New strategies to generate induced pluripotent stem cells

Direct reprogramming of somatic cells to a pluripotent state, substantiated only three years prior, is one of the most rapidly developing areas of stem cell research. The generation of patient-derived pluripotent cells applicable to disease modelling, drug screening, toxicology tests and, ultimately, autologous cell-based therapies, has the potential to revolutionize medicine. Since 2006, when Takahashi and Yamanaka first reported the generation of induced pluripotent stem cells from murine fibroblasts via retroviral transduction of a defined set of transcription factors, various new methods have been developed to refine and improve reprogramming technology. This review focusses on these evolving strategies to generate genetically unmodified or reprogramming factor-free iPSCs.