Titanium Dioxide Nanoparticles Disturb the Fibronectin-Mediated Adhesion and Spreading of Pre-osteoblastic Cells

Abstract

In the context of rapid development of nanoparticles (NPs) for industrial applications, the question of their toxicity and biological effects must be considered. In this work, we have assessed the influence of titanium dioxide NPs on the adhesion and spreading of MC-3T3 pre-osteoblasts by using a cell subclone that does not produce its own extracellular matrix. Petri dishes were coated with the important adhesion protein fibronectin (Fn). By incubating these Fn-coated surfaces with different amounts of TiO(2) NPs, we have shown that the adhesion of pre-osteoblasts is disturbed, with an important decrease in the number of adherent cells (from 40 to 75% depending upon the concentration and type of NPs). Petri-dish surfaces were analyzed with environmental scanning electron microscropy (ESEM), with images showing that TiO(2) NP aggregates are bound to the layer of adsorbed Fn molecules. The cells cultured on these Fn/NP surfaces adopted an irregular shape and an aberrant organization of actin cytoskeleton, as revealed by fluorescence microscopy. Most importantly, these results, taken together, have revealed that the actin cytoskeleton forms abnormal aggregates, even on top of the nucleus, that coincide with the presence of large aggregates of NPs on top of cells. On the basis of these observations, we propose that some Fn molecules are able to desorb from the Petri dish surface to coat TiO(2) NPs. Fn/NP complexes are not attached firmly enough on the surface to allow for normal cell adhesion/spreading and the development of tense actin fibers. These results stress the paramount need for the assessment of the toxicology of NPs, with special attention to their interactions with biomolecules.

Titanium Dioxide Nanoparticles Alter the Cellular Phosphoproteome in A549 Cells

“…This accumulation did not lead to any change in the morphology of cells, and we did not detect the presence of stress fibers ( Figure 5). The impact of TiO 2 -NPs on cytoskeleton integrity highlighted in this phosphoproteome analysis is consistent with the literature [17,[76][77][78][79][80][81][82][83][84]. Indeed, TiO 2 -NPs have been shown to impair the expression of genes involved in cytoskeleton maintenance [17,81].…”

“…Indeed, TiO 2 -NPs have been shown to impair the expression of genes involved in cytoskeleton maintenance [17,81]. It has also been shown to induce disorganization of microtubules and of the actin network [76,79,80,83]. Moreover, in an acellular study, TiO 2 -NPs were also shown to inhibit tubulin polymerization and change its conformation [77].…”

Nano-metals forming bacteria in Egypt. I. Synthesis, characterization and effect on some phytopathogenic bacteria in vitro

“…Therefore, the characterization of NPs is important to evaluate the functional aspects of the synthesized particles. Characterization is performed using a variety of analytical techniques, including UV- VIS spectroscopy 11 , X-ray diffractometry 12 , Raman scattering 13 , 14 , Energy-Dispersive X-Ray 15 , Transmission electron microscopy 16 , vibrating sample magnetometer 17 , Particle size analysis 18 , and inductively coupled plasma-optical emission spectrometry 19 .…”

Molecular responses of alveolar epithelial A549 cells to chronic exposure to titanium dioxide nanoparticles: A proteomic view

“…Besides these endpoints, original effects of TiO 2 -NP have also been described, e.g. impairment of cellular adhesion as well as autophagy [5][6][7]. Contrary to ultrafine particles, epidemiology failed to demonstrate a direct link between exposure to TiO 2 -NPs and cancer.…”