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PubMed2006

Chondrocyte apoptosis and expression of Bcl-2, Bax, Fas, and iNOS in articular cartilage in patients with Kashin-Beck disease.

OBJECTIVE: Kashin-Beck disease (KBD) is a chronic, endemic osteochondropathy principally occurring in children. We investigated apoptotic chondrocyte death and the expression of Bcl-2, Bax, Fas, and inducible nitric oxide synthase (iNOS) in articular cartilage from patients with KBD in order to determine the pathogenesis of chondronecrosis in KBD. METHODS: Samples of articular cartilage were divided into 2 groups: control children (15 samples from 15 cases), and children with KBD (15 samples from 15 cases). KBD patients were diagnosed according to "Pathological Criteria to Diagnose KBD in China." Chondrocyte apoptosis was detected by TUNEL staining, and Bcl-2, Bax, Fas, and iNOS-positive articular chondrocytes were stained by immunohistochemistry. Articular cartilage was classified in 3 zones, and positive findings were counted by light microscopy for cytoplasmic staining by polyclonal antibodies of Bcl-2, Bax, Fas, and iNOS and apoptotic chondrocytes by TUNEL. RESULTS: The percentage of positive apoptotic chondrocytes stained by TUNEL in the middle zone of articular cartilage from the KBD patient group (33.60% +/- 2.71%) was higher than that of controls (1.33% +/- 0.41%; p < 0.01). The percentages of chondrocytes staining for Bcl-2, Bax, Fas, and iNOS in KBD patients were significantly higher than in controls (p < 0.01); the remarkable difference in Bcl-2, Bax, Fas, and iNOS expression among the upper, middle, and deep cartilage zones was also seen in KBD articular cartilage (p < 0.01); and staining for Bcl-2, Bax, Fas, and iNOS in KBD patients was prominent in the upper zone (41.93% +/- 12.26%, 45.60% +/- 15.78%, 53.60% +/- 16.49%, 45.47% +/- 14.02%, respectively) and the middle zone (14.93% +/- 3.50%, 13.87% +/- 4.32%, 23.27% +/- 4.83%, 21.67% +/- 6.82%) of articular cartilage. CONCLUSION: The apoptotic chondrocytes and Bcl-2, Bax, Fas, and iNOS-positive chondrocytes were significantly more numerous in patients with KBD than in controls.

Adolescent↗
PubMed2002

Interaction of chondrocytes, extracellular matrix and growth factors: relevance for articular cartilage tissue engineering.

UNLABELLED: The abundant extracellular matrix of articular cartilage has to be maintained by a limited number of chondrocytes. Vice versa, the extracellular matrix has an important role in the regulation of chondrocyte function. OBJECTIVE: In this review we discuss the role of the extracellular matrix in the regulation of chondrocyte function and the relevance for cartilage tissue engineering. To reach this goal the international literature on this subject has been searched with a major focus on the last 5 years. RESULTS: Structural matrix macromolecules (e.g. collagen, hyaluronate), but also growth factors (e.g. IGF-I, TGF beta) entrapped in the matrix and released under specific conditions affect chondrocyte behavior. These factors communicate with the chondrocyte via specific membrane receptors. In this way there is a close interaction between the extracellular and intracellular milieu. Articular cartilage has a limited capacity of intrinsic repair, which has resulted in the development of tissue engineering approaches to repair damaged cartilage. Successful application of scaffolds has to take into account the important role of both soluble and insoluble matrix-derived factors in cartilage homeostasis. CONCLUSION: Functional tissue engineering will only be realized when the scaffolds used will provide cartilage cells with the correct extracellular signals.

Annexins↗
PubMed2005

Osteochondrosis and copper: histology of articular cartilage from foals out of copper supplemented and non-supplemented dams.

