In-vitro Testing for Identification of Long-term Effects of Nanoparticles

Human exposure to nanoparticles increases because nano-sized materials are included in food, consumer and medicinal products, as well as being present in the environment. Routine cytotoxicity screening evaluates effects only upon acute exposure, usually 24h, but prolonged contact with nanoparticles might result in intracellular accumulation and disturbance of cell function. We studied effects of polystyrene particles, carbon nanotubes, and silica nanoparticles on endothelial cells and on monocytes using various culturing systems (microcarrier, CELLine CL350, and sub-culturing) for up to 28d. Particles were physicochemically characterized, cellular uptake studied, and cellular localization determined. Nanoparticles formed aggregates to different extent and accumulated in lysosomes to different degree. Exposure systems were suitable to different extent for the evaluation of chronic cytotoxicity. CELLine CL350 and sub-culturing of an aliquot of the exposed cells was less suitable than culture on microcarriers and sub-culturing by transfer of all exposed cells to a larger culture vessel. Cytotoxicity after long-term exposure was higher than after acute exposure. Differences between particles and cell lines were observed and adaptation to nanoparticle damage was also seen.