microRNAs: important regulators of stem cells

Stem cells are undifferentiated cells and have multilineage differentiation potential. Generally, stem cells are classified into adult stem cells, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Stem cells have great potential in clinical therapy due to their pluripotency and self-renewal ability. microRNAs (miRNAs) are small non-coding RNAs which are evolutionarily conserved and participate in the pathogenesis of many diseases, cell cycle regulation, apoptosis, aging, cell fate decisions, and different signaling pathways. Different kinds of stem cells possess distinct miRNA expression profiles. Our review summarizes the critical roles of miRNAs in stem cell reprogramming, pluripotency maintenance, and differentiation. In the future, miRNAs may greatly contribute to stem cell clinical therapy and have potential applications in regenerative medicine.