Progress towards liver and lung-directed gene therapy with helper-dependent adenoviral vectors.

Helper-dependent adenoviral vectors (HDAd) have several characteristics making them very attractive for human gene therapy. These vectors are completely devoid of viral coding sequences and are able to mediate high efficiency transduction in vivo to direct high level transgene expression with negligible chronic toxicity. Progress towards liver and lung directed gene therapy with HDAd as well as the current obstacles facing human applications and possible strategies to overcome these obstacles are discussed.