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Recently, FN1 fusions to receptor tyrosine kinase genes have been identified in soft tissue tumors with calcified chondroid matrix named calcifying chondroid mesenchymal neoplasms (CCMNs). We collected 33 cases of CCMN from the French network for soft tissue and bone tumors. We performed wholeexome RNA sequencing, expression analysis, and genome-wide DNA methylation profiling in 33, 30, and 20 cases of CCMN compared with a control group of tumors, including noncalcified tenosynovial giant cell tumor (TGCT). Among them, 15 cases showed morphologic overlap with soft tissue chondroma, 8 cases with tophaceous pseudogout, and 10 cases with chondroid TGCT. RNA-sequencing revealed a fusion of FN1 in 76% of cases (25/33) with different 5' partners, including most frequently FGFR2 (14 cases), TEK or FGFR1. Among CCMN associated with FGFR1 fusions, 2 cases had overexpression of FGF23 without tumor-induced osteomalacia. Four CCMN had PDGFRA::USP8 fusions; 3 of which had histologic features of TGCT and were located in the hip, foot, and temporomandibular joint (TMJ). All cases with FN1::TEK fusion were located at TMJ and had histologic features of TGCT with or without chondroid matrix. They formed a distinct cluster on unsupervised clustering analyses based on whole transcriptome and genome-wide methylome data. Our study confirms the high prevalence of FN1 fusions in CCMN. In addition, through transcriptome and methylome analyses, we have identified a novel subgroup of tumors located at the TMJ, exhibiting TGCTlike features and FN1::TEK fusions. [ABSTRACT FROM AUTHOR]

Stem cell-based therapy holds promise for cartilage regeneration in treating knee osteoarthritis (KOA). Injectable hydrogels have been developed to mimic the extracellular matrix (ECM) and facilitate stem cell growth, proliferation, and differentiation. However, these hydrogels face limitations such as poor mechanical strength, inadequate biocompatibility, and suboptimal biodegradability, collectively hindering their effectiveness in cartilage regeneration. This study introduces an injectable, biodegradable, and self-healing hydrogel composed of chitosan–PEG and PEG–dialdehyde for stem cell delivery. This hydrogel can form in situ by blending two polymer solutions through injection at physiological temperature, encapsulating human adipose-derived stem cells (hADSCs) during the gelation process. Featuring a 3D porous structure with large pore size, optimal mechanical properties, biodegradability, easy injectability, and rapid self-healing capability, the hydrogel supports the growth, proliferation, and differentiation of hADSCs. Notably, encapsulated hADSCs form 3D spheroids during proliferation, with their sizes increasing over time alongside hydrogel degradation while maintaining high viability for at least 10 days. Additionally, hADSCs encapsulated in this hydrogel exhibit upregulated expression of chondrogenic differentiation genes and proteins compared to those cultured on 2D surfaces. These characteristics make the chitosan–PEG/PEG–dialdehyde hydrogel–stem cell construct suitable for direct implantation through minimally invasive injection, enhancing stem cell-based therapy for KOA and other cell-based treatments. [ABSTRACT FROM AUTHOR]

Background: The relationship between thyroid hormone (TH) levels in vivo and osteoarthritis (OA) remains inconclusive. This study aims to investigate the association between TH levels and OA, analyze the effect of triiodothyronine on hypertrophic chondrocyte differentiation and OA progression, and identify potential target genes of triiodothyronine in OA to evaluate its diagnostic value. Methods: Two-sample mendelian randomization method was used to probe the causal links between hyperthyroidism and OA. Differentially expressed genes (DEGs) from two RNA-sequencing data in Gene Expression Omnibus (GSE199847 and GSE114007) and enrichment analysis of DEGs (166 commonly upregulated genes and 71 commonly downregulated genes of GSE199847 and GSE114007) was performed to analyze the effect of triiodothyronine (T3) on hypertrophic chondrocyte differentiation and OA. C28/I2 cells treated with T3 and reverse transcription and quantitative real-time polymerase chain reaction were used to validate T3 targeted genes. The diagnostic performance of target genes was assessed by the receiver operating characteristic (ROC) curve and area under the curve (AUC). Results: There was a positive causal association between hyperthyroidism and OA (IVW result, OR = 1.330, 95% CI 1.136–1.557, P = 0.0004). Weighted median and Weighted mode analysis also demonstrated that hyperthyroidism had a positive causal association with OA (p < 0.05, OR > 1). Bioinformatics analysis indicated T3 can partially induce the emergence of late hypertrophic chondrocyte and promote OA through extracellular matrix organization, blood vessel development, skeletal system development and ossification. Post-T3 treatment, MAFB, C1QTNF1, COL3A1 and ANGPTL2 were significantly elevated in C28/I2 cells. ROC curves in GSE114007 showed that AUC of all above genes were ≥ 0.7. Conclusions: This study identified that hyperthyroidism has a positive causal association with OA by MR analysis. T3 induced hypertrophic chondrocytes promote OA progression by upregulating genes such as MAFB, C1QTNF1, COL3A1 and ANGPTL2, which can also serve as OA diagnosis. [ABSTRACT FROM AUTHOR]

Background: Temporomandibular joint osteoarthritis (TMJOA) has a high incidence rate, but its pathogenesis remains unclear. Circadian rhythm is an important oscillation in the human body and influences various biological activities. However, it is still unclear whether circadian rhythm affects the onset and development of TMJOA. Methods: We disrupted the normal rhythm of rats and examined the expression of core clock genes in the mandibular condylar cartilage of the jaw and histological changes in condyles. After isolating rat mandibular condylar chondrocytes, we upregulated or downregulated the clock gene Per1, examined the expression of cartilage matrix-degrading enzymes, tested the activation of the GSK3β/β-CATENIN pathway and verified it using agonists and inhibitors. Finally, after downregulating the expression of Per1 in the mandibular condylar cartilage of rats with jet lag, we examined the expression of cartilage matrix-degrading enzymes and histological changes in condyles. Results: Jet lag led to TMJOA-like lesions in the rat mandibular condyles, and the expression of the clock gene Per1 and cartilage matrix-degrading enzymes increased in the condylar cartilage of rats. When Per1 was downregulated or upregulated in mandibular condylar chondrocytes, the GSK3β/β-CATENIN pathway was inhibited or activated, and the expression of cartilage matrix-degrading enzymes decreased or increased, which can be rescued by activator and inhibitor of the GSK3β/β-CATENIN pathway. Moreover, after down-regulation of Per1 in mandibular condylar cartilage in vivo, significant alleviation of cartilage degradation, cartilage loss, subchondral bone loss induced by jet lag, and inhibition of the GSK3β/β-CATENIN signaling pathway were observed. Circadian rhythm disruption can lead to TMJOA. The clock gene Per1 can promote the occurrence of TMJOA by activating the GSK3β/β-CATENIN pathway and promoting the expression of cartilage matrix-degrading enzymes. The clock gene Per1 is a target for the prevention and treatment of TMJOA. [ABSTRACT FROM AUTHOR]

Background: Reduced viability in the deepest zones of osteochondral allografts (OCAs) can weaken the subchondral interface, potentially increasing the risk of failure. This reduction may result from nutritional imbalances due to uneven media distribution or interference from bone marrow elements. Purpose: To investigate whether culturing OCAs using a rotary shaker or removing the bone marrow elements would increase graft cellular viability. Study Design: Controlled laboratory study. Methods: Bovine osteochondral explants were stored for 28 days at 4°C under 3 different conditions (n = 6 explants per group): static (control group), rotary shaker at 150 rpm (shaker group), and static after removal of bone marrow elements using a Waterpik device (Waterpik group). Chondrocyte viability was assessed using live/dead staining across the entire tissue and in each zone (superficial, middle, deep). Subchondral bone viability was assessed using TUNEL (terminal deoxynucleotidal transferase–mediated biotin–deoxyuridine triphosphate nick-end labeling) staining to detect apoptotic cells. Results: Both shaker (64.2%; P =.010) and Waterpik (65.6%; P =.005) conditions showed significantly higher chondrocyte viability compared with control (49.8%). When samples were analyzed by zone, the shaker and Waterpik groups displayed higher cellular viability at the middle zone (shaker = 60.6%, P <.001; Waterpik = 56.1%, P <.001) and deep zone (shaker = 63.1%, P =.018; Waterpik = 61.5%, P =.025) than the control group (25.6% at middle zone; 32.8% at deep zone). Additionally, shaker (56.7%; P =.018) and Waterpik (51.4%; P =.007) groups demonstrated a lower percentage of apoptotic cells in subchondral bone compared with control (88.0%). No significant differences were observed between the shaker and Waterpik groups in any of the analyses. Conclusion: Both rotary shaking and removal of bone marrow elements during storage of osteochondral explants led to higher chondrocyte viability at the middle and deep zones of the graft compared with the static storage condition. Enhancing nutrition delivery to the graft could improve its quality, potentially improving outcomes of OCA transplantation. Clinical Relevance: The use of a rotary shaker or the removal of bone marrow elements may significantly improve the culture conditions, increasing graft viability and integrity after OCA storage. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a three-dimensional (3D) cell model in order to evaluate the effectiveness of a traditional Chinese medicine decoction in the treatment of arthritis. Chondrocytes (ATDC5) and osteoblasts (MC3T3-E1) were 3D printed separately using methacryloyl gelatin (GelMA) hydrogel bioinks to mimic the natural 3D cell environment. Both cell types showed good biocompatibility in GelMA. Lipopolysaccharide (LPS) was added to the cell models to create inflammation models, which resulted in increased expression of inflammatory factors IL-1β, TNF-α, iNOS, and IL-6, and decreased expression of cell functional genes such as Collagen II (COLII), transcription factor SOX-9 (Sox9), Aggrecan, alkaline phosphatase (ALP), RUNX family transcription factor 2 (Runx2), Collagen I (COLI), Osteopontin (OPN), and bone morphogenetic protein-2 (BMP-2). The created inflammation model was then used to evaluate the effectiveness of Dangguiniantongtang (DGNT) decoctions. The results showed that DGNT reduced the expression of inflammatory factors and increased the expression of functional genes in the cell model. In summary, this study established a 3D cell model to assess the effectiveness of traditional Chinese medicine (TCM) decoctions, characterized the gene expression profile of the inflammatory state model, and provided a practical reference for future research on TCM efficacy evaluation for arthritis treatment. [ABSTRACT FROM AUTHOR]

