Table 4 Loading approaches of exosome-based on the newest advancement

Sonication

Uses ultrasound with high frequency to transfer therapeutic cargos

Loading efficiency is high as showed that siRNA loaded into EV by sonication at a 325% increase than electroporation

Can keep the integrity of the cargo against deformation

Incubation can solve the instability of exosomes after exosome-liposome fusion

This technique can load chemicals, proteins, small nucleic acids, and nanomaterials

Sonication can load a wide range of bioactive molecules into exosomes, including small and large molecules

The circulation period is not affected by sonication since incubation can reform the temporarily generated pores in the exosome membrane

[151,152,153,154]

pH gradient

It depends on the change in the biochemical environment inside and outside the exosome

High loading efficiency as sonication approach

Nucleic acid (miRNA or mRNA) cargos can be protected and very stable when in a low pH environment

Exosomes in the ex vivo acidity environment appear stable

Its loading efficiency comparable to the sonication method

Able to load large cargos such as CRISPR/Cas9 vector

Remaining period increases because low pH allows more activity and stability

[155]

Exosome-liposome fusion

The principle is lipid-lipid fusion between exosome and liposome

High loading ability to hydrophobic and hydrophilic compounds

The fusion of exosome and liposome approach could protect cargo from the plasma and immune system and makes the cargo more stable

Increase the hybrid exosome stability more than exosome alone

Hydrophobic drugs and hydrophilic drugs

This approach provides a great opportunity to load large cargos such as CRISPR/Cas9 vector

Because of their endogenous nature, the hybrid exosomes (exosome-liposome complex) have a longer circulating period, which makes it considered an approach for loading cargos

[156,157,158]