Exosome subpopulations: the isolation and the functions in diseases

Exosomes are nanoscale extracellular vesicles secreted by cells. Exosomes mediate intercellular communication by releasing their bioactive contents (e.g., DNAs, RNAs, lipids, proteins, and metabolites). The components of exosomes are regulated by the producing cells of exosomes. Due to their diverse origins, exosomes are highly heterogeneous in size, content, and function. Depending on these characteristics, exosomes can be divided into multiple subpopulations which have different functions. Efficient enrichment of specific subpopulations of exosomes helps to investigate their biological functions. Accordingly, numerous techniques have been developed to isolate specific subpopulations of exosomes. This review systematically introduces emerging new technologies for the isolation of different exosome subpopulations and summarizes the critical role of specific exosome subpopulations in diseases, especially in tumor occurrence and progression.