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Celllular Uptake and Clearance of TIO2 Nanoparticles
Citation:
Ortenzio, J., L. Degn, D. Abdulhadi, R. Zucker, AND W. Boyes. Celllular Uptake and Clearance of TIO2 Nanoparticles. Society of Toxicology (SOT) Annual Meeting, San Diego, CA, March 23 - 27, 2015.
Impact/Purpose:
will be presented at the Society of Toxicology Annual Meeting, March 23-27, 2015, San Diego, CA
Description:
Differential rates of cellular uptake and clearance of engineered nanomaterials may influence the propensity for tissue accumulation under chronic exposure conditions. A retinal pigment epithelial cell line (ARPE-19) was used to investigate 1) if Ti02 (Degussa, P25) nanoparticles affect cell prol_iferation, 2) if cellular uptake differs when exposed to a single dose or the same total dose level divided into fractional daily doses, and 3) clearance of particles from cells relative to cellular proliferation.ARPE-19 cells were plated at 2 densities (confluent and non-confluent), stained with CellTrace Far Red, an agent used for cell proliferation assays, and treated with Ti02 nanoparticle suspensions (3 or 10 ugjml). After 24 or 48 hours, the cells were examined by flow cytometry. Changes in the fluorescent profile (indicative ofcellular proliferation) were compared to light scattering data (indicative of internalized nanoparticles). Cells treated with nanoparticle suspensions showed a decreased rate of cell proliferation. Two assays supported reduced cell cycling (Hoechst 33342; DAPI +detergent lysis). Side scatter signal was not changed in confluent cells over time, suggesting that the particles were not cleared.We then examined cellular response using various in vitro treatment regimens. Cells were exposed to an equivalent dose of TiOz nanoparticles delivered either in oneday (3 ug/ml) or over a course of three days (1ug/ml/d). Nanoparticle •internalization was again evaluated with flow cytometry light scattering. Delivereddose was also evaluated based on phototoxicity in which cell viability was measured by a live/dead assay (calcein-AM/propidium iodide) after exposure to UV light. Results suggest that cellular uptake was equivalent in the single and split-dose conditions, the presence of internalized nanoparticles did not inhibit subsequent uptake of nanoparticles, and that low level, long term exposure has a. potential for cumulative cellular uptake.This abstract does not reflect EPA policy.