The purpose of this study is to determine the safety and effectiveness of the Tissue Genesis® Icellator Cell Isolation System™ in Critical Limb Ischemia. The Icellator System™ device removes certain cells from the adipose (fat) tissue which will be used to treat patients with blockages in the arteries of their lower legs that may require a future amputation, which is caused by severe peripheral artery disease (PAD). The purpose of this study is to determine if treatment with cells that have been removed from the Icellator System™ device will reduce the number of major amputations and deaths in a six month time period.