The Mechanism Of Apoptosis Induced By TiO₂-nanoparticles And SiO₂-nanoparticles On Huvecs In Vitro

Objective The objective is to determine the apoptotic effects and potentialmolecular mechanism of titanium dioxide nanoparticles and silica dioxidenanopaticles with different diameters on human umbilical vein endothelial cells(HUVECs), assessing their potential health risks on human cardiovascular system.Methods CCK-8, Hoechst staining, PI staining and Western blot were used todetermined the apoptosis of four diameters of TiO2-NPs (10,30,50,100nm) and fourdiameters of SiO2-NPs (10,25,50,100nm) in different concentrations on theHUVECs cells in vitro. The Bax, Bcl-2, Caspase-3, Caspase-7, Caspase-9, PARPprotein levels in HUVECs cells exposed to four diameters of TiO2-NPs and fourdiameters of SiO2-NPs in different concentrations were determined by Western blot.Results1. HUVECs cells treated with different particle sizes and different concentrationsof TiO2-NPs and SiO2-NPs, have different degrees of inhibition on cell proliferation.In the same size, the cell survival rate decreased significantly with the particleconcentration increases. Under the same concentration, cell survival rate decreasedwith TiO2-NPs size increased and decreased with SiO2-NPs decreased.2. Deeper color, nuclear fragmentation and typical apoptotic bodies were found inHUVECs after treated with nanoparticles by Hoecst33258staining.3. Flow cytometry showed that in the same size, the apoptosis rate was increasedwith the increase of concentration. Under the same concentration, cell apoptosis rateincreased with increasing TiO2-NPs size and with decreasing SiO2-NPs size.4. Western Blot showed, the expression of Bax/Bcl-2ratio, Cleaved Caspase-3,Cleaved Caspase-7, Cleaved Caspase-9, Cleaved PARP protein level increased withthe particle size increases in TiO2-NPs treatment group; the expression of Bax/Bcl-2ratio, Cleaved Caspase-3, Cleaved Caspase-7, Cleaved Caspase-9, Cleaved PARPprotein level increased with the particle size decreases in SiO2-NPs treatment group. Conclusions1. Two different particle size of TiO2nanoparticles and SiO2inhibited theproliferation of human umbilical vein endothelial cells and induced its apoptosis.2. Molecular mechanisms of apoptosis is related to the expression of Bax/Bcl-2ratioand the activation of Caspase-3,-7,-9and PARP after HUVECs cells treated with twokinds of nanoparticles.