Objectives: Autogenous vein remains the conduit of choice for infrainguinal reconstruction despite a high failure rate. Failure is primarily due to the development of intimal hyperplasia. Gene transfer approaches have been successfully applied in arteries but little is known about gene transfer in vein grafts. The purpose of the present study was to characterize the efficacy, cellular targets and time course of β-galactosidase adenoviral gene transfer in a vein graft model.Methods: Young adult male New Zealand white rabbits underwent carotid artery interposition bypass grafting using ipsilateral reversed external jugular vein. Immediately prior to interposition grafting, the in situ external jugular vein was infected with an adenovirus expressing β-galactosidase (n = 16). The contralateral native jugular vein (n = 16) and carotid artery (n = 8) were concurrently infected with an identical adenovirus preparation. At 3, 7 or 14 days, vessels were harvested and β-galactosidase protein expression was quantitated by ELISA and specific cell types expressing β-galactosidase were identified by X-Gal staining and by immunohistochemistry.Results: At 3 days, endothelial and advential cells, but not medial smooth muscle cells, were efficiently transduced in all three groups of vessels. The endothelium of the vein graft group alone demonstrated activation and intense inflammation. Transgene expression in vein grafts was approximately 50% of arteries and ungrafted veins at 3 days and 6-fold lower at 1 week.Conclusions: Early endothelial transfer efficiency is equivalent in normal arteries and veins. Vein grafts, however, lose transgene expression at a markedly faster rate coincident with evidence of endothelial inflammation. Exposure of the vein graft endothelium to arterial flow conditions, not the adenoviral vector, appears to cause the reduced transgene expression. Accelerated loss of transgene expression in vein grafts has important implications for designing therapeutic gene transfer strategies.