Circulating microRNAs: emerging biomarkers of liver disease

Development of reliable, noninvasive biomarkers that allow for diagnosis, risk stratification, and monitoring of disease changes over time or in response to specific therapies represents a key priority in the field of hepatology. Recent evidence has uncovered the role of microRNAs as potential ideal biomarkers of liver injury in various acute and chronic liver diseases. These small noncoding RNAs are released to the extracellular space in a stress-specific manner and are remarkably stable in most bodily fluids including blood, where they circulate in specific compartments including extracellular vesicles and protein complexes. In this review, the authors provide a concise overview of available information on the emerging role of quantitation of circulating microRNAs in different liver diseases and their use as biomarkers for both diagnosis and prognosis assessment. Additionally, several key issues that still need to be addressed for microRNAs to become useful tools in daily clinical practice are critically reviewed.