title: beta-Galactosidase staining following intracoronary infusion of cationic liposomes in the in vivo rabbit heart is produced by microinfarction rather than effective gene transfer: a cautionary tale.
abstract: The myocardium is a potential target for the expression of exogenous genes to treat inherited and acquired diseases. Although adenovirus-mediated gene transfer has resulted in high-level gene transfer in vivo via direct intramyocardial injection and via a percutaneous intra-arterial route, the time-course of gene expression is limited by host immune responses. It was the aim of this study to test whether cationic liposome-mediated gene transfer, which does not suffer from the aforementioned problems, was feasible in the adult rabbit myocardium via a percutaneous transluminal approach. Doses of plasmid DNA encoding lacZ from 200-800 micrograms complexed to cationic liposomes resulted in X-gal conversion at day 3 with associated myocardial damage. We hypothesised that the damage was associated with macro-aggregates of cationic liposomes-DNA occluding the microcirculation. When such aggregates were excluded no X-gal conversion was seen in vivo. In order to show that X-gal conversion occurs in areas of infarction in the myocardium we caused closed chest infarction by deploying a platinum micro-embolisation coil in the circumflex coronary artery. At day 3 X-gal conversion was observed in the territory supplied by the occluded artery. Thus, microinfarction causes the false positive appearance of gene transfer when using a lacZ reporter gene.
authors.affiliation: Department of Cardiology, United Medical and Dental School of Guys' Hospitals, London, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Wright
authors.forename: E
authors.initials: E
authors.lastname: Rosenthal
authors.forename: L
authors.initials: L
authors.lastname: Stewart
authors.forename: L M
authors.initials: LM
authors.lastname: Wightman
authors.forename: A D
authors.initials: AD
authors.lastname: Miller
authors.forename: D S
authors.initials: DS
authors.lastname: Latchman
authors.forename: M S
authors.initials: MS
authors.lastname: Marber
mesh_terms: D000818:Animals; D001794:Blood Pressure; D006328:Cardiac Catheterization; D004562:Electrocardiography; D005189:False Positive Reactions; D005697:Galactosides / Q000378:metabolism; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000009:adverse effects / Q000379:methods*; D007211:Indoles / Q000378:metabolism; D008081:Liposomes; D009203:Myocardial Infarction / Q000201:enzymology* / Q000209:etiology / Q000473:pathology; D011817:Rabbits; D015854:Up-Regulation; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D005697:Galactosides; D007211:Indoles; D008081:Liposomes; D001616:beta-Galactosidase; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside