Table 2.

Comparison of current exosome extraction techniques

Methodology	Mechanisms	Advantages	Disadvantages
Ultracentrifugation	Sequential separation based on density and particle size[82]	Simple handling and a high number of vesicles obtained	a time-consuming process; low purity; high equipment cost; Disruption of exosome integrity
Density gradient centrifugation	Ultracentrifugation combined with sucrose density gradients[82]	High purity of the obtained exosomes	Cumbersome and time-consuming steps
Ultrafiltration	Separation and extraction of different particle size[83]	Simple operation, timesaving, cost-efficient operation, high output, and efficiency	the pressure and shear forces during filtration deform and damage the exosomes
Magnetic-activated cell sorting(MACS)	Separation of labelled cells bound to magnetic beads using a magnetic field[84]	High specificity and ease of handling	Low efficiency and susceptibility of exosome bioactivity to pH and salt concentration
Separation of exosomes by sieving	Exosomes are sieved out of the sample through the membrane using pressure or electric fields	Short separation times and high purity	Low recovery rate
Size exclusion chromatography	Separation of molecules of different sizes and numbers using molecular sieves[83]	Precise separation of small and large molecules	Time-consuming, not suitable for large sample sizes
Polymer-based precipitation technology	Polyethylene glycol (PEG) binds to hydrophobic proteins and lipid molecules for co-precipitation[85].	Low impact on isolated exosomes	Low purity and recovery, high levels of heterogeneous proteins, uneven particle size, destruction of exosomes
Reagent Kits	Multiple	No special equipment is required, simple operation, high purity, and high recovery of exosomes	Just starting to develop, less variety and high cost