engleski

Expression of BMP-3, BMP-7, CDMP-1 and CDMP-2 in healthy and osteoarthritic knee articular cartilage in elderly people

Cartilage-derived morphogenetic proteins 1 and 2 (CDMP-1 and CDMP-2) are members of the bone morphogenetic protein (BMP) family. Localization studies establish the involvement of CDMP-1 and CDMP-2 in development, growth and maintenance of cartilaginous tissues. Furthermore, BMP-7 is the only member of BMP family, along with CDMPs, found to be expressed by chondrocytes in adult articular cartilage. BMP-7 stimulates the synthesis of proteoglycans that may play a role in the maintenance of a steady-state concentration of proteoglycans in human articular cartilage. Some data show that the synthesis of proteoglycans in explants of bovine articular cartilage is increased by BMP-3. The early events in the OA are changes in the metabolism and biochemistry of articular cartilage matrix. Great loss of cartilage tissue is a late event. Thus increased degradation of cartilage matrix is a key event in the development of OA. However, since cartilage matrix is continuously turned over under physiological conditions, loss of the matrix may be the result of defective mechanisms for replacement and repair of matrix. The aim was to investigate the expression of CDMPs and BMPs in healthy articular cartilage from elderly people and OA cartilage. Ten cartilage samples of knee joint were taken postmortem from human donors (70 yr) and from eleven patients with knee joint osteoarthritis who underwent total knee athroplasty. The samples were stained with Safranin-O and by immunohistochemistry using polyclonal antibodies specific for CDMP-1, CDMP-2, BMP-3, and BMP-7. In the articular cartilage of elderly people with strong reduction in proteoglycan staining we detected high level of CDMPs and BMPs expression in the cells of all cartilage layers. In the tangential and partly in transitional layers we found diffuses matrix positive staining or pericellular space positive staining. In the articular cartilage without proteogycan reduction, we found low level of CDMPs and BMPs expression in the cells of transitional layer and matrix positive staining in the superficial layer. In OA cartilage we found BMP-3 and BMP-7 cytoplasmic staining with very strong positive matrix staining. These results imply the role of CDMPs and BMPs in maintenance of cartilage homeostasis, protection or repair.

articular cartilage; BMPs; CDMPs

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