Human Chondrocyte Cultures Research Articles

SAT0443 In Vitro Effects of Canakinumab on Human Osteoarthritic Chondrocytes

BackgroundCanakinumab is a human IgGκ monoclonal antibody targeting Interleukin (IL)-1β; its action involves the neutralization of the signaling of IL-1β, the most important cytokine in the pathogenesis of Osteoartrhitis (OA)....

A cell adhesion molecule (Ig‐SF/hemolin) from caterpillar regulates cell survival and induces extracellular matrix components in human osteoarthritic chondrocytes (LB528)

Background: Losac is a hemolin from Lonomia obliqua caterpillar that promotes blood coagulation through proteolytic activation of factor X. In HUVECs, Losac increased cell proliferation and inhibited the apoptosis induced by starvation. Additionally, we have observed the cytoprotective effect of rLosac in other cell types, such as neurons and fibroblasts. Recombinant Losac (rLosac) was obtained from bacteria system. This report aims to investigate the potential of rLosac as a chondroprotective agent in human articular chondrocytes and to analyze its capacity to stimulate the production of extracellular matrix molecules and to reduce senescence. Methods: Primary cultures of human chondrocytes were prepared from cartilage of osteoarthritic knee joints obtained from 4 donors (age range: 68‐83) undergoing total knee replacement surgery. The study was carried out in full accordance with local ethics guidelines, and cartilage samples were collected after obtaining written informed consent of the donors. Chondrocytes were treated with rLosac and several parameters were measured: specific senescence‐associated beta‐galactosidase activity, cell viability by the MTT assay, production of extracellular matrix molecules by western blot and immunofluorescence microscopy, and cell cycle by flow cytometry. Results: rLosac was found to be an effective anti‐apoptotic agent, as evidenced by the strong inhibition of cellular death. The cytoprotective effect was observed specially starting from 48h and 72h of treatment, even in the presence of IL‐1β (50 ng/ml) to induce an inflammatory environment. Moreover, rLosac was able to reduce the expression of β‐galactosidade after 6 days of treatment. In addition, rLosac stimulated the production of collagen type I, laminin and fibronectin, and to increase the expression of the receptor of collagen type I, and to decrease the expression of IL‐1β. Conclusion: rLosac has the potential to become a therapeutic agent for protection of articular cartilage against the progression of osteoarthritic diseases.Grant Funding Source: CETICs/FAPESP (Processo No. 2013/07467‐1), CAPES, INCTTox‐CNPq

Efficacy and safety of ginger in osteoarthritis patients: a systematic review and meta-analysis of randomized placebo-controlled trials

Efficacy and safety of ginger in osteoarthritis patients: a systematic review and meta-analysis of randomized placebo-controlled trials

A5.1 Culture OF human chondrocytes in high glucose induces inflammatory markers and impairs autophagy

Background and ObjectivesAccumulating evidence indicates that Diabetes Mellitus is an independent risk factor for severe osteoarthritis (OA). Understanding the mechanisms involved is essential for designing preventive strategies and targeted therapies...

Effect of oxygen tension on tissue-engineered human nasal septal chondrocytes.

Tissue-engineered nasal septal cartilage may provide a source of autologous tissue for repair of craniofacial defects. Although advances have been made in manipulating the chondrocyte culture environment for production of neocartilage, consensus on the best oxygen tension for in vitro growth of tissue-engineered cartilage has not been reached. The objective of this study was to determine whether in vitro oxygen tension influences chondrocyte expansion and redifferentiation. Proliferation of chondrocytes from 12 patients expanded in monolayer under hypoxic (5% or 10%) or normoxic (21%) oxygen tension was compared over 14 days of culture. The highest performing oxygen level was used for further expansion of the monolayer cultures. At confluency, chondrocytes were redifferentiated by encapsulation in alginate beads and cultured for 14 days under hypoxic (5 or 10%) or normoxic (21%) oxygen tension. Biochemical and histological properties were evaluated. Chondrocyte proliferation in monolayer and redifferentiation in alginate beads were supported by all oxygen tensions tested. Chondrocytes in monolayer culture had increased proliferation at normoxic oxygen tension (p = 0.06), as well as greater accumulation of glycosaminoglycan (GAG) during chondrocyte redifferentiation (p < 0.05). Chondrocytes released from beads cultured under all three oxygen levels showed robust accumulation of GAG and type II collagen with a lower degree of type I collagen immunoreactivity. Finally, formation of chondrocyte clusters was associated with decreasing oxygen tension (p < 0.05). Expansion of human septal chondrocytes in monolayer culture was greatest at normoxic oxygen tension. Both normoxic and hypoxic culture of human septal chondrocytes embedded in alginate beads supported robust extracellular matrix deposition. However, GAG accumulation was significantly enhanced under normoxic culture conditions. Chondrocyte cluster formation was associated with hypoxic oxygen tension.

