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PubMed2004

Immunohistochemical collagen analysis of the most superficial layer in adult articular cartilage.

We investigated immunohistochemically the collagen type of the most superficial layer in 10 normal adult human articular cartilage specimens obtained from eight femoral heads and one each of the femoral condyle and the talus using routine light microscopy and polarizing microscopy. A membrane-like structure with strong bire-fringence covering the articular surface was observed under polarizing microscopy in each specimen. This structure was stained with anti-type I and anti-type III collagen antibodies but not with anti-type II collagen antibody. This immunohistochemical finding was identical to that in synovial tissue. The results of this study confirm that the most superficial layer of adult normal articular cartilage consists not of type II collagen but of types I and III, and that this layer is absolutely independent from its deeper layer.

Adult↗
PubMed1982

Replacement of epiphyseal bone with methylmethacrylate: its effect on articular cartilage.

Methylmethacrylate cement was used as a substitute for the epiphyseal bone of the canine proximal femora, after femoral neck osteotomy. The effects of different volumes of acrylic cement on the integrity of trabecular bone and articular cartilage and the effects of different types of fixation of the osteotomy site were assessed clinically, radiologically and histologically. Degenerative changes occurring in the articular cartilage were greatest when a large area of epiphyseal bone was replaced with methylmethacrylate. These degenerative changes varied proportionately with the rigidity of fixation at the osteotomy site. Rigid fixation resulted in a better clinical and radiographic assessment and a decrease in histopathologic changes in the articular cartilage.

Animals↗
PubMed2005

Type II collagen synthesis in the articular cartilage of a rabbit model of osteoarthritis: expression of type II collagen C-propeptide and mRNA especially during early-stage osteoarthritis.

BACKGROUND: The aim of this study was to observe time course changes in type II collagen synthesis in various regions of articular cartilage affected with osteoarthritis (OA) by examining the expression of type II collagen C-propeptide (pCOL II-C) and mRNA in a rabbit OA model. METHODS: Osteoarthritis was experimentally induced by partial lateral meniscectomy in the knees of Japanese white rabbits. The cartilage of the animals was then examined histologically over time. The degenerative area of articular cartilage was divided into three areas, according to the degree of degeneration. The ability to synthesize type II collagen was estimated by the immunohistological staining of pCOL II-C and the in situ hybridization of mRNA in type II collagen. RESULTS: The positive rate of pCOL II-C immunostaining in chondrocytes was highest in the central-degenerative region 1 week after surgery, and the highest rate in the para-degenerative region was observed 2 and 4 weeks after surgery. The percentage of pCOL II-C positive cells increased as the histological degeneration score increased to moderate degeneration and then decreased with further progression of the severity of cartilage degeneration. Examination by in situ hybridization revealed that the regions marked by strong pCOL II-C mRNA expression were similar to those indicated by the immunohistology results. CONCLUSIONS: These results suggest that the type II collagen-synthesizing potential of chondrocytes is highest in moderately degenerated areas of OA articular cartilage. Cartilage repair continues to be seen even as OA advances, although the reaction varies depending on the stage of OA.

Animals↗
PubMed2005

Automatic segmentation of the articular cartilage in knee MRI using a hierarchical multi-class classification scheme.

Osteoarthritis is characterized by the degeneration of the articular cartilage in joints. We have developed a fully automatic method for segmenting the articular cartilage in knee MR scans based on supervised learning. A binary approximate kNN classifier first roughly separates cartilage from background voxels, then a three-class classifier assigns one of three classes to each voxel that is classified as cartilage by the binary classifier. The resulting sensitivity and specificity are 90.0% and 99.8% respectively for the medial cartilage compartments. We show that an accurate automatic cartilage segmentation is achievable using a low-field MR scanner.

Algorithms↗
PubMed1994

Cross-validation of cyanogen bromide-peptide ratios to measure the proportion of type II collagen in pepsin digests of equine articular cartilage, meniscus, and cartilage repair tissue.

