Type X collagen synthesis in human osteoarthritic cartilage. Indication of chondrocyte hypertrophy. |
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Authors: | K von der Mark T Kirsch A Nerlich A Kuss G Weseloh K Glückert H St?ss |
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Institution: | Max-Planck-Society, Department of Orthopaedics, Waldkrankenhaus St. Marien, Erlangen, Federal Republic of Germany. |
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Abstract: | OBJECTIVE: To investigate the appearance of hypertrophic chondrocytes in osteoarthritic (OA) cartilage, using type X collagen as a specific marker. METHODS. The biosynthesis of type X collagen was examined by metabolic labeling of freshly isolated articular chondrocytes with 3H-proline, immunoprecipitation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the synthesized collagens. Extracellular deposition of types X and II collagen was analyzed immunohistochemically. RESULTS. Immunostaining revealed an irregular distribution of type X collagen, which was localized around chondrocyte clusters in fibrillated OA cartilage, but was absent from the noncalcified region of normal articular cartilage. Freshly isolated OA chondrocytes synthesized predominantly type X collagen, while control chondrocytes synthesized mostly type II collagen. CONCLUSION. Our findings indicate focal premature chondrocyte differentiation to hypertrophic cells in OA cartilage. |
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