Contribution of adenoviral-mediated superoxide dismutase gene transfer to the reduction in nitric oxide-induced cytotoxicity on human islets and INS-1 insulin-secreting cells

Aims/hypothesis. Vulnerability of pancreatic islets to oxygen free radicals and nitric oxide contributes to islet transplantation obstacles. This susc eptibility can be linked to the low expression levels of antioxidant enzyme s in islets. Our aim was to investigate the effect of overexpressing Cu/Zn superoxide dismutase in human islets through a simple procedure on the cyto toxic effects of two nitric oxide donors: 3-morpholinosydnonimine (SIN-1) a nd S-Nitroso-N-acetyl-D,L-penicillamine (SNAP). Methods. Cultured human islets and INS-1 rat-derived insulin-secreting cell s were transfected by an E1-deleted adenovirus carrying Cu/Zn SOD cDNA unde r the control of a cytomegalovirus (CMV) promoter (AdSOD). The viability of the cells was tested by the WST-1 assay (Roche, Indianapolis, Ind., USA). Results. The AdSOD procedure allowed SOD activity to increase by twofold to threefold for 2 to 8 days following transfection. Adenovirus-driven SOD ov erexpression was associated with a significant reduction of SIN-1-induced c ytotoxicity on human islets (69.9 +/- 10.5% protection at 200 mu mol/l and 40.5 +/- 8.9% protection at 400 mu mol/l) and INS-1 cells (82.2 +/- 8.8% pr otection at 200 mu mol/l and 31.1 +/- 5.8% protection at 400 mu mol/l). Pro tection against increasing doses of SNAP was AdSOD dose-dependent. Transfec ted islets released significantly more insulin than control islets in gluco se-theophyllin-stimulated conditions, without or following exposure to SNAP . Conclusions/interpretation. We thus established that adenoviral-induced ove rexpression of Cu/Zn SOD can be beneficial to human islet endocrine functio n and resistance to nitric oxide cytotoxicity. These data could be relevant for the development of new strategies aimed at preventing NO-induced beta- cell damage in an islet transplantation setting.