Enhanced gene transfer to rabbit jugular veins by an adenovirus containinga cyclic RGD motif in the HI loop of the fiber knob

Gene therapy using recombinant adenoviral vectors represents a promising th erapeutic tool to prevent vein graft stenosis, the main complication of cor onary artery bypass grafting. However, the low transduction efficiency of v ascular smooth muscle cells and endothelial cells (EC) is a potential limit ation, presumably due to the low levels of functional adenovirus receptor ( coxsackie:adenovirus receptor; CAR). Designing vectors specifically targete d to a, integrins is a strategy that might overcome the poor expression of CAR in vascular smooth muscle cells and EC. RGD, a receptor-binding motif t hat can interact with a, integrins, was inserted into the HI loop and at th e C-terminus of the adenoviral fiber protein in two separate adenovirus vec tors encoding a B-galactosidase reporter gene. Av1nBgCRGD (C-terminus) and Av1nBgHIRGD (HI loop) were evaluated in EC in culture and in jugular vein o rgan culture. Transduction of primary rat and rabbit EC with Av1nBgHIRGD wa s significantly more efficient when compared to Av1nBgCRGD or Av1nBg. Trans duction of mouse, rat and rabbit jugular veins in organ culture using Av1nB g showed that adenovirus-mediated gene expression was greatest in rabbit ju gular veins compared to rat and mouse veins. Av1nBgHIRGD augmented gene exp ression approximately four-fold in rabbit jugular veins when compared to Av 1nBg. Histochemical analysis showed that numerous EC but few smooth muscle cells were transduced at all vector concentrations. A substantial number of adventitial fibroblasts were transduced only at the highest vector concent rations of Av1BgHIRGD. These findings demonstrate that integrin-targeted ve ctors allow for enhanced gene delivery to veins and strengthen the viabilit y of adenoviral-mediated gene transfer of therapeutic transgenes to human v eins prior to vein grafting. Copyright (C) 2001 S. Karger AG, Basel.