Neoangiogenesis drives the replacement of mineralized cartilage by trabecular bone during bone growth regulated by molecules like e.g. VEGF, OPG and RANKL and the close interaction of progenitors of osteoblasts, chondrocytes, endothelial cells and osteoclasts/chondroclasts. The Heparan sulfate proteoglycan Syndecan-1 (Sdc-1) plays a role in the interaction between osteoclasts and osteoblasts and the development of blood vessels. As the processes of osteogenesis and angiogenesis are closely related to each other in bone, we expected Sdc-1 to have an influence on vessel structure during aging. Therefore, angiogenesis at the growth plate in mice of different ages was compared and the influence of Syndecan-1 deficiency was characterized. Animals: C57BL/6 (WT) and Sdc1−/− mice were used for native bone analysis at 4, 12 and 18 month age. Femura were dissected, cryoprotected and embedded. Histology: Embedded bones were sectioned into 80um thick slices so that the 3D network of the vascularization of the bone could be visualized using an anti-Endomucin antibody and DAPI as counter staining. For semi-automatical quantification of the vessel bulbs we used a custom made software. In vitro angiogenesis: For aortic ring assay, aortic tissue was isolated from 4 month old mice, cut into 0.5mm rings and embedded in collagen type I matrix. Microvessel outgrowth was quantified after 6 days of culture.Introduction and Objective
Materials and Methods
