Effects Of Eu³⁺ And Nano Eu₂O₃ On Growth Of Human Hepatic Cells And Hepatoma Cells

With the in-depth studies and wide applications of rare earth compounds and rare earth oxide nanoparticles, rare earth elements will eventually enter the human body through the food chain. Rare earth powder existing a variety of exposure from the collection to the preparation has a direct impact on human health, therefore the biological safety of application of rare earth element has aroused an extensive interest. Meanwhile, the biological and toxicological effects of rare earth research also have been a hot issue.Eu3+is widely used in biological field; NanoEu2O3 is a kind of material that can emit red fluorescent. In the present study, we report the impact of Eu3+and nanoEu2O3 on the HL7702 and HepG2 cells using MTT, morphological observation and flow cytometry methods. Also it is the first report that nano Eu2O3 can be internalized by live HL7702 and HepG2 cells by laser scanning confocal microscope. The specific results are shown as below:1. The effects of Eu3+on the HL-7702 and HepG2 cells:the MTT method shows that Eu3+at low concentrations (≤100μmol·L-1) can promote the HL7702 cell growth and slightly inhibit the proliferation of HepG2 cells with a concentration-dependent and time-dependent characteristics. Eu3+can promote the proliferation of HL-7702 cells by increasing the ratio of S-phase cells; on the contrary, Eu3+arrest the ratio of G0/G1-phase of HepG2 cells and trigger cell apoptosis.2. The impacts of nanoEu2O3 on the HL-7702 and HepG2 cells:nano Eu2O3 can be internalized by live HL7702 and HepG2 cells by laser scanning confocal microscope assay. MTT assay showed that nanoEu2O3 can reduce the viability of HL7702 and HepG2 cells. The cell cycle histogram also showed that nanoEu2O3 at low concentrations does not make a great impact on proliferation of two kinds of cells, whereas it can trigger HL7702 cells apoptosis at high concentrations (≥800μg·mL-1) and can suspend HepG2 cells division and arrest the ratio of S phase when its concentration is more than 600μg·mL-1. Morphological characteristics of apoptosis were observed for HL7702 cells, and HepG2 cells had obvious vacuolization phenomenon. Apoptosis detection indicated that maximum apoptosis rate of HL7702 cells was 17.9%, while no significant apoptosis in HepG2 cells was observed in the experimental range of concentration.