Fig. 6.

C12-200-siRNA particles elicit cellular uptake by macropinocytosis. (A) Fluorescently labeled siRNA formulated with C12-200 was incubated with HeLa cells in the presence of labeled markers of various endocytic pathways. siRNA-containing particles colocalize with labeled dextran, a fluid phase marker known to enter cells via macropinocytosis (White arrows). (B) Fluorescence labeling of actin fibers reveals membrane ruffling (White arrows) and actin rearrangement, hallmark indicators of uptake by macropinocytosis, within 15 min of exposure of HeLa cells to C12-200-siRNA particles. (C,D) Prior exposure of cells to EIPA and Cytochalasin D, inhibitors of macropinocytosis and actin polymerization, respectively, reduce uptake of C12-200-siRNA particles in dose-dependent fashion. (s.d., n = 3, *** P < 0.005; ** P < 0.01; * P < 0.05