Reporter Systems for Assessments of Extracellular Vesicle Transfer

Strategies for labelling of exogenous and endogenous extracellular vesicles and their application for in vitro and in vivo functional studies

This review presents a comprehensive overview of labelling strategies for endogenous and exogenous extracellular vesicles, that can be utilised both in vitro and in vivo. It covers a broad spectrum of approaches, including fluorescent and bioluminescent labelling, and provides an analysis of their applications, strengths, and limitations. Furthermore, this article presents techniques that use radioactive tracers and contrast agents with the ability to track EVs both spatially and temporally. Emphasis is also placed on endogenous labelling mechanisms, represented by Cre-lox and CRISPR-Cas systems, which are powerful and flexible tools for real-time EV monitoring or tracking their fate in target cells. By summarizing the latest developments across these diverse labelling techniques, this review provides researchers with a reference to select the most appropriate labelling method for their EV based research.

Intercellular Molecular Transfer Mediated by Extracellular Vesicles in Cancer

Among multiple pathways of intercellular communication operative in multicellular organisms, the trafficking of extracellular vesicles (EVs) and particles (EP) represents a unique mode of cellular information exchange with emerging roles in health and disease, including cancer. A distinctive feature of EV/EP-mediated cell-cell communication is that it involves simultaneous short- or long-range transfer of numerous molecular constituents (cargo) from donor to recipient cells. EV/EP uptake by donor cells elicits signalling or metabolic responses, or else leads to EV-re-emission or degradation. EVs are heterogeneous membranous structures released from cells via increasingly defined mechanisms involving either formation of multivesicular endosomes (exosomes) or budding from the plasma membrane (ectosomes). EPs (exomeres, supermeres) are membraneless complex particles, smaller than EVs and of less defined biogenesis and function. EVs/EPs carry complex assemblies of proteins, lipids and nucleic acids (RNA, DNA), which they shuttle into intercellular milieu, body fluids and recipient cells, via surface contact, fusion and different forms of internalization (endocytosis, micropinocytosis). While the physiological functions of EVs/EPs communication pathways continue to be investigated, their roles in cancer are increasingly well-defined. For example, EVs are involved in the transmission of cancer-specific molecular cargo, including mutant, oncogenic, transforming, or regulatory macromolecules to indolent, or normal cells, sometimes triggering their quasi-transformation-like states, or phenotypic alterations. Conversely, a reciprocal and avid uptake of stromal EVs by cancer cells may be responsible for modulating their oncogenic repertoire, as exemplified by the angiocrine effects of endothelial EVs influencing cancer cell stemness. EV exchanges during cancer progression have also been implicated in the formation of tumour stroma, angiogenesis and non-angiogenic neovascularization processes, immunosuppression, colonization of metastatic organ sites (premetastatic niche), paraneoplastic and systemic pathologies (thrombosis, diabetes, hepatotoxicity). Thus, an EV/EP-mediated horizontal transfer of cellular content emerges as a new dimension in cancer pathogenesis with functional, diagnostic, and therapeutic implications.

Unraveling the Multifaceted Roles of Extracellular Vesicles: Insights into Biology, Pharmacology, and Pharmaceutical Applications for Drug Delivery

Extracellular vesicles (EVs) are nanoparticles released from various cell types that have emerged as powerful new therapeutic option for a variety of diseases. EVs are involved in the transmission of biological signals between cells and in the regulation of a variety of biological processes, highlighting them as potential novel targets/platforms for therapeutics intervention and/or delivery. Therefore, it is necessary to investigate new aspects of EVs' biogenesis, biodistribution, metabolism, and excretion as well as safety/compatibility of both unmodified and engineered EVs upon administration in different pharmaceutical dosage forms and delivery systems. In this review, we summarize the current knowledge of essential physiological and pathological roles of EVs in different organs and organ systems. We provide an overview regarding application of EVs as therapeutic targets, therapeutics, and drug delivery platforms. We also explore various approaches implemented over the years to improve the dosage of specific EV products for different administration routes.

CD63-Snorkel tagging for isolation of exosomes

Exosomes (Exo) are important mediators of inter-cellular communications; however, no effective method is available for isolating, thus characterizing, cellular-specific exosomes in vivo. Since CD63 is a reliable marker for exosomes, we have developed a tagging strategy, term "CD63-Snorkel (CD63-SNKL)", in which CD63 at its intracellular C-terminus was fused to a fragment of PDGFRB that contains the transmembrane domain tethered to multiple epitope tags (HA, His, and FLAG) displayed in tandem on surface. We found that the CD63-SNKL protein has similar subcellular localizations as endogenous CD63 and can be effectively sorted into Exo. Furthermore, Exo secreted from CD63-SNKL-transduced cells can be effectively captured on anti-HA magnetic beads and eluted with HA peptides. Thus, CD63-SNKL may be engineered for isolating and tracking endogenous tissue-specific Exo in vivo.

Regulation of Extracellular Vesicle-Mediated Immune Responses against Antigen-Specific Presentation

Extracellular vesicles (EVs) produced by various immune cells, including B and T cells, macrophages, dendritic cells (DCs), natural killer (NK) cells, and mast cells, mediate intercellular communication and have attracted much attention owing to the novel delivery system of molecules in vivo. DCs are among the most active exosome-secreting cells of the immune system. EVs produced by cancer cells contain cancer antigens; therefore, the development of vaccine therapy that does not require the identification of cancer antigens using cancer-cell-derived EVs may have significant clinical implications. In this review, we summarise the molecular mechanisms underlying EV-based immune responses and their therapeutic effects on tumour vaccination.

Mesenchymal Stem Cell-Derived Small Extracellular Vesicles: A Novel Approach for Kidney Disease Treatment

Globally, kidney disease has become a serious health challenge, with approximately 10% of adults suffering with the disease, and increasing incidence and mortality rates every year. Small extracellular vesicles (sEVs) are 30 nm-100 nm sized nanovesicles released by cells into the extracellular matrix (ECM), which serve as mediators of intercellular communication. Depending on the cell origin, sEVs have different roles which depend on internal cargoes including, nucleic acids, proteins, and lipids. Mesenchymal stem cell (MSCs) exert anti-inflammatory, anti-aging, and wound healing functions mainly via sEVs in a stable and safe manner. MSC-derived sEVs (MSC-sEVs) exert roles in several kidney diseases by transporting renoprotective cargoes to reduce oxidative stress, inhibit renal cell apoptosis, suppress inflammation, and mediate anti-fibrosis mechanisms. Additionally, because MSC-sEVs efficiently target damaged kidneys, they have the potential to become the next generation cell-free therapies for kidney disease. Herein, we review recent research data on how MSC-sEVs could be used to treat kidney disease.