Collagen type I and type II were purified from equine flexor tendon and articular cartilage, respectively. Equal amounts of these collagens were cleaved with cyanogen bromide, and 11 mixtures containing increasing proportions of type II collagen were separated in seven identical sodium dodecyl sulfate-polyacrylamide gels. The density of bands was measured in wet gels and the peak areas were used to form six ratios of peptide bands that had polynomial relationships with the known proportions of type I and type II collagen in the mixtures. Calibration curves for determining the proportion of type II collagen in the mixtures were constructed using ratios and combinations of ratios of peak areas. Cross-validation was used to identify calibration curves with the smallest squared prediction error or squared average prediction error for all combinations of ratios. Ratios of peak areas of each one of the seven gels were treated, in turn, as the "unknown," and a prediction was carried out using these unknowns and the ratios from the other six gels. Two ratios had the smallest squared average prediction error and calibration curves were computed for these ratios with all seven gels. These curves were used to estimate the proportion of type II collagen in the pepsin-soluble and the pepsin-resistant fractions of articular cartilage inner and outer meniscus, and cartilage repair tissue. Cross-validation enabled selection of the cyanogen bromide-peptide ratios for calibration curves that resulted in the most accurate estimation of the proportion of type II collagen in pepsin digests of tissues.

Animals↗
PubMedDate not supplied

Repair of articular cartilage defects with cultured chondrocytes on polysulphonic membrane: experimental studies in rabbits.

INTRODUCTION: Autologous osteochondral transplantation is one method that can be used to create hyaline or hyaline-like repair in a defect area. The purpose of the present study was to repair full-thickness articular cartilage defects in 9 rabbit knee joints with autologous cultured chondrocytes. METHODS: An articular cartilage defect was created on the patellar groove of the femur. The defect was filled with chondrocytes cultured in vitro and placed into the knee on a polysulphonic membrane. At 8 weeks after the operation, the reparative tissue was analyzed macroscopically and histologically. RESULTS: At 8 weeks after the operation, the surfaces of the reparative tissue were smooth, and the defects were filled with mature hyaline cartilage in 5 cases. In 2 cases, the reparative hyaline cartilage was immature and there was worse integration of grafted tissue into the adjacent normal cartilage. In 2 cases, the surface of the grafted area was irregular, and the reparative tissue was disintegrated and incompletely differentiated. CONCLUSION: The results suggest that transplantation of autologous chondrocytes cultured in vitro and placed into the knee on polysulphonic membrane is effective in repairing an articular cartilage defect.

Animals↗
PubMed2005

Influence of proteoglycan contents and of tissue hydration on the frictional characteristics of articular cartilage.

In this work, the hypothesis that water content and substances present on the articular surface play an important role in lubrication through the formation of a layer with a high content of water on the articular surface is analysed. The hydrophilic properties of proteoglycans exposed at the articular surface and hydration of tissue are the main responsible factors for the formation of this layer. The role of the articular surface in the frictional characteristics of articular cartilage was examined using specimens (femoral condyles of pigs) with intact and wiped surfaces tested in intermittent friction tests. Results indicated that the intact condition presented low friction in comparison with the wiped condition. The measured water loss of the articular cartilage after sliding and loading indicated a gradual decrease in the water content as the time evolved, and rehydration was observed after the submersion of unloaded specimens in the saline bath solution. Micrographic analyses indicated the presence of a layer covering the articular surface, and histological analyses indicated the presence of proteoglycans in this superficial layer. The hydration of the cartilage surface layer and proteoglycan in this layer influence lubrication.

Animals↗
PubMed2000

Quantitative assessment of the effect of 0.05% chlorhexidine on rat articular cartilage metabolism in vitro and in vivo.

Wound infection remains a problem. Syringe and needle jet lavage of chlorhexidine gluconate 0.05% removed or killed 99.8% of contaminating bacteria within 1 minute in a wound model. In clinical use, however, possible toxicity to articular cartilage is a concern. In an established intact rat patella model in vitro, 1 minute of exposure to chlorhexidine 0.05% and chlorhexidine jet lavage did not significantly alter cartilage metabolism. A 1-hour exposure decreased metabolic activity. In vivo, a 30-minute exposure with or without rinsing produced no impairment of metabolic activity 6 weeks later, suggesting that cartilage has the potential for biological recovery. However, injecting and leaving chlorhexidine 0.05% in the joints was detrimental to the metabolic activity of the articular cartilage as assessed 6 weeks later. Thus, chlorhexidine gluconate 0.05% could be used on normal articular cartilage. Any potential damage from prolonged exposure can be avoided by rinsing after 1 minute.

Animals↗
PubMed1994

[The mechanism of articular cartilage degeneration in osteoarthritis].

