rhBMP-2, rhVEGF165, rhPTN and thrombin-related peptide, TP508 induce chemotaxis of human osteoblasts and microvascular endothelial cells

Osteogenesis and angiogenesis are inter-linked and tightly regulated processes involved in growth, repair, and bone remodeling. Bone morphogenic protein 2 (BMP-2), vascular endothelial growth factor (VEGF), pleiotrophin (PTN) and thrombin-related peptide, TP508 have all been found to have the ability to promote bone fracture healing by enhancing both the osteogenesis and angiogenesis processes. One of the underlying mechanisms proposed is that mediators for osteogenesis may also be involved in mediating angiogenesis and vice versa. The aim of this study was to examine the chemotactic effects of rhBMP-2, rhVEGF165, rhPTN and TP508 on human osteoblasts and endothelial cells. Using a direct-viewing chemotaxis assay system, we report for the first time, the direct quantitative observation of chemotaxis of both human osteoblastc cells and microvascular endothelial cells towards sources of rhBMP-2, rhVEGF165, rhPTN and TP508. This study confirmed that rhBMP-2, rhVEGF165, rhPTN and TP508 have chemotactic effects on both human osteoblastic and endothelial cells, indicating that these factors are directly involved in promoting angiogenesis and osteogenesis by recruiting osteoblasts and endothelial cells via chemotaxis.