Induction of nerve growth factor expression and release by mechanical and inflammatory stimuli in chondrocytes: possible involvement in osteoarthritis pain

IntroductionNerve growth factor (NGF) level is increased in osteoarthritis (OA) joints and is involved in pain associated with OA. Stimuli responsible for NGF stimulation in chondrocytes are unknown. We investigated whether mechanical stress and proinflammatory cytokines may influence NGF synthesis by chondrocytes.MethodsPrimary cultures of human OA chondrocytes, newborn mouse articular chondrocytes or cartilage explants were stimulated by increasing amounts of IL-1β, prostaglandin E2 (PGE2), visfatin/nicotinamide phosphoribosyltransferase (NAMPT) or by cyclic mechanical compression (0.5 Hz, 1 MPa). Before stimulation, chondrocytes were pretreated with indomethacin, Apo866, a specific inhibitor of NAMPT enzymatic activity, or transfected by siRNA targeting visfatin/NAMPT. mRNA NGF levels were assessed by real-time quantitative PCR and NGF released into media was determined by ELISA.ResultsUnstimulated human and mouse articular chondrocytes expressed low levels of NGF (19.2 ± 8.7 pg/mL, 13.5 ± 1.0 pg/mL and 4.4 ± 0.8 pg/mL/mg tissue for human and mouse articular chondrocytes and costal explants, respectively). Mechanical stress induced NGF release in conditioned media. When stimulated by IL-1β or visfatin/NAMPT, a proinflammatory adipokine produced by chondocytes in response to IL-1β, a dose-dependent increase in NGF mRNA expression and NGF release in both human and mouse chondrocyte conditioned media was observed. Visfatin/NAMPT is also an intracellular enzyme acting as the rate-limiting enzyme of the generation of NAD. The expression of NGF induced by visfatin/NAMPT was inhibited by Apo866, whereas IL-1β-mediated NGF expression was not modified by siRNA targeting visfatin/NAMPT. Interestingly, PGE2, which is produced by chondrocytes in response to IL-1β and visfatin/NAMPT, did not stimulate NGF production. Consistently, indomethacin, a cyclooxygenase inhibitor, did not counteract IL-1β-induced NGF production.ConclusionsThese results show that mechanical stress, IL-1β and extracellular visfatin/NAMPT, all stimulated the expression and release of NGF by chondrocytes and thus suggest that the overexpression of visfatin/NAMPT and IL-1β in the OA joint and the increased mechanical loading of cartilage may mediate OA pain via the stimulation of NGF expression and release by chondrocytes.

YKL-40 as a novel factor associated with inflammation and catabolic mechanisms in osteoarthritic joints.

YKL-40 is associated with tissue injury and inflammation, and consequently to diseases in which these mechanisms lead to tissue degradation, for example, asthma and rheumatoid arthritis. The purpose of the present study was to investigate if YKL-40 is also a significant factor in osteoarthritis (OA) by assessing associations of YKL-40 with mediators related to the pathogenesis of OA: cartilage destructing matrix metalloproteinases (MMPs) and proinflammatory cytokines interleukin-6 (IL-6) and interleukin-17 (IL-17). Cartilage, synovial fluid (SF), and plasma samples were obtained from 100 OA patients undergoing total knee replacement surgery. SF levels of YKL-40 (1027.9 ± 78.3 ng/mL) were considerably higher than plasma levels (67.2 ± 4.5 ng/mL) and correlated with YKL-40 released from cartilage samples obtained from the same patients (r = 0.37, P = 0.010), indicating that YKL-40 is produced by OA cartilage. Interestingly, YKL-40 concentrations in OA SF correlated positively with MMP-1 (r = 0.36, P = 0.014), MMP-3 (r = 0.46, P = 0.001), IL-6 (r = 0.57, P < 0.001), and IL-17 (r = 0.52, P = 0.010) levels. Moreover, IL-6 and IL-17 enhanced YKL-40 production in human primary chondrocyte cultures. The present study introduces YKL-40 as a cartilage-derived factor associated with mediators of inflammation and cartilage destruction involved in the pathogenesis of OA.

