Table 1.

Summary of different exosome isolation methods. To summarize the aforementioned isolation methods, we used a relative scaling to compare each factor listed: +++ (high), ++ (intermediate), or + (low), and in the case that grading was not applicable, we used a yes or no equivalence. Specificity: ability to separate exosomes; recovery: the amount of exosome (exosomal yield); purity: ability to separate exosomes with little contamination; sample volume: the amount of sample needed; time: ability to finish the processing in a short amount of time; cost: amount of money needed to perform the procedure; specialized equipment: need for expensive equipment; complexity: difficult to follow and need for training before use; efficiency: high quality sample processing; functionality of exosomes: ability to use the exosomes for functional studies without changing their efficacy; scalability: ability to process a large amount of sample without overly increasing time, cost, or personnel needed. dUC: differential ultracentrifugation, UF: ultrafiltration, PEG: poly-ethylene glycol-based precipitation, IA: immunoaffinity capture, MF: microfluidics, SEC: size-exclusion chromatography.

	dUC	UF	PEG	IA	MF	SEC
Mechanism of separation	Size, density	Size and molecular weight; through a filter membrane	Surface charge, solubility	Specific binding of antibodies to exosome markers	Immuno- affinity, density, and size	Size, shape, and molecular weight; large particles are eluted first
Specificity 1	++	+	+	+++	+++	++
Recovery 1	++	+++	+++	++	+	+++
Purity 1	+++	+	+	+++	+++	+++
Sample volume 1	++	++	+	++	+	+
Time 1	+++	+++	++	+++	++	+
Cost 1	+	++	+	+++	+++	+
Specialized equipment 2	++	+	+	+	++	+
Complexity 1	++	+	+	++	+++	+
Efficiency 1	++	++	++	++	+++	+++
Functionality of EVs 2	++	++	++	+	+	+++
Scalability 1	++	++	+++	+	+	+++

¹: + (low); ++ (intermediate); +++ (high). ²: + (no); ++ (yes).