CYTOTOXICITY OF GOLD NANOPARTICLES IN VITRO

Abstract

Particles of nano-dimension are believed to be more biologically reactive than their bulk counterparts due to their small size and larger surface area to volume ratio. While gold in its bulk form has long been considered an inert, noble metal with some therapeutic value, it is not yet well established whether gold nanoparticles (AuNPs) are biologically toxic. In this study, the effects of human lung fibroblast and small airways epithelial cells treated with serum coated 20nm diameter size AuNPs were examined. The AuNPs were readily taken up by MRC-5 cells and were found to cause inhibition of cell proliferation, induction of oxidative DNA damage as well as autophagy concomitant with oxidative stress. There were significant dysregulation of genes associated with cell cycle regulation, DNA repair and oxidative stress pathways. In addition, we observed formation of autophagosomes under transmission electron microscopy (TEM) and an upregulation of autophagy proteins, MAP-LC3 and ATG 7 in AuNP-treated cells. AuNP treatment also induced upregulation of antioxidants and expression of stress response proteins. In summary, exposure to AuNPs is a potential source of oxidative stress in human lung fibroblasts - and autophagy may be a cellular defence mechanism against oxidative stress-induced toxicity.