An in vitro method to survey DNA methylation in peripheral blood mononuclear cells (PBMCs) treated by airborne particulate matter (PM10)

Effect of titanium dioxide nanoparticles on DNA methylation of human peripheral blood mononuclear cells

The aim of the current study was to investigate the effect of well-characterized TiO₂ nanoparticles on DNA methylation of peripheral blood mononuclear cells (PBMCs) in vitro. Maximum non-toxic concentration of nanoparticles for PBMCs was determined by MTT assay. The effect of TiO₂ nanoparticles at concentrations of 25-100 μg/ml on DNA methylation of PBMCs was investigated by measuring the %5-mC alterations through an ELISA assay. The physicochemical analysis showed that the TiO₂ nanoparticles were crystalline, pure and in the anatase phase. Peaks related to Ti-O tensile vibrations were observed in the range of 1510 cm^-1. The size of nanoparticles was in the range of 39-74 nm with an average hydrodynamic diameter of 43.82 nm. According to the results of the MTT test, 100 μg/ml was found to be maximum non-toxic concentration. The %5-mC in treated PBMCs revealed that TiO₂ nanoparticles could lead to DNA hypomethylation in PBMCs. The %5-mC difference compared with the negative control was found to be 2.07 ± 1.02% (P = 0.03). The difference of %5-mC between the 25 and 100 μg/ml concentration of nanoparticles was statistically significant (P = 0.02). The results of the current study show that the TiO₂ nanoparticles cause DNA hypomethylation in PBMCs in a dose-response manner. Therefore, it is recommended to evaluate the effects of cytotoxicity and epigenotoxicity of commonly used nanoparticles before their use.

An in vitro method to evaluate hemolysis of human red blood cells (RBCs) treated by airborne particulate matter (PM10)

Air pollutants are capable to enter bloodstream through the nose, mouth, skin and the digestive tract. Hemolysis is the premature destruction of red blood cells (RBCs) membranes. This can affect metabolism of RBCs and reduce cell life. Each of these adverse effects could lead to anemia, jaundice and other pathological conditions. Hemolysis can induce by the mineral components adsorbed on the particles. The aim of this study was to evaluate hemolysis of RBCs treated by airborne PM₁₀ (PM with aerodynamic diameter ≤ 10 μm) in vitro. Study had two main stages including sampling and preparation of PM₁₀ suspension, and hemolysis test. Particle samples were collected by means of a high-volume sampler on fiberglass filters. The PM₁₀ was extracted through dry ultrasonic method. Blood sample was incubated by PM₁₀ at concentrations 50-300 μg/mL for 3 h. Hemolysis percent was assessed through measurement of Hemoglobin concentration in test samples and total blood hemoglobin (TBH) sample by the cyanmethemoglobin method. Analysis of variance (ANOVA) and Tukey post-hoc test were applied to compare mean values of hemolysis percent between different PM concentrations. Method used in current study is suggested for investigation of toxic effects of airborne particle matter (PM₁, PM_2.5 and PM₁₀) on human RBCs.