Effect of PRP and PPP on proliferation and migration of human chondrocytes and synoviocytes in vitro

Abstract Cartilage tissue engineering can provide substantial relief to people suffering from degenerative cartilage disease, such as osteoarthritis. The autologous platelet-rich plasma (PRP) application appears to improve cartilage healing due to its ability to positively influence cellular mechanisms, mainly in cells from synovium and cartilage. Primary cultures of human synovial fluid stem cells (synoviocytes, SCs) and chondrocytes (CCs) were exposed to various concentrations of non-activated PRP and plateletpoor plasma (PPP) prepared by apheresis. Cell proliferation and migration were evaluated in real-time with the non-invasive xCELLigence System. It was found that PRP had a similar effect on the growth of cells as fetal bovine serum (FBS). Surprisingly, our proliferation assay results indicated that 50% PPP had the largest effect on both cell types, with a statistically significant increase in cell number (P&lt;0.001) compared to the (0% FBS) in vitro control. The migratory ability of SCs was significantly enhanced with 10% PRP and 0.8% hyaluronic acid (HA). HA also augmented migration of CCs. In summary, these results demonstrate that directed cell proliferation and migration are inducible in human articular CCs and SCs, and that both platelet-derived fractions may exert a positive effect and modulate several cell responses that are potentially involved in tissue integration during cartilage repair.

Conditioned medium as a strategy for human stem cells chondrogenic differentiation

Paracrine signalling from chondrocytes has been reported to increase the synthesis and expression of cartilage extracellular matrix (ECM) by stem cells. The use of conditioned medium obtained from chondrocytes for stimulating stem cells chondrogenic differentiation may be a very interesting alternative for moving into the clinical application of these cells, as chondrocytes could be partially replaced by stem cells for this type of application. In the present study we aimed to achieve chondrogenic differentiation of two different sources of stem cells using conditioned medium, without adding growth factors. We tested both human bone marrow-derived mesenchymal stem cells (hBSMCs) and human Wharton's jelly-derived stem cells (hWJSCs). Conditioned medium obtained from a culture of human articular chondrocytes was used to feed the cells during the experiment. Cultures were performed in previously produced three-dimensional (3D) scaffolds, composed of a blend of 50:50 chitosan:poly(butylene succinate). Both types of stem cells were able to undergo chondrogenic differentiation without the addition of growth factors. Cultures using hWJSCs showed significantly higher GAGs accumulation and expression of cartilage-related genes (aggrecan, Sox9 and collagen type II) when compared to hBMSCs cultures. Conditioned medium obtained from articular chondrocytes induced the chondrogenic differentiation of MSCs and ECM formation. Obtained results showed that this new strategy is very interesting and should be further explored for clinical applications.

Wnt signaling is involved in human articular chondrocyte de-differentiation in vitro

Osteoarthritis is the most prevalent form of arthritis in the world. Certain signaling pathways, such as the wnt pathway, are involved in cartilage pathology. Osteoarthritic chondrocytes undergo morphological and biochemical changes that lead to chondrocyte de-differentiation. We investigated whether the Wnt pathway is involved in de-differentiation of human articular chondrocytes in vitro. Human articular chondrocytes were cultured for four passages in the presence or absence of IL-1 in monolayer or micromass culture. Changes in cell morphology were monitored by light microscopy. Protein and gene expression of chondrocyte markers and Wnt pathway components were determined by Western blotting and qPCR after culture. After culturing for four passages, chondrocytes exhibited a fibroblast-like morphology. Collagen type II and aggrecan protein and gene expression decreased, while collagen type I, matrix metalloproteinase 13, and nitric oxide synthase expressions increased. Wnt molecule expression profiles changed; Wnt5a protein expression, the Wnt target gene, c-jun, and in Wnt pathway regulator, sFRP4 increased. Treatment with IL-1 caused chondrocyte morphology to become more filament-like. This change in morphology was accompanied by extinction of col II expression and increased col I, MMP13 and eNOS expression. Changes in expression of the Wnt pathway components also were observed. Wnt7a decreased significantly, while Wnt5a, LRP5, β-catenin and c-jun expressions increased. Culture of human articular chondrocytes with or without IL-1 not only induced chondrocyte de-differentiation, but also changed the expression profiles of Wnt components, which suggests that the Wnt pathway is involved in chondrocyte de-differentiation in vitro.