Circular RNAs (circRNAs) are involved in osteoarthritis (OA) progression. This study aimed to investigate the role and molecular mechanisms of circMYO1C in OA. CircMYO1C was upregulated in OA‐ and interleukin‐1β (IL‐1β)‐exposed chondrocytes. The results indicated that circMYO1C knockdown repressed the inflammatory factors (tumor necrosis factor alpha [TNF‐α], interleukin‐6 [IL‐6], interleukin‐8 [IL‐8], etc.) and apoptosis of chondrocytes following IL‐1β exposure. CircMYO1C was an N6‐methyladenosine (m6A)‐modified circRNA with m6A characteristics. High mobility group box 1 (HMGB1) was a target of circMYO1C. IL‐1β exposure increased the stability and half‐life (t1/2) of HMGB1 mRNA, while silencing circMYO1C reduced HMGB1 mRNA stability. Taken together, circMYO1C targets the m6A/HMGB1 axis to promote chondrocyte apoptosis and inflammation. The present study demonstrates that the circMYO1C/m6A/HMGB1 axis is essential for OA progression, highlighting a novel potential therapeutic target for clinical OA. [ABSTRACT FROM AUTHOR]

Background: Multiple epiphyseal dysplasia-4 (MED-4, MIM 226900) is a rare autosomal recessive disease characterized by disproportionate height and early onset osteoarthritis of the lower limbs. MED-4 is caused by homozygous or compound heterozygous pathogenic variants in the SLC26A2 gene. However, the underlying pathogenic mechanisms in chondrocytes remains unknown. This study aimed to identify the pathogenic variants within a MED-4 family and explore the molecular etiology of this condition in human primary chondrocyte cells. Methods: Clinical data were recorded and peripheral blood samples were collected for analysis. Whole exome sequencing (WES) and bioinformatic analyses were performed to determine causative variants. Wild-type SLC26A2 and corresponding mutant expression plasmids were constructed and transfected into human primary chondrocytes. The expression and subcellular distribution of SLC26A2 protein in chondrocytes were detected by immunoblotting and immunofluorescence. Effects of these variants on chondrocytes viability and apoptosis were measured by Cell Counting Kit-8 (CCK-8) assay. Expression of genes related to cartilage homeostasis was subsequently analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Results: We identified two compound heterozygous variants c.1020_1022delTGT(p.Val341del) and c.1262 T > C(p.Ile421Thr) in the SLC26A2 gene in the patients. Mutant SLC26A2Val341del and SLC26A2Ile421Thr proteins were distributed in relatively few cells and were observed only within the nucleus. The viability of chondrocytes with the SLC26A2 variant group was similar to the wild-type (WT) group. However, the protein expressions of SLC26A2Val341del and SLC26A2Ile421Thr were decreased compared with SLC26A2WT. Expression levels of matrix metallopeptidase 13 (MMP13), α-1 chain of type X collagen (COL10A1), and Runt-related transcription factor 2 (RUNX2) were significantly decreased in the variant group. However, aggrecan (ACAN) expression was higher in the variant group than the WT group. Conclusions: Overall, our data demonstrate that the variants p.Val341del and p.Ile421Thr in SLC26A2 cause MED-4 and that these two variants promote chondrocyte proliferation while inhibiting chondrocyte differentiation. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA), a chronic joint disease affecting over 500 million individuals globally, is characterized by the destruction of articular cartilage and joint inflammation. Conventional treatments are insufficient for repairing damaged joint tissue, necessitating novel therapeutic approaches. Mesenchymal stem cells (MSCs), with their potential for differentiation and self-renewal, hold great promise as a treatment for OA. However, challenges such as MSC viability and apoptosis in the ischemic joint environment hinder their therapeutic effectiveness. Hydrogels with biocompatibility and degradability offer a three-dimensional scaffold that support cell viability and differentiation, making them ideal for MSC delivery in OA treatment. This review discusses the pathological features of OA, the properties of MSCs, the challenges associated with MSC therapy, and methods for hydrogel preparation and functionalization. Furthermore, it highlights the advantages of hydrogel-based MSC delivery systems while providing insights into future research directions and the clinical potential of this approach. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is now widely acknowledged as a low-grade inflammatory condition, in which the intrinsic immune system plays a significant role in its pathogenesis. While the involvement of macrophages and T cells in the development of OA has been extensively reviewed, recent research has provided mounting evidence supporting the crucial contribution of NK cells in both the initiation and advancement of OA. Accumulated evidence has emerged in recent years indicating that NK cells play a critical role in OA development and progression. This review will outline the ongoing understanding of the utility of NK cells in the etiology of OA, focusing on how NK cells interact with chondrocytes, synoviocytes, osteoclasts, and other immune cells to influence the course of OA disease. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a potentially toxic element able to interfere with cellular functions and lead to disease or even death. Cd accumulation has been demonstrated in cartilage, where it can induce damage in joints. The aim of this study was to evaluate the effect of CdCl2 on primary cultures of human chondrocytes and the possible protective effect of seleno-methionine (Se-Met). Human primary articular chondrocytes were cultured and treated as follows: control groups, cells challenged with 7.5 μM and 10 μM CdCl2 alone, and cells pretreated with 10 and 20 μM Se-Met and then challenged with 7.5 μM and 10 μM CdCl2. Twenty-four hours after incubation, cell viability, histological evaluation with hematoxylin–eosin stain, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed. Furthermore, reverse transcription-PCR was carried out to evaluate mRNA levels of BAX, BAK1, CASP-3, and CASP-9. After CdCl2 challenge at both doses, a reduced cell viability and an overexpression of BAX, BAK1, CASP-3, and CASP-9 genes, as well as a high number of TUNEL-positive cells, were demonstrated, all parameters becoming higher as the dose of CdCl2 was increased. The pretreatment with Se-Met lowered the expression of all considered genes, improved cell viability and morphological changes, and reduced the number of TUNEL-positive cells. It was concluded that Se-Met plays a protective role against CdCl2-induced structural and functional changes in chondrocytes in vitro, as it improved cell viability and showed a positive role in the context of the apoptotic pathways. It is therefore suggested that a translational, multifaceted approach, with plant-based diets, bioactive functional foods, nutraceuticals, micronutrients, and drugs, is possibly advisable in situations of environmental pollution caused by potentially toxic elements. [ABSTRACT FROM AUTHOR]

Purpose of the Study: The evaluation of anti-apoptotic and chondroprotective properties of a single injection of PRP using immunohistochemistry (IHC). Methods: This was a placebo-controlled blinded experimental study. Ten healthy Dunkin Hartley guinea pigs were selected. One knee of each animal was injected with a single injection of PRP (Group A); the contralateral knee acted as a control and was injected with a single injection of normal saline (Group B). These groups were further divided into A3 and B3 based on the timeline of animal sacrifice (3 months) and A6 and B6 (6 months). The formalin-preserved articular cartilage blocks were subjected to IHC to stain Aggrecan, Caspase-3, and Collagen-2. Results: The mean IHC score was significantly low for Caspase-3 (p—0.029) in intervention group (A3) in comparison to placebo control group (B3) pointing towards decreased apoptosis. The mean IHC values were significantly higher for Collagen II (p—0.011) for intervention group (A6) in contrast to control group (B6); values were also significantly low for Caspase-3 (p—0.029) in A6 as compared to B6. The mean Caspase-3 values were significantly higher in A6 as compared to A3 (p—0.029). Conclusion: The impact of a solitary injection of PRP on upregulation of anabolic pathways inside cartilage is relatively slower as compared to its effect on downregulation of apoptotic pathways. Even a single PRP injection holds the potential to change cartilage microenvironment, but the effects are not long lasting. [ABSTRACT FROM AUTHOR]

