Gene-eluting stents:: Comparison of adenoviral and adeno-associated viral gene delivery to the blood vessel wall in vivo

Gene-eluting stents are being evaluated in animals as an alternative approach to inhibiting in-stent restenosis. Adeno-associated virus type 2 (AAV2) and adenovirus are commonly used for gene transfer applications. We tested the hypothesis that these vectors can achieve prolonged and localized gene delivery to the vessel wall, using stents as delivery platforms. Ad beta Gal (5 x 10(9) plaque-forming units) and AAV2 beta Gal (5.3 x 10(9) DNase-resistant particles) were used to coat BiodivYsio stents with matrix HI coating ( Abbott Vascular Devices, Galway, Ireland). After balloon injury, external iliac arteries of New Zealand White rabbits were stented. The reverse transcription-polymerase chain reaction was used to assess viral spread. Expression of LacZ was demonstrated with both vectors at five time points ( 3, 7, 14, 21, and 28 days). In the adenovirus group the median percentage of cells expressing the transgene on day 3 was 2.73%, which increased to a median expression of 7.31% at 28 days ( p > 0.05). Expression was localized to medial cells on day 3, but was observed predominantly in neointimal cells on day 28. In the AAV group, day 3 expression was 5.78%, which decreased to 2.12% on day 28 ( p = 0.05). No systemic dissemination of virus was seen in any group. Adenovirus- and AAV2-coated stents can be used to deliver genes to the blood vessel wall for up to 28 days.