Cell Stem CellProtocol ReviewGu idelines and Techniqu es for the Generationof Indu ced Plu ripotent Stem CellsNimet Maherali 1,2 and Konrad Hochedlinger1,*1Massachusetts General Hospital Center for Regenerative Medicine and Cancer Center, Harvard Stem Cell Institute,Department of Stem Cell and Regenerative Biology, 185 Cambridge Street, Boston, MA 02114, USA2Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA*Correspondence: khochedlinger@helix.mgh.harvard.eduDOI 10.1016/j.stem.2008.11.008Direct reprogramming of somatic cells to induced pluripotent stem cells (iPSCs) provides an invaluableresource for regenerative medicine, enabling the generation of patient-specific cells of any lineage withoutthe use of embryonic material. A variety of methods exist for iPSC derivation, all reliant upon manipulationof a select group of transcription factors. We compare the currently reported protocols, identify essentialsteps common to these methods, and suggest minimal criteria for defining fully reprogrammed cells. In ad-dition, specific procedures aimed to optimize reproducible iPSC derivation are presented, with an emphasison standardization of certain parameters for accurate comparison between independent experiments.The generation of pluripotent cells from differentiated adult cellshas vast therapeutic implications, particularly in the context ofin vitro disease modeling, pharmaceutical screening, and cellularreplacement therapies. In addition, the ability to revert somaticcells to an embryonic state provides a unique tool to dissectthe molecular events that permit the conversion of one celltype to another.Previously devised strategies to induce pluripotency, such assomatic cell nuclear transfer (cl...
