(60a) In Vitro Toxicity Of Gold Nanoparticle On Human Lung Fibroblast Cells

Nanomaterials/nanoparticles are finding popularity in many therapeutic and research applications due to their versatility, ease of synthesis, and unique properties. Thus far, the majority of efforts in nanotechnology are on the application front, and not many studies have focused on the effect of nanomaterials on human health and the environment. Recent research has brought to light concerns over the safety of use of nanomaterials and also the long-term adverse effect of their use. Hence it is essential for us to establish the toxicity, safety and risks involved in the usage of these nanoparticles. In the current work, human fetal lung fibroblast cell line MRC-5 were treated with 0.1, 0.5 and 1nM concentrations of 20nm size gold nanoparticles for 24, 48 and 72 hours. Measures of cytotoxicity taken include Trypan Blue exclusion cell viability assay, real-time PCR arrays and HPLC for DNA dOH8 damage. MRC-5 cells were found to internalize the gold nanoparticles after 72 hours in culture which were visible under TEM. The nanoparticles mostly gathered in clusters inside cellular vacuoles. These dense particle clusters were verified to be gold through EDAX X-ray microanalysis. The nanoparticle treatment did not seem to have an acute effect on the cells after 24, 48 and 72 hours of treatment. There were no visible differences in the cell morphology between the treated and control groups. There was also no significant difference in non-viable cells between the treatment and control groups after 24, 48 and 72 hours of incubation. However when comparing the total cell count in the control, 0.5 and 1nM treatment groups at 72 hours exhibited significant difference (p<0.05, one-way ANOVA). In the DNA damage test, the 0.1 and 0.5nM particle treatment yielded OHdG/106dG values that were close to or lower than the value of control. On the contrary, the value of 1nM nanogold treated cells was far higher than control. This suggests that 1nM nanogold may have a damaging effect to cells and destroy DNA. Similar observations were found when gene expression profiling of 84 key cell cycle related genes was performed on the 1nM nanoparticle treated cells against untreated MRC-5 cells after 72 hours using the Human Cell Cycle RT2 Profiler? PCR Array System (SuperArray, Bioscience Corp., USA). Of the 84 key genes assayed, all were detected in both the treatment and control, however, only 19 genes were found to be significantly downregulated in the treated cells (p<0.05). Cell cycle regulators MAD2, Cyclin B2 (HsT17299) and Cyclin B1 (CCNB) were found to be the most downregulated. The rest of the 19 genes such as BRCA1, Hus1, ATLD/HNGS1, AT-V1/AT-V2 are various DNA damage response genes involved in maintaining cellular genomic integrity. In all, gold nanoparticles may not affect cell viability in short-term but affect cell proliferation and cause DNA damage. Its mechanism of action and involvement are yet to be elucidated.