Identification of Soluble 14‐3‐3∊ as a Novel Subchondral Bone Mediator Involved in Cartilage Degradation in Osteoarthritis

Mechanical stress plays an important role in cartilage degradation and subchondral bone remodeling in osteoarthritis (OA). The remodeling of the subchondral bone could initiate cartilage loss in OA through the interplay of bone and cartilage. The aim of this study was to identify soluble mediators released by loaded osteoblasts/osteocytes that could induce the release of catabolic factors by chondrocytes. Murine osteoblasts/osteocytes were subjected to cyclic compression, and then conditioned medium from either compressed (CCM) or uncompressed (UCM) cells was used to stimulate mouse chondrocytes. Chondrocyte expression of matrix metalloproteinase 3 (MMP-3), MMP-13, type II collagen, and aggrecan was assessed by reverse transcription-polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay. Soluble mediators released by compressed osteoblasts/osteocytes were identified using iTRAQ (isobaric tags for relative and absolute quantification), a differential secretome analysis. Subchondral bone and cartilage samples were isolated from OA patients, and culture medium conditioned with OA subchondral bone or cartilage was used to stimulate human chondrocytes. Stimulation of mouse chondrocytes with CCM strongly induced the messenger RNA (mRNA) expression and protein release of MMP-3 and MMP-13 and inhibited the mRNA expression of type II collagen and aggrecan. Differential secretome analysis revealed that 10 proteins were up-regulated in compressed osteoblasts/osteocytes. Among them, soluble 14-3-3∊ (s14-3-3∊) dose-dependently induced the release of catabolic factors by chondrocytes, mimicking the effects of cell compression. Addition of a 14-3-3∊ blocking antibody greatly attenuated the CCM-mediated induction of MMP-3 and MMP-13 expression. Furthermore, in human OA subchondral bone, s14-3-3∊ was strongly released, and in cultures of human OA chondrocytes, s14-3-3∊ stimulated MMP-3 expression. The results of this study identify s14-3-3∊ as a novel soluble mediator critical in the communication between subchondral bone and cartilage in OA. Thus, s14-3-3∊ may be a potential target for future therapeutic or prognostic applications in OA.

Celecoxib-loaded PLGA/cyclodextrin microspheres: Characterization and evaluation of anti-inflammatory activity on human chondrocyte cultures

PLGA microspheres were prepared as a sustained release system for the intra-articular administration of celecoxib (CCB). The microspheres were prepared in the presence of different concentrations of dimethyl-β-cyclodextrin (DM-β-Cyd), by the simple oil-in-water emulsion/evaporation solvent method. The microspheres were evaluated as to surface morphology, size and technological properties (such as encapsulation efficiency, drug loading capacity and drug release). Ex vivo studies on cultures of human chondrocytes were performed in order to evaluate the influence of the polymeric carriers on the pharmacological activity of CCB. All systems ranged from about 1 to 5μm in size and had a high encapsulation efficiency percentage ranging from about 80% to 90% (w/w), except for CCB-loaded-PLGA microspheres containing the highest amount of DM-β-Cyd, in which a dramatic drop in the encapsulation efficiency was observed (about 54%, w/w). FIB images evidenced the fact that the microspheres had a porous structure in the presence of the highest amount of DM-β-Cyd. The macrocycle modulated the release profiles of CCB from the microspheres, producing in some cases a zero-order kinetic release. Ex vivo biological studies demonstrated that DM-β-Cyd improved the drug's anti-inflammatory activity. Thus, CCB-loaded PLGA/cyclodextrin microspheres may have a potential therapeutic application in the treatment of osteo- and rheumatoid arthritis.

5-Arylidene-4-Thiazolidinone Derivatives Active as Antidegenerative Agents on Human Chondrocyte Cultures

5-Arylidene-2-oxo-4-thiazolidinones and 2-phenylimino analogues were evaluated for their antidegenerative activity on human chondrocyte cultures stimulated by IL-1β and for their inhibitory capability against matrix metalloproteinase- 13. Our results indicated that 5-arylidene-4-thiazolidinone derivatives 1-9 exhibit antidegenerative activity and could block multiple cartilage destruction during the osteoarthritic process. Out of the selected compounds, (5-arylidene- 2,4-dioxothiazolidin-3-yl)acetic acids 7-9 showed significant effectiveness in reducing NO release and restoring normal levels of GAGs in chondrocytes treated with IL-1β. Moreover, benzoic acids 1, 5 and 6 proved to be effective MMP-13 inhibitors and were able to restore normal levels of GAGs.

