In recent decades, titanium dioxide (TiO2) nanoparticles have been used in various applications, including paints, coatings, and food. However, data are lacking on the toxicological aspects associated with their use. The aim of this study was to assess the inhalation toxicity of TiO2 nanoparticles in rats by using inhalation exposure. Male Wistar rats were exposed to TiO2 nanoparticles for 2 weeks (6 hr/day, 5 days/week) at a mean mass concentration of 11.39 +/- 0.31 mg/m3. We performed time-course necropsies at 1, 7, and 15 days after exposure. Lung inflammation and injury were assessed on the basis of the total and individual cell counts in bronchoalveolar lavage fluid (BALF), and by biochemical assays, including an assay for lactate dehydrogenase (LDH). Furthermore, histopathological examination was performed to investigate the lungs and nasal cavity of rats. There were no statistically significant changes in the number of BALF cells, results of biochemical assays of BALF and serum, and results of cytokine analysis. However, we did observe histopathological changes in the nasal cavity tissue. Lesions were observed at post-exposure days 1 and 7, which resolved at post-exposure day 15. We also calculated the actual amounts of TiO2 nanoparticles inhaled by the rats. The results showed that the degree of toxicity induced by TiO2 nanoparticles correlated with the delivered quantities. In particular, exposure to small particles with a size of approximately 20 nm resulted in toxicity, even if the total particle number was relatively low.
Animals ; Bronchoalveolar Lavage Fluid ; Cell Count ; Humans ; Inhalation ; Inhalation Exposure ; L-Lactate Dehydrogenase ; Lung ; Male ; Nanoparticles ; Nasal Cavity ; Paint ; Pneumonia ; Rats ; Rats, Wistar ; Titanium

The incidence rate of lung cancer is continually increasing, and lung cancer is the leading cause of cancer-related death worldwide. Nevertheless, few therapeutic methods are available for lung cancer. Therefore, establishing appropriate lung cancer animal models is important to investigate mechanisms and to evaluate new drugs for lung cancer. In the present study, we transplanted non-small cell lung cancer A549 human adenocarcinoma cells (2x10(4), 2.0x10(5), and 2.0x10(6) cells) into the right lobe of BALB/c nude mice via the intercostal space to develop an orthotopic lung cancer animal model that is minimally invasive and similar to human lung cancer. We then investigated the incidence rate and severity of lung cancer according to the A549 cell number (2x10(4), 2.0x10(5), and 2.0x10(6) cells) and transplantation periods (4~23 days). Lung cancer development was confirmed with gross examination, which was supported by histopathological examination. These results indicate that the incidence rate and severity of lung cancer was increased depending on the number of transplanted cells and transplantation period which the cell number and duration are increasing risk of lung cancer. Thus, this study can provide appropriate reference data to develop an orthotopic lung cancer animal model using the non-small cell lung cancer A549 cell line for researching mechanisms and evaluating candidate drugs, including various approaches for treating lung cancer.
Adenocarcinoma ; Animals ; Carcinoma, Non-Small-Cell Lung ; Cell Count ; Cell Line ; Humans ; Incidence ; Lung ; Lung Neoplasms ; Mice ; Mice, Nude ; Models, Animal ; Transplants