Zinc oxide nanoparticles induced oxidative stress in mouse bone marrow mesenchymal stem cells.

Engineered nanoparticles are developed for various applications in industrial, electrical, agricultural, pharmaceutical and medical fields due to their unique properties. Nanoparticles such as TiO(2) and ZnO are widely used in cosmetics for UV protection. The toxicological investigations of ZnO NPs are highly recommended because of the increasing use in various industrial and consumer products. The toxic potential of ZnO NPs was assumed to be caused by the release of free Zn+ ions in the medium. Many of the in vivo studies suggest the toxic nature of ZnO NPs, the in vitro studies are certainly important to elucidate the mechanism of toxicity. This study examined the toxicity of ZnO NPs with the average size of 6-8 nm on the isolated mice bone marrow mesenchymal stem cells. The study focuses on the cytotoxicity and oxidative stress-mediated cellular responses upon exposure to ZnO NPs. The results indicated that the exposure to ZnO NPs significantly affects cellular viability in a dose-dependent manner. Formation of reactive oxygen species (ROS) was found to be the mechanism of cellular toxicity. The release of Zn(+) ions from the nanoparticles, due to the instability of ZnO NPs in the acidic compartment of lysosomes, also increases the ROS generation. In addition to increased ROS production, damage of lysosomal membrane and the activation of executioner caspase-3 and caspase-7 were observed, which eventually ends in apoptosis.

Cells-nano interactions and molecular toxicity after delayed hypersensitivity, in guinea pigs on exposure to hydroxyapatite nanoparticles.

The aim of the study was to evaluate the cells-nanoparticle interactions and molecular toxicity after delayed hypersensitivity in Guinea pigs, exposed to hydroxyapatite nanoparticles (HANP). The study focuses on synthesizing and characterizing HANPs and gaining an insight into the cytotoxicity, molecular toxicity, hypersensitivity and oxidative stress caused by them in vitro and in vivo. HANP was synthesized by chemical method and characterized by standard methods. Cytotoxicity was assessed on L929 cells by MTT assay and in vitro studies were carried out on rat liver homogenate. In vivo study was carried out by topical exposure of Guinea pigs with HANP, repeatedly, and evaluating the skin sensitization potential, blood parameters, oxidative stress in liver and brain and DNA damage (8-hydroxyl-2-deoxyguanosine: 8-OHdG) in liver. The results of the study indicated that there was no cytotoxicity (up to 600µg/mL) and oxidative damage (up to 100µg/mL), when exposed to HANPs. It was also evident that, there was no skin sensitization and oxidative damage when HANP were exposed to Guinea pigs.