Biochemistry of articular cartilage. Nature of proteoglycans and collagen of articular cartilage and their role in ageing and in osteoarthrosis.
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Age Factors↗
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[Review of recent acquisitions on the physiopathology of articular cartilage. I. Development of the structure of articular cartilage].
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Animals↗
[Preservation of articular cartilage. 2. Behavior of glycosaminoglycans (GAG) in the intracellular substance of preserved articular cartilage (histo- and biochemical studies)].
Glucosaminoglucanes (acid mucopolysaccharides) were assessed by means of histochemic and biochemic methods in differently preserved articular cartilages of adult Alsatian dogs. Immediately after lyophilization, resp. 14 days after preservation at --196 degrees C., the glucosaminoglucanes decrease, whereas they are present in undiminished concentration after deep-freezing preservation (--18 degrees C. and --78 degrees C.) up to 30 months, and at +4 degrees C. up to 100 days. No more destruction of glucosaminoglucanes occurs after dying of chondrocytes, obviously depending on blocking the glucosaminoglucanes destructing enzymes during the freezing. With regard to the investigations on the vitality, deep-freezing preservation at --18 degrees C. to --78 degrees C. is recommended for storage of avital articular cartilage. Preservation of vital articular cartilage is possible for 28 days at +4 C. in 5 per cent glucose solution.
Animals↗
Reaction of hypochlorous acid with bovine nasal cartilage comparison to pig articular cartilage.
The action of sodium hypochlorite (NaOCl) on bovine nasal cartilage was studied by proton nuclear magnetic resonance (1H-NMR) spectroscopy in order to model degradation processes of cartilage caused by neutrophil-derived hypochlorous acid. Nasal cartilage was chosen as a mean of comparison because it differs from articular cartilage in its composition. It contains some more proteoglycans, i.e. polymeric carbohydrates and less collagen than articular cartilage. This is important for studying the influence of hypochlorous acid on cartilage components (collagen and polysaccharides). Cartilage samples were incubated at 37 degrees C with phosphate buffer in the presence or absence of NaOCl. Supernatants were collected and assayed by NMR-spectroscopy. In the presence of pure phosphate buffer, the supernatants of bovine nasal cartilage were less rich in low molecular mass metabolites (e.g. amino acids, lactate) than articular cartilage. However, intense signals for highly mobile N acetyl groups of cartilage polysaccharides were detectable in nasal cartilage. NaOCl caused an increase in signals for acetate and formiate. Signals for N-acetyl groups rose only during the first 25 minutes of incubation with NaOCl. Then, their concentration decreased markedly. These changes were related to an enhanced release of chondroitinsulfate from nasal cartilage.
Animals↗
Hydroxyapatite deposition in articular cartilage by intra-articular injections of methylprednisolone. A histological, ultrastructural, and x-ray-microprobe analysis in rabbits.
The mineral deposits in rabbit articular cartilage induced by intra-articular injections of glucocorticoid were studied by light and electron microscopy, using histochemical techniques and x-ray-probe microanalysis. This study demonstrated that the mineral deposits consisted of hydroxyapatite crystals. The initial deposition of hydroxyapatite crystals was seen around degenerating chondrocytes, where a halo-like pericellular space contained a large amount of electron-dense amorphous material. The initial precipitation of the crystals with a low ratio of calcium to phosphorus and the subsequent growth of crystals were seen only on or within the electron-dense amorphous material until the crystals formed mature, calcified nodules. The electron-dense amorphous material frequently coexisted with proteoglycans and degenerated collagen fibers. Digestion studies using chondroitinase ABC, papain, or chloroform and methanol suggested that the electron-dense amorphous material consisted of some protein and a small amount of lipid. Matrix vesicles were rarely seen in the calcifying areas. In addition, there was a correlation between sulphur, calcium, and phosphorus in the calcifying areas, where the relative element concentrations were: S (estimation counts of sulphur) = -0.862 X (calcium counts) + 1.472 X (phosphorus counts) + 102.146. This study demonstrated that electron-dense amorphous material, proteoglycans, and degenerated collagen fibers are present in loci where the hydroxyapatite crystals are formed in articular cartilage.
Animals↗
Purified staphylococcal culture medium stimulates neutral metalloprotease secretion from human articular cartilage.
