Exosomes and extracellular vesicles: the path forward.

Over the course of the past several decades, the concept that extracellular vesicles, exosomes and microvesicles, operate as cellular "housekeepers" and as agents for communication between and among cells and tissues, has emerged into one of the most promising yet vexing problems facing the biomedical community. Already, extracellular vesicles from biological fluids are being used for diagnostic purposes and hopes abound for their use as therapeutic agents. However, the most basic mechanistic questions surrounding their biogenesis and function in cellular and tissue homeostasis remain largely unexplored. In this issue of Essays in Biochemistry, the rise of a new intercellular communications pathway is considered from many perspectives-cell biology, physiology, and pathophysiology.