BACKGROUND: Hypoxic damage is one of the major causes of early islet graft failure, and VEGF is known to play a crucial role in revascularization. We tried to evaluate whether the VEGF transgene in an islet graft can increase islet revascularization and; therefore, increase the survival rate of transplanted islets in order to achieve effective glycemic control in diabetic mice models using a non-viral cationic lipid reagent for gene delivery into non- dividing islet cells. METHODS: Human VEGF165 cDNA was transfected into Balb/c mice islets using Effectene, and the vascular neogenesis and glucose levels examined in the recipient syngeneic Balb/c mice. A minimal number of VEGF-transfected islets(100 IEQ/animal) were transplanted into STZ-induced diabetic mice. The recipient mice were classified into three groups: islet transplantation(IT) without intervention(IT-alone group, n=8), IT with an islets transduced rhoJDK-control vector(IT-rhoJDK group, n=8), and IT with an islets transduced rhoJDK-VEGF vector(IT-rhoJDK-VEGF group, n=8). RESULTS: The transfection efficiency was highest with 4microgram/microliter cDNA and 25microliter Effectene(1: 6 weight ratio), with satisfactory cell viability under these conditions. The overproductions of VEGF mRNA and proteins from the conditioned cells were confirmed. A minimal number of the VEGF-transfected islets(100 IEQ/animal) were transplanted into STZ-induced diabetic mice. The control of hyperglycemia in the IT-alone(0/8) and IT-rhoJDK groups(0/8) failed. However, complete abrogation of hyperglycemia and viable islets, and an increased vascularization of the VEGF-transfected grafts were identified in the renal capsules of the IT-rhoJDK-VEGF group(8/8). CONCLUSION: These studies support the utility of VEGF-transfected islet delivery using a cationic lipid reagent to achieve euglycemia with minimal islets via neovascularization.