Table 1 The principles, advantages, and limitations of the exosome loading methods
Loading strategy | Principle | Advantage | Disadvantage | References |
|---|---|---|---|---|
Coincubation | By incubating the exosome or donor cell directly with the drug (typically a lipid-soluble small molecule), the drug can enter the exosome or donor cell by diffusion along a concentration gradient | Simple operation No additional active substance is required | Only fat-soluble drugs can be loaded Low loading efficiency | [109] |
Extrusion | The exosomes were mixed with the drug, and the mixture was then loaded into a syringe-based lipid extruder with a 100-to 400-nm porous membrane at a controlled temperature. During extrusion, the exosome membrane is ruptured and violently mixed with the drug | High yield Suitable for mass production | The properties of the membrane (e.g., zeta potential) and membrane protein structure may be altered Potentially cytotoxic | [110] |
Sonication | The exosomes were incubated with drug molecules, etc., and then the membrane of the exosomes was deformed by sonication and the mechanical shear force of the sonication probe to make the drug enter the exosomes | High drug loading efficiency | The drug may attach to the membrane surface Not effective against hydrophobic drugs | [111] |
Electroporation | An electric field is applied to the exosome suspended in a conductive solution, and the current interferes with the phospholipid bilayer of the exosome, creating temporary holes in the membrane through which drugs, etc., can diffuse into the interior of the exosome | No chemical reagents are introduced High efficiency in loading hydrophilic drugs (e.g., DNA and RNA) | May result in the introduction of drugs that fuse with the cell's own components | [112] |