Thanks to you guys I googled, "stem cell virus animals" and found some promising links! I appreciate you guys emphasizing immunological response. The nice thing about genetic diseases is that they only need to be fixed once, which limits the need for follow-up treatments, which would provoke a significant immune response.
Here is a nice excerpt regarding animal models:
“third-generation adenovirus vectors”: This research focuses on the development of improved production systems for gutless adenovirus vectors and their use for the efficient introduction of large or multiple transgenes into human progenitor and stem cells with minimal vector-related toxicity. In addition to the use of regular third-generation adenovirus vectors for the transient genetic modification of target cells, we have embarked on the generation of new vector types for stable transgene expression in transduced target cells using locus/site-specific transgene integration or homologous recombination. For example, we have generated new adenovirus/adeno-associated virus vectors. These vectors stably integrate into a specific locus on human chromosome 19 and are capable of genetically complementing dystrophin-deficient human myoblasts.