Expression of bone morphogenetic proteins, cartilage-derived morphogenetic proteins and related receptors in normal and osteoarthritic human articular cartilage.

Newborn and adult articular cartilage expresses bone (BMPs) and cartilage derived morphogenetic proteins (CDMPs). These morphogenetic proteins act over membrane receptors (BMPRs). We examined the expression pattern of BMP-7, BMP-3, CDMP-1, CDMP-2 and their receptors in adult normal and osteoarthritic, articular, knee cartilage. Immunostaining was carried out using polyclonal antibodies. The expression of BMP-7,-3, CDMP-1,-2 was detected in all layers of normal articular cartilage with the strongest expression in chondrocytes of the transitional layer. BMP-7 and CDMPs expression decreased in osteoarthritic articular cartilage whereas BMP-3 expression was absent. BMPR-IA and BMPR-II were strongly expressed in both normal and osteoarthritic articular cartilage. BMPR-IB was not expressed in osteoarthritic (OA) cartilage. BMPs and CDMPs with intact signalling play an important role in articular cartilage homeostasis, preventing cartilage degeneration.