Objectives: Abnormal mechanical stress is the pivotal risk factor of temporomandibular joint osteoarthritis (TMJOA). This study investigated the pathogenic mechanism by which abnormal mechanical stress induced chondrocyte senescence. Materials and Methods: Cellular senescence was investigated in the rodent model of unilateral anterior crossbite and in the chondrocytes subjected to mechanical overloading in vitro. The effects of Yes‐associated protein (YAP) in chondrocyte senescence and its correlation with methyltransferase‐like 3 (METTL3) and N6‐methyladenosine (m6A) modification were evaluated. The role of m6A modification in chondrocyte senescence was determined. The therapeutic effects of m6A inhibition in TMJOA were investigated. Results: Senescent chondrocytes were accumulated in the mechanically induced TMJOA lesions in rats and mechanical overloading could trigger chondrocyte senescence in vitro. This mechanical stress‐induced cellular senescence was revealed to be mediated by YAP deficiency that promoted METTL3‐dependent m6A modification. Moreover, inhibition of m6A modification rescued chondrocyte senescence in vitro and in vivo, and suppressed TMJOA progression in rats. Conclusions: This study uncovered the underlying mechanism of mechanically induced senescence in TMJOA from the perspective of epitranscriptomics and revealed the therapeutic potential of m6A inhibition in TMJOA. [ABSTRACT FROM AUTHOR]

Objective: During the development of temporomandibular joint osteoarthritis, endochondral ossification is compromised which leads to condylar degeneration; miR‐335‐5p in endochondral ossification in osteoarthritic condylar cartilage tissue remains unclear. Methods: Up‐regulated microRNA and its target gene were searched for endochondral ossification in osteoarthritis articular cartilage. The effect of increased or decreased miR‐335‐5p on endochondral ossification was evaluated by transfecting miR‐335‐5p mimics or miR‐335‐5p inhibitor in vitro in chondrocytes C28/I2. Finally, we injected the temporomandibular joint of rats intra‐articularly with agomiR‐335 in a unilateral anterior crossbite rat model to determine the in vivo regulation of miR‐335. Results: After the onset of temporomandibular joint osteoarthritis, miR‐335‐5p levels were gradually up‐regulated, whereas endochondral ossification‐related genes were down‐regulated in condylar cartilage specimens. Our results showed that miR‐335 inhibited endochondral ossification after administration of a miR‐335 antagonist into the temporomandibular joint articular cavity of a unilateral anterior crossbite rat model. AgomiR‐335, a miR‐335 agonist, inhibited matrix mineralization in fibrocartilage stem cells in vitro and then miR‐335‐5p negatively regulated chondrocyte activity by directly targeting SP1 via promoting transforming growth factor‐β/Smad signalling. Conclusion: miR‐335‐5p can significantly inhibit endochondral ossification; therefore, its inhibition may be beneficial for the treatment of temporomandibular joint osteoarthritis. [ABSTRACT FROM AUTHOR]

Background: A major limitation of osteochondral allografts (OCA) is the deterioration of cartilage health associated with cell death during prolonged storage. However, little is known about the mechanisms that contribute to chondrocyte death during storage. Purpose/Hypothesis: This study aimed to determine whether bioactive lipid metabolites accumulate in the storage media of OCA and whether they are associated with a loss of chondrocyte viability during prolonged storage. It was hypothesized that free fatty acids (FFAs) would accumulate over time in the storage media of OCA and adversely affect cartilage health during storage. Study Design: Controlled laboratory study. Methods: A group of 21 (n = 6-8 OCA/treatment group) fresh human hemicondylar OCA tissues and media were analyzed after 7, 28, and 68 days of prolonged cold (4°C) storage. Targeted mass spectrometry analysis was used to quantify bioactive FFAs, as well as primary (lipid hydroperoxide [ROOH]) and secondary (malondialdehyde) lipid oxidation products. Chondrocyte viability was measured using a fluorescence-based live/dead assay and confocal microscopy. Results: The concentration of all targeted fatty acid metabolites in storage media was significantly increased with increased cold storage time (P <.05). ROOH was significantly higher on day 28 of cold storage. No difference in secondary ROOH products in storage media was observed. Chondrocyte viability significantly declined in both the en face and the vertical cross-sectional analysis with increased cold storage time and inversely correlated with fatty acid metabolites (P <.05). Conclusion: It is well established that elevated levels of certain FFAs and lipid oxidation products can alter cell function and cause cell death via lipotoxicity and other mechanisms. This work is the first to identify elevated levels of FFA metabolites and primary oxidation lipid products in the storage media from clinical OCA. The concentrations of FFA metabolites were measured at levels (>100 µM) known to induce cell death and were directly correlated with chondrocyte viability. Clinical Relevance: These findings provide important targets for understanding why cartilage health declines during cold storage, which can be used to optimize media formulations and improve graft health. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) is a degenerative disease that affects synovial joints and leads to significant pain and disability, particularly in older adults. Infiltration of macrophages plays a key role in the progression of OA. However, the mechanisms underlying macrophage recruitment in OA are not fully understood. Methods: The Serglycin (SRGN) expression pattern was analyzed, along with its association with macrophage infiltration in OA, using bioinformatic methods. SRGN expression in chondrocytes was altered by small interfering RNA (siRNA) and plasmids. Conditioned media (CM) was obtained from transfected chondrocytes to establish a co-culture model of chondrocytes and THP-1 derived macrophages. The impact of SRGN on macrophage recruitment was evaluated using a transwell assay. Furthermore, the regulatory effect of SRGN on CCL3 was validated through qPCR, WB, and ELISA experiments. Results: In OA patients, the upregulation of SRGN positively correlated with K-L grade and macrophage infiltration. It was found that SRGN expression and secretion were up-regulated in OA and that it can promote macrophage migration in vitro. Further investigation showed that SRGN affects macrophage migration by regulating the expression of CCL3. Conclusion: SRGN in chondrocytes plays a role in promoting the recruitment of THP-1 derived macrophages in vitro by regulating production of CCL3. [ABSTRACT FROM AUTHOR]

Chondrocyte apoptosis is recognized as one of the pathological features involved in cartilage degeneration driving the onset and progression of knee osteoarthritis (OA). This study aimed to determine the molecular mechanism underlying the effect of clusterin (CLU), anti‐apoptotic molecule, in human knee OA chondrocytes. Primary knee OA chondrocytes were isolated from the cartilage of knee OA patients and divided into five groups: (1) the cells treated with interleukin (IL)‐1β, (2) CLU alone, (3) a combination of IL‐1β and CLU, (4) LY294002 (PI3K inhibitor) along with IL‐1β and CLU, and (5) the untreated cells. Production of apoptotic, inflammatory, anabolic, and catabolic mediators in knee OA chondrocytes was determined after treatment for 24 h. Our invitro study uncovered that CLU significantly suppressed the production of inflammatory mediators [nitric oxide (NO), IL6, and tumor necrosis factor (TNF)‐α] and apoptotic molecule (caspase‐3, CASP3). CLU significantly upregulated messenger ribonucleic acid (mRNA) expressions of anabolic factors [SRY‐box transcription factor‐9 (SOX9) and aggrecan (ACAN)], but significantly downregulated mRNA expressions of IL6, nuclear factor kappa‐B (NF‐κB), CASP3, and matrix metalloproteinase‐13 (MMP13). Anti‐apoptotic and anti‐inflammatory effects of CLU were mediated through activating PI3K/Akt signaling pathway. The findings suggest that CLU might have beneficial effects on knee OA chondrocytes by exerting anti‐apoptotic and anti‐inflammatory functions via PI3K/Akt pathway, making CLU a promising target for potential therapeutic interventions in knee OA. [ABSTRACT FROM AUTHOR]

Background: Particulated autograft cartilage implantation is a surgical technique that has been previously described for the repair of osteochondral lesions of the talus (OLT). It uses cartilage fragments harvested from the OLT that are minced into 1-2-mm3 fragments and then immediately reimplanted back into the chondral defect and sealed with fibrin glue during a single-stage surgery. The purpose of this study was to characterize the suitability of these minced cartilage fragments as immediate autograft for the treatment of OLTs. Methods: Thirty-one patients undergoing primary arthroscopic surgery for their OLT consented to have their loose or damaged cartilage fragments removed and analyzed in the laboratory. Harvested specimens were minced into 1- to 2-mm3 fragments and cell count, cell density, and cell viability were determined. In addition, physical characteristics of the OLT lesion were recorded intraoperatively and analyzed including size, location, Outerbridge chondromalacia grade of the surrounding cartilage, density of underlying bone, and whether the surgeon thought the OLT was primarily hyaline or fibrocartilage. Results: An average of 419 000 cells was able to be obtained from the harvested OLT fragments. The cells were 71.2% viable after mincing. Specimens from younger patients and from lesions with worse chondromalacia adjacent to the OLT had significantly higher cell numbers. Those from lateral lesions and with worse neighboring chondromalacia had a significantly higher cell density. None of the remaining physical OLT characteristics studied seemed to significantly affect cell number or viability. Conclusion: A large number of viable cells are available for immediate autografting by removing the loose or damaged cartilage from an OLT and mincing it into 1- to 2-mm3 fragments. These can be reimplanted into the chondral defect in a single-stage surgery. Future clinical studies are needed to determine if the addition of these live autologous cells either alone or in conjunction with other techniques significantly improves the quality of the repair tissue and clinical outcomes. Level of Evidence: Level IV, case series. [ABSTRACT FROM AUTHOR]