Copper (Cu) supplementation of dams in late gestation may be protective against articular cartilage abnormalities in foals. Articular cartilage was harvested from 22 Thoroughbred foals at 160 days of age, at sites predisposed to osteochondrosis (OC), and examined for evidence of early cartilage abnormalities and established dyschondroplastic (DCP) lesions to determine if there were any significant differences due to mare Cu supplementation by injection during late gestation, or foal liver Cu concentration. Cu supplemented mares received calcium Cu edetate injections in late gestation (250 mg at around 220, 248, 276 and 304 days gestation, then every two weeks until foaling). Foals were euthanased at 160 days of age and articular cartilage was harvested from four defined sites. Samples were examined for histological appearance of chondrocytes after staining with haematoxylin and eosin, and were also stained with toluidine blue to indicate proteoglycan content. Alkaline phosphatase (ALP) activity was detected by histochemistry, and histocytochemical techniques were used to determine the expression of cathepsin B. Cu supplementation of the dam, or liver Cu concentration of the foal at birth or 160 days of age had no statistically significant effect on the frequency of cartilage irregularities observed grossly, or abnormalities detected histologically at four defined sites. ALP expression was similar in all samples. Cathepsin B expression varied between sites, and was seen in chondrocyte clusters. The intensity of toludine blue staining varied between sites. Minor histological cartilage abnormalities were observed in cartilage from clinically normal animals. These abnormalities might be 'early' dyschondroplastic lesions, which could resolve or progress. The role of Cu in the development, resolution or progression of dyschondroplastic lesions is poorly understood.

Animal Feed↗
PubMed1999

Denaturation of type II collagen in articular cartilage in experimental murine arthritis. Evidence for collagen degradation in both reversible and irreversible cartilage damage.

Degradation of type II collagen is thought to be a key step in the destruction of articular cartilage in patients with rheumatoid arthritis or osteoarthritis. The aim of this study was to investigate whether type II collagen degradation is associated with cartilage destruction. Type II collagen degradation was studied in two murine arthritis models, zymosan-induced arthritis (ZIA), which develops reversible articular cartilage damage based on proteoglycan analysis, and antigen-induced arthritis (AIA), in which there is irreversible damage to the cartilage. Type II collagen degradation was assayed immunohistochemically using the COL2-3/4m antibody which recognizes denatured type II collagen, such as is produced by collagenase cleavage. In both models, degradation of type II collagen was observed in the non-calcified articular cartilage of arthritic but not of control knees. In the patella-femoral compartment, collagen denaturation started to increase on day 3 (ZIA) and day 7 (AIA) and remained high on day 14. In contrast, in the tibia-femoral compartment, type II collagen breakdown was not increased before 14 days in either model. By 28 days, collagen denaturation was strongly reduced in the patella-femoral compartment in the ZIA model, but persisted in the tibia-femoral compartment in both models. In conclusion, increased type II collagen degradation was found in articular cartilage of both ZIA and AIA animals. Since ZIA does not develop irreversible cartilage destruction, this indicates that cartilage may have the ability to withstand a limited degree of type II collagen degradation without developing irreversible damage.

Animals↗
PubMedDate not supplied

Crystal deposition in normal and diseased articular cartilage: an extended report.

Particles observed on the surfaces of human articular cartilage following trauma and from chondromalacic, osteoarthritic and rheumatoid joints using the scanning electron microscope were analysed by x-ray diffraction technique. The particles contained calcium and phosphorus and they were identified only in structurally abnormal cartilage. These findings suggest that local abnormality of articular cartilage probably underlies crystal-deposition.

Adolescent↗
PubMed2001

Effects of some nonsteroidal anti-inflammatory drugs on articular cartilage of rats in an experimental model of osteoarthritis.

We evaluate the chondrotoxic effects of some nonsteroidal anti-inflammatory drugs (NSAIDs) on articular cartilage in an experimental model of osteoarthritis (OA). Each of 40 Sprague-Dawley rats weighing 0.250 kg and 12 weeks old received weekly injections of sodium iodoacetate (1 mg/0.1 ml NaCl) in the right knees for 8 weeks to induce an experimental model of OA. The left knees served as controls. Four groups were formed of ten rats each. The control group received no medicine. In the other three groups, tiaprofenic acid, diclofenac, and indomethacin were given orally for 12 weeks. At the end of the 20th week, the complete groups were sacrificed and histologic evaluation performed. In the right knees of the control group, specific morphologic changes for OA were observed. Of the three NSAIDs tested, indomethacin was found to have deleterious effects on articular cartilage of both left and right knees. Diclofenac caused a statistically significant increase in the severity of most of the osteoarthritic parameters that were examined in the right knees, whereas tiaprofenic acid was observed to have some beneficial influences on the articular cartilage of right knees. Both diclofenac and tiaprofenic acid displayed the same deleterious effects on articular cartilage of left knees. We conclude that, in the prescription of NSAIDs for OA, it would be appropriate to choose a drug with a protective effect on chondrocytes and articular cartilage.

Alkylating Agents↗
PubMed1995

Cryoscanning electron microscopic study of the surface amorphous layer of articular cartilage.

