Adenoviral gene transfer to intact and denuded arteries: A quantitative, comparative study

Adenoviral gene transfer to the arterial wall is a promising therapeutic strategy for gene therapy of various cardiovascular diseases. Because endothelial loss is an common feature of vascular Injury states, we quantitatively compared the relative efficiency of in-mo adenoviral gene transfer of β-Galactosidase (β-Gal) to Intact and to denuded rabbit carotid arteries (CA). CA were denuded using a 2F Fogarty balloon catheter. For gene transfer, we used luminal dwell with a viral titer of 5 x 10 pfu/ml for 30 minutes. β-Gal gene expression was compared both by assessing blue cell nuclei in histologie sections of x-gal stained vessels and by direct β-Gal protein measurement in vessel extracts using a β-Gal ELISA. Results: A total of 14 vessels were studied for β-Gal expression 3 days after gene transfer. Segments of untransfected CA were used as controls. All gene-transferred vessels stained blue with x-gal. In intact CA (n-8), virtually every endothelial cell expressed β-Gal, but only rare blue cells were seen in the arterial media. In denuded CA (n-6), endothellum was absent and only infrequent smooth muscle cells in the exposed surface of the media expressed β-gal. Deeper penetration through the elastic laminae was not observed. The amount of β-Gal protein in denuded CA (mean ±SD) was 38.2 ±21.a ng/mg protein, compared with 96.8 ±38 ng/mg protein in intact CA (p<0.005). β-gal was not detected in control CA. Conclusion: Gene transfer to rabbit CA is highly efficient and generates high levels of βGal expression. In the absence of medial disruption, the endotnelium is the preferential target of arterial gene transfer. After endothelial denudation, β-Gal levels are approximately 3-fold tower than in intact CA. These findings have important implications for gene transfer applications in vascular injury states.