Hypoxia promotes redifferentiation and suppresses markers of hypertrophy and degeneration in both healthy and osteoarthritic chondrocytes

IntroductionHypoxia is considered to be a positive influence on the healthy chondrocyte phenotype and cartilage matrix formation. However, hypoxia-inducible factors (HIFs) have been implicated in the pathogenesis of osteoarthritis (OA). Thus, we assessed whether healthy and OA chondrocytes have distinct responses to oxygen, particularly with regard to hypertrophy and degradation during redifferentiation.MethodsMonolayer-expanded healthy and OA chondrocytes were redifferentiated for 14 days in pellet cultures under standard (20% oxygen) or hypoxic (2% oxygen) conditions. Cartilage matrix gene expression, matrix quality and quantity, degradative enzyme expression and HIF expression were measured.ResultsIn hypoxia, both healthy and OA chondrocytes had higher human collagen type II, α1 gene (COL2A1), and aggrecan (ACAN) expression and sulfated glycosaminoglycan (sGAG) accumulation, concomitant with lower human collagen type X, α1 gene (COL10A1), and human collagen type I, α1 gene (COL1A1), expression and collagen I extracellular accumulation. OA chondrocytes had significantly lower sGAGs/DNA than healthy chondrocytes, but only in high oxygen conditions. Hypoxia also caused significantly greater sGAG retention and hyaluronic acid synthase 2 (HAS2) expression by OA chondrocytes. Both healthy and OA chondrocytes had significantly lower expression of matrix metalloproteinases (MMPs) MMP1, MMP2, MMP3 and MMP13 in hypoxia and less active MMP2 enzyme, consistent with lower MMP14 expression. However, aggrecanase (ADAMTS4 and ADAMTS5) expression was significantly lowered by hypoxia only in healthy cells, and COL10A1 and MMP13 remained significantly higher in OA chondrocytes than in healthy chondrocytes in hypoxic conditions. HIF-1α and HIF-2α had similar expression profiles in healthy and OA cells, increasing to maximal levels early in hypoxia and decreasing over time.ConclusionsHypoxic culture of human chondrocytes has long been acknowledged to result in increased matrix accumulation, but still little is known of its effects on catabolism. We show herein that the increased expression of matrix proteins, combined with decreased expression of numerous degradative enzymes by hypoxia, minimizes but does not abolish differences between redifferentiated healthy and OA chondrocytes. Hypoxia-induced HIF expression is associated with hypertrophic marker and degradative enzyme downregulation and increased measures of redifferentiation in both healthy and OA chondrocytes. Therefore, though HIFs may be involved in the pathogenesis of OA, conditions that promote HIF expression in vitro promote matrix accumulation and decrease degradation and hypertrophy, even in cells from OA joints.

Chitosan microparticles for “in vitro” 3D culture of human chondrocytes

Chondrocytes are frequently cultured embedded in gels that provide them with a three-dimensional environment. Nevertheless cells in these constructs cannot remodel their neighbourhood when producing their own extracellular matrix. In this work we explore 3D environments that the cells can easily remodel. For this, human mature chondrocytes were cultured in the three-dimensional environment created by chitosan microparticles whose diameter is in the order of magnitude of the cell size. Chondrocytes and microparticles suspensions were mixed and the agglomerates were cultured in static tubes in chondrogenic medium. The poor adhesion between cells and chitosan surface maintained the mobility of the ensemble. In these conditions chondrocytes are viable during the 28 days of culture. The cells produce glycosaminoglycans, S100 and collagen type II up to 14 days of culture although production of type I collagen is also noticeable.

Ruptura de Tendones Extensores de Dedos por Cubito Plus Idiopático Bilateral

Background : Hyaline cartilage has only a very restricted capability of regeneration in the adult. The incidence of chondral lesions at the knee is high, especially those of Grade II/III (Outerbridge). Therapies combining cells and biological scaffolds are promising biological approaches for the treatment of cartilage defects. The aim of this study is to analyze the characteristics of in vitro culture of human chondrocytes on decellularized amniochorionic membrane (ACM). Methods : Between December 2010 and December 2011, 16 samples of cartilage from a living donor were processed, but only 7 of them were analyzed. Chondrocytes were grown and amplified on plastic and on ACM. The following analyses were carried out with those cells: interactions between cells and ACM; ACM capacity as a matrix for cells; and behavior of cells cultured on ACM. Results: In vitro chondrocytes exhibited phenotypic changes in the presence of ACM. The cells were able to adhere and remain on the spongy region of the membrane. Electron microscopy of cultured ACM showed cells, well preserved organelles, endoplasmic reticulum and desmosomes junctions. Conclusions: The feasibility of culturing chondrocytes on ACM was shown in this work. The cells were able to adhere, remain and differentiate on this membrane during the study period.

