Glucose-responsive gene delivery in pancreatic Islet cells via recombinant adeno-associated viral vectors.

PURPOSE: Recent progress in genetic engineering presents the possibility of providing physiologically regulated glucose metabolism in individuals with diabetes. The objective of this study is to explore the feasibility of obtaining glucose dependent gene expression in the pancreatic beta-cell lines via recombinant adeno-associated virus type 2 (rAAV) mediated gene transfer.
METHODS: Two transcription cassettes containing the luciferase gene under the control of the rat insulin I gene promoter and the enhanced green fluorescent protein (EGFP) open reading frame under the control of the immediate early gene promoter of human cytomegalovirus (CMV) were placed in series between the inverted terminal repeats (ITRs) of AAV. The rAAV vectors produced were used to transduce pancreatic beta-cell line grown in the absence or presence of various concentrations of glucose. Luciferase activity assays were performed at 72 hr post-transduction.
RESULTS: Glucose-responsive reporter gene expression was obtained in both calcium phosphate transfected HIT-T15 and betaHC-9 cells, demonstrating regulated luciferase gene expression under control of the insulin gene promoter. At MOI of 100, rAAV-transduced betaHC-9 cells exhibited glucose-dependent luciferase activities, which were approximately 4.3 fold higher than those transfected by the calcium phosphate coprecipitation method at 20 mM glucose.
CONCLUSIONS: Delivery of the insulin gene promoter via rAAV was shown in this study to result in glucose-dependent control of the reporter gene expression. The results suggest that rAAV is an efficient viral vector for gene transfer into the pancreatic islet cells.