Therapeutic efficacy of insulin gene delivery in animal models of diabetes

Objective: Type 1 diabetes (T1DM) is characterized by autoimmune destruction of pancreatic beta cells leading to insulin deficiency. Achieving glucose regulated insulin gene expression by gene therapy is a great area of interest to meet the demand for fluctuating daily glucose levels and necessary to avoid multiple daily injections of insulin. Compared to other cell types, pancreatic beta cells possess unique features such as controlled transcription and translation of proinsulin, presence of glucose-sensing machinery, prohormone convertase expression, and a regulated secretory pathway. Since previous insulin gene delivery to non-beta cell types did not produce successful results, a new lentiviral vector (LentiINS) with insulin promoter hooked up to proinsulin encoding gene was generated using Multisite Gateway Technology to sustain pancreatic beta cellspecific insulin gene expression. Method: A novel lentiviral vector expressing insulin gene under the control of insulin promoter (LentiINS) was constructed using Gateway technology to test its therapeutic potential in T1DM animal model of diabetes as well as in insulin knockout (KO) pancreatic beta cell line. Results: Intraperitoneal delivery of HIV-based LentiINS gene therapy vector resulted in lowering of fasting plasma glucose and improved glucose tolerance of Type 1 diabetic Wistar rats. While diabetic rats exhibited weight loss following STZ injection, LentiINS injected rats retained normal body weight. Reconstitution of insulin gene expression in insulin knock out pancreatic beta cell line resulted in lowering of plasma blood glucose following beta cell transfer under kidney capsule in STZ induced diabetes. Conclusion: Insulin promotor directed insulin gene expression via lentivirus mediated gene delivery represents a new therapeutic strategy directly targeting pancreas fort he treatment of diabetes.. Key words: insulin, gene therapy, type 1 diabetes, crispr