Size-Dependent Cytotoxicity and Genotoxicity of Silver Nanoparticles in Cochlear Cells In Vitro

Abstract

Silver nanoparticles (AgNPs) have been proven to have potent antibacterial properties, offering an attractive alternative to antibiotics in the treatment of several infections such as otitis media. Concerns have been raised though regarding their toxicity. There are few data regarding the toxic effects of AgNPs in cochlear cells. The aim of our study was to evaluate the effects of AgNPs of four sizes as a function of their size on HEI-OC1 cochlear cells and on HaCaT keratinocytes. The cells were treated with different concentrations of AgNPs. We evaluated silver uptake by atomic absorption spectroscopy and transmission electron microscopy (TEM), cytotoxicity with the alamarBlue test, ROS production with 2′,7′-dichloro-dihydro-fluorescein diacetate, and genotoxicity with the comet assay. Silver intracellular concentration increased proportionally with the incubation time and the size of the NPs. Silver uptake was higher in HEI-OC1 cells compared to HaCaT. While after 4 h exposure, only the 50 nm NPs were observed in both cell lines and only the 5 nm NPs were observed in the HaCaT cells, after 24 h, nanoparticles of all sizes could be visualized in both cell lines. The cells showed signs of distress: vacuolizations, autophagosomes, signs of apoptosis, or cellular debris. AgNPs of all sizes reduced viability proportionally with the concentration, HEI-OC1 cells being more affected. The toxicity of AgNPs decreased with the nanoparticle size, and ROS production was dose and size dependent, mainly in the cochlear cells. Genotoxicity assessed by comet assay revealed a higher level of DNA lesions in HEI-OC1 cells after treatment with small-sized AgNPs. The perspective of using AgNPs in the treatment of otitis media, although very attractive, must be regarded with caution: cochlear cells proved to be more sensitive to the toxic effect of AgNPs compared to other cell lines. Potential treatments must be tailored specifically, choosing NPs with minimum toxicity towards auditory cells.

Comparative Study of the Cytotoxic Effect of Silver Nanoparticles on Human Lymphocytes and HPB-ALL Cell Line: As an In Vitro Study

“…In the study of Perde-Schrepler et al (23), the cytotoxicity and genotoxicity effects of silver nanoparticles were investigated by the size-dependent method in cochlear cells. They concluded that all sizes of nanoparticles had toxicity to cochlear cells (18). Shahbazzadeh et al (29) evaluated the cytotoxicity of silver nanoparticles on fibroblasts and mesenchymal stem cells and they showed that these nanoparticles had less toxic effects on healthy cells.…”

“…Silver nanoparticles can enter the cell through diffusion or endocytosis to disrupt the mito-Copyright © 2020, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited chondria, produce reactive oxygen species (18) and damage to proteins and nucleic acids in the cells and ultimately leads to the inhibition of cell division. When oxidation stress occurs, ROS production is beyond the capacity of the antioxidant defense system (19)(20)(21)(22).…”

Excess Ascorbate is a Chemical Stress Agent against Proteins and Cells

“…In the first plate, every well was treated with 10 µL Alamar Blue cell viability stain (Invitrogen, Thermo Fisher Scientific, Waltham, MA, USA) as described previously [47]. After 2 h of incubation the plates were measured at 540 nm/620 nm emission using a Synergy2 multiplate reader (BioTek Company, Winooski, VT, USA).…”

Cytotoxicity of bismuth nanoparticles in the murine macrophage cell line RAW 264.7

“…For example, gold NPs no larger than 6 nm enter the cell nucleus, whereas large NPs (10 or 16 nm) penetrate through the cell membrane and are found only in the cytoplasm [44]. Moreover, larger gold and silver NPs have been found to be less toxic than smaller ones for several cells lines [45,46]. The BiNPs used to the current study had a wide size distribution range, typical for laser ablation-produced NPs, as monodisperse suspensions are possible but difficult to achieve [47].…”