Cardiac AAV9 Gene Delivery Strategies in Adult Canines: Assessment by Long-term Serial SPECT Imaging of Sodium Iodide Symporter Expression

Abstract

Heart failure is a leading cause of morbidity and mortality, and cardiac gene delivery has the potential to provide novel therapeutic approaches. Adeno-associated virus serotype 9 (AAV9) transduces the rodent heart efficiently, but cardiotropism, immune tolerance, and optimal delivery strategies in large animals are unclear. In this study, an AAV9 vector encoding canine sodium iodide symporter (NIS) was administered to adult immunocompetent dogs via epicardial injection, coronary infusion without and with cardiac recirculation, or endocardial injection via a novel catheter with curved needle and both end- and side-holes. As NIS mediates cellular uptake of clinical radioisotopes, expression was tracked by single-photon emission computerized tomography (SPECT) imaging in addition to Western blot and immunohistochemistry. Direct epicardial or endocardial injection resulted in strong cardiac expression, whereas expression after intracoronary infusion or cardiac recirculation was undetectable. A threshold myocardial injection dose that provides robust nonimmunogenic expression was identified. The extent of transmural myocardial expression was greater with the novel catheter versus straight end-hole needle delivery. Furthermore, the authors demonstrate that cardiac NIS reporter gene expression and duration can be quantified using serial noninvasive SPECT imaging up to 1 year after vector administration. These data are relevant to efforts to develop cardiac gene delivery as heart failure therapy.

A modifier screen identifies DNAJB6 as a cardiomyopathy susceptibility gene

“…This hypothesis was supported by our observation in zebrafish, where overexpression of dnajb6b(L) in cardiomyocytes reduced the mortality rate in anemia-induced CM (Supplemental Figure 5). To test the cardioprotective function of Dnajb6(L) in mammals, we used the adeno-associated virus serotype 9 (AAV9) medicated gene delivery system (25). Robust ectopic expression of Dnajb6(L) in mouse heart was detected (Figure 5, A and B).…”

“…Clones with correct insertional direction were identified by direct sequencing. The production of recombinant AAV9 was carried out as described previously (25). Briefly, AAV vectors were generated by packaging AAV2-based recombinant genomes in AAV9 capsids.…”

AAV Vectors for Efficient Gene Delivery to Rodent Hearts

“…However, for the efficient delivery of genes to the entire rodent myocardium via systemic injection, AAV9 has clearly emerged as the most promising serotype ([3, 4] and reviewed in [5]).…”

Non-invasive detection of adeno-associated viral gene transfer using a genetically encoded CEST-MRI reporter gene in the murine heart

“…However, such techniques are not scalable to large animal models or clinical settings. Alternative reporter imaging techniques including sodium-iodide (Na/I) transporter imaging using single photon emission computed tomography (SPECT) require radioactive probes 10 . Subsequently, clinical monitoring of gene expression patterns requires either undesirable repeated radiation exposure or extrapolation from repeated biopsies 5 .…”