Wang, Ling

Objective— Tissue factor pathway inhibitor (TFPI) is the primary regulator of the tissue factor (TF) coagulation pathway. As such, TFPI may regulate the proangiogenic effects of TF. TFPI may also affect angiogenesis independently of TF, through sequences within its polybasic carboxyl terminus (TFPI C terminus [TFPIct]). We aimed to determine the effects of TFPI on angiogenesis and the role of TFPIct. Methods and Results— Transgenic overexpression of TFPI attenuated angiogenesis in the murine hindlimb ischemia model and an aortic sprout assay. In vitro, TFPI inhibited endothelial cell migration. Peptides within the human TFPIct inhibited endothelial cell cord formation and migration in response to vascular endothelial growth factor (VEGF) 165 but not VEGF121. Furthermore, exposure to human TFPIct inhibited the phosphorylation of VEGF receptor 2 at residue Lys951, a residue known to be critical for endothelial cell migration. Finally, systemic delivery of a murine TFPIct peptide inhibited angiogenesis in the hindlimb model. Conclusion— These data demonstrate an inhibitory role for TFPI in angiogenesis that is, in part, mediated through peptides within its carboxyl terminus. In addition to its known role as a TF antagonist, TFPI, via its carboxyl terminus, may regulate angiogenesis by directly blocking VEGF receptor 2 activation and attenuating the migratory capacity of endothelial cells.

Abstract Here, we report an intrinsic property of gold nanoparticles (nanogold): they can interact selectively with heparin-binding glycoproteins and inhibit their activity. Gold nanoparticles specifically bound vascular permeability factor/vascular endothelial growth factor (VPF/VEGF)-165 and basic fibroblast growth factor, two endothelial cell mitogens and mediators of angiogenesis resulting in inhibition of endothelial/fibroblast cell proliferation in vitro and VEGF-induced permeability as well as angiogenesis in vivo. In contrast, nanogold did not inhibit VEGF-121 or epidermal growth factor, two non–heparin-binding growth factors, mediated cell proliferation. Gold nanoparticles significantly inhibited VEGF receptor-2 phosphorylation, intracellular calcium release, and migration and RhoA activation in vitro. These results report for the first time a novel property of gold nanoparticles to bind heparin-binding proteins and thereby inhibit their subsequent signaling events.