Exosomal circRNAs: biogenesis, effect and application in human diseases

Exosomes have emerged as critical mediators of intercellular communication, both locally and systemically, by regulating a diverse range of biological processes between cells. Circular RNA (circRNA) is a novel member of endogenous noncoding RNAs with widespread distribution and diverse cellular functions. Recently, circular RNAs have been identified for their enrichment and stability in exosomes. In this review, we outline the origin, biogenesis and function of exosomal circRNAs as well as their roles in various diseases. Although their precise roles and mechanisms of gene regulation remain largely elusive, exosomal circRNAs have potential applications as disease biomarkers and novel therapeutic targets.