Extracellular vesicles (EVs) are lipid enclosed particles that are naturally released by cells. EVs have been implicated in the delivery of different molecules between cells. As EVs are made of lipids, they overcome the many barriers associated with the delivery of highly polar molecules into lipophilic cells. Regenerative medicine has taken advantage of the intrinsic nature of EVs to deliver cargo and has harnessed their natural ability for the delivery of nucleic acids and other polar molecules to diseased tissue.
EVs have advantages over some cell therapies as they can be less immunogenic, have a longer shelf life and do not replicate, presenting a lower risk of tumor generation. Synthetic drug carriers can be toxic and immunogenic; EVs overcome toxicity and immunogenicity because they are derived from benign or autologous sources and some possess the ability to target specific tissue. 
Murphy DE, de Jong OG, Brouwer M, et al. Extracellular vesicle-based therapeutics: natural versus engineered targeting and trafficking. Exp Mol Med. 2019;51(3):32. doi:10.1038/s12276-019-0223-5