The purpose of this study is to determine the efficacy of graft pretreatment with the E2F decoy, CGT003, as compared to placebo, on the occurrence of graft failure among patients who receive autogenous vein grafts to treat chronic critical limb ischemia; on the occurrence of clinically significant graft stenosis (more than or equal to 70%); and on the incidence of critical limb ischemia (e.g., gangrene, non-healing ischemic ulcers or ischemic rest pain).