Can controlled cellular reprogramming be achieved using microRNAs?

Since a technique was reported for generating induced pluripotent stem cells (iPSCs), various groups worldwide have reprogrammed human and mouse somatic cells into iPSCs using a range of techniques and pluripotency genes. Progress in iPSC research has opened up a novel avenue in autologous regenerative medicine, whereby patient-specific pluripotent cells could potentially be derived from adult somatic cells. However, several limitations currently prohibit their use in clinical settings, including the viral DNA delivery system and the exogenous overexpression of pluripotency genes. New strategies are therefore needed to ensure the safe and efficient production of iPSCs, and to guide their differentiation into the desired lineages required to repair damaged tissue and treat disease. Here, we present an overview of recent research into cellular reprogramming. We focus on the feasibility of microRNA-based strategies for reprogramming somatic cells into pluripotent stem cells, thus obviating the need to introduce viruses or DNA into donor cells, and therefore ameliorating the risks associated with reprogramming techniques. In light of the critical roles of microRNAs in maintaining the pluripotent state and in regulating cell-lineage specification and epigenetic modifications of chromatin, we also discuss the potential role of microRNAs as candidates for controlled cellular reprogramming and induction of cell fate conversion beyond lineages without reversion to a pluripotent state. Further research into the microRNAs involved in iPSC reprogramming and their potential roles in controlled cellular reprogramming will add another dimension to our understanding of the molecular mechanisms involved in cellular reprogramming.