A coenzyme A (CoA-SH)-responsive dual electrochemical and fluorescence-based sensor was designed utilizing an MnO2-immobilized-polymer-dot (MnO2@D-PD)-coated electrode for the sensitive detection of osteoarthritis (OA) in a peroxisomal β-oxidation knockout model. The CoA-SH-responsive MnO2@D-PD-coated electrode interacted sensitively with CoA-SH in OA chondrocytes, triggering electroconductivity and fluorescence changes due to cleavage of the MnO2 nanosheet on the electrode. The MnO2@D-PD-coated electrode can detect CoA-SH in immature articular chondrocyte primary cells, as indicated by the significant increase in resistance in the control medium (R24h = 2.17 MΩ). This sensor also sensitively monitored the increase in resistance in chondrocyte cells in the presence of acetyl-CoA inducers, such as phytol (Phy) and sodium acetate (SA), in the medium (R24h = 2.67, 3.08 MΩ, respectively), compared to that in the control medium, demonstrating the detection efficiency of the sensor towards the increase in the CoA-SH concentration. Furthermore, fluorescence recovery was observed owing to MnO2 cleavage, particularly in the Phy- and SA-supplemented media. The transcription levels of OA-related anabolic (Acan) and catabolic factors (Adamts5) in chondrocytes also confirmed the interaction between CoA-SH and the MnO2@D-PD-coated electrode. Additionally, electrode integration with a wireless sensing system provides inline monitoring via a smartphone, which can potentially be used for rapid and sensitive OA diagnosis. [ABSTRACT FROM AUTHOR]

Introduction: Nanofat is an effective cell therapy for osteoarthritis (OA). However, it has clinical limitations due to its short half-life. We developed Nanofat lysate (NFL) to overcome the defect of Nanofat and explore its anti-OA efficacy and mechanism. Methods: Monoiodoacetate (MIA) was employed to establish rat OA model. For pain assessment, paw withdrawal latency (PWL) and thermal withdrawal latency (TWL) were evaluated. Degeneration of cartilage was observed by histopathological and immunohistochemical examination. Primary chondrocytes were treated with TNF-α to establish the cellular model of OA. MTT, wound healing, and transwell assays were performed to assess effects of NFL on chondrocytes. RNA-seq, qPCR and Western blot assays were conducted to clarify the mechanism of NFL. Results and Discussion: The animal data showed that PWL and TWL values, Mankin's and OARSI scorings, and the Col2 expression in cartilage were significantly improved in the NFL-treated OA rats. The cellular data showed that NFL significantly improved the proliferation, wound healing, and migration of chondrocytes. The molecular data showed that NFL significantly restored the TNF-α-altered anabolic markers (Sox9, Col2 and ACAN) and catabolic markers (IL6 and Mmp13). The RNA-seq identified that TGF-β-Smad2/3 signaling pathway mediated the efficacy of NFL, which was verified by qPCR and Western blot that NFL significantly restored the abnormal expressions of TGFβR2, phosphorylated-Smad2, phosphorylated-Smad2/3, Col2, Mmp13 and Mmp3. After long-term storage, NFL exerted similar effects as its fresh type, indicating its advantage of storability. In sum, NFL was developed as a new therapeutic approach and its anti-OA efficacy and mechanism that mediated by TGF-β-Smad2/3 signaling was determined for the first time. Besides, the storability of NFL provided a substantial advantage than other living cell-based therapies. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a common degenerative joint disease which currently lacks of effective agents. It is therefore urgent and necessary to seek an effective approach that can inhibit inflammation and promote cartilage matrix homeostasis. Cartilage progenitor cells (CPCs) are identified as a cell population of superficial zone in articular cartilage which possess strong migration ability, proliferative capacity, and chondrogenic potential. Recently, the application of CPCs may represent a novel cell therapy strategy for OA treatment. There is growing evidence that extracellular vesicles (EVs) are primary mediators of the benefits of stem cell-based therapy. In this study, we explored the protective effects of CPCs-derived EVs (CPCs-EVs) on IL-1β-induced chondrocytes. We found CPCs-EVs exhibited chondro-protective effects in vitro. Furthermore, our study demonstrated that CPCs-EVs promoted matrix anabolism and inhibited inflammatory response at least partially via blocking STAT3 activation. In addition, liquid chromatography-tandem mass spectrometry analysis identified 991 proteins encapsulated in CPCs-EVs. By bioinformatics analysis, we showed that STAT3 regulatory proteins were enriched in CPCs-EVs and could be transported to chondrocytes. To promoting the protective function of CPCs-EVs in vivo, CPCs-EVs were modified with cationic peptide ε-polylysine-polyethylene-distearyl phosphatidylethanolamine (PPD) for surface charge reverse. In posttraumatic OA mice, our results showed PPD modified CPCs-EVs (PPD-EVs) effectively inhibited extracellular matrix catabolism and attenuated cartilage degeneration. Moreover, PPD-EVs down-regulated inflammatory factors expressions and reduced OA-related pain in OA mice. In ex-vivo cultured OA cartilage explants, PPD-EVs successfully promoted matrix anabolism and inhibited inflammation. Collectively, CPCs-EVs-based cell-free therapy is a promising strategy for OA treatment. [ABSTRACT FROM AUTHOR]

Background: We aimed to analyze the outcomes of intraarticular extra virgin olive oil (EVOO) injection on mechanically induced rabbit knee osteoarthritis (OA) by studying the morphological, histological, and radiological findings. Methods: The study was conducted on 32 New Zealand White rabbits. The randomly numbered subjects were divided into two main groups. The rabbits numbered 1 to 16 were selected to be the group to receive EVOO, and the remaining were selected into a control group. Both groups were separated into two subgroups for short-term (five weeks) and long-term (10 weeks) follow-up. Anterior cruciate ligament transection was applied on the left knees of all the rabbits via medial parapatellar arthrotomy to simulate knee instability. Immediately after the surgical procedure, 0.2 cc of EVOO was injected into the knee joint of rabbits numbered 1–16, and the control group received 0.2 cc of sterile saline. On the 14th day, long-term group subjects were administered another dose of 0.2 cc EVOO intraarticularly. Results: The gross morphological scores of the control group subjects were significantly different from the EVOO group for both short-term (p = 0,055) and long-term (p = 0,041) scores. In parallel, the MRI results of the EVOO subjects were significantly different from the control group for both short-term and long-term follow-up assessment scores (p = 0.017, p = 0.014, respectively). The Mankin scoring results showed that there were statistically significant differences between the EVOO and control group in the comparison of both total scores (p = 0.001 for short-term and p = 0.004 for long-term) and subgroup scoring, including macroscopic appearance, chondrocyte cell number, staining, and Tidemark integrity in both short-term (p = 0.005, p = 0.028, p = 0.001, p = 0.005, respectively) and long-term assessments (p = 0.002, p = 0.014, p < 0.001, p = 0. 200, respectively). Conclusions: We have observed promising outcomes of intra-articular application of extra virgin olive oil in the treatment of acute degenerative osteoarthritis in rabbit knees. Due to its potential cartilage restorative and regenerative effects, EVOO, when administered intra-articularly, may be a promising agent to consider for further research in the treatment of OA. [ABSTRACT FROM AUTHOR]