5-Arylidene-4-Thiazolidinone Derivatives Active as Antidegenerative Agents on Human Chondrocyte Cultures

5-Arylidene-4-Thiazolidinone Derivatives Active as Antidegenerative Agents on Human Chondrocyte Cultures

Development of a Neutralizing Antibody Specific for the Active Form of Matrix Metalloproteinase-13

Matrix metalloproteinase-13 (MMP-13) is important in the pathology of osteoarthritis (OA). Although MMP-13 is considered a therapeutic target for OA, it is unclear how MMP-13 activity is regulated by the system that comprises various proteinases and their inhibitors. MMP-13 neutralizing antibodies could be a useful tool for investigating the involvement of MMP-13 in cartilage degeneration in OA-affected joints because antibodies possess high affinity and specificity compared with low-molecular weight chemical compounds. On the basis of three-dimensional structure and amino acid sequence information on MMP-13, we selected an appropriate antigen peptide and generated a neutralizing antibody by immunizing mice with the antigen. The most significant property of monoclonal antibody 14D10 was the specific binding to the active form of MMP-13, but not to the latent form, or other MMPs. With this property, active MMP-13 was measured selectively by an enzyme-linked immunosorbet assay. Furthermore, 14D10 suppressed the cleavage of type II collagen in human articular chondrocyte cultures, and 14D10 is thought to inhibit MMP-13 activity effectively. Thus, the highly selective MMP-13 neutralizing antibody (14D10) might be a useful tool for investigating the mechanism of type II collagen degradation in arthritic pathology.

Interpreted gene expression of human dermal fibroblasts after adipo-, chondro- and osteogenic phenotype shifts

Autologous cell-based therapies promise important developments for reconstructive surgery. In vitro expansion as well as differentiation strategies could provide a substantial benefit to cellular therapies. Human dermal fibroblasts, considered ubiquitous connective tissue cells, can be coaxed towards different cellular fates, are readily available and may altogether be a suitable cell source for tissue engineering strategies. Global gene expression analysis was performed to investigate the changes of the fibroblast phenotype after four-week inductions toward adipocytic, osteoblastic and chondrocytic lineages. Differential gene regulation, interpreted through Gene Set Enrichment Analysis, highlight important similarities and differences of induced fibroblasts compared to control cultures of human fibroblasts, adipocytes, osteoblasts and articular chondrocytes. Fibroblasts show an inherent degree of phenotype plasticity that can be controlled to obtain cells supportive of multiple tissue types.

A Wnt/β‐catenin negative feedback loop inhibits interleukin‐1–induced matrix metalloproteinase expression in human articular chondrocytes

The results of recent animal studies suggest that activation of Wnt/β-catenin signaling in articular chondrocytes might be a driving factor in the pathogenesis of osteoarthritis (OA) by stimulating, for instance, the expression of matrix metalloproteinases (MMPs). The aim of this study was to investigate the role of Wnt/β-catenin signaling in interleukin-1β (IL-1β)-induced MMP expression in human chondrocytes. Primary cultures of human, murine, and bovine articular chondrocytes as well as human mesenchymal stem cells and mouse embryonic fibroblasts were used in the experiments. Multiple strategies for the activation and inhibition of signaling pathways were utilized. Reporter assays and coimmunoprecipitation were performed to study the interaction between β-catenin and NF-κB. In contrast to the role of Wnt/β-catenin in animal chondrocytes, in human chondrocytes it was a potent inhibitor of MMP-1, MMP-3, and MMP-13 expression and generic MMP activity both in basal conditions and after IL-1β stimulation. This effect was independent of the T cell factor/lymphoid enhancer factor family of transcription factors but rather was attributable to an inhibitory protein-protein interaction between β-catenin and NF-κB. IL-1β indirectly activated β-catenin signaling by inducing canonical Wnt-7B expression and by inhibiting the expression of canonical Wnt antagonists. Wnt/β-catenin signaling in human chondrocytes had an unexpected anticatabolic role by counteracting NF-κB-mediated MMP expression induced by IL-1β in a negative feedback loop.