Gold Nanoparticles do not Affect the Global Transcriptional Program of Human Umbilical Vein Endothelial Cells: A DNA-Microarray Analysis

Nanoscience/technology is a burgeoning field with tremendous potential for biomedical applications. For nanomedicinal applications of engineered nanomaterials, it is extremely important to address their toxicity and biological effects. For example colloidal gold has a prolonged history of use but so far no systemic studies have been aimed to address the biological effects of these nanomaterials and there is still debate about the long term effects on health and environmental impact of any type of nanomaterials, in general. Here we have used DNA microarray analysis to address the effect of gold nanoparticles on the global transcriptional program of human umbilical vein endothelial cells. W ! we incubated human umbilical vein endothelial cells (HUVEC) with 5 nm-size To address this issue gold nanoparticles in conditions of no serum to avoid bin di ng/sequestration of gold nanoparticles by serum-derived ingredients. Intracellular uptake of gold nanoparticles by HUVECs with or without serum was confirmed by transmission electron microscopy (TEM). Two different but conceptually similar experiments were performed. In the first, HUVECs were grown to 80% confluency and then serum-starved for 24 h after which the cells were incubated with gold nanoparticles for 1 h and 24 h in serum-free condition respectively. Total RNA isolated after the indicated times were subjected to analysis by whole-genome DNA-microarray. Global comparison level of gene expression at the mRNA level by HUVECs cultured in presence or in absence of gold nanoparticles produced correlation co-efficients of 0.985 and 0.973 for 1 h and 24 h experiments, respectively, indicating no effect of gold nanoparticles on global gene expression. Manual examination of the microarray results revealed potential differences in the level of mRNA expression for some genes, however, RT-PCR showed no significant difference in expression for any of the genes examined, further supporting the results obtained by microarray. In the second set of experiments, HUVECs obtained under similar conditions were freed of residual serum and immediately put back into serum-free media in presence or absence of gold nanoparticles. Total RNA obtained from these cells grown for 1 and 4 h were subjected to DNA-microarray-based analysis as above. These experiments also did not reveal any significant differences in the global pattern of mRNA expression attributable to gold nanoparticles (R-2 values of 0.995 and 0.994 for 1 h and 4 h experiments, respectively). RT-PCR of the selected genes confirmed this observation. Taken together, these results suggest a lack of a direct effect of gold nanoparticles on the overall physiology of HUVECs. These results have implications on the use of gold nanoparticles as a delivery vehicle into target cells for eventual clinical applications.