In order to elucidate the structure near the articular surface, frozen unfixed hydrated articular cartilage with subchondral bone from the pig knee was examined using a cryoscanning electron microscope (cryo-SEM). This method is considered to reduce the introduction of artefacts due to fixation and drying. An amorphous layer, without a collagen-fibril network or chondrocytes, covered most of the surface of the cartilage. This layer was termed the surface amorphous layer. It showed various appearances, which were classified into 4 groups. The average thickness of the layer did not differ among the 8 anatomical regions from which the specimens were taken. The thickness of the layer was found to correlate with the type of appearance of the layer. The 4 appearances associated with thicknesses in descending order are: 'streaked', 'foliate', 'spotted', and 'vestigial'. The surface layer observed in the cryo-SEM was thicker than that observed by a conventional SEM. This difference may be attributable to dehydration of the specimen used in specimen preparation for the latter technique. The layer was also observed in articular cartilage taken from human and rabbit knees. The layer was found to be unstable and to have very variable features. Its thickness and appearance may be influenced by various factors such as dehydration, fluid absorption or mechanical stress.

Animals↗
PubMed2002

Co-localization of insulin-like growth factor binding protein 3 and fibronectin in human articular cartilage.

OBJECTIVE: The anabolic cytokine insulin-like growth factor I (IGF-I) stimulates chondrocyte synthesis of matrix macromolecules and several lines of evidence suggest that it has a major role in maintaining articular cartilage and possibly in cartilage repair. Despite the apparent importance of IGF-I in articular cartilage metabolism and its potential importance in joint diseases, little is known about the regulation of IGF-I activity within the tissue. Insulin-like growth factor binding proteins (IGFBPs) bind IGF-I and can modify its activity. At least three IGFBPs are expressed by chondrocytes: IGFBP-3, -4 and -5. Localization of IGFPBs in the articular cartilage extracellular matrix (ECM) could create reservoirs of IGF-I within the articular cartilage ECM and thereby regulate local IGF-I levels. We hypothesized that ECM molecules bind and concentrate IGFPBs in the pericellular/territorial matrix. DESIGN: Semi-quantitative immunohistological measures of co-localization were used to compare the spatial distribution of IGFBP-3, -4, and -5 with the distributions of three peri-cellularly-enriched matrix molecules fibronectin, tenascin-C, and type VI collagen in osteoarthritic and non-osteoarthritic human articular cartilage. Purified proteins were used in an agarose diffusion assay to compare IGFBP-3 binding to the same three matrix proteins. RESULTS: IGFBP-3 associated with fibronectin in the pericellular/territorial matrix (approximately 40% co-localization) but not with tenascin-C, or type VI collagen (approximately 6% and approximately 15% co-localization respectively, P< 0.05). Neither IGFBP-4, nor IGFBP-5 were associated with any of the three ECM proteins (P< 0.05). In agarose diffusion assays IGFBP-3 interacted with fibronectin and heparan sulfate proteoglycan but not with type VI collagen or tenascin-C. CONCLUSIONS: Direct binding between purified IGFBP-3 and fibronectin and the strong co-localization the two proteins in the cartilage matrix support the hypothesis that IGFPB-3 and fibronectin help regulate local IGF-I levels.

Adult↗
PubMed2006

The involvement of aggrecan polymorphism in degeneration of human intervertebral disc and articular cartilage.

The functions of the intervertebral disc and of articular cartilage are intimately related to their aggrecan content. Aggrecan is a proteoglycan that interacts with hyaluronan to form large aggregates, which are responsible for the ability of the tissues to resist compressive loads. This function is related to the structure of aggrecan, and in particular to the large number of chondroitin sulphate chains present on its core protein. The chondroitin sulphate chains are present in two adjacent regions of the aggrecan core protein, termed the CS1 and CS2 domains. In the human, the region of the aggrecan gene encoding the CS1 domain exhibits size polymorphism, which can result in variation in the degree of chondroitin sulphate substitution of aggrecan in different individuals. This raises the possibility that the functional properties of aggrecan may vary between individuals, and that those individuals with an inferior aggrecan structure may be more susceptible to premature intervertebral disc or articular cartilage degeneration. Several studies have been performed to demonstrate such an association, but the results have been ambiguous. This review explains the relationship between aggrecan structure and function, describes the technique used to assess aggrecan polymorphism and the conclusions and limitations of the data obtained to date, and discusses the implications for tissue degeneration and clinical practice.

Aggrecans↗
PubMed1984

In vitro growth of bovine articular cartilage chondrocytes in various capacitively coupled electrical fields.

