Liver-Derived Exosomes and Their Implications in Liver Pathobiology

The liver has a wide range of physiological functions in the body, and its health is maintained by complex cross-talk among hepatic cells, including parenchymal hepatocytes and nonparenchymal cells. Exosomes, which are one method of cellular communication, are endosomal-derived small vesicles that are released by donor cells and delivered to the target cells at both short and long distances. Because exosomes carry a variety of cargoes, including proteins, mRNAs, microRNAs and other noncoding RNAs originating from donor cells, exosomes convey cellular information that enables them to potentially serve as biomarkers and therapeutics in liver diseases. Hepatocytes release exosomes to neighboring hepatocytes or nonparenchymal cells to regulate liver regeneration and repair. Nonparenchymal cells, including hepatic stellate cells, liver sinusoidal endothelial cells, and cholangiocytes, also secrete exosomes to regulate liver remodeling upon liver injury. Exosomes that are released from liver cancer cells create a favorable microenvironment for cancer growth and progression. In this review, we summarize and discuss the current findings and understanding of exosome-mediated intercellular communication in the liver, with a particular focus on the function of exosomes in both health and disease. Based on the current findings, we suggest the potential applications of exosomes as biomarkers and therapeutics for liver diseases.