066 Direct Comparison of Adenoviral and Adeno-Associated Viral Vectors for Efficiency of Gene Transfer in Ischemic Wound

Abstract

Tissue ischemia is a common occurrence in many disease processes including chronic wounds, stroke, solid tumors, and myocardial infarction. The application of gene delivery for healing of wounds has demonstrated increasing therapeutic promises in animal models. Adenoviral vectors have been successfully used for gene delivery to the ischemic wound. However, these vectors typically demonstrate short, transient transgene expression while eliciting significant cytotoxic immune response. Adeno-associated viral vectors (AAV) do not have those limitations; however, scant information is available about their transfection efficiency under low-oxygen tension. The goal of this study was to compare AAV vector with adenoviral vector in terms of relative efficiency of gene delivery and cytotoxic immune response in ischemic wounds. Reporter constructs Ad5-LacZ and AAV-LacZ (108 pfu/wound) were injected onto the dermis of rabbit ear prior to creation of ischemic wounds. Wounds were harvested at postoperative day 10. Frozen sections of the wounds were fixed in cold acetone and stained with an in situ β-gal staining kit. Intense expression of β-gal was observed with both vectors; however, transduction rates with AAV vector was approximately 10-fold lower than Adenovirus. Unlike Adenovirus, no noticeable inflammatory cell infiltration was observed with AAV injection. Even when the dosage of AAV was increased to 109 pfu/wound inflammatory cell infiltration remained negligible. Thus our data indicates that both AAV and adenoviral vectors are suitable to use in gene-therapy experiments in ischemic tissues. The particular advantage of AAV is the ability to transfect with higher doses while at lower dose maximal transfection rate seems to be more with Adenovirus.