Previous attempts to target arterial smooth muscle cells (SMCs) for gene delivery using liposomal or retroviral methods were limited by low transfection efficiency. We therefore evaluated the efficiency of adenovirus-mediated gene delivery in cultured vascular SMCs and in an in vivo model of balloon injury-induced SMC cell proliferation.Methods and Results.
We used a recombinant adenovirus, Ad.RSVβgal, which contained the β-galac-tosidase (β-gal) histochemical marker gene. For in vitro studies, rat aortic SMCs were incubated in media containing Ad.RSVβgal for 5 to 120 minutes. The proportion of SMCs expressing the β-gal gene product increased from 25% (5-minute exposure) to 80% (120-minute exposure). For in vivo studies, uninjured and injured rat carotid segments were incubated with 0.5 to 1.0×109 pfu Ad.RSVβgal for 45 minutes. Uninjured arteries showed adenovirus-mediated gene transfer limited to the endothelium. Injured arteries were exposed to adenovirus 0, 3, 7, or 12 days after injury. In these segments, β-gal expression was minimal with infection at 0 or 3 days after injury but marked when infection was delayed until 7 or 12 days after injury. Neointimal cells constituted the dominant target of adenovirus gene transfer, with efficiency of gene transfer ranging from 10% to >75%. Medial SMCs, whether covered or uncovered by neointimal cells, were minimally infected. Infection with a control adenovirus vector showed no β-gal staining.Conclusions.
Recombinant adenovirus selectively targets neointimal cells with high-efficiency gene transfer. This suggests that adenovirus vectors should be useful in targeting cells for the delivery of genes whose products may be relevant to the treatment of restenosis. (Circulation.1993;88:2838–2848.)