¹Department of Clinical Pharmacology, Groningen University Institute for Drug Exploration (GUIDE), University of Groningen, The Netherlands

²Department of Cardiology, University of Groningen, The Netherlands

³Department of Medical Microbiology, Molecular Virology Section, University of Groningen, The Netherlands

⁴Department of Therapeutic Gene Modulation, University of Groningen, The Netherlands

Correspondence to: A J M Roks, Department of Clinical Pharmacology, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands

Previously, we demonstrated that recombinant Semliki Forest virus (SFV) vector rapidly and selectively transfers genes into cultured vascular smooth muscle cells (VSMC), leaving endothelial cells (EC) unaffected. From this, we hypothesized that recombinant SFV in vivo only transfers genes into the media of balloon-injured but not intact vessel, that gene expression in VSMC is fast, and that the specificity of SFV for VSMC is caused by specific binding sites. To address these hypotheses, we studied the time course of in vivo SFV-LacZ and Ad-LacZ expression in balloon-injured rat aorta. In addition, the fusion characteristics of fluorescent pyrene-labeled SFV were explored in cultured VSMC and EC. In intact aorta, no LacZ expression was found in the intima or media at 24 h. In contrast, in denuded aorta, LacZ expression was detected in as early as 12 h after incubation. LacZ expression was predominantly present in the media. Ad-LacZ expression started after 12 h, but was predominantly present in the adventitia. Ad-LacZ expression in the media started after 72 h. In vitro transfection with SFV showed that fusion was higher and, moreover, saturable in VSMC as compared with EC, indicating the presence of specific SFV binding sites on VSMC, but not EC. From this we conclude that in vivo selectivity of SFV in balloon-injured vessels is based on the removal of the endothelium, which results in accessibility of VSMC in the media that carry specific binding sites for the SFV vector.

Gene Therapy 2001 9, 95-101. DOI: 10.1038/sj/gt/3301632

Semliki Forest virus; adenovirus; vascular smooth muscle cells; endothelial cells; rat aorta; balloon injury; gene therapy