For the genome editing methods detailed above to make changes in the target cells, they must be tailored to them. In human medical applications, the distinction between in vivo therapies and ex vivo therapies is important for this purpose. During in vivo therapies, so-called viral vectors, which guide the editing tools to the target cells like a ferry, are introduced directly into the patients. In ex vivo therapies, the cells are modified outside of the body under laboratory conditions and then introduced into the patients. The “transport” is then carried out via viral vectors, mRNA or other proteins, electroporation procedures, or combinations of these transport routes.

The efficiency of the transport of editing tools is vital to meeting clinical goals because editing the cells altered by the disease can only provide therapeutic benefit when the cells are reached and then altered in sufficient numbers. For example, concerning diseases such as cystic fibrosis, multiple organs and thus cell types are affected by the disease. At the same time, not all tissue types in the human body are equally accessible via the viral vectors mentioned above. Therefore, a major goal of basic research is to improve the efficiency and, at the same time, the safety of the delivery of editing tools.