Craniofacial bone defects are observed in a variety of clinical situations and their reconstructions require coordinated coupling between angiogenesis and osteogenesis. After 3 weeks bone regeneration was evaluated using micro-computed tomography TH1338 and histologic examination. Pericyte recruitment into the defects was examined using immunofluorescence staining with anti-NG2 and anti-CD31 antibodies. recruitment and osteoblastic differentiation of pericyte cells were assessed with Boyden chamber assay staining of calcified nodules RT-PCR and Western blot analyses. Combined administration of COMP-Ang1 and BMP2 synergistically enhanced bone repair along with the increased population of CD31 (an endothelial cell marker) and NG2 (a specific marker of TH1338 pericyte) positive cells. cultures of pericytes consistently showed that pericyte infiltration into the membrane pore of Boyden chamber was more enhanced by the combination treatment. In addition the combination further increased the osteoblast-specific gene expression including bone sialoprotein (BSP) osteocalcin (OCN) and osterix (OSX) phosphorylation of Smad/1/5/8 and mineralized nodule formation. COMP-Ang1 can enhance BMP2-induced cranial bone regeneration TH1338 with increased TH1338 pericyte recruitment. Combined delivery of the proteins might be a therapeutic strategy to repair cranial bone damage. Introduction Repair of bone defects requires a coordinated coupling between osteogenesis and angiogenesis for regeneration [1]. It involves a multistep process that includes migration proliferation and differentiation of several types of cells such as endothelial TH1338 cells fibroblasts osteoblasts osteoclasts and pericytes within the bone microenvironment [2 3 Angiogenesis has an impact on bone formation since oxygen nutrients osteoinductive factors and stem cells are supplied into the defect area through the blood stream. In addition the formation of vascular wall contributes to migration of osteoblast progenitor cells such as pericytes into target site [4]. Pericytes are specialized cells that wrap around the endothelial cells of capillaries and venules and play critical roles in TH1338 various physiological contexts including support of vascular structure and function initiation of vessel sprouting and stabilization of vessel. Mesenchymal stem cells (MSCs) and pericyte progenitors are both perivascular cells with comparable multipotent properties regardless of tissue of origin; they are shown to be capable of differentiating into osteoblasts chondrocytes adipocytes and fibroblasts under special stimulations [5 6 Moreover pericytes have come under increasing scrutiny as possible osteogenic precursors because they express the bone matrix protein such as BSP and OCN. Thus a growing interest exists in the recruitment proliferation and osteoblastic differentiation of pericytes for therapeutic bone regeneration. Proliferation and recruitment of pericytes are under the influence of angiogenic growth factors which are secreted from surrounding cells in the microenvironment such as endothelial cells. For example endothelial-derived PDGF-BB and HB-EGF coordinately regulate pericyte recruitment during vasculogenic tube assembly and stabilization [7 8 VEGF-A and angiopoietin-1 (Ang-1) also act on pericytes in an autocrine and paracrine manner to stimulate their proliferation and migration with activation of their receptors [9 10 Bone morphogenetic proteins (BMPs) are well characterized as the most potent osteoinductive factors to differentiate MSCs into osteoblasts and play a critical role in osteogenesis fracture repair and bone regeneration [11]. Since recombinant BMP2 became available many animal studies have been performed to examine the induction of bone Rabbit polyclonal to c-Myc (FITC) formation and repair of bony defects following implantation of BMP2 [12]. Combined treatment with angiogenic factors and BMPs has been considered for the improvement of reconstruction of large craniofacial defects. Delivery of VEGF and BMPs synergizes to enhance the repair of critical sized-bone defects or ectopic bone formation [13 14 FGF2 and BMP2 also showed a synergistic mineralization in cell cultures from elderly mouse and human bone [15]. The.