Exosome nanotechnology: An emerging paradigm shift in drug delivery Exploitation of exosome nanovesicles for systemic in vivo delivery of RNAi heralds new horizons for drug delivery across biological barriers

The demonstration that dendritic cell (DC)-derived exosomes can be exploited for targeted RNAi delivery to the brain after systemic injection provides the first proof-of-concept for the potential of these naturally occurring vesicles as vehicles of drug delivery. As well as being amenable to existing in vivo targeting strategies already in use for viruses and liposomes, this novel approach offers the added advantages of in vivo safety and low immunogenicity. Fulfilment of the potential of exosome delivery methods warrants a better understanding of their biology, as well as the development of novel production, characterisation, targeting and cargo-loading nanotechnologies. Ultimately, exosome-mediated drug delivery promises to overcome important challenges in the field of therapeutics, such as delivery of drugs across otherwise impermeable biological barriers, such as the blood brain barrier, and using patient-derived tissue as a source of individualised and biocompatible therapeutic drug delivery vehicles.