ADENOVIRUS-MEDIATED CATALASE GENE-TRANSFER REDUCES OXIDANT STRESS IN HUMAN, PORCINE AND RAT PANCREATIC-ISLETS

Susceptibility of pancreatic islets to oxidant stress may affect islet viability and contribute to primary non function of allo- or xenogeni c grafts. We investigated the influence of overexpression of catalase (CAT) on the viability of human, porcine and rat islets, as well as IN S-1 beta-cell line. Islets were transfected with a replication-deficie nt adenovirus vector containing human CAT cDNA under the control of th e adenovirus major late promoter (AdCAT) or a vector containing no for eign gene (AdNull) and used as a control. Oxidant stress was induced 4 8 h later by xanthine oxidase-hypoxanthine (XO 25 mU/ml, HX 0.5 mmol/l ) or hydrogen peroxide (100 or 250 mu mol/l). Islet cell viability was assessed 72 h after CAT transfer by 4-[3-(4-Idophenyl)-2-(4 nitrophen yl)-2H-5-tetrazolio]-1,2,benzene disulphonate (WST-1) test. Baseline c atalase activity was three to fourfold lower in porcine than in human islets, CAT activity was reproducibly increased 2.5- to 7-fold in AdCA T infected islets, at least for 13 days. Overall, AdCAT conferred on h uman and pig islets a protection of 26.1 +/- 6.1 and 21.2 +/- 9.8% on XOHX injury and 35.4 +/- 4.2 and 57.9 +/- 10.5% on H2O2 stress. Simila rly, rat islet cells and INS-1 cells were protected on XOHX stress by 17.8 +/- 2.3 and 30.8 +/- 8.7%, respectively. AdNull had no effect. Ba sal and stimulated insulin secretion was preserved in AdCAT-transfecte d human islets despite a XOHX challenge. This study validates adenovir us-mediated catalase gene transfer as a realistic approach to reduce n on specific inflammation effects on human or porcine islet grafts. Mor eover the relevance of defense mechanisms, previously suggested in hum an islets, is here illustrated in porcine islets.