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[Display omitted] Extracellular vesicles (EVs) are submicron cell-secreted structures containing proteins, nucleic acids and lipids. EVs can functionally transfer these cargoes from one cell to another to modulate physiological and pathological processes. Due to their presumed biocompatibility and capacity to circumvent canonical delivery barriers encountered by synthetic drug delivery systems, EVs have attracted considerable interest as drug delivery vehicles. However, it is unclear which mechanisms and molecules orchestrate EV-mediated cargo delivery to recipient cells. Here, we review how EV properties have been exploited to improve the efficacy of small molecule drugs. Furthermore, we explore which EV surface molecules could be directly or indirectly involved in EV-mediated cargo transfer to recipient cells and discuss the cellular reporter systems with which such transfer can be studied. Finally, we elaborate on currently identified cellular processes involved in EV cargo delivery. Through these topics, we provide insights in critical effectors in the EV-cell interface which may be exploited in nature-inspired drug delivery strategies. [ABSTRACT FROM AUTHOR]

Abstract: Extracellular vesicles (EVs) are specialised endogenous carriers of proteins and nucleic acids and are involved in intercellular communication. EVs are therefore proposed as candidate drug delivery systems for the delivery of nucleic acids and other macromolecules. However, the preparation of EV-based drug delivery systems is hampered by the lack of techniques to load the vesicles with nucleic acids. In this work we have now characterised in detail the use of an electroporation method for this purpose. When EVs were electroporated with fluorescently labelled siRNA, siRNA retention was comparable with previously published results (20–25% based on fluorescence spectroscopy and fluorescence fluctuation spectroscopy), and electroporation with unlabelled siRNA resulted in significant siRNA retention in the EV pellet as measured by RT-PCR. Remarkably, when siRNA was electroporated in the absence of EVs, a similar or even greater siRNA retention was measured. Nanoparticle tracking analysis and confocal microscopy showed extensive formation of insoluble siRNA aggregates after electroporation, which could be dramatically reduced by addition of EDTA. Other strategies to reduce aggregate formation, including the use of cuvettes with conductive polymer electrodes and the use of an acidic citrate electroporation buffer, resulted in a more efficient reduction of siRNA precipitation than EDTA. However, under these conditions, siRNA retention was below 0.05% and no significant differences in siRNA retention could be measured between samples electroporated in the presence or absence of EVs. Our results show that electroporation of EVs with siRNA is accompanied by extensive siRNA aggregate formation, which may cause overestimation of the amount of siRNA actually loaded into EVs. Moreover, our data clearly illustrate that electroporation is far less efficient than previously described, and highlight the necessity for alternative methods to prepare siRNA-loaded EVs. [Copyright &y& Elsevier]

Among several factors behind drug resistance evolution in malaria is the challenge of administering overall doses that are not toxic for the patient but that, locally, are sufficiently high to rapidly kill the parasites. Thus, a crucial antimalarial strategy is the development of drug delivery systems capable of targeting antimalarial compounds to Plasmodium with high specificity. In the present study, extracellular vesicles (EVs) have been evaluated as a drug delivery system for the treatment of malaria. EVs derived from naive red blood cells (RBCs) and from Plasmodium falciparum -infected RBCs (pRBCs) were isolated by ultrafiltration followed by size exclusion chromatography. Lipidomic characterization showed that there were no significant qualitative differences between the lipidomic profiles of pRBC-derived EVs (pRBC-EVs) and RBC-derived EVs (RBC-EVs). Both EVs were taken up by RBCs and pRBCs, although pRBC-EVs were more efficiently internalized than RBC-EVs, which suggested their potential use as drug delivery vehicles for these cells. When loaded into pRBC-EVs, the antimalarial drugs atovaquone and tafenoquine inhibited in vitro P. falciparum growth more efficiently than their free drug counterparts, indicating that pRBC-EVs can potentially increase the efficacy of several small hydrophobic drugs used for the treatment of malaria. [ABSTRACT FROM AUTHOR]

Exosomes are cell-derived extracellular vesicles of 30-150 nm in size and are involved in intercellular communication. Because of their bioactive cargo, consisting of proteins, RNA and lipids, and their natural ability to deliver these biomolecules to recipient cells, exosomes are increasingly being studied as novel drug delivery vehicles or as cell-free approaches to regenerative medicine. However, one of the major hurdles for clinical translation of therapeutic strategies based on exosomes is their low yield when produced under standard culture conditions. Exosomes are vesicles of endocytic origin and are released when multivesicular endosomes fuse with the plasma membrane. Here, we demonstrate that interfering with endolysosomal trafficking significantly increases exosome release. Furthermore, these exosomes retain their regenerative bioactivity as demonstrated by pro-survival and angiogenesis assays using both cardiomyocytes and endothelial cells. These results may be employed to increase exosome production for studying biological functions or to improve clinical translation of exosome-based therapeutics. Exosomes are cell-derived vesicles and are involved in intercellular communication. Exosomes have great potential as drug delivery systems or mediators of regenerative medicine; however, low exosome yield is a major challenge for development of exosome-based therapeutics. Here, we demonstrate that interfering with endolysosomal trafficking enhances release of exosomes with regenerative bioactivity. Unlabelled Image [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) are nanoparticles which are released by cells from all three domains of life: Archaea, Bacteria and Eukarya. They can mediate cell-cell communication by transferring cargoes such as proteins and nucleic acids between cells. EVs receive great interest in both academia and industry as they have the potential to be natural drug carriers or vaccine candidates. However, limitations to their clinical translation exist as efficient isolation, loading, labelling and surface-engineering methods are lacking. In this article, we investigate a 'post-insertion' approach, which is commonly used in the functionalization of liposomes in the pharmaceutical field, on two different EV types: mammalian cell-derived EVs and bacteria-derived EVs. We aimed to find an easy and flexible approach to functionalize EVs, thereby improving the labelling, isolation, and surface-engineering. [ABSTRACT FROM AUTHOR]