Vascular Gene Transfer of Phosphomimetic Endothelial Nitric Oxide Synthase (S1177D) Using Ultrasound-Enhanced Destruction of Plasmid-Loaded Microbubbles Improves Vasoreactivity

Abstract
Background— Local gene therapy has enormous potential for the treatment of vascular disease. We determined whether diagnostic ultrasound-mediated destruction of plasmid-loaded albumin microbubbles is a feasible and efficient technique for local vascular gene delivery. For gene transfer, we used a phosphomimetic, active endothelial nitric oxide synthase (eNOS) construct in which Ser1177 was replaced by aspartic acid (S1177D) and exhibits a 2-fold higher basal activity than the wild-type enzyme. Methods and Results— Gas-filled microbubbles (3.0±1.2 μm) were created by sonication of 5% human albumin in the presence of plasmid DNA encoding for LacZ or eNOS S1177D. Porcine coronary arteries were perfused with DNA-loaded albumin microbubbles in vitro, exposed to diagnostic ultrasound (5 seconds), and incubated for a further 24 hours. Detection of the β-galactosidase in LacZ-transfected vessels revealed a predominant staining of endothelial cells without any functional impairment of vasoreactivity. Western blott...