Objective: Interferon regulatory factor 1 (IRF1) is a transcriptional regulator conventionally associated with immunomodulation. Recent molecular analyses mapping DNA binding sites of IRF1 have suggested its potential function in DNA repair. However, the physiologic significance of this noncanonical function remains unexplored. Here, we investigated the role of IRF1 in osteoarthritis (OA), a condition marked by senescence and chronic joint inflammation. Methods: OA progression was examined in wild‐type and Irf1−/− mice using histologic assessments and microcomputed tomography analysis of whole‐joint OA manifestations and behavioral assessments of joint pain. An integrated analysis of assay for transposase‐accessible chromatin with sequencing and whole transcriptome data was conducted for the functional assessment of IRF1 in chondrocytes. The role of IRF1 in DNA repair and senescence was investigated by assaying γ‐H2AX foci and senescence‐associated beta‐galactosidase activity. Results: Our genome‐wide investigation of IRF1 footprinting in chondrocytes revealed its primary occupancies in the promoters of DNA repair genes without noticeable footprint patterns in those of interferon‐responsive genes. Chondrocytes lacking IRF1 accumulated irreversible DNA damage under oxidative stress, facilitating their entry into cellular senescence. IRF1 was down‐regulated in the cartilage of human and mouse OA. Although IRF1 overexpression did not elicit an inflammatory response in joints or affect OA development, genetic deletion of Irf1 caused enhanced chondrocyte senescence and exacerbated post‐traumatic OA in mice. Conclusion: IRF1 offers DNA damage surveillance in chondrocytes, protecting them from oxidative stress associated with OA risk factors. Our study provides a crucial and cautionary perspective that compromising IRF1 activity renders chondrocytes vulnerable to cellular senescence and promotes OA development. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is linked with increased incidence and severity of osteoarthritis. The purpose of this study was to determine the effect of extracellular glucose within the normal blood glucose and hyperglycemic range on catabolic enzyme production by chondrocytes isolated from osteoarthritic (OA) and macroscopically normal (MN) human cartilage under oxygenated (18.9% oxygen) and hypoxic (1% oxygen) conditions. OA and MN chondrocytes were maintained in 4, 6, 8, or 10 mM glucose for 24 h. Glucose consumption, GLUT1 glucose transporter levels, MMP13 and ADAMTS5 production, and levels of RUNX2, a transcriptional regulator of MMP13, ADAMTS5, and GLUT1, were assessed by enzyme‐linked assays, RT‐qPCR and/or western blot. Under oxygenated conditions, glucose consumption and GLUT1 protein levels were higher in OA but not MN chondrocytes in 10 mM glucose compared to 4 mM. Both RNA and protein levels of MMP13 and ADAMTS5 were also higher in OA but not MN chondrocytes in 10 mM compared to 4 mM glucose under oxygenated conditions. Expression of RUNX2 was overall lower in MN than OA chondrocytes and there was no consistent effect of extracellular glucose concentration on RUNX2 levels in MN chondrocytes. However, protein (but not RNA) levels of RUNX2 were elevated in OA chondrocytes maintained in 10 mM versus 4 mM glucose under oxygenated conditions. In contrast, neither RUNX2 levels or MMP13 or ADAMTS5 expression were increased in OA chondrocytes maintained in 10 mM compared to 4 mM glucose in hypoxia. Elevated extracellular glucose leads to increased glucose consumption and increased RUNX2 protein levels, promoting production of MMP13 and ADAMTS5 by OA chondrocytes in oxygenated but not hypoxic conditions. These findings suggest that hyperglycaemia may exacerbate chondrocyte‐mediated cartilage catabolism in the oxygenated superficial zone of cartilage in vivo in patients with undertreated type 2 diabetes, contributing to increased OA severity. [ABSTRACT FROM AUTHOR]

Securing high-quality cell sources is important in regenerative medicine. In this study, we developed a device that can accumulate autologous stem cells in the body. When small wire-assembled molds were embedded in the dorsal subcutaneous pouches of beagles for several weeks, collagen-based tissues with minimal inflammation formed inside the molds. At 3 weeks of embedding, the outer areas of the tissues were composed of immature type III collagen with large amounts of cells expressing SSEA3 or SSEA4 markers, in addition to growth factors such as HGF or VEGF. When separated from the tissues by collagenase treatment, approximately four million cells with a proportion of 70% CD90-positive and 20% SSEA3- or SSEA4-positive cells were recovered from the single mold. The cells could differentiate into bone or cartilage cells. The obtained cell-containing tissues are expected to have potential as therapeutic materials or cell sources in regenerative medicine. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a degenerative joint disease commonly found in elderly people and obese patients. Currently, OA treatments are determined based on their condition severity and a medical professional's advice. The aim of this study was to differentiate human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs) into chondrocytes for transplantation in OA-suffering guinea pigs. hWJ-MSCs were isolated using the explant culture method, and then, their proliferation, phenotypes, and differentiation ability were evaluated. Subsequently, hWJ-MSCs-derived chondrocytes were induced and characterized based on immunofluorescent staining, qPCR, and immunoblotting techniques. Then, early-OA-suffering guinea pigs were injected with hyaluronic acid (HA) containing either MSCs or 14-day-old hWJ-MSCs-derived chondrocytes. Results showed that hWJ-MSCs-derived chondrocytes expressed specific markers of chondrocytes including Aggrecan, type II collagen, and type X collagen proteins and β-catenin, Sox9, Runx2, Col2a1, Col10a1, and ACAN gene expression markers. Administration of HA plus hWJ-MSCs-derived chondrocytes (HA-CHON) produced a better recovery rate of degenerative cartilages than HA plus MSCs or only HA. Histological assessments demonstrated no significant difference in Mankin's scores of recovered cartilages between HA-CHON-treated guinea pigs and normal articular cartilage guinea pigs. Transplantation of hWJ-MSCs-derived chondrocytes was more effective than undifferentiated hWJ-MSCs or hyaluronic acid for OA treatment in guinea pigs. This study provides a promising treatment to be used in early OA patients to promote recovery and prevent disease progression to severe osteoarthritis. [ABSTRACT FROM AUTHOR]

Joint-resident chondrogenic precursor cells have become a significant therapeutic option due to the lack of regenerative capacity in articular cartilage. Progenitor cells are located in the superficial zone of the articular cartilage, producing lubricin/Prg4 to decrease friction of cartilage surfaces during joint movement. Prg4-positive progenitors are crucial in maintaining the joint's structure and functionality. The disappearance of progenitor cells leads to changes in articular hyaline cartilage over time, subchondral bone abnormalities, and the formation of ectopic ossification. Genetic labeling cell technology has been the main tool used to characterize Prg4-expressing progenitor cells of articular cartilage in vivo through drug injection at different time points. This technology allows for the determination of the origin of progenitor cells and the tracking of their progeny during joint development and cartilage damage. We endeavored to highlight the currently known information about the Prg4-producing cell population in the joint to underline the significance of the role of these cells in the development of articular cartilage and its homeostasis. This review focuses on superficial progenitors in the joint, how they contribute to postnatal articular cartilage formation, their capacity for regeneration, and the consequences of Prg4 deficiency in these cells. We have accumulated information about the Prg4+ cell population of articular cartilage obtained through various elegantly designed experiments using transgenic technologies to identify potential opportunities for further research. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterised by the formation of a hyperplastic pannus, as well as cartilage and bone damage. The pathogenesis of RA is complex and involves broad interactions between various cells present in the inflamed synovium, including fibroblast-like synoviocytes (FLSs), macrophages, and T cells, among others. Under inflammatory conditions, these cells are activated, further enhancing inflammatory responses and angiogenesis and promoting bone and cartilage degradation. Novel treatment methods for RA are greatly needed, and mesenchymal stromal cells (MSCs) have been suggested as a promising new regenerative and immunomodulatory treatment. In this paper, we present the interactions between MSCs and RA-FLSs, and macrophages and T cells, and summarise studies examining the use of MSCs in preclinical and clinical RA studies. [ABSTRACT FROM AUTHOR]

Introduction: Osteoarthritis (OA) is an inflammatory disorder of synovial joints which is mainly treated with therapeutic agents showing side effects associated with the gastrointestinal (GI) and metabolic system. Consequently, there is urgent need for a potent, safe and novel agent for treating OA and related disorders. Enoxolone is a pentacyclic triterpenoid obtained from the herb liquorice. Based on earlier findings, we postulated that enoxolone may produce chondroprotective activity by exerting anti-inflammatory, anti-catabolic and oxidative stress-decreasing effects. Material and methods: The chondrocytes were extracted from the femoral head articular cartilage of healthy rats. Immunofluorescence staining was done for identification of chondrocytes. Cell viability and proliferation studies were done using Cell Counting Kit-8. Apoptotic cells were identified by TUNEL assay and flow cytometry analysis. Autophagy was assessed by monodansylcadaverine assay. Western blot analysis was done for expression of proteins. Results: In the present study we investigated the protective effect of enoxolone on interleukin 1β (IL-1β) treated Iry chondrocytes in vitro. Treatment with IL-1β resulted in a significant reduction in cell viability of cells in increasing dose and time. Treatment with enoxolone along with IL-1β caused a significant decrease in growth inhibition. Also, enoxolone inhibited the IL-1β mediated apoptosis and activation of caspase-3 in cells. We also observed that enoxolone elevated the levels of p-ERK1/2, light chain 3 (LC3)-II and Beclin-1 (autophagy markers) in chondrocytes. The expression of (LC3)-II and Beclin-1 was decreased when the cells were treated with U0126 (ERK1/2 inhibitor). Conclusions: Our findings demonstrate that enoxolone could suppress inflammatory signaling and apoptosis via the ERK1/2 pathway in chondrocytes. [ABSTRACT FROM AUTHOR]

