Also referred to as a cell therapy. In an ex vivo therapy, cells are removed from the body for modification. Modification is done by administering therapy directly to the cells before they are returned to the body. In the case of ex vivo CRISPR/Cas9 therapies, CRISPR/Cas9 is used to modify the extracted cells to repair them back to their proper function or add desired functions. The engineered cells are then administered to the patient so they can treat a particular disease.