Inclusion Biogenesis, Methods of Isolation and Clinical Application of Human Cellular Exosomes

Abstract

Exosomes are a heterogenous subpopulation of extracellular vesicles 30–150 nm in range and of endosome-derived origin. We explored the exosome formation through different systems, including the endosomal sorting complex required for transport (ESCRT) and ESCRT-independent system, looking at the mechanisms of release. Different isolation techniques and specificities of exosomes from different tissues and cells are also discussed. Despite more than 30 years of research that followed their definition and indicated their important role in cellular physiology, the exosome biology is still in its infancy with rapidly growing interest. The reasons for the rapid increase in interest with respect to exosome biology is because they provide means of intercellular communication and transmission of macromolecules between cells, with a potential role in the development of diseases. Moreover, they have been investigated as prognostic biomarkers, with a potential for further development as diagnostic tools for neurodegenerative diseases and cancer. The interest grows further with the fact that exosomes were reported as useful vectors for drugs.

<p>Exosome: A Review of Its Classification, Isolation Techniques, Storage, Diagnostic and Targeted Therapy Applications</p>

“…At present, more researches are on ESCRT-dependent and ESCRT-independent mechanisms. [14][15][16] However, it has recently been reported that certain components, such as four-transmembrane domain proteins and lipid raft, are also involved in the formation of some exosomes. 17,18 Therefore, the exact mechanism remains controversial.…”

“…It has strong specificity, high sensitivity, high purity and high yield, and does not set the upper limit of the starting sample volume when based on magnetic beads. 16,58,59 For example, the enzyme-linked immunosorbent analysis technique based on microplates is used to enrich exosomes in fluids such as serum, plasma and urine. Quantitative detection and analysis found that the yield of exosomes harvested by this method is equivalent to that of ultracentrifugation, but the demand of samples is much smaller.…”

Therapeutic Use of Extracellular Vesicles for Acute and Chronic Lung Disease

“…The techniques used for EV quantification include protein concentration, nanoparticle tracking analysis, tunable resistive pulse sensing, vesicle flow cytometry, surface plasma resonance, and electron microscopy. There are many recent reviews describing the predominant methods currently being used in the field [11,13,[70][71][72]. The culture conditions and external stimuli of MSCs during EV production can alter the rate of EVs secreted and the EV composition, with resultant changes in the observed effects [17][18][19]73].…”

Development of New Strategies Using Extracellular Vesicles Loaded with Exogenous Nucleic Acid

“…That may have repercussions on their extraction; for example, isolated exosomes may contain subpopulations with a distinct size range. Therefore, an optimal method for the exosome isolations would require large pools of purification procedures, a high recovery yield, high purity of exosomes, and high efficiency [75]. Several exosomes isolation techniques have been developed, each exploiting a particular property of exosomes, such as their density, shape, size, and unique surface proteins, to aid their isolation [76].…”