Selective neointimal gene transfer in an avian model of vascular injury

Avian models of atherosclerosis helped pioneer the study of vascular biolog y, and offer economic and technical advantages over mammalian models. As an initial step towards investigating important molecular pathways involved i n avian atherogenesis and restenosis, we developed a recombinant adenovirus (Ad) which expresses the reporter gene beta-galactosidase (beta-gal), and applied it to cultured chicken vascular smooth muscle cells (SMCs) and a ro oster model of acute vascular injury. In cultured chicken SMCs, recombinant gene expression increased as a function of multiplicity of infection (MOI) and incubation time. Maximal expression occurred at an MOI of 10(4) plaque -forming units (pfu)/cell with approximately 50% of quiescent and non-quies cent chicken SMCs expressing beta-gal. Human aorta SMCs had two- to four-fo ld increased beta-gal expression compared with chicken SMCs at all MOI and incubation times. in vivo instillation of recombinant Ad into uninjured roo ster femoral artery segments revealed low efficiency endothelial cell expre ssion of the reporter gene. In contrast, recombinant Ad infection of rooste r femoral artery segments 3-21 days after balloon injury revealed up to 60% of luminal surface beta-gal expression, confined predominantly to the neoi ntimal layer. Peak reporter gene expression efficiencies occurred in arteri al segments infected 3 days after balloon injury. Uninfected and control Ad infected arteries had no detectable beta-gal expression. Rooster neointima l cells targeted by the recombinant Ad were identified as alpha-smooth musc le actin containing cells by immunohistochemistry. We conclude that Ad-medi ated gene transfer is efficient and selective for the neointima in the roos ter acute vascular injury model, and offers the potential to efficiently in troduce exogenous genes that may impact on the injury response. This model of acute vascular injury may also be manipulated into more established avia n models of atherosclerosis, permitting the investigation of acute injury p rogression to chronic injury. (C) 1999 Elsevier Science Ireland Ltd. All ri ghts reserved.