Isolated articular cartilage chondrocytes from 1- to 3-week-old male Holstein calf knee joints were formed into pellets containing 4 X 10(6) isolated cells and were grown in tissue culture medium (minimum essential medium/NCTC 135) containing either 1 or 10% newborn calf serum (NBCS) in plastic Petri dishes in 5% CO2 and air at 37 degrees C in saturation humidity. On the 4th postisolation day either [35S]sulfate or [3H]thymidine was added to the medium, and the pellets were exposed for 24 h to capacitively coupled electrical fields (10, 100, 250, and 1,000 V peak-to-peak, 60 kHz, sine wave signals). The pellets were then harvested, dialyzed, hydrolyzed, and assayed for DNA, protein, [35S]sulfate incorporation, and [3H]thymidine incorporation. Results indicated that at 250 V peak-to-peak there was a statistically significant increase in [35S]sulfate in 1% NBCS and a statistically significant increase in [3H]thymidine in 10% NBCS. At potentials above or below 250 V no changes were noted. Thus, articular cartilage chondrocytes grown in pellet form can be stimulated to increase glycosaminoglycan synthesis or to increase cell proliferation by an appropriate capacitively coupled electrical field. The importance of the serum concentration in the medium in evaluation of biosynthesis in vitro is noted.

Animals↗
PubMed2004

Photoshop-based image analysis of canine articular cartilage after subchondral damage.

INTRODUCTION: The validity of histopathological grading is a major problem in the assessment of articular cartilage. Calculating the cumulative strength of signal intensity of different stains gives information regarding the amount of proteoglycan, glycoproteins, etc. Using this system, we examined the medium-term effect of subchondral lesions on initially healthy articular cartilage. MATERIALS AND METHODS: After cadaver studies, an animal model was created to produce pure subchondral damage without affecting the articular cartilage in 12 beagle dogs under MRI control. Quantification of the different stains was provided using a Photoshop-based image analysis (pixel analysis) with the histogram command 6 months after subchondral trauma. RESULTS: FLASH 3D sequences revealed intact cartilage after impact in all cases. The best detection of subchondral fractures was achieved with fat-suppressed TIRM sequences. Semiquantitative image analysis showed changes in proteoglycan and glycoprotein quantities in 9 of 12 samples that had not shown any evidence of damage during the initial examination. Correlation analysis showed a loss of the physiological distribution of proteoglycans and glycoproteins in the different zones of articular cartilage. CONCLUSION: Currently available software programs can be applied for comparative analysis of histologic stains of hyaline cartilage. After subchondral fractures, significant changes in the cartilage itself occur after 6 months.

Animals↗
PubMed2004

Repair of extensive articular cartilage defects in horses by autologous chondrocyte transplantation.

Damaged adult articular cartilage has very limited capacity to heal. Autologous chondrocyte transplantation (ACT) has been used clinically and studied in experimental animals in an attempt to provide biologically based cartilage regeneration. This study evaluated cartilage repair following ACT in a large animal model over a period of 2 years. Articular cartilage defects (10 mm in diameter, full-thickness) were created in the minor load-bearing area on the lateral talus of tibiotarsal joints of eight adult horses. In each animal, the right joint was repaired using autologous chondrocytes injected beneath the periosteum, as in the original ACT procedure (Brittberg, M., A. Lindahl, A. Nilsson, C. Ohlsson, O. Isaksson, and L. Peterson N. Engl. J. Med. 331:889-895, 1994): the left joint remained untreated to serve as a control. Clinical and pathological evaluation was within the range of normal for all horses at both time points. Compared to untreated defects, ACT resulted in significantly improved defect filling with a well-integrated neocartilage and comparable expression of cartilage-specific markers. The histological score (Peterson, L., T. Minas, M. Brittberg, A. Nilsson, E. Sjogren-Jansson, and A. Lindahl Clin. Orthop. 374:212-234, 2000) (10.4 +/- 0.9 for ACT and 5.6 +/- 3.9 for controls, all animals, p = 0.016) indicated that ACT contributed to the reparative process. For the first time, the efficacy of ACT was demonstrated in a large animal model supporting the potential of ACT for cartilage regeneration in patients.

Animals↗
PubMed2001

Roles of articular cartilage aging and chondrocyte senescence in the pathogenesis of osteoarthritis.

