人关节软骨脱细胞基质的制备

目的制备人关节软骨脱细胞基质。方法切取人关节软骨,对之冷冻干燥后,采取化学去污剂TritonX100及DNA酶和RNA酶等试剂制备脱细胞的人关节软骨。做HE、番红0及软骨蛋白聚糖(aggrecan)免疫组化染色等方法进行检测。结果HE染色、番红0染色均显示细胞陷窝内己无细胞结构番红花0染色阳性;软骨蛋白聚糖免疫组化染色阳性。结论人关节软骨冻干后,经去污剂酶等处理方法可脱去软骨的细胞成分,并且保留了软骨细胞外基质,成功制备了人关节软骨脱细胞基质。     

Increased degradation and alteered tissue distribution of cartilage oligomeric matrix protein in human rheumatoid and osteoarthritic cartilage

We investigated the degradation and tissue distribution of cartilage oligomeric matrix protein in normal, osteoarthritic, and rheumatoid arthritic articular cartilage of the human knee. Cartilage was subjected to sequential extractions with buffers containing neutral salt, with EDTA, and finally with guanidine/HCl and then was analyzed by Western blotting with a polyclonal antiserum to human cartilage oligomeric matrix protein. Western blots of the nine neutral salt extracts from normal cartilage revealed mostly intact pentameric molecules of cartilage oligomeric matrix protein, in contrast to the 13 osteoarthritic and five rheumatoid arthritic cartilage samples that demonstrated marked degradation of cartilage oligomeric matrix protein as noted by a predominance of reduction-sensitive bands at approximately 150 kDa and nonreduction-sensitive bands in the 67–94 kDa range. The EDTA and guanidine/HCl extracts from all groups were similar and showed mostly intact molecules of cartilage oligomeric matrix protein, with smaller amounts of degraded cartilage oligomeric matrix protein identical to those resolved by the Western blots of the neutral salt extracts. Western blots of matched pairs of synovial fluid and cartilage extracts demonstrated cartilage oligomeric matrix protein fragments of the same molecular mass. Competitive enzyme-linked immunosorbent assay revealed significantly less cartilage oligomeric matrix protein in rheumatoid articular cartilage than in either normal or osteoarthritic cartilage. In contrast to normal cartilage, where cartilage oligomeric matrix protein was predominately localized to the interterritorial matrix throughout all zones of the matrix, with increased staining in the deeper cartilaginous zones, the most intense staining in osteoarthritic cartilage was in the superficial zones of fibrillated cartilage, with little to no immunostaining in the midzones and relatively poor staining in the deeper cartilaginous zones. This distribution was the inverse of that for proteoglycans, as demonstrated by toluidine blue staining, where proteoglycans were depleted primarily from the superficial fibrillated cartilage. In mild to moderately affected rheumatoid cartilage, the tissue distribution of cartilage oligomeric matrix protein was similar to the distribution of proteoglycans, with relatively uniform staining of the interterritorial and territorial matrices. In more severely affected rheumatoid cartilage, the superficial zones demonstrated punctate immunostaining for cartilage oligomeric matrix protein in the interterritorial and territorial matrices, and staining was restricted to the territorial matrix in the deep cartilaginous zones. It is evident from this study that (a) noncollagenous proteins such as cartilage oligomeric matrix protein are greatly affected in arthritis. (b) degradation fragments released from the matrix into the synovial fluid reflect the processes occurring within the matrix, and (c) different zones of the articular cartilage are susceptible to degradation of cartilage oligomeric matrix protein in the different disease processes.     

S-100 protein in human articular cartilage

We studied the immunohistochemical distribution of the alpha and beta subunits of S-100 protein in human articular cartilage by the Avidin-Biotin Complex method using monoclonal antibodies against each subunit. Immunostaining for both subunits was detected in chondrocytes in superficial. intermediate, and deep zones of normal articular cartilage. In the matrix, only the superficial zone was stained positively. In arthrotic joints, we detected intense immunostaining in clustered chondrocytes in the hypercellular area. and weak or no immunostaining in isolated chondrocytes in the hypocellular area of articular cartilage.     

