NO-mediated DNA damage induced by polystyrene nanoparticles triggers program cell death in mesenchymal stem cells

Daily contact with considerable amounts of polystyrene nanoparticles (PSNPs) may cause harmful effects on the living organisms, through mechanisms that are not fully understood. The study aimed to evaluate the cytotoxic and genotoxic effects of PSNPs (size 200 nm and 40 nm) in mesenchymal stem cells (MSCs). In order to estimate cellular uptake and retention of nanoplastics, PSNP-treated cells have been analyzed by transmission electron microscopy. For assessing morphology and viability of MSCs after PSNP treatment at two environmentally relevant doses (0.47 and 4.7 μl/ml) for 24 hours, HE and Giemsa staining were performed. Annexin V‑FITC/PI assay was used to quantify PSNPs-mediated cell death. Genotoxicity of PSNPs was evaluated by Comet test. The capacity of PSNPs to trigger the production of free radicals in MSCs was also evaluated. TEM confirmed endocytosis of PSNPs. Decreased cell volume, nuclear hyperchromatism, edge aggregation, and formation of densely stained apoptotic bodies, indicated that PSNP-treated MSCs undergo apoptosis. The presented data showed that both concentration of PS particles significantly increased early apoptotic cell death in comparison to untreated cells. Moreover, both doses of PSNPs significantly increased the genetic damage index in MSCs in dose-dependent manner. In conclusion, PSNPs penetrate, accumulate and induce cytotoxic and genotoxic damage in MSCs.