Human articular cartilage released significantly increased levels of metal-dependent enzymes capable of degrading collagen, casein, and gelatin at a neutral pH following exposure to a sterile, purified fraction of Staphylococcus aureus culture medium. Neutral metalloprotease activity was determined by radiolabeled substrate assays and substrate gel analysis. The enzymes were activated with 4-aminophenylmercuric acetate and were inhibited by 1,10-phenanthroline and ethylenediamine tetraacetic acid. Protein immunoblots demonstrated that type I collagenase and stromelysin (matrix metalloproteinase III) secretion was increased following staphylococcal medium challenge. The profile of enzymatic activity induced by staphylococcal medium was directly comparable to that observed with interleukin-1, which was used as a positive control. The staphylococcal medium had no inherent proteolytic activity. Increased production of the neutral metalloproteases collagenase and stromelysin may significantly contribute to the extensive cartilage destruction noted in staphylococcal septic arthritis.
Cartilage, Articular↗
Studies on the in vitro incubation procedure for [35S]sulphate labelling of articular cartilage glycosaminoglycans.
Articular cartilage from cow and calf femoral condyles was incubated in Tyrodes solution containing [35S]sulphate for different periods up to 80 min. Glycosaminoglycans from the cartilage tissue and incubation medium were fractionated on Cetylpyridinium chloride and ECTEOLA cellulose microcolumns. The incorporation of [35S]sulphate into all individual fractions of chondroitin sulphate and keratan sulphate was found to be linear from 20 to 80 min incubation time. As a rule the total specific activities of keratan sulphate and chondroitin sulphate were similar for both calves and cows. The proteoglycan material recovered from the medium amounted to about 1% of the tissue dry weight and was found to have a higher chondroitin sulphate: keratan sulphate ratio than the corresponding cartilage tissue for both calf and cow. The solubility profiles for the newly synthesised glycosaminoglycans, obtained from determination of the radioactivity in the individual fractions, were compared with those of glycosaminoglycans already present. These curves indicated that newly synthesised chondroitin sulphate had a higher average molecular size than that present in the tissue whereas the newly synthesised keratan sulphate had a smaller average molecular size. These newly synthesised components were also detected in the proteoglycans recovered from the incubation medium.
Animals↗
Cryopreservation of intact human articular cartilage.
Damaged articular cartilage (AC) impairs joint function and many treatment techniques are being investigated to determine their long term results. Successful cryopreservation of AC can provide a reliable source of intact matrix with viable chondrocytes to maintain the cartilage over long periods of time. This study investigated the application of an established cryopreservation protocol to determine the recovery of intact chondrocytes from human AC. Ten millimeter diameter osteochondral dowels were harvested from two human donors. The cryopreservation protocol was performed and the samples were rapidly warmed from varying experimental holding temperatures (-10, -20, -30, -40 degrees C), with and without plunging into liquid nitrogen, using 1 M dimethyl sulfoxide as cryoprotectant. The cartilage was stained with membrane integrity dyes and viewed under fluorescence microscopy. The percent of intact chondrocytes was compared to fresh controls. Low recovery of intact chondrocytes was recorded from all temperature levels with and without cryoprotectant. The results of this experiment demonstrated that the cryopreservation procedure used to achieve moderate success with intact sheep AC was not successful with intact human AC and further investigation is required.
Adolescent↗
Vitreous preservation of articular cartilage grafts.
Articular cartilage has proved refractory to satisfactory cryopreservation using conventional freezing methods. Therefore, an ice-free cryopreservation method by vitrification was tested. Osteochondral plugs from New Zealand White rabbits were preserved using either a freezing method or an ice-free vitrification method of cryopreservation. Preserved and fresh control plugs were implanted in the tibial plateau of allogeneic recipients. A modified O'Driscoll grading scale, based on gross pathology, histopathology, and histochemistry, was used to evaluate the explants.The histology of fresh and vitrified explants was essentially the same, while the frozen cryopreserved explants were devoid of chondrocytes and only fibroblastlike cells were observed. The O'Driscoll grading indicated that both fresh and vitrified plugs performed significantly better than frozen plugs (p < or =.05). The results demonstrate the feasibility of vitrification as a storage method for cartilaginous tissues.
Animals↗
Donor cell fate in tissue engineering for articular cartilage repair.
Articular cartilage repair is a clinical challenge because of its limited intrinsic healing potential. Considerable research has focused on tissue engineering and transplantation of viable chondrogenic cells to enhance cartilage regeneration. However, the question remains: do transplanted allogenic cells survive in the repair with time? This study assessed donor cell fate after transplantation of male New Zealand White rabbit perichondrium cell and polylactic acid constructs into osteochondral defects created in the medial femoral condyles of female New Zealand White rabbits. Repair tissue was harvested at 0, 1, 2, 3, 7, and 28 days after implantation and was evaluated for cell viability and total cell number using confocal microscopic analysis. The number of donor cells in each sample was estimated using quantitative polymerase chain reaction targeting a gender-specific gene present on the Y-chromosome, the sex-determining region Y gene, and a control deoxyribonucleic acid present in male and female cell deoxyribonucleic acid, the matrix metalloproteinase-1 gene promoter. Average cell viability was found to be 87% or more at all times. Donor cells were present in repair tissue for 28 days after implantation. However, the number of donor cells declined from approximately 1 million at Time 0 to approximately 140,000 at 28 days. This decline in donor cells was accompanied by a significant influx of host cells into the repair tissue. This study shows that the sex-determining region Y gene is a valuable marker for tracking the fate of transplanted allogenic cells in tissue engineering.
