Endothelial progenitor cell number and function. Endothelial progenitor cells (EPCs) from diabetic patients and healthy individuals were cultured for five days. (a) Circulating EPCs were labeled with CD34 and KDR cell surface antigens, and then identified by flow cytometry. The bars represent the number of circulating EPCs in the two study groups. (b) The numbers of colony-forming units (CFUs) of EPCs were counted manually in the two study groups. (c) Nitric oxide (NO) content in the medium was determined by measuring the intensity of DAF-2 fluorescence in the EPC culture medium. (d) NAD(P)H oxidase activity in EPCs from type 2 diabetes patients and healthy individuals and (e) Superoxide anion (O2-) generation by EPCs from type 2 diabetic patients and healthy individuals were measured by the lucigenin-enhanced chemiluminescence assay. (f) SOD activity in EPCs of type 2 diabetic patients and healthy individuals. The results in c, d, e, and f are expressed as a percentage of fluorescence intensity of the healthy group. Data are expressed as mean or percentage ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001. DM represents diabetic patients.