Engineering exosomal microRNAs in human pluripotent stem cells

Abstract Stem cells possess unique properties of self-renewal and multilineage differentiation potentials. In addition, stem cells also exhibit important trophic function, by secreting large numbers of regulatory molecules such as cytokines and extracellular vesicles (EVs). Among them, exosomal miRNAs (exo-miRNAs), a type of small noncoding RNAs sorted in EVs, play an important role in the regulation of gene expression in various biological processes through cell–cell communications. As incorporated into EVs, exo-miRNAs can be delivered to recipient cells as cargos to regulate cellular behaviors. This chapter reviews the function of exo-miRNAs in EVs derived from stem cells, including mesenchymal stem cells and pluripotent stem cells, and summarizes current knowledge on the characteristics of miRNA expression at undifferentiated and lineage-primed stages of stem cells. Furthermore, the role of stem-cell-derived exo-miRNAs in regulating the phenotype of somatic and progenitor cells is also analyzed in order to elucidate their participations and the therapeutic function in specific diseases. Lastly, this work summarizes current approaches and progresses in engineering exo-miRNAs and EVs derived by stem cells toward potential clinical applications.