Human-induced pluripotent stem cells: derivation, propagation, and freezing in serum- and feeder layer-free culture conditions.

The recent discovery of genomic reprogramming of human somatic cells to an embryonic stem (ES) cell-like pluripotent state provides a unique opportunity for stem cell research. The reprogrammed cells, named as induced pluripotent stem (iPS) cells, possess many of the properties of ES cells and represent one of the most promising sources of patient-specific cells for use in disease model, development of pharmacology and toxicology, screening teratogens, and regenerative medicine. Here we describe the detailed methods for the generation of undifferentiated human iPS (hiPS) cells in feeder layer- and serum-free conditions. This system eliminates direct contact of stem cells with MEFs and reduces use of unknown serum factors that may have undesired activities and enables consistency in large-scale and long-term expansion of undifferentiated hiPS cells. Our findings greatly simplify the method for induction of pluripotency and bring it one step closer to clinical applications. Moreover, the established hiPS cells showed chromosomal stability during long-term culture.