The primary objective of the Phase I ascending dose trial is to investigate the safety and tolerability of intramuscular (gastrocnemius) injections of human neural stem cell product, CTX, in patients with peripheral arterial disease (Fontaine Stage II through IV). This trial is based on independent preclinical data from a leading academic research institution that has been submitted for publication. Inclusion of patients with Fontaine Stage II is justified as these patients have a lower incidence of background events and will facilitate distinction between events which are possibly intervention-related versus spontaneous events associated with underlying advanced atherosclerosis. The trial is designed to treat 9-18 patients and evaluate safety measures over a 12 month follow-up period.