Gene delivery to the vasculature mediated by low-titre adeno-associated virus serotypes 1 and 5.

Background Vascular gene therapy requires safe and efficient gene transfer in vivo. Recombinant adeno-associated virus (AAV) is a promising viral vector but its use in the vasculature has produced conflicting results and serotypes other than AAV2 have not been intensively studied. We investigated the efficiency of alternative AAV serotypes for vascular gene delivery in vitro and in vivo. Methods Vascular cell lines were transduced in vitro with AAV vectors. Rabbit carotid arteries were transduced with AAV1, 2 and 5 encoding enhanced green fluorescent protein (eGFP) (∼1.4 × 109 DNAse-resistant particles (drp)). Gene transfer in vivo was assessed at 14 and 28 days. High-titre doses of AAV2 encoding β-galactosidase in vivo were also studied. Results In vitro, transgene expression was not observed in endothelial cells using AAV2 whereas the use of serotypes 1 and 5 resulted in detectable levels of transgene expression. Coronary artery smooth muscle cells (CASMCs) transduced with AAV2 demonstrated higher levels of GFP expression than AAV1 or 5. Transgene expression in vivo was noted using low-titre AAV1 and AAV5 (∼1.4 × 109 drp) in the media and adventitia. Only delivery of AAV1eGFP resulted in neointimal formation (3/7 vessels examined), with transgene expression noted in the neointima. Transgene expression with AAV2 was not detected in any layer of the blood vessel wall using low titre (∼109 drp). However, high-titre (∼1011 drp) AAV2 resulted in transduction of cells in the media and adventitia but not the endothelium. Conclusions AAV1 and AAV5 have advantages over AAV2 for vascular gene delivery at low titres. Copyright © 2007 John Wiley & Sons, Ltd.