Introduction: Type I diabetes (TID) mellitus results from the T-cell mediated autoimmune destruction of the insulin-producing pancreatic beta cells. Gene therapy is one strategy being actively explored to cure TID by affording non β-cells the ability to secrete insulin in response to physiological stimuli. The aim of the present study was to determine if our methodology could reverse diabetes in pacreatectomised Westran pigs and show pancreatic differentiation in the liver.

Methods: Lentiviral vectors produced using 293T cells were purified and concentrated by tangential flow filtration and ultracentrifugation. Following delivery of INS-FUR to 9 pancreatectomised Westran pigs, an intravenous glucose tolerance test (IVGTT) was performed after a 14hr fast in animals with lowered blood glucose levels. Liver, pancreas, kidney, spleen and lung were harvested at the experimental endpoint Expression of pancreatic hormones and β-cell transcription factors was determined by RT-PCR. Triple immunofluorescent staining for the pancreatic hormones was performed on pancreas and liver tissue sections.

Results: Whilst transient reduction in blood glucose was detected in a number of animals, only one pig maintained normal fasting blood glucose levels.  PCR analysis of the liver tissue revealed expression of several β-cell transcription factors including the key factors PDX-1 and Neurod1, pancreatic hormones glucagon and somatostatin, but not endogenous pig insulin. Triple fluorescent immunostaining showed extensive insulin staining and a small amount of glucagon and somatostatin protein expression was also seen, all of which indicate that pancreatic transdifferentiation of the liver tissue occurred.

Conclusion: Our data suggest that this regimen may ultimately be employed clinically to cure TID, however more work is required to replicate the successful reversal of diabetes in increased numbers of pigs.