Uptake mechanism of furosemide-loaded pegylated nanoparticles by cochlear cell lines.

This study tests the hypothesis that pegylated nanoparticles (NPs) could be taken up by the cochlear cells [House Ear Institute-organ of Corti 1 (HEI-OC1) and Stria vascularis K-1 (SVK-1)], through endocytic pathways. Furthermore, the in vitro drug release and the cytotoxicity of Furosemide (FUR)-loaded NPs on these two cochlear cells are investigated. FUR-loaded pegylated NPs are prepared by the emulsion-solvent diffusion method without surfactant. The NPs are characterized for particle mean diameter, polydispersity index (PDI), morphology, percent drug encapsulation efficiency (EE%), and FUR release kinetics. The methyl tetrazolium salt (MTS) and lactate dehydrogenase (LDH) bioassays are used to evaluate in vitro, the cytotoxicity of FUR-loaded NPs and native FUR. The NPs uptake is investigated using confocal microscopy, microplate reader/fluorimetry, and flow cytometry. Spherical NPs with a mean diameter range of 133-210 nm and PDI values varying from 0.037 to 0.41 are produced. The FUR EE% is 86% and the drug is released from the NPs according to the zero-order and Higuchi models. After treatment with blank NPs, the percentage of cell viability and cell death are 95.96% and 8.95%, in HEI-OC1 cells, respectively. The NPs are internalized by HEI-OC1 cells through a clathrin-dependent pathway. In addition, results show that NPs can be taken up via clathrin and cytoskeleton mediated pathways in SVK-1 cells. The internalization of the pegylated NPs can enhance the drug toxicity by necrosis in a dose-dependent and sustained release manner. The formulated NPs provide a promising template for a targeted drug delivery system to the inner ear.