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Virchows Arch (2012) 461:205210 DOI 10.1007/s00428-012-1274-3
ORIGINAL ARTICLE
Chondroclasts are mature osteoclasts which are capable of cartilage matrix resorption
H. J. Knowles & L. Moskovsky & M. S. Thompson &
J. Grunhen & X. Cheng & T. G. Kashima &
N. A. Athanasou
Received: 25 January 2012 /Revised: 8 May 2012 /Accepted: 25 June 2012 /Published online: 11 July 2012 # Springer-Verlag 2012
Abstract Multinucleated cells termed chondroclasts have been observed on the deep surface of resorbed hyaline cartilage but the relationship of these cells to macrophages and osteoclasts and their role in rheumatoid arthritis (RA) and other arthritic conditions is uncertain. Multinucleated cells in RA and other arthritic conditions showing evidence of cartilage resorption were characterised immunohisto-chemically for expression of macrophage/osteoclast markers. Mature human osteoclasts formed from circulating monocytes and tissue macrophages were cultured for up to 4 days on slices of human cartilage and glycosaminoglycan (GAG) release was measured. Multinucleated cells resorbing unmineralised cartilage were seen in osteoarthritis, RA, septic arthritis, avascular necrosis and in four cases of giant cell tumour of bone that had extended through the subchondral bone plate. Chondroclasts expressed an osteoclast-like phenotype (TRAP+, cathepsin K+, MMP9+, CD14, HLA
DR, CD45+, CD51+ and CD68+). Both macrophages and osteoclasts cultured on cartilage released GAG. These findings indicate that chondroclasts have an osteoclast-like phenotype and that mature human osteoclasts are capable of cartilage matrix resorption. Resorption of unmineralised subchondral cartilage by chondroclasts and macrophages
can be a feature of joint destruction in inflammatory and non-inflammatory arthropathies as well as inflammatory and neoplastic subchondral bone lesions.
Keywords Osteoclast . Chondroclast . Cartilage . Resorption
AbbreviationsRANKL Receptor activator of nuclear factor kappa B ligandM-CSF Macrophage-colony stimulating factor MMP Matrix metalloproteinaseTRAP Tartrate-resistant acid phosphataseOA OsteoarthritisGAG Glycosaminoglycan
Introduction
Resorption or degradation of the deep surface of joint cartilage is seen in a number of pathological conditions, including inflammatory and non-inflammatory arthropathies as well as primary and secondary epiphyseal tumours and infections involving overlying cartilage. Multinucleated cells termed chondroclasts have been identified at sites of mineralised and non-mineralised articular hyaline cartilage erosion in the rheumatoid joint [13]. These cells have not been characterised in other arthritic conditions and remain poorly defined in terms of their relationship to other matrix-resorbing cells, particularly osteoclasts.
Osteoclasts are multinucleated cells which...