Molecular engineering of vein bypass grafts

Surgical bypass of arterial occlusions using autogenous vein provides an effective treatment for many patients with advanced coronary or peripheral atherosclerosis. However, the long-term benefit of bypass surgery is limited by the development of de novo occlusive lesions within the vein graft, which occurs in a significant percentage of patients over time. The pathophysiology of vein graft failure involves a complex interplay between an acute vascular injury response and the hemodynamic adaptation of the vein to arterial forces. Cell proliferation, inflammation, and matrix metabolism are critical components of postimplantation remodeling. Conventional pharmacotherapy has had limited impact on graft failure. Vein grafts present a unique and attractive opportunity for molecular engineering, which is defined for purposes of this review as the local application of genomic (eg, gene transfer or gene inhibition) or proteomic interventions designed to alter the healing response. The critical enabling technologies for these strategies are described, with a perspective on preclinical and clinical development for this indication. The recently completed clinical trials of edifoligide (E2F decoy oligodeoxynucleotide) provide important lessons for future studies. A better understanding of the remodeling response of vein grafts in humans is required to design effective molecular therapies and to define the appropriate target populations and surrogate markers for future clinical trials.