Animals↗
Repair of articular cartilage defects: part I. Basic Science of cartilage healing.
Articular cartilage injuries result in numerous clinical symptoms, such as pain and decreased functional levels. The limited reparative capabilities of hyaline cartilage results in the generation of repair tissue that lacks the structure and biomechanical properties of normal cartilage. Chondrocytes are unable to adequately proliferate, migrate, and synthesize high-quality repair tissue in response to blunt, superficial, or deep penetrating trauma. Extensive research has been conducted to understand the healing process and devise techniques that would enhance this response. Part I of this paper will discuss the basic science of cartilage repair. Part II, which will be published in the February issue, will present the treatment options.
Animals↗
[Cell transplantation therapy for the treatment of articular cartilage defect].
Articular cartilage destruction is a major problem in rheumatoid arthritis patients. However, there is no treatment that is widely accepted to regeneratively repair the lesion. When the joint cartilage is destructed progressively and activity of daily life is worsened, joint arthroplasty is the most common treatment to relieve joint pain though it has limited survivorship and sometimes severe complications. Recently in order to repair cartilage defect, new method with cell transplantation; autologous cultured chondrocyte transplantation has been put into clinical practice. And we also have reported autologous cultured-expanded bone marrow mesenchymal cell transplantation. These methods have possibility to repair cartilage defect with good quality histologically, biochemically and biomechanically.
Arthritis, Rheumatoid↗
Variation in the effects of mononuclear cell products from different individuals on metalloproteinase secretion from human articular cartilage.
Human articular cartilage in organ culture shows a variable degree of endogenous metalloproteinase secretion depending on the individual from whom it was obtained. Cartilage with low endogenous levels are stimulated by interleukin 1 (IL-1) to levels comparable to the high endogenous group. Total blood mononuclear cell products obtained from different individuals either behave in a manner similar to that seen with IL-1, which results in sustained high levels of enzyme secretion, or show an initial stimulation followed by a subsequent dropoff in enzyme secretion even though incubation is continued in the presence of mononuclear cell products. The factor(s) causing this dropoff can be distinguished from IL-1. Production and regulation of such factors may reflect a mechanism whereby the action of IL-1 can be controlled during the inflammatory response.
Adult↗
Scanning electron microscopic study of age-related surface changes in rat femoral head articular cartilage.
The articular surface of the femoral heads of young (5 month-old) and old (21 month-old) female rats were examined with the use of the scanning electron microscope using an especially sensitive preparative technique in which the femoral heads were fixed in a glutaraldehyde-paraformaldehyde fixative, post-fixed in OsO4, dehydrated in ethanol and critical point dried. The articular surfaces of the young group were relatively smooth with only small ridges, which may represent superficial collagen fibrils embedded in a proteoglycan matrix. The old group's articular surfaces differed in 2 ways from the surfaces obtained from the young group. First, circumscribed depressions (roughly 20-25 micrometers in diameter) were found, which may represent the empty lacunae of superficial-layer chondrocytes. Secondly, the articular surface was 'roughened', apparently by numerous exposed collagen fibrils that may have been exposed as a result of a loss of superficial proteoglycans. It is concluded that our methodology of tissue preparations for observation with the scanning electron microscope is a sensitive and practical technique that could be useful for characterizing early morphological manifestations of articular cartilage degenerative changes.
Aging↗
Presence of cartilage-derived morphogenetic proteins in articular cartilage and enhancement of matrix replacement in vitro.
