Exosomes (EXO) are secreted membrane nanoparticles formed by fusion of multivesicular bodies (MVBs) with the plasma membrane. The size of exosomes is about 30-150nm. Exosomes can be purified from in vitro cultures of cells. Like VLPs, EXO also shows outstanding immunogenicity and have the membrane structure close to that of the native plasma membrane.

Overexpressed membrane proteins (MPs) were inserted in the host cell membrane and secreted out as Exosomes which can be purified and used for a series of downstream studies. Unlike VLPs, the purified EXO has minimal cytotoxicity. However, not all MPs can be included in EXO and secreted into medium.