Objective: To explore the efficacy and potential mechanism of Fengshi Gutong capsule (FSGTC) in osteoarthritis (OA) inflammation. Methods: The impact of FSGTC on laboratory indicators of OA patients was explored using data mining technology and association rule analysis. Then, the OA cell model was constructed by inducing chondrocytes (CHs) with interleukin‐1β (IL‐1β). In the presence of FSGTC intervention, the regulatory mechanism of PACER/COX2/PGE2 in OA‐CH viability and inflammatory responses was evaluated. Results: Retrospective data mining showed that FSGTC effectively reduced inflammation indexes (ESR, HCRP) of OA patients. Cell experiments showed that LncRNA PACER (PACER) silencing inhibited the proliferation activity of OA‐CHs, increased the level of COX2 protein, elevated the levels of PGE2, TNF‐α, and IL‐1β, and decreased the levels of IL‐4 and IL‐10 (p <.01). On the contrary, FSGTC‐containing serum reversed the effect of PACER silencing on OA‐CHs (p <.01). After the addition of COX2 pathway inhibitor, the proliferation activity of OA‐CHs was enhanced; the levels of PGE2, TNF‐α, and IL‐1β were decreased while the levels of IL‐4 and IL‐10 were increased (p <.01). Conclusion: FSGTC inhibits IL‐1β‐induced inflammation in CHs and ameliorates OA by upregulating PACER and downregulating COX2/PGE2. [ABSTRACT FROM AUTHOR]

Aims: Evidence is accumulating of the therapeutic benefits of mesenchymal stromal cells (MSCs) in diabetes‐related conditions. We have identified a novel population of stromal cells within islets of Langerhans – islet stellate cells (ISCs) – which have a similar morphology to MSCs. In this study we characterize mouse ISCs and compare their morphology and function to MSCs to determine whether ISCs may also have therapeutic potential in diabetes. Methods: ISCs isolated from mouse islets were compared to mouse bone marrow MSCs by analysis of cell morphology; expression of cell‐surface markers and extracellular matrix (ECM) components; proliferation; apoptosis; paracrine activity; and differentiation into adipocytes, chondrocytes and osteocytes. We also assessed the effects of co‐culture with ISCs or MSCs on the insulin secretory capacity of islet beta cells. Results: Although morphological similar, ISCs were functionally distinct from MSCs. Thus, ISCs were less proliferative and more apoptotic; they had different expression levels of important paracrine factors; and they were less efficient at differentiation down multiple lineages. Co‐culture of mouse islets with ISCs enhanced glucose induced insulin secretion more effectively than co‐culture with MSCs. Conclusions: ISCs are a specific sub‐type of islet‐derived stromal cells that possess biological behaviors distinct from MSCs. The enhanced beneficial effects of ISCs on islet beta cell function suggests that they may offer a therapeutic target for enhancing beta cell functional survival in diabetes. [ABSTRACT FROM AUTHOR]

We describe here a case of canine mammary benign mixed tumor with sebaceous metaplasia in the right fifth mammary gland of an eight-year-old, intact female Poodle dog. Grossly, the mass was firm with off-white, poorly lobulated cut surfaces. Histologically, the luminal epithelial cells and myoepithelial cells proliferated with cartilage formation and focal squamous metaplasia. Moreover, a large number of nests of various sizes, which were filled with foamy cells in the center and associated with basaloid reserve-like cells in the periphery, showed sebaceous gland-like structures. Immunohistochemically, myoepithelial cells and reserve-like cells in the metaplastic sebaceous gland-like structures were CK14, α-smooth muscle actin (α-SMA) and p63 positive, suggesting a possibility that these two components may have a common cell of origin. [ABSTRACT FROM AUTHOR]

Recent research has identified that miR-539-3p impedes chondrogenic differentiation, yet its specific role and underlying mechanisms in childhood-onset osteoarthritis (OA) remain unclear. This study found that miR-539-3p levels were considerably lower in cartilage samples derived from childhood-onset OA patients compared to the control group. Enhancing miR-539-3p expression or suppressing RUNX2 expression notably reduced apoptosis, inflammation, and extracellular matrix (ECM) degradation in OA chondrocytes. In contrast, reducing miR-539-3p or increasing RUNX2 had the opposite effects. RUNX2 was confirmed as a direct target of miR-539-3p. Further experiments demonstrated that miR-539-3p targeting RUNX2 effectively lessened apoptosis, inflammation, and ECM degradation in OA chondrocytes, accompanied by changes in key molecular markers like reduced caspase-3 and matrix metallopeptidase 13 (MMP-13) levels, and increased B-cell lymphoma 2 (Bcl-2) and collagen type X alpha 1 chain (COL2A1). This study underscores the pivotal role of miR-539-3p in alleviating inflammation and ECM degradation in childhood-onset OA through targeting RUNX2, offering new insights for potential therapeutic strategies against this disease. [ABSTRACT FROM AUTHOR]

Objectives: This study investigated a novel strategy for improving regenerative cartilage outcomes. It combines fractional laser treatment with the implantation of neocartilage generated from autologous dynamic Self-Regenerating Cartilage (dSRC). Methods: dSRC was generated in vitro from harvested autologous swine chondrocytes. Culture was performed for 2, 4, 8, 10, and 12 weeks to study matrix maturation. Matrix formation and implant integration were also studied in vitro in swine cartilage discs using dSRC or cultured chondrocytes injected into CO2 laser-ablated or mechanically punched holes. Cartilage discs were cultured for up to 8 weeks, harvested, and evaluated histologically and immunohistochemically. Results: The dSRC matrix was injectable by week 2, and matrices grew larger and more solid with time, generating a contiguous neocartilage matrix by week 8. Hypercellular density in dSRC at week 2 decreased over time and approached that of native cartilage by week 8. All dSRC groups exhibited high glycosaminoglycan (GAG) production, and immunohistochemical staining confirmed that the matrix was typical of normal hyaline cartilage, being rich in collagen type II. After 8 weeks in cartilage lesions in vitro, dSRC constructs generated a contiguous cartilage matrix, while isolated cultured chondrocytes exhibited only a sparse pericellular matrix. dSRC-treated lesions exhibited high GAG production compared to those treated with isolated chondrocytes. Conclusions: Isolated dSRC exhibits hyaline cartilage formation, matures over time, and generates contiguous articular cartilage matrix in fractional laser-created microenvironments in vitro, being well integrated with native cartilage. [ABSTRACT FROM AUTHOR]

Objectives: We genetically modified dedifferentiated chondrocytes (DCs) using lentiviral vectors and adenoviral vectors encoding TGF-β3 (referred to as transgenic groups below) and encapsulated these DCs in the microcavitary hydrogel and investigated the combinational effect on redifferentiation of the genetically manipulated DCs. Results: The Cell Counting Kit-8 data indicated that both transgenic groups exhibited significantly higher cell viability in the first week but inferior cell viability in the subsequent timepoints compared with those of the control group. Real-time polymerase chain reaction and western blot analysis results demonstrated that both transgenic groups had a better effect on redifferentiation to some extent, as evidenced by higher expression levels of chondrogenic genes, suggesting the validity of combination with transgenic DCs and the microcavitary hydrogel on redifferentiation. Although transgenic DCs with adenoviral vectors presented a superior extent of redifferentiation, they also expressed greater levels of the hypertrophic gene type X collagen. It is still worth further exploring how to deliver TGF-β3 more efficiently and optimizing the appropriate parameters, including concentration and duration. Conclusions: The results demonstrated the better redifferentiation effect of DCs with the combinational use of transgenic TGF-β3 and a microcavitary alginate hydrogel and implied that DCs would be alternative seed cells for cartilage tissue engineering due to their easily achieved sufficient cell amounts through multiple passages and great potential to redifferentiate to produce cartilaginous extracellular matrix. [ABSTRACT FROM AUTHOR]

Microtia is a congenital auricle dysplasia with a high incidence and tissue engineering technology provides a promising strategy to reconstruct auricles. We previously described that the engineered cartilage constructed from microtia chondrocytes exhibited inferior levels of biochemical and biomechanical properties, which was proposed to be resulted of the decreased migration ability of microtia chondrocytes. In the current study, we found that Rho GTPase members were deficient in microtia chondrocytes. By overexpressing RhoA, Rac1, and CDC42, respectively, we further demonstrated that RhoA took great responsibility for the decreased migration ability of microtia chondrocytes. Moreover, we constructed PGA/PLA scaffold-based cartilages to verify the chondrogenic ability of RhoA overexpressed microtia chondrocytes, and the results showed that overexpressing RhoA was of limited help in improving the quality of microtia chondrocyte engineered cartilage. However, coculture of adipose-derived stem cells (ADSCs) significantly improved the biochemical and biomechanical properties of engineered cartilage. Especially, coculture of RhoA overexpressed microtia chondrocytes and ADSCs produced an excellent effect on the wet weight, cartilage-specific extracellular matrix, and biomechanical property of engineered cartilage. Furthermore, we presented that coculture of RhoA overexpressed microtia chondrocytes and ADSCs combined with human ear-shaped PGA/PLA scaffold and titanium alloy stent fabricated by CAD/CAM and 3D printing technology effectively constructed and maintained auricle structure in vivo. Collectively, our results provide evidence for the essential role of RhoA in microtia chondrocytes and a developed strategy for the construction of patient-specific tissue-engineered auricular cartilage. [ABSTRACT FROM AUTHOR]

