| Type I diabetes is a debilitating disease that results from the autoimmune destruction of the insulin-producing beta cells in the pancreas. The only current treatment for Type I diabetes is insulin, which must be administered several times daily, creating significant quality of life issues, necessitating the development of a long-term treatment strategy for Type I diabetes. Gene therapy is a promising technology that offers the potential for a long-term correction of a disease by the delivery of therapeutic genes by viral and non-viral vectors. In this study, we attempted to develop a gene therapy vector for the treatment of Type I diabetes.; To develop a vector for Type I diabetes, we tested the existing viral and non-viral gene delivery vectors in the pancreas in vivo in mice, to determine which vectors resulted in stable, high-level expression of the delivered transgene. Our initial study indicated that both adenoviral and adeno-associated viral (AAV) vectors were able to transduce to the pancreas, but with differing transduction efficiencies and durations of expression. A newly developed serotype of AAV, serotype 8, was shown to result in both high expression levels and persistent expression of the delivered transgene with minimal immunogenicity, suggesting it would be an ideal vector for the delivery of a therapeutic transgene.; In the second and third part of this study, we attempted to correct Type I diabetes in the diabetic streptozotocin (STZ) mouse model. Recent studies have demonstrated that adult liver cells have the potential to differentiate into insulin-producing cells by the delivery of several key pancreatic transcription factors to the livers of diabetic mice, resulting in a correction of diabetes. We attempted to use adeno-associated virus serotype 8 vectors to deliver these pancreatic transcription factors to the liver, in an attempt to induce the transdifferentiation of the liver to the pancreas. We were unable to achieve transdifferentiation using AAV vectors, nor were we able to correct diabetes in these mice. Subsequent studies suggest that expression of the pancreatic transcription factors in the liver alone is insufficient to induce transdifferentiation, and that an adenoviral component may be involved in the transdifferentiation event. |
