New approaches for the generation of induced pluripotent stem cells.

INTRODUCTION The advent of induced pluripotent stem cell (iPSC) technology has opened up new vistas to generate patient-specific pluripotent stem cells from somatic cells. During the last 5 years, the iPSCs produced from a variety of somatic cell sources are found to be very similar, if not identical to embryonic stem cells. Invariably these cells are produced by viral transduction of four transcriptional factors that renders these cells unfit for therapeutic purposes. AREAS COVERED This review discusses current developments emphasising on new and improved methods of generating iPSCs, including minimal or no genetic modifications via excisable lentiviral and transposon vectors or through repeated application of transient plasmid, episomal and adenovirus vectors. Recent use of small molecules, synthetic mRNA and microRNAs is also reviewed. EXPERT OPINION iPSC technology is emerging as an unprecedented opportunity in biomedical research, disease modeling, drug discovery and regenerative medicine. However, to harness the full potential of this technology, a number of issues that need to be resolved pertaining to iPSC safety, stability, culture variability, their comparison with ES cells, the reprogramming mechanisms and better ways to direct a specific reprogramming process including lineage specifications.