The purpose of this study is to measure the concentration of cells and proteins in the patient's blood during administration of Nuopogen (Filgrastim), a medication that is FDA approved for stem cell mobilization, in combination with a programmed pneumatic compression device (PPCD) (Art-Assist Device). The Art-Assist Device is an FDA approved device that promotes blood flow in the patient's legs. A patient will be prescribed this device and this drug to help improve the poor circulation in his/her leg. The use of Nuopogen along with the Art-Assist Device has not been approved by the FDA and is considered experimental.