Prolonged control of insulin-dependent diabetes via intramuscular expression of plasmid-encoded single-strand insulin analogue

• DOI: 10.1016/j.gendis.2022.05.009
• Publication Date: 2022-05-24T01:20:16Z
• Authors: Lu Deng; Ping Yang; Caixia Li; Lifang Xie; Wanling Lu; Yanhan Zhang; Ming Liu; Gang Wang
• Keywords: Medicine (General); 0303 health sciences; Single-strand insulin analogue (SIA); Diabetes; Synthetic promoter; QH426-470; Plasmid; 3. Good health; 03 medical and health sciences; Gene therapy; R5-920; Full Length Article; Genetics; Intramuscular injection

Daily insulin injection is necessary for the treatment of the insulin-dependent diabetes. However, the process is painful and inconvenient. Accordingly, we have made exploratory efforts to establish an alternative method for continuous insulin supply via intramuscular injection of a designed plasmid encoding the single-strand insulin analogue (SIA), which provides safe, effective and prolonged control of insulin-dependent diabetes. To generate a SIA, a short flexible peptide was alternatively introduced into the natural proinsulin to replace its original long and rigid C-peptide. Then, the synthetic promoter SP301 was used to drive potent and specific expression of SIA in skeletal muscle cells. By combining the Pluronic L64 and low-voltage electropulse (L/E), the specialized gene delivery technique was applied to efficiently transfer the constructed plasmid into skeletal muscle cells via intramuscular injection. Through these efforts, a plasmid-based intramuscular gene expression system was established and improved, making it applicable for gene therapy. The plasmid-expressed SIA showed biological functions that were similar to that of natural insulin. A single L/E-pSP301-SIA administration provided sustained SIA expression in vivo for about 1.5 months. In addition, the diabetic mice treated with L/E-pSP301-SIA were much healthier than those with other treatments. This plasmid-based system was safe for the treatment of diabetes and did not cause immune responses or pathological damage. The results confirmed that, in a mouse model, long-term positive effects were achieved by a single intramuscular L/E-pSP301-SIA injection, which consequently provided reliable experimental basis for its clinical application for the treatment of diabetes mellitus with promising prospects.