Intracellular delivery of protein and RNA therapeutics represents a major challenge. Here, we develop highly potent engineered extracellular vesicles (EVs) by incorporating bio-inspired attributes required for effective delivery. These comprise an engineered mini-intein protein with self-cleavage activity for active cargo loading and release, and fusogenic VSV-G protein for endosomal escape. Combining these components allows high efficiency recombination and genome editing in vitro following EV-mediated delivery of Cre recombinase and Cas9/sgRNA RNP cargoes, respectively. In vivo, infusion of a single dose Cre loaded EVs into the lateral ventricle in brain of Cre-LoxP R26-LSL-tdTomato reporter mice results in greater than 40% and 30% recombined cells in hippocampus and cortex respectively. In addition, we demonstrate therapeutic potential of this platform by showing inhibition of LPS-induced systemic inflammation via delivery of a super-repressor of NF-ĸB activity. Our data establish these engineered EVs as a platform for effective delivery of multimodal therapeutic cargoes, including for efficient genome editing.

Extracellular vesicles (EVs) are biological nanoparticles with important roles in intercellular communication, and potential as drug delivery vehicles. Here we demonstrate a role for the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in EV assembly and secretion. We observe high levels of GAPDH binding to the outer surface of EVs via a phosphatidylserine binding motif (G58), which promotes extensive EV clustering. Further studies in a Drosophila EV biogenesis model reveal that GAPDH is required for the normal generation of intraluminal vesicles in endosomal compartments, and promotes vesicle clustering. Fusion of the GAPDH-derived G58 peptide to dsRNA-binding motifs enables highly efficient loading of small interfering RNA (siRNA) onto the EV surface. Such vesicles efficiently deliver siRNA to multiple anatomical regions of the brain in a Huntington’s disease mouse model after systemic injection, resulting in silencing of the huntingtin gene in different regions of the brain.

Multiple studies have described extracellular microRNAs (ex-miRNAs) as being remarkably stable despite the hostile extracellular environment, when stored at 4ºC or lower. Here we show that many ex-miRNAs are rapidly degraded when incubated at 37ºC in the presence of serum (thereby simulating physiologically relevant conditions). Stability varied widely between miRNAs, with half-lives ranging from ~1.5 hours to more than 13 hours. Notably, ex-miRNA half-lives calculated in two different biofluids (murine serum and C2C12 mouse myotube conditioned medium) were highly similar, suggesting that intrinsic sequence properties are a determining factor in miRNA stability. By contrast, ex-miRNAs associated with extracellular vesicles (isolated by size exclusion chromatography) were highly stable. The release of ex-miRNAs from C2C12 myotubes was measured over time, and mathematical modelling revealed miRNA-specific release kinetics. While some ex-miRNAs reached the steady state in cell culture medium within 24 hours, the extracellular level of miR-16 did not reach equilibrium, even after 3 days in culture. These findings are indicative of miRNA-specific release and degradation kinetics with implications for the utility of ex-miRNAs as biomarkers, and for the potential of ex-miRNAs to transfer gene regulatory information between cells.