Heparin interferes with the uptake of liposomes in glioma.

In glioblastoma, a malignant primary brain tumor, liposomes have shown promise in pre-clinical and early phase clinical trials as delivery vehicles for therapeutics. However, external factors influencing cellular uptake of liposomes in glioma cells are poorly understood. Heparin and heparin analogues are commonly used in glioma patients to decrease the risk of thrombo-embolic events. Our results show that heparin inhibits pegylated liposome uptake by U87 glioma and GL261 cells in a dose dependent manner in vitro, and that heparin-mediated inhibition of uptake required presence of fetal bovine serum in the media. In a subcutaneous model of glioma, Cy5.5 labeled liposomes could be detected with in vivo imaging after direct intra-tumoral injection. Ex-vivo analysis with flow cytometry showed a decreased uptake of liposomes into tumor cells in mice treated systemically with heparin compared to those treated with vehicle only.

Extracellular communication between brain cells through functional transfer of Cre mRNA mediated by extracellular vesicles.

In the central nervous system (CNS), the crosstalk between neural cells is mediated by extracellular mechanisms, including brain-derived extracellular vesicles (bdEVs). To study endogenous communication across the brain and periphery, we explored Cre-mediated DNA recombination to permanently record the functional uptake of bdEVs cargo over time. To elucidate functional cargo transfer within the brain at physiological levels, we promoted the continuous secretion of physiological levels of neural bdEVs containing Cre mRNA from a localized region in the brain by in situ lentiviral transduction of the striatum of Flox-tdTomato Ai9 mice reporter of Cre activity. Our approach efficiently detected in vivo transfer of functional events mediated by physiological levels of endogenous bdEVs throughout the brain. Remarkably, a spatial gradient of persistent tdTomato expression was observed along the whole brain, exhibiting an increment of more than 10-fold over 4 months. Moreover, bdEVs containing Cre mRNA were detected in the bloodstream and extracted from brain tissue to further confirm their functional delivery of Cre mRNA in a novel and highly sensitive Nanoluc reporter system. Overall, we report a sensitive method to track bdEV transfer at physiological levels, which will shed light on the role of bdEVs in neural communication within the brain and beyond.

Illuminating cellular and extracellular vesicle-mediated communication via a split-Nanoluc reporter in vitro and in vivo.

Tools to effectively demonstrate and quantify functional delivery in cellular communication have been lacking. This study reports the use of a fluorescently labeled split Nanoluc reporter system to demonstrate and quantify functional transfer between cells in vitro and in a subcutaneous tumor mouse model. Our construct allows monitoring of direct, indirect, and specifically extracellular vesicle-mediated functional communication.

Extracellular communication between brain cells through functional transfer of Cre mRNA.

In the central nervous system (CNS), the crosstalk between neural cells is mediated by extracellular mechanisms, including brain-derived extracellular vesicles (bdEVs). To study endogenous communication across the brain and periphery, we explored Cre-mediated DNA recombination to permanently record the functional uptake of bdEVs cargo overtime. To elucidate functional cargo transfer within the brain at physiological levels, we promoted the continuous secretion of physiological levels of neural bdEVs containing Cre mRNA from a localized region in the brain by in situ lentiviral transduction of the striatum of Flox-tdTomato Ai9 mice reporter of Cre activity. Our approach efficiently detected in vivo transfer of functional events mediated by physiological levels of endogenous bdEVs throughout the brain. Remarkably, a spatial gradient of persistent tdTomato expression was observed along the whole brain exhibiting an increment of more than 10-fold over 4 months. Moreover, bdEVs containing Cre mRNA were detected in the bloodstream and extracted from brain tissue to further confirm their functional delivery of Cre mRNA in a novel and highly sensitive Nanoluc reporter system. Overall, we report a sensitive method to track bdEVs transfer at physiological levels which will shed light on the role of bdEVs in neural communication within the brain and beyond.

Uptake, functionality, and re-release of extracellular vesicle-encapsulated cargo.