Immunohistochemical and biochemical studies were undertaken in order to investigate the mechanism of articular cartilage degeneration in human osteoarthritis. Polyclonal antibodies [anti-CB (cyanogen bromide) peptide antibodies] that specifically reacted with unwound alpha-chains and CNBr-derived peptides of human Type II collagen were utilized to identify degradation of Type II collagen fibers in articular cartilage. In the case of human osteoarthritic cartilage with mild degeneration, the most prominent staining by the anti-CB peptide antibodies was found in the superficial fibrillation and in the inter-territorial matrix of the superficial and mid-zones. In contrast, these regions showed weak staining by both anti-Type II collagen antibodies and anti-proteoglycan antibodies. Moreover, staining by anti-fibronectin antibodies and anti-dermatan sulfate proteoglycan antibodies was observed around cell clusters in the superficial zone. Synthesis of Type II collagen and proteoglycans was also investigated using cultured human chondrocytes obtained from mildly or moderately osteoarthritic cartilage. Chondrocytes from mildly degenerated cartilage showed increased synthetic activity, while cells from moderately degenerated cartilage showed decreased activity. These findings indicated that degeneration in osteoarthritic cartilage was initiated in the superficial zone and then gradually progressed to the mid and deep zones.

Antibodies, Monoclonal↗
PubMed1991

Oxidation of articular cartilage glyceraldehyde-3-phosphate dehydrogenase (G3PDH) occurs in vivo during carrageenin-induced arthritis.

Articular cartilage proteoglycan biosynthesis was substantially inhibited by the competitive glycolytic inhibitor 2-deoxyglucose (approximately 65% at 100 mM), but to a much lesser degree (approximately 10%) by the oxidative phosphorylation uncoupler, 2,4-dinitrophenol. These results confirm that articular cartilage proteoglycan synthesis mostly utilises ATP which is generated by glycolysis. In addition, we have utilised the loss of the relatively specific labelling of glyceraldehyde-3-phosphate dehydrogenase (G3PDH) by [3H]-iodoacetic acid to show that rabbit articular G3PDH is oxidised in vivo during the animal model of acute arthritis, carrageenin-induced arthritis, in the same way as we have previously shown that cartilage G3PDH is oxidised after in vitro exposure to sublethal doses of H2O2. The oxidation of rabbit G3PDH in vivo (18 hr post-injection) corresponds with the maximal influx of PMNL cells into the arthritic synovial fluid and with substantial inhibition of proteoglycan core protein synthesis. We propose that H2O2 released from "activated" PMNLs and macrophages is responsible for the "down-regulation" of biosynthetic processes found in cartilage during acute inflammation.

2,4-Dinitrophenol↗
PubMed1994

Optimization of cryopreservative procedures for human articular cartilage chondrocytes.

Procedures are being developed which use isolated articular cartilage (AC) chondrocytes to restore damaged articular surfaces. The availability of isolated human chondrocytes for transplantation may be increased by low-temperature storage (banking). At present, no single method of freezing chondrocytes has been proven to be optimal. In this project, two different freezing protocols, I and II, were compared. Protocol I used freezing rates of -1 degrees C/min down to a temperature of -40 degrees C. Protocol II used a freezing rate of -1 degree C/min down to -10 degrees C and faster rates thereafter. Cells were stored for 2 weeks at -196 degrees C. Survival and function of the cells after thawing were evaluated by histological examination and determination of 35S- and 3H-thymidine incorporation after 1 and 2 weeks of high-density monolayer culture. Cells frozen with protocol I showed better function and survival (99.75%) than cells frozen with protocol II (85%). Both groups showed slowing of metabolism and replication after freezing when compared with controls. We conclude that controlled freezing of adult human chondrocytes at rates of -1 degrees C/min improves survival. Banking of human AC chondrocytes may be feasible using protocol I, although some questions regarding the long-term behaviour of human AC chondrocytes after cryopreservation remain to be answered.

Aged↗
PubMed1978

Articular cartilage changes mechanically induced "in vivo". An experimental method approach in animals.

A machine designed upon the principles of a crank lever mechanism was built to produce excessive use of the joints of small animals by means of continuous flexion-extension movements. Articular cartilage changes could be consistently produced after 5 to 10 days of exercise. Histochemical studies of the articular cartilage demonstrated a decrease in proteoglycan and an increase in acid phosphatase. These findings suggest that this animal model may be of value for the analysis of the earliest degenerative stages of the articular cartilage.

