Objective. The process of N-glycosylation is involved in the pathogenesis of various diseases. However, little is known about the contribution of changes in N-glycans in osteoarthritis (OA). The aim of this study was to identify the alterations in N-glycans in human OA cartilage, to characterize the messenger RNA (mRNA) expression of N-glycan biosynthesis enzyme genes (N-glycogenes) in mouse articular chondrocytes during cartilage degradation, and to analyze the relationship between altered N-glycan patterns and mechanisms of cartilage degradation.Methods. Alterations in N-glycans were analyzed in human OA cartilage and degraded mouse cartilage by high-performance liquid chromatography and mass spectrometry. N-glycogene mRNA expression in mouse chondrocytes was measured using reverse transcription-polymerase chain reaction. To assess the relationship between the altered N-glycans and degradation of mouse cartilage, experiments involving either knockdown or overexpression of N-glycogenes were performed in mouse articular chondrocytes.Results. Alterations in high-mannose type N-glycans were observed in both human OA cartilage and degraded mouse cartilage. The expression of ␤1,2N-acetylglucosaminyltransferase I (GlcNAc-TI) mRNA, which converts high-mannose type N-glycans, was significantly increased in degraded mouse cartilage. Mouse chondrocytes with suppressed GlcNAc-TI expression had reduced levels of matrix metalloproteinase 13 (MMP-13) and ADAMTS-5 (aggrecanase 2) mRNA following stimulation with interleukin-1␣ (IL-1␣). In contrast, mouse chondrocytes overexpressing GlcNAc-TI had increased levels of MMP-13 and ADAMTS-5 mRNA following stimulation with IL-1␣.Conclusion. These findings indicate that alterations in high-mannose type N-glycans and N-glycogenes in chondrocytes correlate with the release of MMP-13 and ADAMTS-5 during cartilage degradation. These findings suggest that N-glycans play a crucial role in the initiation and progression of OA.Osteoarthritis (OA), the most common joint disease, is characterized by the degradation of articular cartilage, which frequently leads to disability in older persons, particularly in performing daily activities. Chondrocytes are the only cells in cartilage responsible for the synthesis and degradation of the extracellular matrix (ECM). Chondrocyte metabolism is regulated by genetic and environmental factors, such as the composition of the ECM, soluble mediators, and mechanical factors. A breakdown in the balance of this metabolism results in cartilage degradation. Elucidation of the pathogenesis of OA requires a better understanding of the mechanism of cartilage degradation. Despite the large number of biomechanical and biochemical studies performed to clarify the mechanisms of cartilage degradation (1-7), these mechanisms remain unclear.Glycobiology, the study of the biologic functions of sugar chains bound to proteins and lipids, was recently applied to molecular-based studies in the biomedical field (8-11). The majority of glycans attached to proteins

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Objective This study aimed to compare standard saline lavage to combination saline and high-pressure carbon dioxide (CO) lavage in removing marrow elements from osteochondral allografts. Design Six fresh hemicondyles were obtained. Three osteochondral allograft plugs (15-mm diameter, 6-mm depth) were harvested from each hemicondyle and randomized to 1 of 3 treatment arms: A, no lavage; B, 1 L standard saline lavage; C, simultaneous saline (1 L) and 1-minute high-pressure CO lavage. After hematoxylin and eosin staining, a "percentage fill" of remaining marrow elements was calculated for each overall sample and then repeated in 3 distinct compartments for each sample based on depth from surface: 1, deepest third; 2, middle third; and 3, most superficial third. Trial arms B and C were compared with 1-tailed Student t tests. Results Group A had an overall percentage fill of 51.2% ± 8.8%. While both lavage techniques decreased overall remaining marrow elements, group B yielded significantly higher percentages of remaining marrow elements than group C (28.6% ± 16.5%, 14.6% ± 8.7%, P = 0.045). On depth analysis, group A exhibited homogenous filling of trabecular space (63.0% ± 15.5%, 67.6% ± 13.7%, and 55.2% ± 10.1% in zones 1, 2, and 3, respectively). Both lavage arms equally removed marrow elements from superficial zone 3 (B, 17.4% ± 9.2%; C, 15.6% ± 12.4%, P = 0.41) and middle zone 2 (B, 30.2% ± 17.7%; C, 21.4% ± 15.5%, P = 0.18). However, group C lavage removed significantly more marrow elements in deep zone 1 than group B (29.7% ± 10.9%, 58.5% ± 25.2%, P = 0.01). Conclusion Combination saline and high-pressure CO lavage more effectively clears marrow elements from osteochondral allografts than saline alone.