1. The idea
This is one of the few idea that came directly out of the box. It was suppose to supply the genetic therapy with a support to the gene insertion, and so, it won't alter anymore the chromosome of the under-treatment cells. Obviously, it could also be the place for inserting gene for protecting the organism before an infection or disease.
2. How to
We would have need to rebuild every promoter to be eukaryotic one and also rebuild the replication origin. Moreover, we wanted to find a way to put the plasmid in the nucleus of the cell and to make sure that during the replication a similar number of plasmid will be detained by the freshly divided cells.
We discovered that some yeast cell already possess plasmids, like saccharomyces cerevisiae but even if it is an interesting idea it may be too ambitious, and we would need to work on eukaryotic cell representing a harsh condition to fulfill.