| The subject of this defense is the design of an effective polymeric gene delivery system to deliver the newly constructed soluble RAE-1 plasmid locally to the pancreatic islets for the prevention of type-1 diabetes. A targeting, bioreducible polymeric gene carrier was constructed to deliver therapeutic genes to the pancreatic islet microvasculature. The bioreducible cationic polymer poly(cystamine bisacrylamide -- diamino hexane) (p(CBA-DAH)) has demonstrated high transfection efficiency and low cytotoxicity. Targeting properties were added to the cationic polymer through modification with PEG and the targeting peptide CHVLWSTRC, known to target the EphA2 and EphA4 receptors. The PEG will serve to improve stability and tissue selectivity, while the moiety will target EphA2 and A4, overexpressed in the pancreatic microvasculature. The targeting polymer Eph-PEG-p(CBA-DAH) shows selective uptake by the target cell line, indicative of the targeting properties that will be seen in systemic administration.;The pathogenesis of type-1 diabetes is complicated, and a clear, single mechanism has yet to be identified. However, reports have indicated that the activating receptor NKG2D plays an important role in the development of disease. Exploiting a natural phenomena observed in tumors, plasmid DNA encoding for a soluble ligand to NKG2D (sRAE-1g) was isolated and engineered into a plasmid expression system. This plasmid can then be delivered to the pancreas. The shedding of this soluble ligand can reduce interaction between the beta-cell bound ligands, effectively protecting the beta-cells from autoimmune destruction and preventing type 1 diabetes. |
