Adenovirus transduction is required for the correction of diabetes using Pdx-1 or Neurogenin-3 in the liver.

The regeneration of insulin-producing cells in vivo has emerged as a promising method for treating type I diabetes. Pancreatic duodenal homeobox-1 (Pdx-1), NeuroD, and Neurogenin-3 (Ngn3) are pancreatic transcription factors important for the development of insulin-producing cells in the liver. Other groups have demonstrated that adenoviral-mediated transgene expression of these transcription factors in the liver can reverse hyperglycemia in diabetic mice. We delivered Pdx-1 and Ngn3 to the livers of diabetic mice using adeno-associated virus (AAV) serotype 8, a vector that has been shown to result in non-toxic, persistent, high level expression of the transgene. We were unable to correct hyperglycemia in mice with streptozotocin-induced diabetes using AAV vectors expressing Pdx-1 and Ngn3. However, when we co-delivered these transcription factor expression cassettes in non-viral vectors with an irrelevant adenoviral vector, we were able to correct hyperglycemia in diabetic animals. Further studies demonstrated that an antigen-dependent immune response elicited by the adenoviral capsid together with the expression of a pancreatic transcription factor was required for restoration of serum insulin levels by the liver. Our results suggest that a host response to adenovirus in combination with expression of a pro-endocrine pancreas transcription factor is sufficient to induce insulin production in the livers of diabetic mice.