Metal toxicity represents a signifcant public health concern and contributes to many toxic metal-exposure related diseases. In particular, toxic metals promote the oxidative stress in stem cells and endothelial progenitor cells (EPCs). EPCs that are presented in peripheral blood function to replenish aging damaged endothelial cells and play important role in the maintenance of vasculature and neovascularization. Given the links between oxidative injury, endothelial cell dysfunction and vascular disease, we focused our investigation on the response of CD34-positive cells to chelation by DMSA.