S-100 protein in human articular cartilage

We studied the immunohistochemical distribution of the alpha and beta subunits of S-100 protein in human articular cartilage by the Avidin-Biotin Complex method using monoclonal antibodies against each subunit. Immunostaining for both subunits was detected in chondrocytes in superficial, intermediate, and deep zones of normal articular cartilage. In the matrix, only the superficial zone was stained positively. In arthrotic joints, we detected intense immunostaining in clustered chondrocytes in the hypercellular area, and weak or no immunostaining in isolated chondrocytes in the hypocellular area of articular cartilage.     

Production of cartilage oligomeric matrix protein (COMP) by cultured human dermal and synovial fibroblasts

OBJECTIVE: Cartilage oligomeric matrix protein (COMP) is a large disulfide-linked pentameric protein. Each of its five subunits is approximately 100,000 Da in molecular weight. COMP was originally identified and characterized in cartilage and it has been considered a marker of cartilage metabolism because it is currently thought not to be present in other joint tissues, except for tendon. To confirm the tissue specificity of COMP expression we examined cultured human dermal fibroblasts, human foreskin fibroblasts, and normal human synovial cells for the synthesis of COMP in culture. METHOD: Normal synovial cells and normal human dermal foreskin fibroblasts were isolated from the corresponding tissues by sequential enzymatic digestions and cultured in media containing 10% fetal bovine serum until confluent. During the final 24 h of culture, the cells were labeled with 35S-methionine and 35S-cysteine in serum- and cysteine/methionine-free medium. The newly synthesized COMP molecules were immunoprecipitated from the culture media with a COMP-specific polyclonal antiserum, or with monoclonal antibodies or affinity-purified COMP antibodies. The immunoprecipitated COMP was analyzed by electrophoresis in 5.5% polyacrylamide gels. For other experiments, synovial cells cultured from the synovium of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were similarly examined. RESULTS: A comparison of the amounts of COMP produced by each cell type (corrected for the DNA content) revealed that synovial cells produced > or = 9 times more COMP than chondrocytes or dermal fibroblasts. COMP could be easily detected by immunoprecipitation in all cell types. Electrophoretic analysis revealed a distinct band with an apparent MW of 115-120 kDa in samples from each of the three cell types, regardless of the antibody used. COMP expression in cultures of synoviocytes derived from OA and RA patients showed that OA and RA synovial cells produced similar amounts of monomeric COMP of identical size to those COMP monomers produced by normal synovial cells. The addition of TGF-beta to these cultures resulted in an increase in COMP production in normal, OA and RA synovial cells (45, 116 and 115% respectively). CONCLUSION: These studies demonstrate that substantial amounts of COMP are produced by several mesenchymal cells including synoviocytes and dermal fibroblasts. These findings raise important concerns regarding the utility of measurements of COMP levels in serum or in synovial fluid as markers of articular cartilage degradation because of the likelihood that a substantial proportion of COMP or COMP fragments present in serum or synovial fluid may be produced by cells other than articular chondrocytes.     

Effect of cartilage oligomeric matrix protein on mesenchymal chondrogenesis in vitro

OBJECTIVE: Cartilage oligomeric matrix protein (COMP) mutations have been identified as responsible for two arthritic disorders, multiple epiphyseal dysplasia (MED) and pseudoachondroplasia (PSACH). However, the function of COMP in chondrogenic differentiation is largely unknown. Our investigation focuses on analyzing the function of normal COMP protein in cartilage biology. METHODS AND RESULTS: To explore the function of COMP we make use of an in vitro model system for chondrogenesis, consisting of murine C3H10T1/2 mesenchymal cells maintained as a high-density micromass culture and stimulated with bone morphogenetic protein 2 (BMP-2). Under these culture conditions, C3H10T1/2 cells undergo active chondrogenesis in a manner analogous to that of embryonic limb mesenchymal cells, and have been shown to serve as a valid model system to investigate the mechanisms regulating mesenchymal chondrogenesis. Our results indicate that ectopic COMP expression enhances several early aspects of chondrogenesis induced by BMP-2 in this system, indicating that COMP functions in part to positively regulate chondrogenesis. Additionally, COMP has inhibitory effects on proliferation of cells in monolayer. However, at later times in micromass culture, ectopic COMP expression in the presence of BMP-2 causes an increase in apoptosis, with an accompanying reduction in cell numbers in the micromass culture. However, the remaining cells retain their chondrogenic phenotype. CONCLUSIONS: These data suggest that COMP and BMP-2 signaling converge to regulate the fate of these cells in vitro by affecting both early and late stages of chondrogenesis.     

