Exosomes as drug delivery systems: A brief overview and progress update

Exosomes are intracellular membrane-based vesicles with diverse compositions that are involved in biological and pathological processes. Since the discovery of exosomes, they have been used as diagnostic biomarkers and as potential drug delivery vehicles based on their size and competence to transfer biological materials to recipient cells. The properties of exosomes such as biocompatibility, preferred tumor homing, adjustable targeting efficiency, and stability make them striking and excellent drug delivery vehicles for use in various diseases and cancer therapy. In this article, we provide a brief overview of the biogenesis, functions, and contents of exosomes along with the separation and characterization techniques. Our major focus is on the recent progress made in application of exosomes as drug delivery systems involving delivery of small molecules, macromolecules, and nucleotides. Further, we discuss the challenges faced when using exosomes as a drug delivery vehicle.