Targeting recombinant adeno-associated virus vectors to enhance gene transfer to pancreatic islets and liver

Abstract

Human pancreatic islet cells and hepatocytes represent the two most likely target cells for genetic therapy of type I diabetes. However, limits to the efficiency of rAAV serotype 2 (rAAV2)-mediated gene transfer have been reported for both of these cell targets. Here we report that nonserotype 2 AAV capsids can mediate more efficient transduction of islet cells, with AAV1 being the most efficient serotype in murine islets, suggesting that receptor abundance could be limiting. In order to test this, we generated rAAV particles that display a ligand (ApoE) that targets the low-density lipoprotein receptor, which is present on both of these cell types. The rAAV/ApoE viruses greatly enhanced the efficiency of transduction of both islet cells ex vivo and murine hepatocytes in vivo when compared to native rAAV2 serotype (220and four-fold, respectively). The use of receptor-targeted rAAV particles may circumvent the lower abundance of receptors on certain nonpermissive cell types.

Long-term correction of murine glycogen storage disease type Ia by recombinant adeno-associated virus-1-mediated gene transfer

“…25,26 For comparison to the rAAV8 results, we also placed the G6Pase-a gene in AAV1-G6Pase-a under the chicken b-actin promoter/CMV enhancer. In all, 12 G6Pase-a À/À mice were infused neonatally with 5 Â 10 11 particles of AAV1-G6Pase-a (AAV1-G6Pase-a-1X).…”

Heart-targeted adeno-associated viral vectors selected by in vivo biopanning of a random viral display peptide library

“…Genetic modification of the AAV2 capsid by oligonucleotide insertions, random mutagenesis or DNA shuffling is able to circumvent some of these limitations. [8][9][10][17][18][19] Whereas larger peptides up to the size of GFP (238 amino acids) could be accommodated at the VP2 N-terminus 15,[20][21][22][23][24][25] the addition of small peptides up to 34 amino acids is tolerated at several positions of the AAV2 capsid. 1 Among the tolerated insertion sites for small peptides, insertions in the AAV2 heparin binding domain 26,27 adjacent to amino acids 587 or 588 was most successful.…”

Gene Delivery Systems: Tailoring Vectors to Reach Specific Tissues

“…Insertion after position 138 of the 28-amino acid ApoE-derived ligand led to a 90-fold increase in pancreatic islet cells in-vitro transduction. Additionally, a four-fold increase of human antitrypsin expression was observed compared to unmodified AAV vector transduction (Loiler et al, 2003). Viral dose can be reduced 100-fold with similar transduction results as a consequence of ApoE-derived ligand insertion with a critical impact on side effect reduction.…”

“…For AAV2-derived vectors, peptides inserted in positions 1, 34, 138, 161, 459, 584, 587 and 588 (relative to VP1 start codon) are displayed on the vector surface, and allow production of vectors with similar viral titers to those observed for unmodified AAV2 vectors (Shi et al, 2001;Wu et al, 2000b). Most of the studies have used positions 138 (VP2 N-terminal), 587 and 588 (HSPG binding domain) to insert peptides ranging from 5 to 272 amino acids (Loiler et al, 2003;Nicklin et al, 2001a;Perabo et al, 2006;Shi et al, 2001;White et al, 2007;White et al, 2004;Wu et al, 2000b;Yu et al, 2009). Capsid protein modifications have improved gene delivery to lung (Kwon & Schaffer, 2008), endothelial cells (Nicklin et al, 2001a), pancreatic islets (Loiler et al, 2003), vascular tissue (White et al, 2004), atherosclerotic lesions (White et al, 2007), muscle (Yu et al, 2009), myocardium (Yang et al, 2009), and cancer cells .…”