尿草酸钙晶体基质蛋白的分离及理化特征

为了进一步了解晶体基质蛋白（ＣＭＰ）的理化特性和其在结石形成中的作用，利用ＤＥＡＥＳｅｐｈａｄｅｘＡ５０、ＳｅｐｈａｄｅｘＧ２００对草酸钙结晶中的基质蛋白进行了分离，并用ＳＤＳＰＡＧＥ、双向电泳和Ｗｅｓｔｅｒｎｂｌｏｔ进行检测。结果表明：ＣＭＰ是草酸钙过饱和方法制备的晶体基质中的主要成分，其分子量为３１０００，等电点为５．０～５．５；Ｗｅｓｔｅｒｎｂｌｏｔ证明与抗人凝血酶原抗体有交叉反应。结果认为ＣＭＰ是活化的人凝血酶原片段     

骨关节炎患者滑液中COMP水平与病情严重程度的相关性研究

背景：软骨寡聚基质蛋白（cartilage oligomeric matrix protein,COMP）是软骨中非胶原蛋白的主要成分,软骨的损伤、修复和代谢变化均可能影响COMP的表达水平。目的：研究骨关节炎（osteoarthritis,OA）患者关节滑液中COMP水平与病变严重程度的相关性,探讨注射玻璃酸钠对关节滑液中COMP的影响。方法：52例膝关节0A患者接受关节内注射玻璃酸钠治疗,治疗前、治疗后6个月行X线片检查,按Kellgren放射学诊断标准评级,记录治疗前和治疗开始后5周、6个月时患者膝关节的WOMAC评分。采用ELISA方法测定在接受透明质酸钠治疗前、治疗开始后5周关节液中的COMP水平。19例因半月板或韧带损伤接受关节镜手术的患者作为正常对照组。结果：OA组患者滑液中COMP水平明显高于对照组,有统计学差异（P=0．036）。OA组患者滑液中COMP水平与OA严重程度（WOMAC评分）呈正相关（P=0．001）,与影像学Kellgren分级标准无相关性（P=0．12）。结论：滑液中COMP水平与OA病变严重程度呈正相关,测定OA患者血中COMP水平对进一步研究OA发病机理、早期发现并采取有效防治策略及监测防治效果具有极其重要的意义。     

Age-related biological characterization of mesenchymal progenitor cells in human articular cartilage

Adult articular cartilage has a low regeneration capacity due to lack of viable progenitor cells caused by limited blood supply to cartilage. However, recent studies have demonstrated the existence of chondroprogenitor cells in articular cartilage. A critical question is whether these mesenchymal progenitor cells are functionally viable for tissue renewal and cartilage repair to postpone cartilage degeneration. This study was designed to compare the number and function of mesenchymal progenitor cells in articular cartilage collected from human fetuses, healthy adults (aged 28-45 years), and elderly adults (aged 60-75 years) and cultured in vitro. We detected multipotent mesenchymal progenitor cells, defined as CD105+/CD166+ cells, in human articular cartilage of all ages. However, mesenchymal progenitor cells accounted for 94.69%±2.31%, 4.85%±2.62%, and 6.33%±3.05% of cells in articular cartilage obtained from fetuses, adults, and elderly patients, respectively (P<.001). Furthermore, fetal mesenchymal progenitor cells had the highest rates of proliferation measured by cell doubling times and chondrogenic differentiation as compared to those from adult and elderly patients. In contrast, alkaline phosphatase levels, which are indicative of osteogenic differentiation, did not show significant reduction with aging. However, spontaneous osteogenic differentiation was detected only in mesenchymal progenitor cells from elderly patients (with lower Markin scales). The lower chondrogenic and spontaneous osteogenic differentiation of mesenchymal progenitor cells derived from elderly patients may be associated with the development of primary osteoarthritis. These results suggest that measuring cartilage mesenchymal progenitor cells may not only identify underlying mechanisms but also offer new diagnostic and therapeutic potential for patients with osteoarthritis.     

