Fig. 1. Lipid-mediated plasmid internalization. MAT B III cells were incubated with LF 2000/(DNA/YOYO-1) lipoplexes and observed at (A) 5 min and (B) 1 h with a fluorescent microscope. The pictures correspond to the overlay of light transmission and epifluorescence images (using the analySIS software). Exposure time for the fluorescence microscopy observations: 100 ms. Obj. × 100.

Fig. 2. Ultrasound-mediated plasmid internalization. MAT B III cells were sonoporated with YOYO-1 labelled DNA and observed at (A) 5 min and (B) 1 h post-sonoporation, using a focused transducer (2.25 MHz) at P- = 570 kPa in the presence of an UCA at a concentration of 25 particles/cell (using the analySIS software). Exposure time for the fluorescence microscopy observations: 500 ms. Obj. × 100. Note that all the observed cells showed similar patterns of fluorescence.

Fig. 3. Kinetics of plasmid internalization. MAT B III cells were sonoporated alone (- -x- -) or in the presence of an UCA at a concentration of 30 particles/cell (-Δ-), and were analyzed by flow cytometry for 24 h. For comparison, MAT B III cells were also transfected with Lipofectamine 2000 (- -□- -).

Fig. 4. Comparison between plasmid internalization and gene expression at 24 h post-sonoporation. Percentage of PI-positive cells (♦) and percentage of plasmid-internalizing cells (DNA/YOYO-1 positive cells) or transfected cells (GFP-positive cells) were analyzed by flow cytometry 24 h post-sonoporation at P- = 570 kPa using a focused transducer operating at a transmitted frequency of 2.25 MHz.

Fig. 5. Kinetics of DNA/YOYO-1 (-♦-) and FITC-dextran 150S (- -□- -) internalization into MAT B III cells. Cells were sonoporated in the presence of an UCA at a concentration of 30 particles/cell, using a focused transducer operating at 2.25 MHz at P- = 570 kPa, and were analyzed by flow cytometry.

Fig. 6. Kinetics of gene expression. Mat B III cells were analyzed by flow cytometry following sonoporation (2.25MHz, P- = 570 kPa) in the presence of an UCA at a concentration of 25 particles/cell (-♦-), and following lipofection (- -□- -). Results are expressed (A) as the percentage of normalized positive cells (defined as the % of positive cells at time (t) divided by the % at 24 h when the maximum level of expression was observed), and (B) in terms of fluorescence intensity (in arbitrary units: AU).