Exosomes: new molecular targets of diseases

Abstract

Extracellular vesicles (EVs) comprise apoptotic bodies, microvesicles and exosomes, and they perform as key regulators in cell-to-cell communication in normal as well as diseased states. EVs contain natural cargo molecules, such as miRNA, mRNA and proteins, and transfer these functional cargos to neighboring cells or more distant cells through circulation. These functionally active molecules then affect distinct signaling cascades. The message conveyed to the recipient cells is dependent upon the composition of the EV, which is determined by the parent cell and the EV biogenesis. Because of their properties such as increased stability in circulation, biocompatibility, low immunogenicity and toxicity, EVs have drawn attention as attractive delivery systems for therapeutics. This review focuses on the functional use of exosomes in therapy and the potential advantages and challenges in using exosomes for therapeutic purposes.

Figure 1

Biogenesis and release of extracellular vesicles: represented diagram depicts a typical extracellular vesicle biogenesis and release.

Figure 2

Proposed structure of a mid-size exosome (40–60 nm in diameter). A vesicle contains cytosol of the parent cell and expresses the extracellular domains of different transmembrane proteins reflecting the type of parent cell from which it is derived.

Figure 3

Electron micrographs of mouse bone marrow derived primary macrophage cells treated with or without lipopolysaccharide (LPS). (A) Exosomes in the untreated cells; (B) exosomes after treatment with LPS; (C) exosomes secreted outside the cells; MVB, multivesicular body; Bars: 100 nm.

Figure 4

Exosomes play roles in drug delivery: exosomes isolated from different cell types are rich in miRNA, RNA and protein. These molecules can further modified and reinserted into the exosomes for different therapeutic applications.