Renal cell carcinoma (RCC) is a significant cause of mortality worldwide. To date, many atypical metastatic sites have been observed and reported in patients with RCC. However, to the best of our knowledge, there have been no reported cases of thyroid cartilage metastasis in the context of RCC metastasis. Herein, we present the case of a 68-year-old man who developed left arm pain that led to an RCC diagnosis. First, evaluation by pan-computed tomography (CT) denoted right kidney RCC and identified left humeral metastasis. Subsequently, 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) was performed after right nephrectomy and left humeral lesion excision and fixation. Interestingly, few intramedullary hypermetabolic lesions were observed in addition to a single intensely hypermetabolic thyroid cartilage lesion indicative of oligometastases. This case underscores the importance of 18F-FDG PET/CT in the evaluation of RCC disease for baseline staging and beyond. [ABSTRACT FROM AUTHOR]

Efferocytosis, an intrinsic regulatory mechanism to eliminate apoptotic cells, will be suppressed due to the delayed apoptosis process in aging‐related diseases, such as osteoarthritis (OA). In this study, cartilage lesion‐localized hydrogel microspheres are developed to remodel the in situ efferocytosis to reverse cartilage senescence and recruit endogenous stem cells to accelerate cartilage repair. Specifically, aldehyde‐ and methacrylic anhydride (MA)‐modified hyaluronic acid hydrogel microspheres (AHM), loaded with pro‐apoptotic liposomes (liposomes encapsulating ABT263, A‐Lipo) and PDGF‐BB, namely A‐Lipo/PAHM, are prepared by microfluidic and photo‐cross‐linking techniques. By a degraded porcine cartilage explant OA model, the in situ cartilage lesion location experiment illustrated that aldehyde‐functionalized microspheres promote affinity for degraded cartilage. In vitro data showed that A‐Lipo induced apoptosis of senescent chondrocytes (Sn‐chondrocytes), which can then be phagocytosed by the efferocytosis of macrophages, and remodeling efferocytosis facilitated the protection of normal chondrocytes and maintained the chondrogenic differentiation capacity of MSCs. In vivo experiments confirmed that hydrogel microspheres localized to cartilage lesion reversed cartilage senescence and promoted cartilage repair in OA. It is believed this in situ efferocytosis remodeling strategy can be of great significance for tissue regeneration in aging‐related diseases. [ABSTRACT FROM AUTHOR]

In various biological systems, analyzing how cell behaviors are coordinated over time would enable a deeper understanding of tissue-scale response to physiologic or superphysiologic stimuli. Such data is necessary for establishing both normal tissue function and the sequence of events after injury that lead to chronic disease. However, collecting and analyzing these large datasets presents a challenge—such systems are time-consuming to process, and the overwhelming scale of data makes it difficult to parse overall behaviors. This problem calls for an analysis technique that can quickly provide an overview of the groups present in the entire system and also produce meaningful categorization of cell behaviors. Here, we demonstrate the application of an unsupervised method—the Variational Autoencoder (VAE)—to learn the features of cells in cartilage tissue after impact-induced injury and identify meaningful clusters of chondrocyte behavior. This technique quickly generated new insights into the spatial distribution of specific cell behavior phenotypes and connected specific peracute calcium signaling timeseries with long term cellular outcomes, demonstrating the value of the VAE technique. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is the most prevalent form of arthritis, characterized by a complex pathogenesis. One of the key factors contributing to its development is the apoptosis of chondrocytes triggered by oxidative stress. Involvement of peroxisome proliferator-activated receptor gamma (PPARγ) has been reported in the regulation of oxidative stress. However, there remains unclear mechanisms that through which PPARγ influences the pathogenesis of OA. The present study aims to delve into the role of PPARγ in chondrocytes apoptosis induced by oxidative stress in the context of OA. Primary human chondrocytes, both relatively normal and OA, were isolated and cultured for the following study. Various assessments were performed, including measurements of cell proliferation, viability and cytotoxicity. Additionally, we examined cell apoptosis, levels of reactive oxygen species (ROS), nitric oxide (NO), mitochondrial membrane potential (MMP) and cytochrome C release. We also evaluated the expression of related genes and proteins, such as collagen type II (Col2a1), aggrecan, inducible nitric oxide synthase (iNOS), caspase-9, caspase-3 and PPARγ. Compared with relatively normal cartilage, the expression of PPARγ in OA cartilage was down-regulated. The proliferation of OA chondrocytes decreased, accompanied by an increase in the apoptosis rate. Down-regulation of PPARγ expression in OA chondrocytes coincided with an up-regulation of iNOS expression, leading to increased secretion of NO, endogenous ROS production, and decrease of MMP levels. Furthermore, we observed the release of cytochrome C, elevated caspase-9 and caspase-3 activities, and reduction of the components of extracellular matrix (ECM) Col2a1 and aggrecan. Accordingly, utilization of GW1929 (PPARγ Agonists) or Z-DEVD-FMK (caspase-3 inhibitor) can protect chondrocytes from mitochondrial-related apoptosis and alleviate the progression of OA. During the progression of OA, excessive oxidative stress in chondrocytes leads to apoptosis and ECM degradation. Activation of PPARγ can postpone OA by down-regulating caspase-3-dependent mitochondrial apoptosis pathway. [ABSTRACT FROM AUTHOR]

Osteoarthritis is the most prevalent type of degenerative arthritis. It is characterized by persistent pain, joint dysfunction, and physical disability. Pain relief and inflammation control are prioritised during osteoarthritis treatment Mume Fructus (Omae), a fumigated product of the Prunus mume fruit, is used as a traditional medicine in several Asian countries. However, its therapeutic mechanism of action and effects on osteoarthritis and articular chondrocytes remain unknown. In this study, we analyzed the anti-osteoarthritis and articular regenerative effects of Mume Fructus extract on rat chondrocytes. Mume Fructus treatment reduced the interleukin-1β-induced expression of matrix metalloproteinase 3, matrix metalloproteinase 13, and a disintegrin and metalloproteinase with thrombospondin type 1 motifs 5. Additionally, it enhanced collagen type II alpha 1 chain and aggrecan accumulation in rat chondrocytes. Furthermore, Mume Fructus treatment regulated the inflammatory cytokine levels, mitogen-activated protein kinase phosphorylation, and nuclear factor-kappa B activation. Overall, our results demonstrated that Mume Fructus inhibits osteoarthritis progression by inhibiting the nuclear factor-kappa B and mitogen-activated protein kinase pathways to reduce the levels of inflammatory cytokines and prevent cartilage degeneration. Therefore, Mume Fructus may be a potential therapeutic option for osteoarthritis. [ABSTRACT FROM AUTHOR]

Osteoarthritis is a morbid and costly condition affecting an increasingly larger segment of the population with a lack of effective treatment options. The pathophysiology of osteoarthritis is poorly understood; cell senescence is deemed to be contributory. Senescence of joint tissues particularly chondrocytes, synoviocytes (fibroblasts), and adipocytes is implicated in the pathogenesis through the production of senescence-associated proteins. Senescence-associated proteins are cytokines, matrix degradation enzymes, and chemokines that contribute to an inflammatory milieu which leads to the propagation of senescence. Senescence-modifying therapies include senolytics which eliminate senescent cells and senomorphics which inhibit the senescence-associated protein production of senescent cells. Treatments being investigated include novel agents as well as agents previously used in other conditions in rheumatology and other fields. [ABSTRACT FROM AUTHOR]

Recent studies have found that chondrocytes not only represent the cells targeted by rheumatoid arthritis （RA） but may also themselves induce the disease. This dual role indicates the significance of chondrocytes in the pathology of RA. This article summarizes the important roles played by chondrocytes in RA, providing a reference for the pathogenesis and treatment of RA. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a long-term, persistent joint disorder characterized by bone and cartilage degradation, resulting in tightness, pain, and restricted movement. Current attempts in cartilage regeneration are cell-based therapies using stem cells. Multipotent stem cells, such as mesenchymal stem cells (MSCs), and pluripotent stem cells, such as embryonic stem cells (ESCs), have been used to regenerate cartilage. However, since the discovery of human-induced pluripotent stem cells (hiPSCs) in 2007, it was seen as a potential source for regenerative chondrogenic therapy as it overcomes the ethical issues surrounding the use of ESCs and the immunological and differentiation limitations of MSCs. This literature review focuses on chondrogenic differentiation and 3D bioprinting technologies using hiPSCS, suggesting them as a viable source for successful tissue engineering. Methods: A literature search was conducted using scientific search engines, PubMed, MEDLINE, and Google Scholar databases with the terms 'Cartilage tissue engineering' and 'stem cells' to retrieve published literature on chondrogenic differentiation and tissue engineering using MSCs, ESCs, and hiPSCs. Results: hiPSCs may provide an effective and autologous treatment for focal chondral lesions, though further research is needed to explore the potential of such technologies. Conclusions: This review has provided a comprehensive overview of these technologies and the potential applications for hiPSCs in regenerative medicine. [ABSTRACT FROM AUTHOR]

