You are correct, this is a germ-line modification. "Tour de force" did not refer to the transfection technique per se but to the fact that the way they are using it to address their question (the biology of aneuploidities) is kind of peculiar, direct and cool. For the technical details, refer to the original article
O'Doherty A et al An aneuploid mouse strain carrying human chromosome 21 with down syndrome phenotypes. Science. 2005 Sep 23;309(5743):2033-7.
In general, you can find original references in general by entering the respective researcher's name and the journal if you know it into
pubmed. It's usually the most recent entry. Furthermore, if you need, you can get access to nearly any full text article by joining as a full member and asking us in the full member literature sharing section.
I heavily doubt that we will ever see non-cell based whole-chromosome therapy. (I'm saying literally "never" because I think it is one of those things that we would no longer consider worth doing when and if we were able to do them.) Cell based, i.e. modifying stem cells in vitro in this way and then using them for therapy is likely and already happening in mice.