Acid Phosphatase↗
PubMed2004

Factors influencing the oxygen concentration gradient from the synovial surface of articular cartilage to the cartilage-bone interface: a modeling study.

OBJECTIVE: There is very little information on the gradients of oxygen concentration from the synovial surface to the subchondral bone in articular cartilage. Cartilage is usually regarded as hypoxic, even though cellular metabolism is inhibited at low oxygen concentrations. We therefore measured rates of cellular consumption of oxygen and used these rates to calculate oxygen tension profiles across articular cartilage. METHODS: The rate of oxygen consumption by bovine articular chondrocytes was measured in vitro, either in intact cartilage slices or in isolated chondrocytes. The oxygen tension profile across articular cartilage was predicted by solving a 1-dimensional reaction-diffusion equation. The effect of synovial fluid oxygen concentration, cell density, cartilage thickness, and influx of oxygen from the subchondral bone on the oxygen profile in the tissue was examined. RESULTS: Oxygen consumption rates were relatively independent of oxygen tension at high oxygen tensions (5-21%), where they were approximately 10 nmoles/10(6) cells/hour for both isolated chondrocytes and for cartilage slices. Below 5% oxygen, the rate fell in an oxygen tension-dependent manner. Analysis showed that the oxygen profile across cartilage fell steeply in all but the thinnest cartilage samples but only fell to approximately 1% for low oxygen tensions in synovial fluid, with no supply from the subchondral bone. CONCLUSION: The oxygen tension in normal cartilage is not likely to fall to 1% except under abnormal conditions. Oxygen tensions within cartilage are strongly affected by a number of factors, including oxygen concentrations in synovial fluid, cartilage thickness, cell density, and cellular oxygen consumption rates. Supply from the subchondral bone may be of particular importance.

Animals↗
PubMed2000

The influence of the resolution and contrast on measuring the articular cartilage volume in magnetic resonance images.

The progression of OA in patients may be followed by measuring the volume of articular cartilage from MR images. We attempted to determine the reproducibility of volume measurements of articular cartilage made from magnetic resonance images of the knees and the dependence of the reproducibility on image resolution and contrast-to-noise. A fat-suppressed 3D technique was used to generate four image sets with different image resolution. Each patient was imaged twice to obtain image pairs at each resolution. To assess the dependence of reproducibility on noise we generated six image sets for each patient by adding noise to the original images and repeating the comparison. On each image set, the femoral, tibial, and patellar cartilage were outlined by a combination of computer and manual methods, and the images were used to calculate the volume of each cartilage plate. Comparing the coefficient of variance between the volume measurements made from the two visits, the volume measurements made from images with the highest resolution (0.275 x 0.275 x 1.0 mm) had the highest reproducibility. The high resolution images of the tibia and femur had the least partial-volume averaging and, as a result, better defined the boundaries between cartilage and adjacent tissues. A different trend was evident for the patella. For studies of osteoarthritis therapies, we recommend using MR images with the highest possible in-plane spatial resolution to provide the most reproducible volume measurements of knee cartilage.

Body Mass Index↗
PubMed1999

The long-term effect of a short course of transforming growth factor-beta1 on rat articular cartilage.

The long-term effect of 3 days' topical administration of TGF-beta1 on unloaded articular cartilage in growing rats was investigated. Three to five rats were sacrificed on days 15, 30, 45, 60 and 90 after the last injection and the patellas were subjected to light and electron microscopic evaluation. The patellas showed age-related changes when entering the maturation phase. Absence of a hypertrophic zone and formation of a subchondral bone plate were observed in both treated rats and controls from that time point. Reduction of total cell amount was observed between older and younger patellas in both treated rats and controls. TGF-beta1 treatment resulted in accelerated maturation and ageing. Furthermore, the administration of TGF-beta1 resulted in a higher unmineralized cartilage with an increased total amount of cells in the intermediate zone. Matrix areas showing ultrastructural features of disturbed matrix composition were seen in the deeper part of this zone at all time points, but in the treated patellas only. The present results indicate that TGF-beta1 treatment may induce changes in articular cartilage in some respects similar to those seen in the early stages of degenerative and inflammatory joint diseases.

Animals↗