VPB1278 - Influence of titanium dioxide particles on redox processes in human erythrocytes in vitro

Background: During the last decades, it was believed that titanium and its compounds are biologically inert, which led to its widespread use in medical practice. However, the growing number of published studies on the effects of TiO2 confirms the importance of studying the issue of its biosafety.

Aims: The aim of this work is to evaluate the possibility of titanium dioxide particles of different sizes (nano- and microparticles, food titanium) influencing the redox balance of human erythrocytes in vitro.

Methods: Erythrocytes were separated by centrifugation of blood at 2000 g during 5 min in PBS buffer pH 7.4. After they were diluted to 2% hematocrit in the same buffer and loaded with titanium dioxide particles at a final concentration of 0.01 mg/ml and incubated for 3 hours at 37°C with constant stirring. ROS level was assessed by fluorescent of 2',7'-dichlorodihydrofluorescein diacetate (DCFDA). Catalase glutathione and peroxidase activity were assessed by the standard methods. Statistical analysis was carried out using Wilcoxon test (n=7).

Results: It was shown that during short-term exposure (30 min), all studied particles were able to stimulate the formation of ROS in erythrocytes. Also, under the conditions of modelling oxidative stress using tert-butyl hydroperoxide all the particles increased the level of DCFDA fluorescent. But food titanium dioxide mostly contributes to the observed effect.
It was found that all types of the particles after a 3-h incubation reduce the activity of antioxidant defence enzymes (glutathione peroxidase and catalase) by an average of 20% (p < 0.05), but the difference between the effects of different types of particles could not be identified.

Conclusion(s): Thus, it has been shown that titanium dioxide particles are capable of stimulating the oxidative processes development in the cell, and, also inhibiting the work of its defence system, which may contribute to their toxic effect.