Exosomes are extracellular vesicles released by the vast majority of cell types 
both in vivo and ex vivo, upon the fusion of multivesicular bodies (MVBs) with 
the cellular plasma membrane. Two main functions have been attributed to 
exosomes: their capacity to transport proteins, lipids and nucleic acids between 
cells and organs, as well as their potential to act as natural intercellular 
communicators in normal biological processes and in pathologies. From a clinical 
perspective, the majority of applications use exosomes as biomarkers of disease. 
A new approach uses exosomes as biologically active carriers to provide a 
platform for the enhanced delivery of cargo in vivo. One of the major 
limitations in developing exosome-based therapies is the difficulty of producing 
sufficient amounts of safe and efficient exosomes. The identification of 
potential proteins involved in exosome biogenesis is expected to directly cause 
a deliberate increase in exosome production. In this review, we summarize the 
current state of knowledge regarding exosomes, with particular emphasis on their 
structural features, biosynthesis pathways, production techniques and potential 
clinical applications.