Osteoarthritis (OA), the disease characterized by joint pain and loss of joint form and function due to articular cartilage degeneration, is not an inevitable consequence of aging, but a strong association exists between age and increasing evidence of OA. Aging changes in articular cartilage that increase the risk of articular cartilage degeneration include fibrillation of the articular surface, decrease in the size and aggregation of proteoglycan aggrecans, increased collagen cross-linking and loss of tensile strength and stiffness. These alterations are most likely primarily the result of aging changes in chondrocyte function that decrease the ability of the cells to maintain the tissue including decreased synthetic activity, synthesis of smaller less uniform aggrecans and less functional link proteins and decreased responsiveness to anabolic growth factors. Our recent work suggests that the cause of the age-related loss of chondrocyte function may be progressive senescence of articular cartilage chondrocytes marked by a decline in mitotic activity, increased expression of the senescence-associated enzyme beta-galactosidase and erosion of telomere length. New efforts to prevent the development or progression of OA might include strategies that delay the onset of chondrocyte senescence or replace senescent cells.

Aggrecans↗
PubMed2000

Stimulation of hyaluronan metabolism by interleukin-1alpha in human articular cartilage.

OBJECTIVE: To determine the effects of interleukin-1alpha (IL-1alpha) on the expression of hyaluronan synthase (HAS), CD44, and aggrecan in human articular chondrocytes, and to assess the net result of these metabolic changes on the accumulation of hyaluronan within articular cartilage. METHODS: Normal human articular cartilage slices, as well as isolated chondrocytes, were treated with IL-1alpha. Changes in the relative expression of messenger RNA (mRNA) for HAS-2, CD44, and aggrecan were determined by competitive, quantitative reverse transcriptase-polymerase chain reaction. Hyaluronan accumulation was characterized by staining with a hyaluronan-specific binding protein and by fluorophore-assisted carbohydrate electrophoresis, while proteoglycan content was determined by alcian blue and Safranin O staining, CD44 protein expression by immunohistochemistry, and aggrecan biosynthesis by 35S-sulfate incorporation. Changes in cell-associated matrix sizes were visualized by a particle exclusion assay. RESULTS: IL-1alpha stimulated the expression of HAS-2 and CD44 mRNA (3.5-fold and 3-fold, respectively), but inhibited the expression of aggrecan mRNA. In IL-1-treated chondrocytes, extracellular hyaluronan decreased, while intracellular accumulation of hyaluronan was enhanced. Together with the decrease in expression of aggrecan, a dramatic reduction in cell-associated matrix was observed. IL-1-treated cartilage slices displayed a prominent depletion of aggrecan as well as hyaluronan within the upper layers of the tissue. The regional loss of hyaluronan coincided with a regional up-regulation of CD44. CONCLUSION: These data demonstrate that IL-1alpha stimulates HAS-2 at the same time as it inhibits the expression of aggrecan. Although hyaluronan biosynthesis is up-regulated, so too is the expression of CD44 and the internalization/catabolism of hyaluronan. The net result is a loss of hyaluronan in areas of the articular cartilage where increases in CD44 expression are most prominent. This depletion of hyaluronan in the upper layers of the tissue likely facilitates the prominent loss of aggrecan from the tissue.

Aggrecans↗
PubMed1988

Dermatan sulphate proteoglycan from human articular cartilage. Variation in its content with age and its structural comparison with a small chondroitin sulphate proteoglycan from pig laryngeal cartilage.

Low molecular mass proteoglycans (PG) were isolated from human articular cartilage and from pig laryngeal cartilage, which contained protein cores of similar size (Mr 40-44 kDa). However, the PG from human articular cartilage contained dermatan sulphate (DS) chains (50% chondroitinase AC resistant), whereas chains from pig laryngeal PG were longer and contained only chondroitin sulphate (CS). Disaccharide analysis after chondroitinase ABC digestion showed that the human DS-PG contained more 6-sulphated residues (34%) than the pig CS-PG (6%) and both contained fewer 6-sulphated residues than the corresponding high Mr aggregating CS-PGs from these tissues (86% and 20% from human and pig respectively). Cross-reaction of both proteoglycans with antibodies to bovine bone and skin DS-PG-II and human fibroblasts DS-PG suggested that the isolated proteoglycans were the humans DS-PG-II and pigs CS-PG-II homologues of the cloned and sequenced bovine proteoglycan. Polyclonal antibodies raised against the pig CS-PG-II were shown to cross-react with human DS-PG-II. SDS/polyacrylamide-gel analysis and immunoblotting of pig and human cartilage extracts showed that some free core protein was present in the tissues in addition to the intact proteoglycan. The antibodies were used in a competitive radioimmunoassay to determine the content of this low Mr proteoglycan in human cartilage extracts. Analysis of samples from 5-80 year-old humans showed highest content (approximately 4 mg/g wet wt.) in those from 15-25 year-olds and lower content (approximately 1 mg/g wet wt.) in older tissue (greater than 55 years). These changes in content may be related to the deposition and maintenance of the collagen fibre network with which this class of small proteoglycan has been shown to interact.

