Pancreatic Transduction by Helper-Dependent Adenoviral Vectors via Intraductal Delivery

Abstract

Pancreatic gene transfer could be useful to treat several diseases, such as diabetes mellitus, cystic fibrosis, chronic pancreatitis, or pancreatic cancer. Helper-dependent adenoviral vectors (HDAds) are promising tools for gene therapy because of their large cloning capacity, high levels of transgene expression, and long-term persistence in immunocompetent animals. Nevertheless, the ability of HDAds to transduce the pancreas in vivo has not been investigated yet. Here, we have generated HDAds carrying pancreas-specific expression cassettes, that is, driven either by the elastase or insulin promoter, using a novel and convenient plasmid family and homologous recombination in bacteria. These HDAds were delivered to the pancreas of immunocompetent mice via intrapancreatic duct injection. HDAds, encoding a CMV-GFP reporter cassette, were able to transduce acinar and islet cells, but transgene expression was lost 15 days postinjection in correlation with severe lymphocytic infiltration. When HDAds encoding GFP under the control of the specific elastase promoter were used, expression was detected in acinar cells, but similarly, the expression almost disappeared 30 days postinjection and lymphocytic infiltration was also observed. In contrast, long-term transgene expression (>8 months) was achieved with HDAds carrying the insulin promoter and the secretable alkaline phosphatase as the reporter gene. Notably, transduction of the liver, the preferred target for adenovirus, was minimal by this route of delivery. These data indicate that HDAds could be used for pancreatic gene therapy but that selection of the expression cassette is of critical importance to achieve long-term expression of the transgene in this tissue.

Identification of miRNAs Involved in Reprogramming Acinar Cells into Insulin Producing Cells

“…With respect to clinical applications, the substitution of first generation adenoviral vectors with other type of vectors that are less immunogenic and toxic than adenovirus, such as AAV or helper-dependent adenoviral (HD-Ad) vectors, is desirable [ 47 ]. Our laboratory has shown that efficient and persistent transduction of the pancreas in vivo is possible using AAV and HD-Ad vectors via intraductal administration [ 48 , 49 ]. Thus, to induce acinar-to-β cell reprogramming in immunocompetent animals and humans, it might be feasible to co-express PNM and miRNAs of interest in vivo (for instance, those that are activated by first generation adenoviral vectors) using AAV or HD-Ad vectors.…”

Magnetic resonance imaging of intra‐pancreatic ductal nanoparticle delivery to islet cells

“…Their data proved that most of the vector genomes were found in the liver, lungs, and spleen via intravenous administration. In contrast, a highly significant reduction of systemic dissemination of vector genomes to these off‐target organs was detected when the same dose of vectors was administered through the intrapancreatic duct …”

“…In contrast, a highly significant reduction of systemic dissemination of vector genomes to these off-target organs was detected when the same dose of vectors was administered through the intrapancreatic duct. 12 These studies point to the fact that the intrapancreatic ductal injection route would result in a better transduction of the target organ with reduced systemic dissemination. An additional important benefit derives from the fact that intrapancreatic duct injection is an approved clinical method.…”

Transgene and islet cell delivery systems using nano-sized carriers for the treatment of diabetes mellitus

“…HDAd eliminate the problem of viral gene expression in transfected cells, which accompanies AAV [45]. HDAd have been reported to show long-term expression of transgenes in the pancreas [46]. …”