting in cell death and cartilage matrix breakdown. Our previous study showed that in monosodium iodoacetate (MIA)-induced OA rats, oral administration of heat-killed Lactobacillus delbrueckii subsp. lactis 557 (LDL557) could significantly decrease OA progression. Accordingly, we designed an in vitro cell culture study aimed at investigating the effects of heat-killed LDL557 extracts on chondrocytes using SW1353 cells (a human chondrosarcoma cell line) challenged with 5 μM MIA to mimic OA conditions. The results showed that the 10 μg/mL LDL557 extracts protected SW1353 cells from MIA-induced death and reduced extracellular matrix (ECM) loss, as evaluated by toluidine blue O staining and extracellular matrix component synthesis with RT-qPCR measurement. This was achieved by decreasing the expression of MIA-induced pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α, while slightly increasing the MIA-suppressed expression of the anti-inflammatory cytokine IL-10, which were evidenced by RT-qPCR analysis. Moreover, the RT-qPCR evaluation also indicated that the LDL557 extracts slightly reduced the expression of COX-2 compared with the control, while it did not reduce the MIA-increased expression of microsomal prostaglandin E synthase-1 (mPGES-1). In addition, the LDL557 extracts influenced neither the matrix-degrading protease expressions measured via RT-qPCR nor the oxidative stress measured via fluorescence flow cytometry in the cells with or without the MIA challenge. This study demonstrates that LDL557 extracts may protect chondrocytes from OA damage by reducing inflammation-related factors and thus mitigating cartilage matrix loss, suggesting LDL557 extracts are attractive alternatives for OA applications.

EZH2/miR-142-3p/HMGB1 axis mediates chondrocyte pyroptosis by regulating endoplasmic reticulum stress in knee osteoarthritis.

Knee osteoarthritis (OA) is still challenging to prevent or treat. Enhanced endoplasmic reticulum (ER) stress and increased pyroptosis in chondrocytes may be responsible for cartilage degeneration. This study aims to investigate the effect of ER stress on chondrocyte pyroptosis and the upstream regulatory mechanisms, which have rarely been reported. The expression of the histone methyltransferase enhancer of zeste homolog 2 (EZH2), microRNA-142-3p (miR-142-3p), and high mobility group box 1 (HMGB1) and the levels of ER stress, pyroptosis, and metabolic markers in normal and OA chondrocytes were investigated by western blotting, quantitative polymerase chain reaction, immunohistochemistry, fluorescence in situ hybridization, fluorescein amidite-tyrosine-valine-alanine-aspartic acid-fluoromethyl ketone (FAM-YVAD-FMK)/Hoechst 33342/propidium iodide (PI) staining, lactate dehydrogenase (LDH) release assays, and cell viability assessments. The effects of EZH2, miR-142-3p, and HMGB1 on ER stress and pyroptosis and the hierarchical regulatory relationship between them were analyzed by chromatin immunoprecipitation, luciferase reporters, gain/loss-of-function assays, and rescue assays in interleukin (IL)-1β-induced OA chondrocytes. The mechanistic contribution of EZH2, miR-142-3p, and HMGB1 to chondrocyte ER stress and pyroptosis and therapeutic prospects were validated radiologically, histologically, and immunohistochemically in surgically induced OA rats. Increased EZH2 and HMGB1, decreased miR-142-3p, enhanced ER stress, and activated pyroptosis in chondrocytes were associated with OA occurrence and progression. EZH2 and HMGB1 exacerbated and miR-142-3p alleviated ER stress and pyroptosis in OA chondrocytes. EZH2 transcriptionally silenced miR-142-3p via H3K27 trimethylation, and miR-142-3p posttranscriptionally silenced HMGB1 by targeting the 3'-UTR of the HMGB1 gene. Moreover, ER stress mediated the effects of EZH2, miR-142-3p, and HMGB1 on chondrocyte pyroptosis. In vivo experiments mechanistically validated the hierarchical regulatory relationship between EZH2, miR-142-3p, and HMGB1 and their effects on chondrocyte ER stress and pyroptosis. A novel EZH2/miR-142-3p/HMGB1 axis mediates chondrocyte pyroptosis and cartilage degeneration by regulating ER stress in OA, contributing novel mechanistic insights into OA pathogenesis and providing potential targets for future therapeutic research.

Polymeric Microneedles for Transdermal Delivery of Human Placental Tissue for the Treatment of Osteoarthritis.

