In Vitro Proliferating Cell Models to Study Cytotoxicity of Silica Nanowires
D.C. Julien, C.C. Richardson, M.F. Beaux II, D.N. McIlroy, R.A. Hill
University of Idaho, US
Keywords: apoptosis, necrosis, cytotoxicty, silica nanowires
Abstract:Proliferating cells representing two disease models (HeLa and Panc 10.05) and a more physiologically relevant cell model (3T3-L1) were used to study the acute toxicological effects silica nanowires (NW). Cellular responses to NW effects were determined over a 4-20 h exposure time-course. Proliferation, viability, metabolic activity, and toxicological mechanism (apoptosis versus necrosis) data showed the following: 3 x 10^4 NW per cell inhibited cell proliferation. The effect was rapid in HeLa cells, but 3T3-L1 and Panc 10.05 cells appeared to be more tolerant to NW, effects being significant only after 20 or 16 h, respectively. HeLa and Panc 10.05 cells showed a dose dependent significant reduction in cellular metabolic activity after 20 h of treatment with NW, while 3T3-L1 cells only showed significant reductions to treatment with doses 3 x10^4 and 3 x 10^3 NW per cell. Assay of NW-invoked mechanism of cell death (caspase 3/7 activity) indicated that apoptosis was minimally induced. Small but significant effects of NW were detected in 3T3-L1 and HeLa cells after 20 h treatment with 3 x10^4 NW per cell. No NW-induction of caspase 3/7 activity was detected for Panc 10.05 cells. Proliferating cells provide a sensitive model to study treatment with silica NW. Silica NW appeared to be well-tolerated by these three cell lines at the doses tested. When effects were detected, cell necrosis and not apoptosis was the main mechanism of silica NW-induced cell death.