[Effect of high-dispersed silica on the cultured rat hepatocytes]

Highdispersed silica (HDS) is an active substance of medicine "Siliks", which demonstrates high protein adsorption property and is used for hatching out toxic agents of protein origin. To discover new potential applications of this substance, it is necessary to study the direct effect of HDS on cell viability. We studied the effects of HDS in concentration 0,0001%, 0,001% and 0,01% on cultured rat hepatocytes at 4 and 24 hours. To estimate the number of alive vs. apoptotic and necrotic cells, fluorescent nucleic dyes Hoechst 33342 and propidium iodide were employed. Cells that underwent autophagic processes were estimated using a specific fluorescent autophagosome marker monodansylcadaverine. We show here that HDS has dose-dependent effect on cell death; the number of cells with apoptotic features increased after 4 hours and in greater extend after 24 hours of treatment with HDS. At the lowest concentration HSD did not significantly affect cell viability, and we observed decrease in postapoptotic necrosis in cell culture. The highest concentration of HSD dramatically increased cell death through both necrosis and apoptosis. At the same time, autophagic activity was suppressed by 0,01% HSD.