title: Generation of human induced pluripotent stem cells by simple transient transfection of plasmid DNA encoding reprogramming factors.
abstract: BACKGROUND
  The use of lentiviruses to reprogram human somatic cells into induced pluripotent stem (iPS) cells could limit their therapeutic usefulness due to the integration of viral DNA sequences into the genome of the recipient cell. Recent work has demonstrated that human iPS cells can be generated using episomal plasmids, excisable transposons, adeno or sendai viruses, mRNA, or recombinant proteins. While these approaches offer an advance, the protocols have some drawbacks. Commonly the procedures require either subcloning to identify human iPS cells that are free of exogenous DNA, a knowledge of virology and safe handling procedures, or a detailed understanding of protein biochemistry.
  
  
  RESULTS
  Here we report a simple approach that facilitates the reprogramming of human somatic cells using standard techniques to transfect expression plasmids that encode OCT4, NANOG, SOX2, and LIN28 without the need for episomal stability or selection. The resulting human iPS cells are free of DNA integration, express pluripotent markers, and form teratomas in immunodeficient animals. These iPS cells were also able to undergo directed differentiation into hepatocyte-like and cardiac myocyte-like cells in culture.
  
  
  CONCLUSIONS
  Simple transient transfection of plasmid DNA encoding reprogramming factors is sufficient to generate human iPS cells from primary fibroblasts that are free of exogenous DNA integrations. This approach is highly accessible and could expand the use of iPS cells in the study of human disease and development.
authors.affiliation: Department of Cell Biology, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
authors.forename: Karim
authors.initials: K
authors.lastname: Si-Tayeb
authors.forename: Fallon K
authors.initials: FK
authors.lastname: Noto
authors.forename: Ana
authors.initials: A
authors.lastname: Sepac
authors.forename: Filip
authors.initials: F
authors.lastname: Sedlic
authors.forename: Zeljko J
authors.initials: ZJ
authors.lastname: Bosnjak
authors.forename: John W
authors.initials: JW
authors.lastname: Lough
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Duncan
mesh_terms: D002454:Cell Differentiation; D065150:Cellular Reprogramming; D004247:DNA; D005347:Fibroblasts / Q000166:cytology; D022781:Hepatocytes / Q000166:cytology; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000166:cytology; D012867:Skin / Q000166:cytology; D014162:Transfection
chemical_list: D004247:DNA