Two Supporting Factors Greatly Improve the Efficiency of Human iPS Cell Generation

Human fibroblasts can be induced into pluripotent stem cells (iPS cells), but the reprogramming efficiency is quite low. Here, we screened a panel of candidate factors in the presence of OCT4, SOX2, KLF4 and c-MYC in an effort to improve the reprogramming efficiency from human adult fibroblasts. We found that p53 siRNA and UTF1 enhanced the efficiency of iPS cell generation up to 100-fold, even when the oncogene c-MYC was removed from the combinations. We further demonstrated that by using a novel combination of the four factors OCT4, SOX2, KLF4 and UTF1, iPS cells could be generated at a frequency at least 10 times higher than using the original four reprogramming factors without c-MYC. The iPS cells generated in this work have a similar gene expression profile and differentiation potential as human embryonic stem (hES) cells. In conclusion, two novel supporting factors that increase the efficiency of direct reprogramming have been identified, and a more-efficient method for the generation of human iPS cells has been developed in the absence of the oncogene c-MYC. Keywords: cell type comparison Total RNA from hFSF, hAFF, hES cells (H1, H7) and 7 established iPS cell lines were labeled with Cy5, hybridized to a human Oligo Microarray (Phalanx Human Whole Genome OneArray™, Phalanx Biotech) according to the manufacturer's protocol. Three technical repetitions were performed. After hybridization, arrays were scanned using GenePix 4000B scanner (Molecular Devices) and processed using the GenePix Pro 6.0 software (Molecular Devices). After removing control probes, a 14/33 presence call (SNR>=5 and foreground-background>0) was used to filter probes for the 33 microarrays, resulting in 12311 probes for further quantile normalization.