Adenoviral vectors for liver-directed gene therapy

Adenoviral vectors currently represent one of the most efficient means of in vivo hepatocyte gene delivery. Consequently, liver-directed gene transfer has been increasingly explored as a promising approach for the treatment of a diverse range of genetic and acquired diseases. Numerous demonstrations of efficacious adenoviral vector-mediated delivery of a wide array of transgenes in several animal species and humans have been reported. In general, transgene expression was efficient, but transient, in many cases lasting < 1 month. Currently, efforts in the field are focused on the development of highly attenuated adenoviral vectors designed to prolong transgene expression by reducing vector immunogenicity and hepatoxicity. Vector optimization strategies include the development of vectors devoid of all viral coding regions, the generation of chimeric vectors engineered to capitalize on favorable aspects of the component viral systems, the development of tissue-specific regulated gene expression, and the development of strategies to circumvent the host immune system. The use of adenoviral vectors for gene therapy of hereditary, malignant and infectious diseases of the liver, and the vector optimization strategies outlined above are discussed in this work.