OBJECTIVE: To investigate the effects of the cartilage-derived morphogenetic proteins (CDMPs) in an in vitro cartilage explant model that mimics the chondrocytic response to matrix depletion, and to demonstrate their presence in articular cartilage. METHODS: Adult bovine articular cartilage and postmortem specimens from adult human donors with and without osteoarthritic (OA) lesions were stained by immunohistochemistry using polyclonal antibodies specific for CDMP-1 and CDMP-2. Extracts of bovine articular cartilage were analyzed by Western blotting for the presence of the CDMPs. Bovine articular cartilage explants were depleted of their matrix by trypsin digestion, followed by a 7-day culture period in a chemically defined serum-free basal medium (BM), with or without recombinant CDMPs 1 and 2. The metabolic activity of chondrocytes was measured by 35S-sulfate incorporation into macromolecules. Newly synthesized proteoglycans (PGs) were analyzed using Sephacryl S-500 HR gel chromatography. The expression levels of the messenger RNA (mRNA) for chondrogenic markers were investigated by Northern analysis. RESULTS: CDMP-1 and CDMP-2 were detected in both bovine and human healthy and OA articular cartilage. Treatment of matrix-depleted cartilage explants with CDMPs 1 and 2 increased equally the incorporation of 35S-sulfate into PGs compared with tissue maintained in BM. Gel chromatography analysis indicated that aggrecan was the predominant PG species. Northern blot analysis showed that the expression of link protein, type II collagen, and aggrecan mRNA transcripts was not modulated by CDMP treatment. CONCLUSION: This study shows the presence of CDMP-1 and CDMP-2 in adult bovine and human articular cartilage. In addition, our in vitro data indicate that CDMPs 1 and 2 stimulate the metabolic activity of articular chondrocytes. Therefore, these signaling molecules may be contributing to the maintenance of the integrity of the joint surface.
Animals↗
In vitro studies of the wear of articular cartilage--III. The wear characteristics of chemical modified articular cartilage when worn against a highly polished characterized stainless steel surface.
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Amino Acids↗
Mechanisms of disruption of the articular cartilage surface in inflammation. Neutrophil elastase increases availability of collagen type II epitopes for binding with antibody on the surface of articular cartilage.
We recently observed that specific antibodies to type II collagen do not bind in appreciable amounts to the intact surface of articular cartilage, whereas antibodies to the minor collagen types V, VI, and IX do. These results suggest that the outermost cartilage surface layer prevented interaction of the antibodies with the major collagen type in articular cartilage. The present studies were designed to investigate the pathogenic mechanisms involved in the disruption of the cartilage surface layer in inflammatory arthritis. Articular cartilage obtained from rabbits undergoing acute antigen-induced arthritis of 72 h duration showed a significant increase in binding of anti-type II antibody to cartilage surfaces compared with normal control cartilage (P less than 0.01). Augmentation of anti-type II binding was also observed upon in vitro incubation of bovine articular slices or intact rabbit patellar cartilage for 1 h with human polymorphonuclear neutrophils (PMN), PMN lysates, or purified human PMN elastase. This increase was not inhibited by sodium azide, nor was it enhanced by incubation of cartilage with the strong oxidant hypochlorous acid. Chondrocyte-mediated matrix proteoglycan degradation in cartilage explants cultured in the presence of cytokines failed to increase antibody binding appreciably. The augmentation in antibody binding seen with PMN lysates was inhibited by the nonspecific serine-esterase inhibitor PMSF, but not by the divalent metal chelator EDTA. The elastase-specific inhibitor AAPVCMK also inhibited most of the PMN-induced increase in antibody binding, whereas the cathepsin G-specific inhibitor GLPCMK was much less effective. Incubation of intact cartilage with purified human PMN elastase indicated that this serine esterase could account for the increase in anti-type II collagen antibody binding to intact cartilage surfaces. These studies suggest that in an inflammatory response, PMN-derived elastase degrades the outer layer of articular cartilage, exposing epitopes on type II collagen. They also help clarify the pathogenic mechanisms involved in early articular cartilage damage in inflammatory joint diseases.
Animals↗
Composition of proteoglycans synthesized in different layers of cultured anatomically intact articular cartilage.
Calf articular cartilage was cultured anatomically intact on its natural bone-support. At day 0 and day 7, respectively, the cartilage was radiolabeled, washed and harvested in 3 successive layers parallel to the articular surface. The proteoglycans were studied after extraction by 4 M guanidine hydrochloride. In the deep layer, the endogenous proteoglycan monomers were slightly smaller, showed an increased polydispersity and the relative amount of keratan sulfate was lower. In addition, chondroitin sulfate side chains were slightly larger and the sulfation degree and proportion of 4-sulfated disaccharides was elevated. At day 0, deep layer chondrocytes incorporated about twice as much [35S]-sulfate into glycosaminoglycans as did superficial chondrocytes. The newly synthesized proteoglycan monomers were the same in all layers with respect to size, dispersity, relative amount of keratan sulfate and size of chondroitin sulfate side chains. The sulfation-pattern, however, changed with depth in the same way as noted in the endogenous proteoglycan population. Small endogenous proteoglycan was present in all layers, but its synthesis was only prominent in the upper layer and decreased with depth. After 7 days culture, the [35S]-sulfate incorporation had increased in the upper half of the cartilage. There was a strong increment in the proportion of 6-sulfated disaccharides of newly synthesized glycosaminoglycan in all layers. The synthesis of small proteoglycan was markedly reduced, especially in the upper layer.
Animals↗