Evaluation of Silver Nanoparticle Mediated Reduction of Neovascularisation (Angiogenesis) in Chicken Model

Abstract

A ngiogenesis is a normal part of growth and healing. Angiogenesis, which is the formation of new blood vessels from pre-existing ones, is a complicated balance between stimulating and inhibiting factors. Though involved in growth, uncontrolled angiogenesis often results in pathological conditions like rheumatoid arthritis, diabetic retinopathy, solid tumor, hemangioma and psoriasis. To overcome pathological angiogenesis several therapeu-tics have been developed by employing monoclonal anti-body (Krämer et al., 2007) like Bevacizumab and vitaxin, inhibitors of angiogenic inducers or their receptor (Jänne et al., 2007), inhibitors of endothelial cell intracellular signalling (Sonpavde et al., 2008) etc. Nano-biotechnology is presently one of the most dynamic disciplines of research in contemporary material science. Different nanoparticles have been shown to modulate angiogenesis. Copper nan-oparticles have been shown to have proangiogenic effect (Mroczek-Sosnowska et al., 2015) where, gold (Arvizo et al., 2011), perflurocarbon nanoparticles (Das et al., 2013), carbon allotropes (Grodzik et al., 2011) etc. have been shown to inhibit angiogenesis. The unique structure of the crystal lattice of silver (Ag) allows it to store atomic oxygen inside the octahedral holes of Ag (0) and probably influences oxygen level in environment (Hamburger and Hamilton, 1951) and possibly this property attribute to the anti-angiogenesis. Nanoparticles of various materials, such as Pt (Platinum), Ag (Silver), Au (gold), PbS (lead sulphide) and fullerene, have been reported to be produced by evaporation/condensation technique (Magnusson et al., 1999; Ranjan et al., 2013). Now a days there is an increas-Research Article Abstract | Neovascularisation is a key event during the growth of solid tumor and the process is called angiogenesis. Tumor cells demands higher oxygen and their glucose requirement is also higher than normal cells, and during the growth of solid tumor new blood vessels also arise rapidly to fulfil the raised requirement of nutrients. Hence targeting the formation of new blood vessel formation leading to deprived nutrition and oxygen supply will lead to inhibited growth of tumor. In the present study, silver nanoparticles were manufactured by green synthesis using Azadirachta indica (neem) leaves and its effect on process of neovascularisation was evaluated. Bioconversion from silver nitrate solution to silver nanoparticles included addition of AgNO 3 (1mM) to fresh leaf broth of Neem and the conversion was allowed to take place for 4 hrs. with continuous agitation at 80 rpm. Formation of silver (Ag) nanoparticle was visualised by change in colour from pale yellow to dark brown. Nanoparticles when subjected to developing embry-onated eggs of chicken were found to reduce the number of viable blood vessels with reduction in number of vessel branch points in chorioallantoic membrane leading to the death of embryo. Silver nanoparticles prepared through bioconversion in the study, successfully reduced angiogenesis in embryonated chicken model and this anti-angiogenic property of Ag nanoparticles, can be explored as a potential therapeutic against pathological angiogenesis and solid tumors by targeting the vasculature.