K Gelse1, S Söder, W Eger, T Diemtar, T Aigner. 1. Cartilage Research, Department of Pathology, University of Erlangen-Nürnberg, Federal Republic of Germany.
Abstract
OBJECTIVE: Osteophytes are non-neoplastic osteo-cartilaginous protrusions growing at the margins of osteoarthritic joints. They can not only be considered as in situ repair tissue, but also represent an excellent in vivo model for induced cartilage repair processes. Our focus was to identify different steps of osteophyte development via analysis of expression patterns of marker genes of chondrocytic differentiation. DESIGN: We performed an extensive analysis of the presence and expression of matrix components using histochemical, immunohistochemical and in situ hybridization technology. RESULTS: Four different stages of osteophyte formation could be identified based on histomorphological and cell biological parameters: starting from mesenchymal condensates, chondrogenic differentiation is indicated by the onset of Col2A and aggrecan expression (stage I). Stage II shows fibrocartilage with an admixture of cartilaginous and fibrous matrix components such as Col2 and aggrecan on the one hand and Col1 on the other hand. The proliferating osteophyte (stage III) shows a zonal organization similar to the fetal growth plate cartilage with extensive chondrocyte hypertrophy in the zones next to ongoing endochondral bone formation. 'Mature' osteophytes (stage IV) resembled largely articular hyaline cartilage with a predominance of Col2 and aggrecan and Col6 found mainly pericellularily. CONCLUSIONS: The development of osteophytes is a good in vivo model to pursue chondrocyte differentiation from pluripotent mesenchymal cells to mature or hypertrophic chondrocytes in situ in the adult. The analysis of marker molecules of mesenchymal differentiation allows to identify different stages of repair tissue development and the transformation from fibrous tissue to neo-cartilage. Tissue architecture and matrix composition in mature osteophytes suggests that metaplastic neo-cartilagenous tissue might be one potential source of cartilage repair tissue in the adult joint. Copyright 2003 Published by Elsevier Science Ltd on behalf of OsteoArthritis Research Society International.
OBJECTIVE: Osteophytes are non-neoplastic osteo-cartilaginous protrusions growing at the margins of osteoarthritic joints. They can not only be considered as in situ repair tissue, but also represent an excellent in vivo model for induced cartilage repair processes. Our focus was to identify different steps of osteophyte development via analysis of expression patterns of marker genes of chondrocytic differentiation. DESIGN: We performed an extensive analysis of the presence and expression of matrix components using histochemical, immunohistochemical and in situ hybridization technology. RESULTS: Four different stages of osteophyte formation could be identified based on histomorphological and cell biological parameters: starting from mesenchymal condensates, chondrogenic differentiation is indicated by the onset of Col2A and aggrecan expression (stage I). Stage II shows fibrocartilage with an admixture of cartilaginous and fibrous matrix components such as Col2 and aggrecan on the one hand and Col1 on the other hand. The proliferating osteophyte (stage III) shows a zonal organization similar to the fetal growth plate cartilage with extensive chondrocyte hypertrophy in the zones next to ongoing endochondral bone formation. 'Mature' osteophytes (stage IV) resembled largely articular hyaline cartilage with a predominance of Col2 and aggrecan and Col6 found mainly pericellularily. CONCLUSIONS: The development of osteophytes is a good in vivo model to pursue chondrocyte differentiation from pluripotent mesenchymal cells to mature or hypertrophic chondrocytes in situ in the adult. The analysis of marker molecules of mesenchymal differentiation allows to identify different stages of repair tissue development and the transformation from fibrous tissue to neo-cartilage. Tissue architecture and matrix composition in mature osteophytes suggests that metaplastic neo-cartilagenous tissue might be one potential source of cartilage repair tissue in the adult joint. Copyright 2003 Published by Elsevier Science Ltd on behalf of OsteoArthritis Research Society International.
Authors: Claudine G James; C Thomas G Appleton; Veronica Ulici; T Michael Underhill; Frank Beier Journal: Mol Biol Cell Date: 2005-08-31 Impact factor: 4.138
Authors: Jason S Rockel; Chunying Yu; Heather Whetstone; April M Craft; Katherine Reilly; Henry Ma; Hidetoshi Tsushima; Vijitha Puviindran; Mushriq Al-Jazrawe; Gordon M Keller; Benjamin A Alman Journal: J Clin Invest Date: 2016-03-28 Impact factor: 14.808