Long term reversal of diabetes in non obese diabetic mice by liver-directed gene therapy

BACKGROUND: Type 1 diabetes (T1D) results from an autoimmune attack against the insulin-producing beta (β)-cells of the pancreas. The aim of this study was to reverse T1D by gene therapy. METHODS: We used a novel surgical technique, which involves isolating the liver from the circulation before delivery of a lentiviral vector carrying furin-cleavable human insulin (INS-FUR), or empty vector to the livers of diabetic non-obese diabetic mice (NOD). This was compared to the direct injection of the vector into the portal circulation. Mice were monitored for body weight and blood glucose. Intravenous glucose tolerance tests (IVGTT) were performed. Expression of insulin and pancreatic transcription factors was determined by reverse transcriptase PCR (RT-PCR) and immunohistochemistry and immunoelectron microscopy was used to localise insulin. RESULTS: Using the novel surgical technique, we achieved long-term transduction (42% efficiency) of hepatocytes, restored normoglycaemia for 150 days (experimental endpoint) and re-established normal glucose tolerance. We showed expression of β-cell transcription factors, murine insulin, glucagon and somatostatin, hepatic storage of insulin in granules. Expression of hepatic markers, C/EBP-β, G6PC, AAT, GLUI, were downregulated in INS-FUR-treated livers. Liver function tests remained normal with no evidence of intrahepatic inflammation or autoimmune destruction of the insulin-secreting liver tissue. By comparison, direct injection of INS-FUR reduced blood glucose levels, no pancreatic transdifferentiation or normal glucose tolerance was observed. CONCLUSIONS: This gene therapy protocol has for the first time permanently reversed T1D with normal glucose tolerance in NOD mice and, as such, opens a novel therapeutic strategy for the cure of T1D. Copyright © 2013 John Wiley & Sons, Ltd.status: publishe