Recent studies implicate hyperglycemia as a cause of vascular complications in diabetes. Our study confirmed that high concentration of glucose (30 mM) induces apoptosis in cultures of human umbilical vein endothelial cells. After 5 days of culture TUNEL positive cells in high concentration of glucose were nearly 63% higher when compared to normal concentration of glucose (5 mM). Transfection of pcDNA3-rat alphaB-crystallin into these cells inhibited high glucose-induced apoptosis by similar to36%, such an effect was not observed when cells were transfected with an empty vector. alphaB-crystallin transfection inhibited by about 35% of high glucose induced activation of caspase-3. High concentration of glucose enhanced formation of reactive oxygen species (ROS) in these cells but this was significantly (p < 0.001) curtailed by transfection of alphaB-crystallin. Results of our study indicate that alphaB-crystallin effectively inhibits both ROS formation and apoptosis in cultured vascular endothelial cells and provide a basis for future therapeutic interventions in diabetic vascular complications. (C) 2004 Elsevier Inc. All rights reserved.