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. Author manuscript; available in PMC: 2014 Oct 1.
Published in final edited form as: Nanomedicine. 2013 Feb 27;9(7):912–922. doi: 10.1016/j.nano.2013.02.006

Figure 4. PEGylation of cSCKs enhances the uptake in alveolar type II epithelial cells.

Figure 4

(A) Fluorescence photomicrographs with differential interference contrast (DIC) overlay show the distribution of fluorescent labeled cSCK in the lung alveoli. Bar=20 μm. (B, C) Confocal microscopy of cSCK in alveolar epithelial cells stained with actin marker (phalloidin, red). (B) Non-PEG cSCKs associated with the cell surface (arrows), cSCK-5PEG internalized in alveolar epithelial type II cells (arrowheads) and DNA stained with TO-PRO-3 (blue). (C) PEGylated cSCK show internalization in type II cells immunostained for prosurfactant protein C (SPC; pseudocolored white). Insets are detail of the indicated regions (*) without phalloidin stain. Bars = 10 μm in B, C. (D–F) Uptake of cSCK in MLE 12 cells detected by flow cytometry 1 h post-incubation. (D) Quantification of cSCK uptake. n=6 independent experiments with duplicate samples (E) Quenching analysis of non-PEGylated cSCK compared to PEGylated-cSCK. Cells were incubated with the indicated cSCK form, analyzed in the absence and then in the presence anti-AF488 antibody. (F) cSCK cell uptake after incubation with artificial surfactant (Survanta) relative to media only. (E, F; n=2 independent experiments with duplicate samples). All data are the mean ± S.D. A significant difference compared to non-PEG cSCK is indicated (*, P < 0.05).