Table 1.

Comparison of the early methods applied for drug loading into engineered extracelluar vesicles (EVs) or exosomes (EXs).

Method	Advantages	Disadvantages	Drug Loaded/Application
Treatment of parental cells with drug	Relatively simple Does not require addition of drug into the system	Low loading efficiency Drugs may be cytotoxic to cells	Paclitaxel (Ptx) [104] Hydrophobic sensitizers (model drug) [141]
Incubation with drug	Simplest method Do not require extra equipement	Low loading efficiency	Curcumin [92,107]; si RNAs [116]; Porphyrins [111]; Catalase [108]; PTX [105]; DOX [129]
Electroporation	Loading with large molecules possible	Disrupts EX integrity siRNA aggregation Low loading efficiency (hydrophobic drugs)	siRNA [112,114]; Porphyrins [111]; DOX [109]; Dextran macromolecules [110]; PTX [105]
Sonication	Increased loading efficiency (compared to other methods) Applicable for small RNAs	Potential deformation of membrane Not efficient for hydrophobic drugs	PTX [105]; Catalase [108]; siRNA, miRNA, ssDNA [114,149]
Extrusion	High drug loading efficiency	Potential deformation of membrane	Porphyrins [111]; Catalase [108]
Freeze/thaw method	Medium loading Fusion of membranes possible [54]	Exosomes may aggregate Low loading Efficiency	Catalase [108]; DOX [129]
Saponin-assisted loading	High drug loading, compared to the other methods used in early reports	Generates pores in EXs Haemolysis/Toxicity concerns [150] Saponin conc. Control & Washing required	Catalase [108]; Porphyrins [111]; DOX [129]