Submitted on June 30, 2008
Accepted on September 17, 2008
Induced Pluripotent Stem Cells Generated Without Viral Integration
Matthias Stadtfeld 1, Masaki Nagaya 2, Jochen Utikal 1, Gordon Weir 2, Konrad Hochedlinger 1*
1 Massachusetts General Hospital Cancer Center and Center for Regenerative Medicine, 185 Cambridge Street, Boston, MA 02114, USA.; Harvard Stem Cell Institute, Cambridge, MA 02138, USA.; Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.; Department of Medicine, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.
2 Section on Islet Transplantation and Cell Biology, Joslin Diabetes Center, One Joslin Place, Boston, MA 02115, USA.; Department of Medicine, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.
* To whom correspondence should be addressed.
Konrad Hochedlinger , E-mail: khochedlinger{at}helix.mgh.harvard.edu
Pluripotent stem cells have been generated from mouse and human somatic cells by viral expression of the transcription factors Oct4, Sox2, Klf4, and c-Myc. A major limitation of this technology is the use of potentially harmful genome-integrating viruses. Here, we generate mouse induced pluripotent stem cells (iPS) from fibroblasts and liver cells by using nonintegrating adenoviruses transiently expressing Oct4, Sox2, Klf4, and c-Myc. These adenoviral iPS (adeno-iPS) cells show DNA demethylation characteristic of reprogrammed cells, express endogenous pluripotency genes, form teratomas, and contribute to multiple tissues, including the germ line, in chimeric mice. Our results provide strong evidence that insertional mutagenesis is not required for in vitro reprogramming. Adenoviral reprogramming may provide an improved method for generating and studying patient-specific stem cells and for comparing embryonic stem cells and iPS cells.
