The ROS content was 1.8, 2.9, and 4.7 times higher compared to the control levels in RTL-W1 cells, 1.5, 1.9, and 3.2 times higher than in T47Dluc cells, and 1.2, 1.4, and 2.2 times higher

than in H295R cells following incubation with CNT at 12.50, 25, and 50 mg/L, respectively (Figure  5). The lowest observed effect concentration (LOEC) was 12.50 mg/L for RTL-W1 and T47Dluc cells, with a no observed effect concentration (NOEC) of 6.25 mg/L. For H295R cells, higher LOEC and NOEC were determined amounting to 25 and 12.5 mg CNT/L, respectively. Figure 5 Generation Maraviroc supplier of ROS in RTL-W1, T47Dluc, and H295R cells. ROS generated in RTL-W1 (A), T47Dluc (B), and H295R (C) cells exposed to MWCNT, selleckchem TCC, and mixture of both substances (1% TCC, with respect to the concentration of CNT). The intensity of H2DCF-DA was measured in cell lysates and normalized to negative/solvent control (=1, dashed line). Data are expressed as mean ± standard deviation of three independent exposure experiments with three internal replicates each. *Statistically significant from the negative control in repeated measures ANOVA on ranks with Dunn’s post hoc and p < 0.05. Discussion Multiwalled carbon nanotubes In the case of long and stiff CNT, it has been argued that analogous

mechanisms to those of other fibrous particles such as asbestos exist [96, 97], which may penetrate the lung and persist in Forskolin clinical trial the tissue. The biopersistence, large aspect ratio, and fibrogenic character of CNT are important features that may cause adverse health effects. Other mechanisms include hydrophobic contact, through which nanoparticles may interrupt cell membranes, disturbing surface protein receptors [98]. Uptake of nanofibers by human macrophages sized smaller than the length of the nanotubes – a process defined as frustrated phagocytosis – has been shown by backscatter scanning electron microscopy [13]. Overall, nanomaterial size and composition plays a distinct role in the cellular response. In addition, this response is variable between cell types and is likely

related to the physiological function of the cell types [95]. However, in our study, flexible multiwalled CNT were investigated for which less concern of their toxic potential has been expressed [99]. Cytotoxicity Exposure of RTL-W1, T47Dluc, and H295R cells to 50 mg CNT/L for 24 or 48 h did not induce acute cell toxicity. This is the first study reporting data of cytotoxicity tests with Baytubes using these three cell lines. Several authors have shown that other types of CNT were cytotoxic to different lung epithelial cell lines [100–102], to human astrocyte D384 cells [100], to skin keratinocyte cells, lung cells, T4 lymphocytes [103], and human epidermal keratinocytes [18]. However, in a recent study, Thurnherr et al. [8] also showed that the same type of industrially produced MWCNT had no effect to another cell line.