This protocol is designed to determine the safety/toxicity and biologic efficacy of direct administration of the AdGVVEGF121.10 vector to the lower limb of individuals with peripheral vascular disease. At the conclusion of the study, in addition to the objective described above, the investigators will demonstrate whether direct administration of AdGVVEGF121.10 to the lower limb will induce growth of collateral blood vessels, and improve blood flow in the region of ischemia.