Gene transfer with echo-enhanced contrast agents: comparison between Albunex, Optison, and Levovist in mice--initial results.
OBJECTIVE
To determine if commercially available echo-enhanced microbubble contrast agents could be used to increase gene transfection efficiency by means of relatively low-intensity ultrasound-mediated microbubble destruction in skeletal muscles.


METHODS
Three types of ultrasound microbubble contrast agents (0.01 mL of albumin [Albunex] and human albumin [Optison] and 10 mg/mL of SH U 508A [Levovist]) were each separately mixed with the reporter plasmid DNA (25 microg) encoding green fluorescent protein (GFP) prior to intramuscular injection into the quadriceps muscle of a mouse thigh bilaterally (seven mice per contrast agent). One of the muscle sites that was injected with plasmid DNA was irradiated with low-intensity therapeutic ultrasound (1 MHz) at an intensity of 2.0 W/cm2 for 2 minutes. Mice were sacrificed 7 days after ultrasound treatment for gene expression assay. The number of GFP-expressing muscle fibers was counted. Statistical significance was determined with a two-tailed Student t test. P <.05 was considered to indicate statistically significant difference.


RESULTS
Muscle tissue exposed to ultrasound with air-filled Albunex or Levovist microbubbles revealed no difference in the number of GFP-expressing muscle fibers compared with the control non-ultrasound-exposed muscle. Albumin-coated octafluoropropane gas-filled Optison microbubbles showed a 10-fold increase in the number of GFP-expressing fibers (P <.05).


CONCLUSIONS
Low-intensity ultrasound with echo-enhanced Optison induced efficient gene transfer unlike that with Albunex or Levovist.
D000418:Albumins / Q000008:administration & dosage; D000818:Animals; D016466:CHO Cells; D003287:Contrast Media / Q000008:administration & dosage*; D006224:Cricetinae; D003412:Cricetulus; D004269:DNA, Bacterial; D005260:Female; D005466:Fluorocarbons / Q000008:administration & dosage; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D007273:Injections, Intramuscular; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D045423:Microbubbles; D010957:Plasmids / Q000235:genetics; D011134:Polysaccharides / Q000008:administration & dosage
D000418:Albumins; C060687:Albunex; D003287:Contrast Media; D004269:DNA, Bacterial; C099458:FS 069; D005466:Fluorocarbons; D008164:Luminescent Proteins; D011134:Polysaccharides; C059891:SHU 508; D049452:Green Fluorescent Proteins