Similar reprogramming experiments were carried out in parallel with human keratinocytes, a somatic cell with a high reprogramming efficiency and fibroblasts, a cell type with Niraparib significantly lower reprogramming efficiency. Two serial spinfections of keratinocyte, fibroblast or astrocyte cultures resulted in over 90%, 50% and 40% of infected cells, respectively. Twelve days after the first infection, we started to observe the appearance of morphological hES-like colonies, coinciding with transgene silencing. However, we also detected partially reprogrammed colonies with non-hES morphological phenotypes, where transgene silencing, based on GFP expression, did not occur. Finally, eighteen days following the initial infection, we either fixed/stained or manually picked the hiPS cell colonies obtained for further culture and characterization. We observed a similar reprogramming efficiency for human astrocytes and keratinocytes, which was much higher when compared to fibroblasts. Similar reprogramming experiments performed using alkaline phosphatase staining to evaluate pluripotent colony formation showed comparable results. To better understand why astrocytes reprogram more efficiently than other cell types such as fibroblasts, we performed a real-time analysis of the expression of genes involved in different aspects of stem cell biology in the H9 hES cell line, astrocytes, keratinocytes and fibroblasts. Using a Pearson correlation as a distance measure between the different sets of values we observed that both, keratinocytes and astrocytes, are closer than fibroblasts to hES cells, which may contribute to the higher reprogramming efficiency of astrocytes. hES cells have a cell cycle signature structure characterized by a very shortG1phaseand ahighpercentage of cellsinS phase. We found that the characteristic stem cell cycle signature of hES cells is acquired in all the ASThiPS cell lines and differs greatly from the cell cycle profile observed in the cells of origin. Consequently, we observed a dramatic change in the expression profile of the cell cycle proteins involved in the G1/S transition in the ASThiPS cell lines to levels similar to those observed in hES cells. The induction of pluripotency by expression of Oct4, Sox2, Klf4 and c-Myc has been reported in human somatic cells of different origin. Recently, the generation of iPS cells from human neural stem cells has been achieved with only the expression of Oct4. These data suggest that the high similarity in the transcriptional program reported between these committed stem cells and hES cells helps to facilitate the reprogramming process. In our work, we demonstrated the ability to generate hiPS cells from a differentiated neural cell type. Furthermore, we showed that human astrocytes generated hiPS with a reprogramming efficiency similar to human keratinocytes, which is much higher than the efficiency observed for other cell types, such as fibroblasts.