Extracellular vesicles (EVs) are membrane-encapsulated particles that carry genetically active and protein/lipid cargo that can affect the function of the recipient cell. A number of studies have described the effect of these vesicles on recipient cells and demonstrated their promise as therapeutic delivery vectors. Here we demonstrate functional delivery of EV-encapsulated RNA and protein cargo through use of luminescence and fluorescence reporters by combining organelle-targeted nanoluciferase with fluorescent proteins. We highlight a mechanism by which cells retain internalized cargo in the endosomal compartment for days, usually leading to content degradation. We also identify a mode through which recipient cells re-release internalized EVs intact after uptake. Highlighting these different fates of EVs in recipient cells sheds light on critical factors in steering functional cargo delivery and will ultimately allow more efficient use of EVs for therapeutic purposes.

RNA delivery by extracellular vesicles in mammalian cells and its applications.

The term 'extracellular vesicles' refers to a heterogeneous population of vesicular bodies of cellular origin that derive either from the endosomal compartment (exosomes) or as a result of shedding from the plasma membrane (microvesicles, oncosomes and apoptotic bodies). Extracellular vesicles carry a variety of cargo, including RNAs, proteins, lipids and DNA, which can be taken up by other cells, both in the direct vicinity of the source cell and at distant sites in the body via biofluids, and elicit a variety of phenotypic responses. Owing to their unique biology and roles in cell-cell communication, extracellular vesicles have attracted strong interest, which is further enhanced by their potential clinical utility. Because extracellular vesicles derive their cargo from the contents of the cells that produce them, they are attractive sources of biomarkers for a variety of diseases. Furthermore, studies demonstrating phenotypic effects of specific extracellular vesicle-associated cargo on target cells have stoked interest in extracellular vesicles as therapeutic vehicles. There is particularly strong evidence that the RNA cargo of extracellular vesicles can alter recipient cell gene expression and function. During the past decade, extracellular vesicles and their RNA cargo have become better defined, but many aspects of extracellular vesicle biology remain to be elucidated. These include selective cargo loading resulting in substantial differences between the composition of extracellular vesicles and source cells; heterogeneity in extracellular vesicle size and composition; and undefined mechanisms for the uptake of extracellular vesicles into recipient cells and the fates of their cargo. Further progress in unravelling the basic mechanisms of extracellular vesicle biogenesis, transport, and cargo delivery and function is needed for successful clinical implementation. This Review focuses on the current state of knowledge pertaining to packaging, transport and function of RNAs in extracellular vesicles and outlines the progress made thus far towards their clinical applications.

Investigating the Potential and Pitfalls of EV-Encapsulated MicroRNAs as Circulating Biomarkers of Breast Cancer.

Extracellular vesicles (EVs) shuttle microRNA (miRNA) throughout the circulation and are believed to represent a fingerprint of the releasing cell. We isolated and characterized serum EVs of breast tumour-bearing animals, breast cancer (BC) patients, and healthy controls. EVs were characterized using transmission electron microscopy (TEM), protein quantification, western blotting, and nanoparticle tracking analysis (NTA). Absolute quantitative (AQ)-PCR was employed to analyse EV-miR-451a expression. Isolated EVs had the appropriate morphology and size. Patient sera contained significantly more EVs than did healthy controls. In tumour-bearing animals, a correlation between serum EV number and tumour burden was observed. There was no significant relationship between EV protein yield and EV quantity determined by NTA, highlighting the requirement for direct quantification. Using AQ-PCR to relate miRNA copy number to EV yield, a significant increase in miRNA-451a copies/EV was detected in BC patient sera, suggesting potential as a novel biomarker of breast cancer.

Circulating MicroRNAs in Cancer.

It is believed that microRNAs have potential as circulating biomarkers of disease; however, successful clinical implementation remains a challenge. This chapter highlights broad variations in approaches to microRNA analysis where whole blood, serum and plasma have each been employed as viable sources. Further discrepancies in approaches are seen in endogenous controls and extraction methods utilized. This has resulted in contradictory publications, even when the same microRNA is targeted in the same disease setting.Analysis of blood samples highlighted the impact of both collection method and storage, on the microRNA profile. Analysis of a panel of microRNAs across whole blood, serum, and plasma originating from the same individual emphasized the impact of starting material on microRNA profile. This is a highly topical field of research with immense potential for translation into the clinical setting. Standardization of sample harvesting, processing and analysis will be key to this translation. Methods of sample harvesting, preservation, and analysis are outlined, with important mitigating factors highlighted.