Effect of Low Level Ionizing Radiation on Endothelial Progenitor Cells in Atherosclerotic Patients with Lower Limb Ischemia

Atherosclerotic heart disease is a chronic life-threatening disease,which is characterized by reduced blood supply to the heart as a result ofthe accumulation of atheromatous plaques within the walls of the arteriesthat supply the myocardium.Progressive atherosclerosis in the coronary arteries may lead tointimal thickening and eventual artery occlusion. Coronary arteryocclusion can cause acute myocardial ischemia as a result of reducedoxygen supply or increased oxygen demand. Convincing evidenceindicates that atherosclerosis is associated with endothelial dysfunction atthe early stage of the disease process.More recently, it has become clear that circulating endothelialprogenitor cells are an alternative mechanism for maintenance and repairof the endothelium, these cells are recruited from the bone marrow,circulate in the peripheral blood, and can differentiate into mature cellswith endothelial characteristics.Postnatal vasculogenesis is the formation of new blood vesselsfrom bone marrow-derived endothelial progenitor cells (EPCs). Thisprocess is regulated, in part, through chemokine signaling gradients thatguide these EPCs to areas of ischemia/injury.Chemokines, a cytokine subset, are inflammatory mediatorsspecifically involved in trafficking of many different cell types includingimmune cells and stem cells. Recent studies have shown that ionizingradiation (IR) can affect CXC chemokine expression in humanfibroblasts.