Biologics targeting matrix-degrading proteases, cartilage repair, and inflammation are emerging as promising approaches for osteoarthritis (OA) treatment. Recent research highlights biologic-human placental tissue (HPT) as a potential OA therapy due to its biocompatibility, abundant protein biofactors, and ability to reduce cartilage degradation by suppressing protease expression. Microneedles (MNs) are receiving growing attention for enhancing transdermal delivery of biologics as an alternative to conventional subcutaneous injections. The lyophilized human placental extract (LHP) loaded polymeric MNs are fabricated using a micromolding technique for transdermal delivery. Ex vivo release studies reveal that MNs exhibit a gradual and consistent release of LHP, indicating a sustained delivery profile. LHP-MNs are nontoxic and anti-inflammatory in nature against human skin cells and interleukin (IL-1β) induced synovial cells. Furthermore, the in vivo study shows that LHP-MNs substantially improve behavioral parameters in OA rat models and lower serum concentrations of tumor necrosis factor- α (TNF-α) and cartilage oligomeric matrix protein (COMP) biomarkers, thereby alleviating knee and ankle joint injuries. Histopathological analysis indicates that LHP-MNs significantly preserve cartilage integrity. The study results suggest that employing polymeric MNs for transdermal delivery of LHP can be a promising treatment approach for OA, with the added benefit of excellent patient compliance.

Hck promotes IL-1β-induced extracellular matrix degradation, inflammation, and apoptosis in osteoarthritis via activation of the JAK-STAT3 signaling pathway

We investigated role of haematopoietic cell kinase (Hck) in osteoarthritis (OA) and to explore the underlying mechanisms driving its effects. An OA animal model was established and after OA induction, rats received intra-articular injections of lentivirus twice a week for four weeks. Rats were divided into four groups: control (healthy rats without OA), OA model (rats with induced OA), OA + Len-si-NC (OA rats treated with a non-targeting control lentivirus), and OA + Len-si-Hck (OA rats treated with lentivirus targeting Hck). Blood samples were collected, and serum cytokine levels were measured using ELISA. Afterward, the rats were sacrificed for histological analysis and TUNEL assay. In vitro, IL-1β-treated human chondrocytes were transfected with Hck, and the effects on cell viability, apoptosis, ECM degradation, and JAK-STAT3 signaling were assessed. Colivelin, a JAK-STAT3 agonist, was used to confirm the pathway’s involvement. Results indicated increased Hck expression in the cartilage tissues of OA rats and in IL-1β-stimulated chondrocytes. Silencing Hck in vivo reduced IL-6 and TNF-α levels, apoptosis, and preserved cartilage structure. In vitro, Hck knockdown in IL-1β-treated chondrocytes resulted in enhanced cell viability, reduced apoptosis, and decreased ECM degradation. Notably, the expression of MMP3 and MMP13 was significantly lowered, while collagen II and aggrecan levels were restored. Additionally, Hck knockdown inhibited JAK-STAT3 activation, which was evident from reduced levels of phosphorylated JAK1 and STAT3. The addition of colivelin reversed these effects, confirming that Hck mediates its effects through the JAK-STAT3 pathway. Overall, our findings indicate that Hck is critical in OA progression by promoting inflammation, apoptosis, and ECM degradation through the JAK-STAT3 signaling pathway activation.

Long-term hypoxic atmosphere enhances the stemness, immunoregulatory functions, and therapeutic application of human umbilical cord mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are usually cultured in a normoxic atmosphere (21%) in vitro, while the oxygen concentrations in human tissues and organs are 1% to 10% when the cells are transplanted in vivo. However, the impact of hypoxia on MSCs has not been deeply studied, especially its translational application. In the present study, we investigated the characterizations of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in hypoxic (1%) and normoxic (21%) atmospheres with a long-term culture from primary to 30 generations, respectively. The comparison between both atmospheres systematically analyzed the biological functions of MSCs, mainly including stemness maintenance, immune regulation, and resistance to chondrocyte apoptosis, and studied their joint function and anti-inflammatory effects in osteoarthritis (OA) rats constructed by collagenase II. We observed that long-term hypoxic culture surpassed normoxic atmosphere during hUC-MSCs culture in respect of promoting proliferation, anti-tumorigenicity, maintaining normal karyotype and stemness, inhibiting senescence, and improving immunoregulatory function and the role of anti-apoptosis in chondrocytes. Furthermore, we demonstrated that the transplantation of long-term hypoxic hUC-MSCs (Hy-MSCs) had a better therapeutic effect on OA rats compared with the hUC-MSCs cultured in the normoxic atmosphere (No-MSCs) in terms of the improved function and swelling recovery in the joints, and substantially inhibited the secretion of pro-inflammatory factors, which effectively alleviated cartilage damage by reducing the expression of matrix metallopeptidase 13 (MMP-13). Our results demonstrate that Hy-MSCs possess immense potential for clinical applications via promoting stemness maintenance and enhancing immunoregulatory function.