Since induced pluripotent stem (iPS) cells were first introduced just a few years ago, their equivalence to embryonic stem cells has not been entirely ascertained. In order to address this question, HSCI Principal Faculty member Konrad Hochedlinger and fellow researchers studied genetically identical mouse embryonic stem cells and iPS cells. They found that the RNA expressed by the two different types of cells was almost identical with the exception of one particular gene cluster that was not expressed in the iPS cells. Interestingly, consistent with a role for these silenced genes in development, those iPS cells in which the cluster was silenced developed into animals poorly, while those in which it was not silenced developed well. Furthermore, when the cells with the silenced cluster were treated with factors that activated the cluster, the cells then developed well. These results are exciting because they suggest a great degree of similarity between iPS and ES cells, which make iPS cells a potentially instructive tool and model for helping researchers understand injury and disease. Also, the identification of a particular gene cluster associated with iPS cells that have the developmental potential of ES cells provides researchers with a helpful assay to determine which iPS cells to work with in order to obtain full developmental potential.

Stadtfeld, M., Apostolou, E., Akutsu, H., Fukuda, A., Follett, P., Natesan, S., Kono, T., Shioda, T., Hochedlinger, K. (2010). Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells. Nature Apr 25. [Epub ahead of print]