Antiangiogenic properties of silver nanoparticles.

Angiogenesis is an important phenomenon involved in normal growth and wound healing processes. An imbalance of the growth factors involved in this process, however, causes the acceleration of several diseases including malignant, ocular, and inflammatory diseases. Inhibiting angiogenesis through interfering in its pathway is a promising methodology to hinder the progression of these diseases. The function and mechanism of silver nanoparticles (Ag-NPs) in angiogenesis have not been elucidated to date. PEDF is suggested to be a potent anti-angiogenic agent. In this study, we postulated that Ag-NPs might have the ability to inhibit angiogenesis, the pivotal step in tumor growth, invasiveness, and metastasis. We have demonstrated that Ag-NPs could also inhibit vascular endothelial growth factor (VEGF) induced cell proliferation, migration, and capillary-like tube formation of bovine retinal endothelial cells like PEDF. In addition, Ag-NPs effectively inhibited the formation of new blood microvessels induced by VEGF in the mouse Matrigel plug assay. To understand the underlying mechanism of Ag-NPs on the inhibitory effect of angiogenesis, we showed that Ag-NPs could inhibit the activation of PI3K/Akt. Together, our results indicate that Ag-NPs can act as an anti-angiogenic molecule by targeting the activation of PI3K/Akt signaling pathways.