oa Effect of TiO2 Nanoparticles in Human Cells from Healthy Individuals and Patients with Respiratory Diseases

Nanotechnology has preceded nanotoxicology and little is known of the effects of nanoparticles in human systems, let alone in diseased individuals. Therefore, the effects of titanium dioxide (TiO2) nanoparticles in peripheral blood lymphocytes from patients with respiratory diseases (lung cancer, chronic obstructive pulmonary disease (COPD) and asthma) were compared with those in healthy Individuals to determine differences in sensitivity to insult from nanoparticles. Ethical permission was obtained to collect peripheral blood lymphocytes from respiratory disease patients and healthy individuals. The Comet assay was performed according to guidelines recommended by Tice et al (1). The micronucleus assay was conducted according to Fenech (2) and ras oncoprotein detection according to Anderson et al (3). The means of Olive tail moments and % tail DNA in peripheral blood lymphocytes were compared in the Comet assay after treatment for 30 minutes with different non-cytotoxic TiO2 concentrations (10, 30 and 50 µg/ml), as well as the negative control of untreated lymphocytes and the positive control of 80 µM (2.72 µg/ml) H2O2 . The results showed statistically significant concentration–dependent DNA damaging effects of TiO2 in both respiratory patient and healthy control groups. In the micronucleus (CBMN) assay, micronuclei (MN) per 1000 binucleated cells of healthy controls, lung cancer, COPD and asthma patients were examined after treatment of blood cultures with two different TiO2 concentrations (5 and 10µg/ml), as well as the negative control of untreated blood cultures and the positive control of 0.4 µM MMC. There was an increase in micronuclei without statistical significance when compared with the untreated control of the patients, but with significance when compared with the negative control of healthy individuals. Furthermore, when modulation of ras p21 expression was investigated, regardless of TiO2 treatment, only lung cancer and COPD patients expressed measurable ras p21 levels.