Various preclinical animal studies have shown the potential of stem cells in re-vascularising ischemic limbs and promoting collateral vessel formation. SVF have the potential to facilitate the formation of new blood vessels and skeletal muscle. Early pilot clinical studies indicate that stem-cell transplantation is feasible and may have beneficial effects in CLI. Injury or inflammation is a prerequisite for the participation of circulating stem cells to home and differentiate on to this microenvironment. The increased vascular permeability and expression of adhesion proteins like integrin assist in stem cell homing. The migratory capacity of stem cells is dependent on natural growth factors such as vascular endothelial growth factor (VEGF), Stromal cell derived factor (SDFI) and stem cell factor (SCF). The expression of VEGF, SDFI and SCF is highly unregulated in the hypoxic muscular tissue and is responsible for the recruitment of the stem cells to assist in the repair mechanism and consequent improvement in limb function.