Comparison of Adenoviral and Adeno-Associated Viral Vectors for Pancreatic Gene DeliveryIn Vivo

Abstract

Although effective gene therapy vectors have been developed for organ systems such as the liver, an effective delivery vector to the pancreas in vivo has remained elusive. Of the currently available viral vectors, adenovirus and adeno-associated virus (AAV) are two of the most efficient at transducing nondividing cells. We have constructed recombinant adenovirus (AdVLacZ), adeno-associated virus serotype 2 (AAV2LacZ), and pseudotyped adeno-associated virus serotype 5 and 8 (AAV5LacZ, AAV8LacZ) carrying the LacZ reporter, and compared the transduction efficiency of these four vectors in the pancreas of mice in vivo. We showed that adenovirus, AAV2, and AAV8 are capable of transducing the pancreas in vivo, but with different expression kinetics, efficiencies of transduction, and persistence. AdVLacZ-transduced pancreas exhibited maximum LacZ expression at 1 week postdelivery, with greater than 90% of expression lost at 4 weeks. AAV2LacZ-transduced pancreas displayed peak LacZ levels at 4 weeks postdelivery, with no significant decrease in expression for up to 8 weeks. AAV8LacZ was at least 10-fold more efficient than AAV2LacZ in transducing the pancreas in vivo, with significant levels of expression detectable at 1 week, whereas AAV5LacZ did not result in any detectable transgene expression at all tested time points. All three vectors primarily transduced pancreatic acinar cell types, with limited transduction of pancreatic endocrine cells. AdVLacZ elicited a significant leukocyte infiltration early after delivery into the pancreas, whereas none of the AAV vectors elicited a significant leukocyte response. None of the tested vectors caused significant changes in serum amylase or blood glucose levels, suggesting that they do not significantly alter pancreatic function. These vectors will be useful for studying novel gene delivery based treatments in animal models for diabetes and other pancreatic disorders. 405

Widespread and Stable Pancreatic Gene Transfer by Adeno-Associated Virus Vectors via Different Routes

“…Thus far, no effective and stable in vivo gene transfer to the islets has been achieved using a variety of gene transfer systems. Recent studies showed that the adenovirus has been the best available vector system, which rendered limited and transient gene transfer to the islets in vivo, but suffered from host immune responses and vector cytotoxicity (17)(18)(19). Direct intrapancreas injection of adeno-associated virus (AAV) vectors containing conventional single-stranded vector DNA genomes also only achieved very limited islet gene transfer (19).…”

Efficient gene delivery to pancreatic islets with ultrasonic microbubble destruction technology

“…However, their utility for targeting pancreatic islets in living animals has proved to be limited. Thus, direct injection of recombinant adenovirus or adeno-associated virus into the pancreas results in variable expression of reporter genes in exocrine cells, with negligible expression in pancreatic islets (5). An alternative approach, jugular vein infusion of a ␤-galactosidase adenovirus into rats during surgical clamping of the hepatic and portal circulation, resulted in ␤-galactosidase expression in 70% of islets.…”

CRISPR-Based Technologies for the Manipulation of Eukaryotic Genomes

“…Adenoviruses are also capable of infecting both replicating and non-replicating cells, but do not integrate their DNA into the host cell genome, and can elicit a strong immune response in animals (Wang et al, 2004). Adenovirus-mediated delivery of Cas9 has been used to achieve in vivo genome editing in mouse lungs (Maddalo et al, 2014) and livers Ding et al, 2014;Wang et al, 2015a).…”