Measurement of cartilage oligomeric matrix protein (COMP) in normal and diseased equine synovial fluids

OBJECTIVE: This study was designed to assay cartilage oligomeric matrix protein (COMP) in equine synovial fluids and to compare the concentration in synovial fluids from normal horses with joint diseased horses. The relationship between the COMP degradation and the matrix metalloproteinase activity in synovial fluids was also investigated. DESIGN: Using COMP antigen prepared from equine articular cartilage and murine monoclonal antibody (12C4) raised against human COMP, an inhibition ELISA was developed. COMP in equine synovial fluids from normal and diseased joints was quantified. Metalloproteinase activities were evaluated in the same synovial fluids by a gelatin degradation ELISA. COMP fragments were evaluated qualitatively by Western blotting. RESULTS: The COMP inhibition ELISA was reliable at concentrations of equine COMP between 62.5 and 2000 ng/ml. COMP values in joint fluids in both aseptic and septic joint disease (19.7+/-15.3 and 16.1+/-11.2 microg/ml, respectively) were significantly (P < 0.001) lower than normal (53.2+/-29.0 microg/ml). The molecular sizes of COMP on immunoblots were different between normal and diseased synovial fluids; more fragments were seen in diseased fluids. The aseptic (26.6 +/- 20.6%) and septic joint disease synovial fluids (36.1 +/- 37.5%) had significantly higher (P < 0.02 and 0.002, respectively) gelatinolytic activities than normal (13.6 +/- 13.7%). There was a negative correlation (R = -0.31, P < 0.002) between COMP level and gelatinase activity.Conclusions We conclude that the fragment pattern and the absolute COMP concentration maybe useful for monitoring joint disease, and that COMP degradation in synovial fluids from progressed joint disease may be due to MMP gelatinolytic activity.     

An experimental study of COMP (cartilage oligomeric matrix protein) in the rabbit menisci

Introduction  

Secondary knee osteoarthritis (OA) is currently associated with meniscal injuries, but the pathogenesis is unclear. We analyzed the distribution of cells and cartilage oligomeric matrix protein (COMP) and its changes in the early stages of degeneration in meniscus.     

Isolation and characterization of a metalloprotease associated with chicken epiphyseal cartilage matrix vesicles

Matrix vesicles are present in the calcifying front and in the site of callus formation of fracture heeling. In calcifying process, matrix vesicles have important roles. The metalloprotease was isolated from matrix vesicles and subsequently characterized. Matrix vesicles obtained from chicken epiphysial cartilage by collagenase digestion and differential centrifugation were further purified by Sepharose CL2B gel filtration. The protease was solubilized from the vesicles and isolated by Sephadex G-150 gel filtration. Disc electrophoresis of the enzyme gave a single protein band. The matrix vesicle protease had a MW of 33,000 daltons, an optimal pH of 7.2, and was inhibited 100% by 0.1 mM EDTA and 0.2 mM o-Phenanthroline. alpha 2-Macroglobulin, ovalbumin, cysteine, penicillamine, ethane-1-hydroxy-1, 1-diphosphonate (EHDP) and pyrophosphate at higher concentrations were also inhibitory. The inhibition by o-phenanthroline was reversed by Co2+, Zn2+, Fe2+ and Cu2+. The protease released from the matrix vesicle at the calcifying front could degrade non-collagenous protein moieties which inhibit precipitation of minerals in the extra-vesicular matrix and thus facilitate mineralization.     

Isolation and characterization of a metalloprotease associated with chicken epiphyseal cartilage matrix vesicles

A metalloprotease has been isolated from matrix vesicles of chicken epiphyseal cartilage and subsequently characterized. Matrix vesicles obtained by collagenase digestion and differential centrifugation were further purified by Sepharose CL2B gel filtration. The protease was solubilized from the vesicles by treatment with deoxycholate and freeze-thawing, and then isolated by Sephadex G150 gel filtration. Disc electrophoresis of the enzyme, which displayed protease activity toward azocasein substrate, gave a single protein band. Based on molecular weight (MW) determination, lack of immunocross reactivity, and differences in electrophoretic migration, there is little possibility of any contamination with external protease from the commercial collagenase used for vesicle preparation. The matrix vesicle protease had a MW of 33,000 and a pH optimum of 7.2 and was completely inhibited by 0.1 mM EDTA and 0.2 mM o-phenanthroline. alpha 2-Macroglobulin, ovalbumin, cysteine, penicillamine, ethane-1-hydroxy-1, 1-diphosphonate (EHDP) and pyrophosphate at higher concentrations were also inhibitory. The inhibition by omicron-phenanthroline was reversed by Co2+, Zn2+, Fe2+, and Cu2+. Protease activity was most abundant in the heavy fraction of matrix vesicles fractionated by discontinuous sucrose density gradient centrifugation. Release of this protease at the calcifying front could degrade noncollagenous protein moieties that inhibit precipitation of minerals in the extravesicular matrix and thus facilitate mineralization.     

