Figure 1

FFA treatment induces hepatocellular steatosis in HCV replicon cells. S3-GFP cells in culture were treated with increasing concentrations of Oleate/Palmitate (2: 1 ratio) and hepatocellular steatosis due to an intracellular fat accumulation was characterized by a number of methods. (A) Fluorescence microscopy showing concentration dependent hepatocellular steatosis in S3-GFP cells 24 h post treatment by Nile Red staining (yellow) and nuclear staining (blue). The images were taken at 40× magnifications. (B) Microfluorometer analysis of intracellular fat accumulation in S3-GFP cells 24 h after FFA treatment. The values are expressed as fold change compared to untreated cells, *P <0.001, Student t test. (C) MTT assay showing the effect of intracellular fat accumulation (dose-dependent) on cellular cytotoxicity of S3-GFP cells in culture. Cell viability was expressed as % of untreated. (D) MTT assay showing cell viability over time (h) for concentrations of FFA up to 0.5 mM. (E) Electron micrograph of FFA-treated (0.5 mM) S3-GFP cells showing intracellular lipid droplet accumulation. (i) Untreated cells, (ii) FFA-treated cells, 4000×magnification, and (iii) 7000× magnification showing fat droplets in the endoplasmic reticulum (ER) (black arrow).