The present invention contemplates compositions and methods for the treatment of vascular grafts both ex vivo and in vivo. Ex vivo treatment comprises completely removing a vessel (i.e., vein or artery) from the body and treating with the compositions of the present invention. In vivo treatment comprises treating the vessel in vivo without removing the vessel completely from the body (albeit one or both ends of the vessel may be closed off in order to focus the treatment in the desired area and/or avoid systemic treatment). In one embodiment, at least a portion of the smooth muscle cells of a vessel (e.g., vein or artery) are transfected ex vivo or in vivo with a vector capable of expressing at least one phosphatase. In a preferred embodiment, smooth muscle cells are transfected with adenovirus vector comprising the gene encoding PTEN.