Epigenetic alterations in human pluripotent stem cells: a tale of two cultures.

Human somatic cells can be reprogrammed into induced pluripotent stem cells (hiPSCs) with wide lineage differentiation potential in culture. However, reprogramming and long-term culture can also induce abnormalities in these pluripotent cells. This minireview discusses recent studies that have identified changes in imprinted gene expression and erosion of X chromosome inactivation in female hiPSCs and how understanding the sources and consequences of epigenetic variability in hiPSCs will impact disease modeling and clinical application in the future.