ARTIFICIAL CAVITATION NUCLEI SIGNIFICANTLY ENHANCE ACOUSTICALLY INDUCED CELL TRANSFECTION

The efficiency of ultrasound-mediated gene transfection was enhanced t hree-to fourfold, compared to previous results, through the use of gre en fluorescent protein reporter gene, cultured immortalized human chon drocytes and artificial cavitation nuclei in the form of Albunex(R), C ells were exposed to 1.0-MHz ultrasound transmitted through the bottom of six-well culture plates containing immortalized chondrocytes, medi a, DNA at a concentration of 40 mu g/mL and Albunex(R) at 50 x 10(6) b ubbles/mL. Transfection efficiency increased linearly with ultrasound exposure pressure with a transfection threshold observed at a spatial average peak positive pressure (SAPP) of 0.12 MPa and reaching about 5 0% of the living cells when exposed to 0.41 MPa SAPP for 20 s, Adding fresh Albunex(R) at 50 x 10(6) bubbles/mL prior to sequential 1-s, 0.3 2- or 0.41-MPa exposures increased transfection with each exposure, re aching 43% transfection after four exposures, Efficient in vitro and i n vivo transfection now appear possible with these enhancements. (C) 1 998 World Federation for Ultrasound in Medicine & Biology.