ADENOVIRAL MEDIATED ISLET GENE TRANSFER

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Diabetes mellitus is a common disorder, estimated to occur in 5 percent of the population of the United States. Diabetes is a major cause of premature death from vascular disease and the leading cause of blindness in working-age adults, of nontraumatic lower extremity amputations, and of renal failure requiring dialysis and transplantation. About 10-15 percent of the total health care budget in the US is spent on diabetes. Thus, diabetes represents a serious burden to the individual and to society. Studies on the pathogenesis of diabetes (both type I and II) indicate that impaired Beta-cell function accounts for the majority of the defects. Although the pathogenesis of the two diseases is different, the underlying metabolic cause of both forms of diabetes is a failure of the pancreatic Beta cells to provide insulin in an amount sufficient to meet the body's needs, leading to hyperglycemia. Improperly controlled hyperglycemia is directly responsible for the development of the specific and non-specific complications of the diabetic state. Beta-cell dysfunction is present in all diabetic patients. Islet allografts may also exhibit Beta-cell dysfunction. In glucose-regulated Beta-cell function, glucose uptake and metabolism are obligatory steps in sending the message which results in an increase in intracellular Ca2+, leading to insulin biosynthesis and secretion. These processes are directly regulated to two proteins: glucose transporters and glucokinase. It was proposed that GLUT2 and glucokinase may function in tandem as primary elements of the glucose sensing apparatus. By overexpression of these genes in pancreatic islets and Beta-cell lines, a significant increase of insulin release has been demonstrated in glucose-induced response. However, this phenomenon has not been studied using human pancreatic islets. In this proposal, we will transfer these candidate gene(s) into human pancreatic islet tissue by vascular delivery of adenoviral vectors and examine whether specific gene transfer will improve islet Beta-cell function in vitro and in vivo. Specifically, we will further define appropriate conditions to achieve highly efficient (greater than 90 percent) gene transfer to human pancreatic islet tissue by delivering viruses through vascular (arterial infusion) perfusion of the whole pancreas prior to islet isolation. We will then assess the metabolic effects of viral infection and gene transfer (1st, 2nd, 3rd generation adenoviral vectors encoding LacZ reporter gene or other specific therapeutic gene(s) on the functional integrity of islet tissue. Finally we will examine the effectiveness of adenoviral mediated gene transfer to pancreatic islets on the correction of Beta-cell dysfunction for the treatment of Type I and II diabetes by transferring the genes for GLUT2 and glucokinase to human islet tissue.