Cell-derived exosomes have been demonstrated to be efficient carriers of small RNAs to neighbouring or distant cells, highlighting the preponderance of exosomes as carriers for gene therapy over other artificial delivery tools. In the present study, researchers from Nanjing University employed modified exosomes expressing the neuron-specific rabies viral glycoprotein (RVG) peptide on the membrane surface to deliver opioid receptor mu (MOR) siRNA into the brain to treat morphine addiction. They found that MOR siRNA could be efficiently packaged into RVG exosomes and was associated with argonaute 2 (AGO2) in exosomes. These exosomes efficiently and specifically delivered MOR siRNA into Neuro2A cells and the mouse brain. Functionally, siRNA-loaded RVG exosomes significantly reduced MOR mRNA and protein levels. Surprisingly, MOR siRNA delivered by the RVG exosomes strongly inhibited morphine relapse via the down-regulation of MOR expression levels. In conclusion, these results demonstrate that targeted RVG exosomes can efficiently transfer siRNA to the central nervous system and mediate the treatment of morphine relapse by down-regulating MOR expression levels. This study provides a brand new strategy to treat drug relapse and diseases of the central nervous system.
(A) Schematic diagram of the production and harvest of RVG-modified exosomes for siRNA delivery. (B) TEM micrographs of RVG exosomes isolated from the culture medium of 293T cells. (C) Exosomes were measured by using Nanosight NS 300 system in the supernatant from cultures cells. The histogram represents particle size distribution. (D) qRT-PCR analysis of siRNA levels in various quantities of exosomes. *P < 0.05; **P < 0.01. (E) qRT-PCR analysis of MOR siRNA levels in various exosomes. (F) qRT-PCR analysis of MOR siRNA levels in anti-AGO2 or anti anti-IgG immunoprecipitated products from RVG exosomes treated with or without AGO2 antibody. RVG-modified exosomes with or without siRNA were isolated from 293T culture medium and immunoprecipitated with or without anti-AGO2 antibody. Then, MOR siRNA levels in immunoprecipitated products from RVG exosomes were assayed by qRT-PCR.