Serum cartilage oligomeric matrix protein and clinical signs and symptoms of potential pre-radiographic hip and knee pathology

OBJECTIVE: To examine the cross-sectional relationship between serum cartilage oligomeric matrix protein (COMP) and hip and knee clinical signs and symptoms in a sample of adults without radiographic hip or knee osteoarthritis (OA). DESIGN: A total of 145 persons with available sera and no evidence of radiographic hip or knee OA (Kellgren-Lawrence grade 0) were randomly selected from the Caucasian participants of the Johnston County Osteoarthritis Project. COMP was quantified by a competitive ELISA assay with a monoclonal antibody 17-C10. Hip and knee clinical signs and symptoms were assessed by physical examination and interview, and their associations with Ln COMP analysed with general linear models. RESULTS: After adjustment for age, gender, body mass index (BMI), and other symptomatic joints, mean Ln COMP was statistically significantly higher among persons with hip-related clinical signs (P=0.018), among those with hip-related symptoms (P=0.046), and among individuals meeting American College of Rheumatology clinical criteria for hip OA (P=0.021). There were no statistically significant associations between any of the knee-related clinical signs and symptoms and Ln COMP. CONCLUSION: Serum COMP may be useful as a biomarker of pre-radiographic hip joint pathology; its utility as a biomarker of pre-radiographic knee joint pathology is unclear.     

Increased serum levels of non-collagenous matrix proteins (cartilage oligomeric matrix protein and melanoma inhibitory activity) in marathon runners

OBJECTIVE: Marathon runners have an increased risk of developing joint disease. During and after a 42-km run, elevation of multiple cytokines occurs in the blood, reflecting inflammatory processes. We compared this cytokine response with serum levels of cartilage oligomeric matrix protein (COMP) and melanoma inhibitory activity (MIA), two markers for joint metabolism and/or damage. METHODS: Serum from eight endurance-trained runners was collected shortly before the start of a marathon run, after 31 km, 42 km, 2 h after the end, on the first and on the second morning after the run. For comparison, serum was obtained from 35 healthy controls and 80 patients with knee joint injury, rheumatoid arthritis or osteoarthritis. Serum levels of C-reactive protein (CRP), interleukin-1beta (IL-1beta), interleukin-1 receptor antagonist (IL-1RA), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble interleukin-6 receptor (sIL-6R, gp80), soluble tumor necrosis factor receptor II (sTNFRII, p75), COMP and MIA were measured by ELISA. RESULTS: Compared with healthy controls, the runner's baseline serum levels of TNF-alpha, sIL-6R, COMP and MIA were significantly increased. COMP and MIA levels, higher than the upper normal limits of 5 microg/ml and 6 ng/ml respectively, were found in seven and five of eight runners. The elevated levels of COMP were similar to those found in joint injury or osteoarthritis, and the elevated levels of MIA were comparable to those reported in rheumatoid arthritis. During the run, the serum levels of IL-1RA, IL-6, TNF-alpha and COMP rose significantly, and gradually returned to baseline within 24 h. Only modest changes of CRP, sIL-6R, sTNFRII and MIA occurred during the run. Late elevations of CRP and MIA were observed after 24 and 48 h. The correlation analysis suggests associations between COMP, sIL-6R, TNF-alpha, IL-1RA on one hand and sTNFRII, and MIA and CRP on the other hand. CONCLUSIONS: Elevated baseline levels of COMP and MIA might reflect increased joint matrix turnover and/or damage due to prior extreme physical training. During the run, COMP was increasing possibly due to the severe physical strain on joint structures, associated with the early inflammation. After the run, MIA and CRP increased within 24 h, suggesting a correlation with later inflammatory processes. Thus, our data suggest that COMP and MIA are markers for distinct aspects of joint metabolism and/or damage in both disease and sport.