Regulation of 'stemness' and stem cell differentiation by microRNAs.

Pluripotency and cellular differentiation are intricate biological processes that are coordinately regulated by a complex set of factors and epigenetic regulators. Human pluripotent stem cell lines can be generated from surplus fertilized eggs or, as demonstrated more recently, from the reprogramming of somatic cells. Standardized culture conditions for the long-term maintenance and propagation of undifferentiated human pluripotent stem cells have also been developed. An objective of current research is to increase the understanding of the molecular mechanisms that regulate stem cell differentiation. The differentiation of human pluripotent stem cells may enable the generation of large quantities of specialized cells that can be used as in vitro tools for drug development, as well as for future applications in regenerative medicine. However, most of the currently used differentiation protocols yield inefficient stem cell quantities and low purity of the final cell preparations. The discovery of microRNAs (miRNAs) and their role as important transcriptional regulators may provide a new means of manipulating stem cell fate. This article provides an overview of some recent advancements made in the fields of both stem cell biology and miRNA.