Fig. 7
Effect of vibrational loading on clathrin- and caveolae-mediated endocytosis and transfection. a Effect of clathrin- and caveolae-mediated endocytosis inhibitors on polyfected and vibropolyfected (5 min, fin = 1,000 Hz, post-delivery set-up) L929 cells. Briefly, cells were pre-treated for 30 min with chlorpromazine (10 µg/mL) or filipin (5 µg/mL) to inhibit clathrin- and caveolae-mediated endocytosis, respectively. Cells were next challenged with lPEI/pGL3 polyplexes for 3.5 hrs and cultured for a further 20 hrs. Data are expressed as a fold decrease in transfection efficiency in cells treated with inhibitors compared to cells transfected in the absence of inhibitors. Data are expressed as mean ± SD (n = 3, * p < 0.05 vs. cells transfected in the absence of inhibitors). b Effect of vibrational loading on clathrin and caveolae expression in polyfected and vibropolyfected L929 cells. Mean Fluorescence Intensity (MFI) of clathrin heavy chain and caveolin-1 proteins normalized to the cell area after transfection with lPEI/pDNA-FITC complexes upon static (polyfection) and vibropolyfection conditions (post-delivery set-up, fin = 1,000 Hz). Data are expressed as mean ± SD (n = 3, * p < 0.05). c Representative CLSM images of polyfected and vibropolyfected (post-delivery set-up, fin = 1,000 Hz) L929 cells. Briefly, cells were transfected for 1 hr, fixed, and clathrin heavy chain and caveolin-1 were immunostained. lPEI/pDNA-FITC polyplexes are in green, clathrin heavy chain and caveolin-1 are in red, while nuclei are in blue. Scale bar = 20 µm