Developmental dysplasia of the hip (DDH) is a developmental disorder characterized by acetabular dysplasia leading to early osteoarthritis. This study examines the role of endoplasmic reticulum stress (ERS) in chondrocyte apoptosis and cartilage degeneration within a DDH model. In the rat model of DDH, created using a swaddling technique, significant deformities in the femoral head and acetabulum were observed, alongside an upregulation of matrix metalloproteinase‐13 in acetabular cartilage. We also noted increased levels of apoptosis and ERS‐related factors in the acetabular cartilage of DDH models. Additionally, rat chondrocytes exposed to high‐magnitude cyclic tensile strain (CTS, 1 Hz, 10% equibiaxial strain) in vitro exhibited elevated ERS and increased apoptosis. Importantly, treatment with the ERS inhibitor 4‐phenylbutyric acid effectively suppressed apoptosis induced by CTS in chondrocytes. Our findings suggest that ERS contributes to the upregulation of apoptosis‐related factors in chondrocytes within the DDH model, indicating the potential of ERS modulation as a therapeutic approach for DDH‐related cartilage degeneration. [ABSTRACT FROM AUTHOR]

Objective: To investigate and explain the beneficial effects of local intra‐articular injection of Salubrinal on temporomandibular joint osteoarthritis (TMJOA) using a rabbit model of anterior disc displacement (ADD). Methods: Rabbits were divided and subjected to surgical ADD. Salubrinal was administered by intra‐articular injection in the TMJ every other day for 2 and 4 weeks after operation. Histological examination and TUNEL staining were then performed. Immunohistochemistry, quantitative real‐time PCR, and Western blot analysis were employed to evaluate the expression of endoplasmic reticulum (ER) stress‐related markers, catabolic factors, extracellular matrix proteins, inflammatory factors, and nuclear factor‐kappa B (NF‐κB) activation. Results: In the ADD groups, we found that Salubrinal partly reversed condylar cartilage deterioration according to the histological analysis. Salubrinal reduced chondrocytes apoptosis while increased matrix components including Collagen II and Aggrecan. Meanwhile, Salubrinal downregulated the catabolic expression of MMP13, ADAMTS5, VEGF, TNF‐α, and IL‐1β. We also observed that Salubrinal inhibited ER stress activation by reducing the expression of GRP78, CHOP, ATF4, and Caspase‐12. Additionally, Salubrinal suppressed the phosphorylation of NF‐κB. Conclusion: These results indicate that Salubrinal alleviates cartilage degradation following ADD, suggesting that intra‐articular injection of Salubrinal is a potential therapeutic approach for preventing TMJOA. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the role of Piezo1 in the malocclusion‐induced osteoarthritic cartilage of the temporomandibular joint. Methods: A temporomandibular joint osteoarthritis model was established using a unilateral anterior crossbite in vivo, and cartilage degeneration and Piezo1 expression were observed by histological and immunohistochemical staining. ATDC5 cells were loaded with 24 dyn/cm2 fluid flow shear stress using the Flexcell device in vitro and expression and function of Piezo1 were evaluated. After identifying the function of Piezo1 in YAP translocation under FFSS conditions, the influence of Piezo1 and YAP on metabolism‐related enzymes under FFSS was detected through a real‐time polymerase chain reaction analysis and western blotting. A UAC‐TMJ injection model was established to observe the therapeutic effect of intra‐articular injection of a Piezo1 inhibitor on osteoarthritic cartilage matrix loss. Results: Piezo1 was overexpressed in the osteoarthritic cartilage and cultured chondrocytes under shear stress. Piezo1 Silencing inhibited the nuclear translocation of YAP and subsequently downregulated the expression of MMP13 and ADAMTS5. Intra‐articular injection of the Piezo1 inhibitor, GsMTx4, could ameliorate proteoglycan degradation in malocclusion‐induced TMJOA and suppressed MMP13 and ADAMTS5 expression. Conclusions: Our results revealed that the activation of Piezo1 promotes mechanical‐induced cartilage degradation through the YAP‐MMP13/ADAMTS5 signaling pathway. [ABSTRACT FROM AUTHOR]

Background: Physiological 0.9% saline is commonly used as an irrigation fluid in modern arthroscopy. There is a growing body of evidence that a hyperosmolar saline solution has chondroprotective effects, especially if iatrogenic injury occurs. Purpose: To (1) corroborate the superiority of a hyperosmolar saline solution regarding chondrocyte survival after mechanical injury and (2) observe the modulatory response of articular cartilage to osmotic stress and injury. Study Design: Controlled laboratory study. Methods: Osteochondral explants were isolated from bovine stifle joints and exposed to either 0.9% saline (308 mOsm) or hyperosmolar saline (600 mOsm) and then damaged with a sharp dermatome blade to attain a confined full-thickness cartilage injury site, incubated in the same fluids for another 3 hours, and transferred to chondropermissive medium for further culture for 1 week. Chondrocyte survival was assessed by confocal imaging, while the cellular response was evaluated over 1 week by relative gene expression for apoptotic and inflammatory markers and mediator release into the medium. Results: The full-thickness cartilage cut resulted in a confined zone of cell death that mainly affected superficial zone chondrocytes. Injured samples that were exposed to hyperosmolar saline showed less expansion of cell death in both the axial (P <.007) and the coronal (P <.004) plane. There was no progression of cell death during the following week of culture. Histological assessment revealed an intact cartilage matrix and normal chondrocyte morphology. Inflammatory and proapoptotic genes were upregulated on the first days postexposure with a notable downregulation toward day 7. Mediator release into the medium was concentrated on day 3. Conclusion: This in vitro cartilage injury model provides further evidence for the chondroprotective effect of a hyperosmolar saline irrigation fluid, as well as novel data on the capability of articular cartilage to quickly regain joint homeostasis after osmotic stress and injury. Clinical Relevance: Raising the osmolarity of an irrigating solution may be a simple and safe strategy to protect articular cartilage during arthroscopic surgery. [ABSTRACT FROM AUTHOR]

La matrice extracellulaire a longtemps été considérée comme un « simple » tissu de soutien des cellules, produisant des forces de tension permettant leur adhésion et les protégeant contre le stress mécanique, en particulier dans le cartilage. Pourtant, un grand nombre des constituants matriciels subissent des modifications structurales très dynamiques, impactant de façon notable les propriétés qu'ils confèrent à l'environnement mais aussi aux cellules. C'est le cas des glycosaminoglycannes, polysaccharides linéaires sulfatés et complexes, présents dans toutes les matrices, mais particulièrement enrichis dans le cartilage, sous la forme de chondroïtines sulfates et d'acide hyaluronique. L'arthrose est encore actuellement principalement identifiée comme une pathologie dégénérative de la matrice cartilagineuse liée à l'usure de l'âge. Mais d'autres phénotypes sont à présent caractérisés et permettent de mieux comprendre les processus physiopathologiques complexes de cette pathologie qui affectent l'ensemble des tissus de l'articulation. Alors que les traitements en cours, visant à combler les déficits en composés matriciels ou à bloquer les activités cataboliques des chondrocytes, ne paraissent plus suffisants pour réparer le cartilage, nous reviendrons dans cet article à la source « glycanique » des composés de la matrice cartilagineuse et à leur rôle dans les processus physiopathologiques de l'arthrose, pour identifier de nouvelles voies de recherches et produits thérapeutiques en devenir. The extracellular matrix has long been considered as a "simple" tissue supporting cells, producing tension forces allowing their adhesion and protecting them against mechanical stress, particularly in cartilage. However, a large number of matrix components undergo very dynamic structural modifications, significantly impacting the properties they confer to the environment but also to cells. This is the case for glycosaminoglycans, linear sulfated and complex polysaccharides, present in all matrices, but particularly enriched in cartilage, in the form of chondroitin sulfates and hyaluronic acid. Osteoarthritis is still mainly identified as a degenerative pathology of the cartilaginous matrix linked to the wear and tear of age. But other phenotypes are now characterized and provide a better understanding of the complex pathophysiological processes of this pathology which affect all joint tissues. Current treatments aimed at making up for deficiencies in matrix compounds or blocking the catabolic activities of chondrocytes, but no longer appear sufficient to repair cartilage. In this context, we will return to the "glycanic" source of the cartilaginous matrix and the role of these complex sugars in the pathophysiological processes of osteoarthritis, to identify new avenues of research and future therapeutic products. [ABSTRACT FROM AUTHOR]