 The study design is a randomized, double-blind, placebo-controlled, parallel group, multi-center, Phase 2 dose-selection study. Seventy-five patients will be enrolled into each of 4 study drug groups 3 groups of Ad2HIF-1αVP16 gene transfer and 1 placebo group for a total of 300 patients overall. Three different doses of Ad2HIF-1αVP16 gene transfer will be studied. The dose range was previously tested in animals and in the Phase 1 human studies. A placebo group is included in the study to compare safety and efficacy of different doses of Ad2HIF-1αVP16 with placebo. Each patient will receive a single set of 20 injections 100 μL each of gene transfer or placebo in one administration to each leg for a total of 40 injections. 