Circulating microRNAs in hematological diseases: principles, challenges, and perspectives.

The complex microRNA (miRNA) network plays an important role in the regulation of cellular processes such as development, differentiation, and apoptosis. Recently, the presence of cell-free miRNAs that circulate in body fluids was discovered. The ability of these circulating miRNAs to mirror physiological and pathophysiological conditions as well as their high stability in stored patient samples underlines the potential of these molecules to serve as biomarkers for various diseases. In this review, we describe recent findings in miRNA-mediated cell-to-cell communication and the functions of circulating miRNAs in the field of hematology. Furthermore, we discuss current approaches to design biomarker studies with circulating miRNAs. This article critically reviews the novel field of circulating miRNAs and highlights their suitability for clinical and basic research in addition to their potential as a novel class of biomarkers.