Table 3 Comparisons of isolation methods
Method | Mechanism | Pros | Cons |
|---|---|---|---|
Centrifugation | Stepwise centrifugation: removing cells and debris at a Low centrifugation speed (300–1000 g), followed by MPs collection at a higher one (10000–20000 g) | The most common and efficient isolation Method Low cost Simple to operate Not easily contaminated Wide range of sample volumes from a few millilitres up to > 100 mL | Low selectivity Risk of aggregation and deformation of MPs Risk of cosedimentation of larger vesicles and protein aggregates |
Size exclusion chromatography | By using a column packed with porous gels, large EVs flow out first than small EVs. Each component is separated according to size | Reducing aggregation of MPs and proteins Maintaining integrity and biological activity of MPs Relatively high purification and inexpensive | In most cases, samples are diluted and re-concentration are required, resulting in long times If there are multiple production cycles, columns need to be washed, sanitized and rebalanced |
Ultrafiltration | Use membranes with specific aperture to remove other components from the sample and retain and concentrate the MPs | Low cost Simple to operate Easy for large scale | Low selectivity Risks of non-specific binding of MPs to membranes and leading to some loss of yield Risks of deformation or rupture of MPs |
Immunoaffinity chromatography | MPs are separated by the specific interaction of antigens on the surface of MPs and antibodies On the beads | High purification Capacity of isolating and quantifying specific sub-population of MPs | High cost Unsuitable for large-volume samples and uneasy for large scale Risks of deformation while elution Accurately sorting a particular type of MPs, thus losing the heterogeneity of MPs |
Microfluidics | The isolation can be based on several aspects, such as shape, size, density, electric charge, specific lipid/proteins on MPs membrane | High purification Fast and simple to operate Capacity of isolating and quantifying specific sub-population of MPs in real time Available for small volume samples | Accurately sorting a particular type of MPs, thus losing the heterogeneity of MPs Risks of deformation on account of the shear stress |