The generation of induced pluripotent stem (iPS) cells has enabled the derivation of patient-specific pluripotent cells and provided valuable experimental platforms to model human disease. Patient-specific iPS cells are also thought to hold great therapeutic potential, although direct evidence for this is still lacking. Here we show that, on correction of the genetic defect, somatic cells from Fanconi anaemia patients can be reprogrammed to pluripotency to generate patient-specific iPS cells. These cell lines appear indistinguishable from human embryonic stem cells and iPS cells from healthy individuals. Most importantly, we show that corrected Fanconi-anaemia-specific iPS cells can give rise to haematopoietic progenitors of the myeloid and erythroid lineages that are phenotypically normal, that is, disease-free. These data offer proof-of-concept that iPS cell technology can be used for the generation of disease-corrected, patient-specific cells with potential value for cell therapy applications.

The events regulating human preimplantation development are still largely unknown owing to a scarcity of material, ethical and legal limitations and a lack of reliable techniques to faithfully amplify the transcriptome of a single cell. Nonetheless, human embryology is gathering renewed interest due to its close relationship with both stem cell biology and epigenetic reprogramming to pluripotency and their importance in regenerative medicine. Carefully timed genome-wide transcript analyses of single oocytes and embryos uncovered a series of successive waves of embryonic transcriptional initiation that start as early as the 2-cell stage. In addition, we identified the hierarchical activation of genes involved in the regulation of pluripotency. Finally, we developed HumER, a database of human preimplantation gene expression, to serve the scientific community. Importantly, our work links early transcription in the human embryo with the correct execution of the pluripotency program later in development and paves the way for the identification of factors to improve epigenetic reprogramming.

Induced pluripotent stem (iPS) cells have generated keen interest due to their potential use in regenerative medicine. They have been obtained from various cell types of both mice and humans by exogenous delivery of different combinations of Oct4 , Sox2 , Klf4 , c-Myc , Nanog , and Lin28 . The delivery of these transcription factors has mostly entailed the use of integrating viral vectors (retroviruses or lentiviruses), carrying the risk of both insertional mutagenesis and oncogenesis due to misexpression of these exogenous factors. Therefore, obtaining iPS cells that do not carry integrated transgene sequences is an important prerequisite for their eventual therapeutic use. Here we report the generation of iPS cell lines from mouse embryonic fibroblasts with no evidence of integration of the reprogramming vector in their genome, achieved by nucleofection of a polycistronic construct coexpressing Oct4 , Sox2 , Klf4 , and c-Myc .