Comparative Cardiac Gene Delivery of Adeno‐Associated Virus Serotypes 1–9 reveals that AAV6 Mediates the Most Efficient Transduction in Mouse Heart

Abstract

Cardiac gene transfer is an attractive tool for developing novel heart disease treatments. Adeno-associated viral (AAV) vectors are widely used to mediate transgene expression in animal models and are being evaluated for human gene therapy. However, it is not clear which serotype displays the best cardiac tropism. Therefore, we curried out this study to directly compare AAV serotypes 1–9 heart transduction efficiency after indirect intracoronary injection. AAV-CMV-luciferase serotypes 1–9 were injected in the left ventricular cavity of adult mice, after cross-clamping the ascending aorta and pulmonary artery. An imaging system was used to visualize luciferase expression at 3-7-21-70-140 days post-injection. Echocardiography was performed to evaluate cardiac function on day 140. At the end of the study luciferase enzyme activity and genome copies of the different AAV serotypes were assessed in several tissues and potential AAV immunogenicity was evaluated on heart sections by staining for macrophage and lymphocyte antigens. Among AAV serotypes 1–9, AAV6 showed the best capability of achieving high transduction levels in the myocardium in a tissue-specific manner, whereas the other serotypes owned less cardiac transduction and more extra-cardiac expression, especially in the liver. Importantly, none of the serotypes tested with this marker gene affected cardiac function nor was associated with inflammation.

Regulation of in vivo cardiac contractility by phospholemman: role of Na+/Ca2+exchange

“…They are not pathogenic in humans (4), and they provide sustained myocardial transduction (7,34). Of the nine AAV serotypes, AAV serotypes 6 and 9 have the earliest (Ͻ7 days after intracoronary injection) and highest expression of the transgene in the heart (34). In the present study, we injected rAAV9 directly into the LV of mice, which resulted in successful expression of the transgene as detected by immunoblotting, fluorescence imaging, and functional measurements.…”

“…They are not pathogenic in humans (4), and they provide sustained myocardial transduction (7,34). Of the nine AAV serotypes, AAV serotypes 6 and 9 have the earliest (Ͻ7 days after intracoronary injection) and highest expression of the transgene in the heart (34).…”

“…In addition, despite Ͻ50% infection efficacy, enhanced ϩdP/dt was already apparent in KO-S68E hearts compared with KO-GFP hearts. More efficient gene delivery methods such as tail vein (34) or retroorbital sinus injection of virus and novel mouse models with inducible expression of S68E mutant in the PLM-KO background would improve the signal-to-noise ratio in whole animal studies. The second limitation is the assumption that the S68E mutant faithfully mimicked the phosphorylated form of PLM.…”

Rescue of Familial Hypertrophic Cardiomyopathy by Altering Sarcomeric Exposure and Response to Calcium

“…Currently, adeno-associated virus vectors are the most potent and promising vectors used for delivery of transgenes to the heart (11,12). They exhibit efficient uptake, stable longterm expression of transferred genes, and tissue specificity dependent upon the viral serotype (13). Of the 11 identified serotypes of adeno-associated viruses, types 6, 8, and specifically 9, have tropism for the heart (14,15).…”

C-Reactive Protein (CRP) Is Essential for Efficient Systemic Transduction of Recombinant Adeno-Associated Virus Vector 1 (rAAV-1) and rAAV-6 in Mice

“…We demonstrate that the presence of the mCRP in the bloodstream increases the efficiencies of rAAV-1 and rAAV-6 muscle transduction in mice more than 10-fold. Since the interactions of rAAV-1 and rAAV-6 with mCRP are mouse specific, the high transduction efficiencies of these vectors reported in a mouse model (13,14) could be inadequate when translating this concept to humans. These data provide further evidence that species-specific interactions of rAAV with components of body fluids must be appropriately taken into account when planning regulatory toxicology and translational gene therapy studies.…”