Optimization of Delivery of Adeno-Associated Virus Mediated Gene Transfer to a Transplanted Heart in a Rat Model

Abstract

Objectives: To optimize transgene expression levels after Adeno-associated virus (AAV)-mediated gene transfer, different delivery methods were compared in a transplant setting.

Materials and Methods: Heterotopic abdominal heart transplants were performed in male Lewis rats (250-280 g). According to the vector application method, animals were divided into 3 groups: group 0.35 mL, containing saline solution AAV2/9-LacZ (2 x 1011 vector genome) was injected directly into the myocardium (apex) immediately after reperfusion. Group 0.3 mL contained a cardioplegic solution AAV2/9-LacZ vectors (3 x 1012 vector genome), which was rapidly injected into the aortic root, with the pulmonary trunk clamped. Before transplant the transfected heart was incubated for 25 minutes in iced cardioplegia. A reperfusion system was applied in group 5 mL. For 25 minutes, a cold solution of cardioplegia and AAV2/9–LacZ vectors (5 x 1012 vector genome) was recirculated through the donor heart. Transplanted grafts were explanted after 3 weeks. To detect and to measure marker gene expression, X-gal staining was performed.

Results: In groups 0.35 mL and 0.3 mL, higher transfection efficiency was observed compared to group 5 mL (P < .05). While positive-stained myocardia were detected around the injection site in group 0.35 mL, the expression pattern was much more homogenous in group 0.3 mL.

Conclusions: Results demonstrate that intracoronary injection of the vectors with the pulmonary trunk clamped leads to the highest and most homogenous distribution of transgene expression in the graft.