engleski

The role of bone morphogens in human osteophyte formation

Apart from degenerative changes in osteoarthritis, formation of new cartilage and bone occurs at the margin of articular surfaces, forming bone spurs, osteophytes. Bone morphogens (BMPs) have an important effect on skeleton during fetal development and postnatal bone regeneration. We therefore investigated their presence in human osteophytes collected during joint replacement surgery. Twenty osteophytes isolated from osteoarthritic hip and kree joints were included in the present study. After dissection from the surrounding tissue, osteophytes were fixed in 4%-PFA, embedded in MMA and cut serially at 200 mm intervals on 5-7 mm slices. To determine structure and presence of BMPs in osteophytes, we used histology (Toluidine blue, Safranine O) and immunohistochemistry. Although osteophyters were different in size, shape and originated from different joints, txey exhibited very similar morphology, characsterized by hyaline cartilage subjected to a cascade similar to endochondral bone formation. Intramembranous ossification was also observed within covering fibrous tissue. BMP family members were differentially localized in defeloping osteophyte tissues. Positive BMP-2 immunostaining was observed in fibrous tissue matrix as well as in osteoblasts ; BMP-3 was found in osteoblasts and osteocytes, with less intense staining observed in cartilage and bone matrix ; BMP-5 staining was discrete and present mainly in osteoblasts ; BMP-6 staining was restricted to young ostecytes and bone dmatrix. BMP-7 was observed in hypertrophic chondrocytes, ossteoblasts, young osteocytes of both endochondral and intramembranous bone matrix. Intense CDMP-1, -2, -3 staining was found in all cartilage cells. The presence of BMPs and CDMPs in osteophytic tissue suggested that different members of BMP family might have specific roles in growth and development of osteophytes.

bone morphogenetic proteins; osteophyte

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