Age Factors↗
PubMed1988

Biodistribution of bis-[beta-(N,N,N-trimethylamino)ethyl]selenide-75Se diiodide, a potential articular cartilage imaging agent.

In an effort to develop a specific radiodiagnostic agent for articular cartilage imaging, we have investigated the biodistribution of bis[beta-(N,N,N-trimethylamino)ethyl]-selenide-75Se diiodide (75Se BISTAES) in rabbits. At an intravenous dose of 5 mg/kg, the greatest localization of the compound occurred in articular cartilage 15 min after injection. The compound was excreted rapidly in the urine. The results suggest that 75Se BISTAES has potential clinical use as an articular cartilage imaging agent.

Animals↗
PubMed2006

Degree of degeneration and chondroitinase ABC treatment of human articular cartilage affect adhesion of chondrocytes.

The aim of the present study was to investigate whether degree of degeneration and chondroitinase ABC treatment of articular cartilage affect adhesion of chondrocytes to its surface. Human articular cartilage explants were harvested from patients undergoing total knee joint replacement arthroplasty, cut into discs of 0.5-0.8 mm thick and 3.75 mm in diameter, and then divided into three groups according to the degree of degeneration: G0, normal; G1, superficial fissures, and G2, deep fissures. These discs were stored at 70 degrees C until use. Chondrocytes (3 x 10(5) cell/mL in 100 microL of medium) isolated from articular cartilage by enzymatic digestion were transferred to a well plate containing cartilage discs and cultured for a maximum of 21 days. The cultures were divided into one of six groups according to the degree of degeneration and treatment of chondroitinase ABC of the disc. The morphologies of the disc surface and of cultured chondrocytes were assessed histologically. Chondrocyte adhesion, proliferation, and synthesis of proteoglycan and protein were analyzed. Chondrocyte adhesion significantly increased on the discs with higher degrees of degeneration, that is, maximum adhesion in G2, G1, and G0, subsequently. However, adhesion was not significantly different among the three groups at day 3. Chondrocyte adhesion on the chondroitinase ABC-treated disc significantly increased in comparison with that on the nontreated discs with the same degree of degeneration. However, proliferation of chondrocytes and synthesis of glycosaminoglycan and protein were not significant, regardless of degree of degeneration or chondroitinase ABC treatment. The present study demonstrated that chondrocyte adhesion on articular cartilage disc increased along with its degree of degeneration and with treatment of chondroitinase ABC, but that proliferation and synthesis of matrix of the cultured chondrocytes were not significantly influenced by both of them.

Aged↗
PubMed2000

Glucosamine HCl reduces equine articular cartilage degradation in explant culture.

Objective To determine whether glucosamine inhibits experimentally induced degradation of equine articular cartilage explants. Methods Articular cartilage was obtained from the antebrachio-carpal and middle joints of horses (2-8 years old) killed for reasons unrelated to lameness. Cartilage discs were harvested from the weight-bearing region of the articular surface and cultured. Media were exchanged daily and the recovered media stored at 4 degrees C. Explants were maintained in basal media 2 days prior to the start of four treatment days. On days 1-4 lipopolysaccharide (LPS, 10 microg/ml) or recombinant human interleukin-1 (rhIL-1, 50 ng/ml) were added to induce cartilage degradation. To test the potential protective effects of glucosamine, the compound was added in three concentrations (0.25, 2.5, or 25 mg/ml) and treatments were performed in triplicate. Controls included wells without LPS, rhIL-1beta, or glucosamine. Nitric oxide, proteoglycan and matrix metalloproteinases (MMP) released into conditioned media and tissue proteoglycan synthesis were measured as indicators of cartilage metabolism. Results Maximal nitric oxide production, proteoglycan release, and MMP activity were detected 1 day after the addition of LPS or rhIL-1beta to the media. The addition of 25 mg/ml of glucosamine prevented the increase in nitric oxide production, proteoglycan release and MMP activity induced by LPS or rhIL-1. Conclusions These data indicate that glucosamine can prevent experimentally induced cartilage degradation in vitro.

Animals↗