Second-generation adenoviral vectors do not prevent rapid loss of transgene expression and vector DNA from the arterial wall

The utility of adenoviral vectors for arterial gene transfer is limited by the brevity of their expression and by inflammatory host responses. As a st ep toward circumventing these difficulties, we used a rabbit model of in vi vo arterial gene transfer to test 3 second-generation vectors: a vector con taining a temperature-sensitive mutation in the E2A region, a vector delete d of E2A, and a vector that expresses the immunomodulatory 19-kDa glycoprot ein (gp19k) from adenovirus 2. Compared with similar first-generation vecto rs, the second-generation vectors did not significantly prolong beta-galact osidase transgene expression or decrease inflammation in the artery wall. A lthough cyclophosphamide ablated the immune and inflammatory responses to a denovirus infusion, it only marginally prolonged transgene expression (94% drop in expression between 3 and 14 days). In experiments performed with "n ull" adenoviral vectors (no transgene), loss of vector DNA from the arteria l wall was also rapid (>99% decrease between 1 hour and 14 days), unrelated to dose, and only marginally blunted by cyclophosphamide. Thus, the early loss of transgene expression after adenoviral arterial gene transfer is due primarily to loss of vector DNA, is not correlated with the presence of lo cal vascular inflammation, and cannot be prevented by use of E2A-defective viruses, expression of gp19k, or cyclophosphamide-mediated immunosuppressio n. Adenovirus-induced vascular inflammation can be prevented by cyclophosph amide treatment or by lowering the dose of infused virus. However, stabiliz ation of adenovirus-mediated transgene expression in the arterial wall is a more elusive goal and will require novel approaches that prevent the early loss of vector DNA.