Cytotoxicity and genotoxicity induced by silica nanoparticles in human dental pulp cell culture
Alkhattab, Omar Rifat
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This study was designed to evaluate the cell attachment efficiency, cell proliferation, cytotoxicity and genotoxicity of different sizes and doses of silica on human dental pulp cell culture. Human dental pulp cells (HDPCs) derived from extracted third molars were cultured in growth media and supplemented with two sizes of silica particles (70 nm – 225 nm) and (1 µm – 5 µm) in different doses: (12.5 µg/mL, 50 µg/mL, 100 µg/mL and 1000 µg/mL) and media without silica particles as a control, for the time intervals of 16h, 24h, 7 and 14 days. Attachment efficiency and cell proliferation were measured by comparing optical density of crystal violet stained cells. Cytotoxicity was measured using water-soluble dye that changes its absorption spectra upon cellular reduction. Genotoxicity was measured using specific antibody-based detection. Cultures with Si-np50, Si-np100, Si--mp12.5, Si-mp50, Si-mp100 at 16h yielded significantly higher attachment efficiency compared to the other doses. Cultures with Si-np50 and Si-np100 showed increased attachment efficiency compared to cultures with their larger microparticles counterparts(P<0.05). Cultures with Si-mp12.5 displayed similar proliferation compared to the control at day 14. Higher doses showed significant reduction in proliferation compared to lower doses in all sizes of Si-np and Si-mp at day 14. All the silica nanoparticles groups showed lower proliferation when compared to their larger microparticles counterparts at 14 days (P<0.05). When comparing different doses in the cytotoxicity assay all the groups displayed cytotoxicity by day 14, except the Si-mp12.5 group. And when comparing different sizes, all the doses of Si-np showed higher levels of cytotoxicity when compared to Si-mp at day 14 (P<0.05). Cultures with 1000 µg/mL group displayed significantly higher genotoxicity in both sizes when compared to lower doses at day 1. When comparing both sizes to each other, nanoparticles showed a higher genotoxicity than microparticles (p < 0.05). In conclusion, the higher doses of silica nanoparticles significantly decreased proliferation and increased cytotoxicity and genotoxicity on normal HDPCs in a dose and size dependent manner. This is the first report to demonstrate the effect of dose and size of silica particles on the proliferation, cytotoxicity and genotoxicity of normal HDPCs.