Table 1 The principles, advantages, and disadvantages of conventional methods of exosomal purification
From: The significance of exosomal RNAs in the development, diagnosis, and treatment of pancreatic cancer
Method | Principle | Advantage | Disadvantages |
|---|---|---|---|
DC | By sequential increase in the centrifugal force, exosomes can be purified according to size and density | Suitable for large-volume samples Applied to purifying Exosomes from cell medium, plasma, and urine Relative technical simplicity | Time and labor cost Expensive equipment Damage due to centrifugal forces Large sample volumes requirement A mix of protein aggregates and lipoproteins |
DGC | With the sample added to the medium of specific density, exosomes can be purified from multiple contaminants by density, mass, and size | Higher purity than that of DC | Same as those of DC |
UF | By using a nanomembrane with a specific pore size and molecular weight cut-off, exosomes can be purified according to size or molecular weight | Saved time and labor consumption Fewer instruments cost Reduced technical difficulty | Damage to exosomes A mix of impurities with similar size or molecular weight Loss of small size exosomes Membrane blocking |
SEC | By using a porous stationary phase with a specific pore size, exosomes can be purified while crossing the pores | Reservation of the biological activity and structural integrity of exosomes Saved time and labor consumption High yields Good reproducibility for purification from serum, plasma, ascites, and saliva | A mix of albumin and lipoproteins Special equipment |
Precipitation | With precipitation reagents added to the sample and incubation, exosomes can be enriched from serum or plasma | Ease of use High yield Lower instruments requirements Commercialization of precipitation kits | A mix of lipoproteins, proteins, and ectosomes Difficult to remove the reagents from exosomes |
Immunoaffinity capture | With antibodies that can recognize specific proteins deposited on the surfaces of magnetic beads, exosomes can be purified while modified beads capture the exosomal proteins | High purity Commercialization of immunoaffinity capture kits Able to separate sub-population exosomes | Damage due to elution Expensive reagents Low capacity A mix of apoptotic bodies and microvesicles |