Table 3 Summary of engineered EVs: Load contents and loading methods

Disease-targeting contents

- Small-molecule drugs (e.g., curcumin, paclitaxel, doxorubicin)

- Nucleic acids (siRNA, miRNA, mRNA)

- Proteins (e.g., CD24)

-Exogenous loading

-Endogenous loading

Therapeutic cargo loading

- Enhanced therapeutic effects (EVs as a drug delivery system)

- Enhanced therapeutic efficiency (EVs as a natural drug)

Tissue and cell-targeting contents

- Proteins (e.g., peptides, antibodies)

- Chemicals (e.g., azide and alkyl groups)

- Biomaterials (e.g., Polyethylene glycol, hydrogels)

-Exogenous loading

-Endogenous loading

-Material-based loading

Tissue and cell targeting, controlled release

- Improved tissue and cell specificity

- Enhanced tissue retention

- Improved therapeutic efficiency

Exogenous loading

Loaded directly on EVs, loading after EVs are purified from cells (postloading)

- Electroporation

- Incubation

- Sonication

- Freeze–thaw

- Extrusion

- Transfection

- Small-molecule drugs

- Small nucleic acids (siRNA, miRNA)

- Chemicals

- Biomaterials

- High loading efficiency

- Fast process

- Flexible drug combinations

Endogenous loading

Loaded directly on cells, loading before EVs are purified from cells (preloading)

- Transient expression

- Incubation

- Transfection

- Epigenetic modifications

- Long-term expression

- Virus transfection

- Genome editing

- Proteins (peptides, antibodies, enzymes)

- Small and large nucleic acids (miRNA, mRNA, lncRNA)

- Genetic precision

- Stable expression

- Large-scale production

Material-based EV engineering

Loaded directly on EVs (postloading)

- Surface-based modifications

- Chemical

- Electrostatic

- Magnetic

- Scaffold-based modifications

- Hydrogel

- Microsphere

- Microneedle

- Chemicals

- Biomaterials

- Prolonged circulation

- Enhanced tissue targeting

- Sustained release

- Local accumulation

- Improved stability