Enhancement of ultrasonically induced cell transfection with artificial cavitation nuclei

Ultrasound mediated gene transfection in cultured immortalized human chondrocytes was enhanced three-fold using artificial cavitation nuclei in the form of Albunex(R). 1.0 MHz ultrasound transmitted through the bottoms of six-well culture plates containing media with green fluorescent protein reporter gene plasmids at a concentration of 40 /spl mu/g/ml and Albunex(R) at 50/spl times/10/sup 6/ bubbles/ml, exhibited a peak transfection efficiency of about 50% of the living cells when exposed to 4/spl times/10/sup 5/ Pascals spatial average peak pressure (SAPP) for 20 minutes. Using these parameters, transfection efficiency increased linearly with ultrasound exposure pressure with a transfection threshold observed at a SAPP of 10/sup 5/ Pascals. Adding fresh Albunex(R) at 50/spl times/10/sup 6/ bubbles/ml prior to sequential one second 3.2 or 4.0/spl times/10/sup 5/ Pascal exposures increased transfection efficiency by 15% for each of three consecutive exposures. Efficient in vitro and perhaps in vivo transfection appears possible with ultrasound.