A Review of Exosomal Isolation Methods: Is Size Exclusion Chromatography the Best Option?

Abstract

Extracellular vesicles (EVs) are membranous vesicles secreted by both prokaryotic and eukaryotic cells and play a vital role in intercellular communication. EVs are classified into several subtypes based on their origin, physical characteristics, and biomolecular makeup. Exosomes, a subtype of EVs, are released by the fusion of multivesicular bodies (MVB) with the plasma membrane of the cell. Several methods have been described in literature to isolate exosomes from biofluids including blood, urine, milk, and cell culture media among others. While differential ultracentrifugation (dUC), has been widely used to isolate exosomes, other techniques including ultrafiltration, precipitating agents such as poly-ethylene glycol (PEG), immunoaffinity capture, microfluidics and size exclusion chromatography (SEC) have emerged as credible alternatives with pros and cons associated with each. In this review, we provide a summary of commonly used exosomal isolation techniques with a focus on SEC as an ideal methodology. We evaluate the efficacy of SEC to isolate exosomes from an array of biological fluids, with a particular focus on its application to adipose tissue-derived exosomes. We argue that exosomes isolated via SEC are relatively pure and functional, and that this methodology is reproducible, scalable, inexpensive, and does not require specialized equipment or user expertise.

Can a Torque Teno Virus (TTV) Be a Naked DNA Particle Without a Virion Structure?

“…However, it has been scientifically proven that exosomes contain TTV DNA and are not affected by DNAse treatment (32). Furthermore, exosomes have also been found in sucrose density gradients that are almost identical to the sucrose density gradients in which TTV's DNA was detected (33)(34)(35). It is well known that the DNA inside the exosomes cannot be digested by DNases (36,37).…”

“…It is well known that the DNA inside the exosomes cannot be digested by DNases (36,37). Interestingly, both the exosomes and TTV genomes share a common biological environment: blood, semen, breast milk, saliva, nasal secretions, tears, bile, urine, and feces (34,35). TTV DNA is called a virus because of its presence in a virus-specific sucrose density and because it is not digestible by DNases (1).…”

Exosome-Based Smart Drug Delivery for Cancer Treatment

“…Consequently, ultracentrifugation is often utilized to further intensify the concentration of the exosome sample [14][15][16]. In exosome isolation through size exclusion chromatography, the payload concentration of exosomes can be determined by analyzing the eluted fractions collected during the chromatographic process [17]. This can be done by quantifying specific cargo molecules, such as proteins or nucleic acids, present in the collected samples.…”