Exosomes and their applications in cell- based therapies

Expanding knowledge about nanometer-sized fluid filled vesicles budding from cells, packaged with molecular cargo has placed exosomes to the stage where innovative engineering techniques translate them for clinical use. Exosomes are exploited for diagnostics and drug delivery systems. These extracellular vesicles (EVs) generated by double invagination of plasma membrane from cells and formation of intracellular multivesicular bodies harboring intraluminal vesicles which are secreted as exosomes of 40-160nm diameter (1). The heterogeneity of exosome is the reflection of its various sizes, content, functional impact and origin. The inherent cell physiology determines the content of exosomes. They may possess membrane proteins, cytosolic and nuclear proteins, nucleic acids, non-coding RNAs, and metabolites (2). At present, 9,769 proteins, 3,408 mRNAs, 2,838 miRNAs and 1,116 lipids have been reported as their composition(3). Exosomes serves as a non-canonical intercellular communication mode with the nexus of composition capable of multicellular and multi-centric targeting simultaneously. The potentiality to deliver molecular cargo to target cells and modify their intracellular mechanisms makes them ideal therapeutic agents and delivery systems for multiple diseases (4). The advantages of exosomal cargos over classical cell-based therapies that includes stem cells are lack of inherent risk, lack of replicating potential, lack of immunogenic response and site specificity(5).