Extracellular Vesicles Derived-LAT1 mRNA as a Powerful Inducer of Colorectal Cancer Aggressive Phenotype

Colorectal cancer (CRC) is the third most common cancer in the world and represents the third most deadly tumor worldwide. About 15–25% of patients present metastasis in the moment of diagnosis, the liver being the most common site of metastization. Therefore, the development of new therapeutic agents is needed, to improve the patients’ prognosis. Amino acids transporters, LAT1 and ASCT2, are described as upregulated in CRC, being associated with a poor prognosis. Extracellular vesicles have emerged as key players in cell-to-cell communication due to their ability to transfer biomolecules between cells, with a phenotypic impact on the recipient cells. Thus, this study analyzes the presence of LAT1 and ASCT2 mRNAs in CRC-EVs and evaluates their role in phenotype modulation in a panel of four recipient cell lines (HCA-7, HEPG-2, SK-HEP-1, HKC-8). We found that HCT 116-EVs carry LAT1, ASCT2 and other oncogenic mRNAs being taken up by recipient cells. Moreover, the HCT 116-EVs’ internalization was associated with the increase of LAT1 mRNA in SK-HEP-1 cells. We also observed that HCT 116-EVs induce a higher cell migration capacity and proliferation of SK-HEP-1 and HKC-8 cells. The present study supports the LAT1-EVs’ mRNA involvement in cell phenotype modulation, conferring advantages in cell migration and proliferation.

Review on Strategies and Technologies for Exosome Isolation and Purification

Exosomes, a nano-sized subtype of extracellular vesicles secreted from almost all living cells, are capable of transferring cell-specific constituents of the source cell to the recipient cell. Cumulative evidence has revealed exosomes play an irreplaceable role in prognostic, diagnostic, and even therapeutic aspects. A method that can efficiently provide intact and pure exosomes samples is the first step to both exosome-based liquid biopsies and therapeutics. Unfortunately, common exosomal separation techniques suffer from operation complexity, time consumption, large sample volumes and low purity, posing significant challenges for exosomal downstream analysis. Efficient, simple, and affordable methods to isolate exosomes are crucial to carrying out relevant researches. In the last decade, emerging technologies, especially microfluidic chips, have proposed superior strategies for exosome isolation and exhibited fascinating performances. While many excellent reviews have overviewed various methods, a compressive review including updated/improved methods for exosomal isolation is indispensable. Herein, we first overview exosomal properties, biogenesis, contents, and functions. Then, we briefly outline the conventional technologies and discuss the challenges of clinical applications of these technologies. Finally, we review emerging exosomal isolation strategies and large-scale GMP production of engineered exosomes to open up future perspectives of next-generation Exo-devices for cancer diagnosis and treatment.

Melatonin, tunneling nanotubes and anastasis: Cheating cell death

When healthy neurons are exposed to toxins or physiological insults such as ischemia, apoptosis is often initiated. Once underway, this mechanistically-well described process was thought to routinely run its course with the disintegration of the cell and phagocytosis of the debris. Within the last decade, the consistency of this process has been questioned. It is now known that some damaged cells can recover, i.e., they avoid death; this restoration process is referred to as anastasis. The reestablishment of a healthy cell phenotype is highly energy-requiring, so optimally functioning mitochondria are obviously beneficial during the regenerative process. Some healthy mitochondria that end up in regenerating cells are transferred there by adjacent healthier cells through tunneling nanotubes. Tunneling nanotubes generally form under stressful conditions when these micron-size tubules link adjacent cells. These tubules transfer soluble factors and organelles, including mitochondria, between the connected cells. When damaged cells receive high APT-producing mitochondria via this means, they support the ability of the cells to recover. Two recent comprehensive publications show that melatonin aids the transfer of mitochondria through nanotubes that connect neurons thereby likely assisting the recovery of the damaged recipient cell. Thus, melatonin not only protects normal neurons from damage by neutralizing the agents that initiate apoptosis, e.g., free radicals, etc., but also reverses this process once it is underway.

The Role of Extracellular Vesicles in the Progression of Tumors towards Metastasis

Extracellular vesicles (EVs) are cell-derived lipid membrane bound vesicles that serve as mediators of intercellular communication. EVs have been found to regulate a wide range of cellular processes through the transference of genetic, protein and lipid messages from the host cell to the recipient cell. Unsurprisingly, this major mode of intracellular communication would be abrogated in cancer. Ever increasing evidence points towards a key role of EVs in promoting tumor development and in contributing to the various stages of metastasis. Tumor released EVs have been shown to facilitate the transference of oncogenic proteins and nucleic acids to other tumor cells and to the surrounding stromal cells, thereby setting up a tumor permissive microenvironment. EVs released from tumor cells have been shown to promote extracellular matrix (ECM) remodeling through the modulation of neighboring tumor cells and stromal cells. EVs released from disseminated tumor cells have been reported to attract circulating tumor cells (CTCs) via chemotaxis and induce the production of specific extracellular matrix components from neighboring stromal cells so as to support the growth of metastatic cells at the secondary tumor site. Circulating levels of tumor derived EVs of patients have been correlated with incidence of metastasis and disease relapse.

The Role of Extracellular Vesicles as a Shared Disease Mechanism Contributing to Multimorbidity in Patients With COPD

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide. Individuals with COPD typically experience a progressive, debilitating decline in lung function as well as systemic manifestations of the disease. Multimorbidity, is common in COPD patients and increases the risk of hospitalisation and mortality. Central to the genesis of multimorbidity in COPD patients is a self-perpetuating, abnormal immune and inflammatory response driven by factors including ageing, pollutant inhalation (including smoking) and infection. As many patients with COPD have multiple concurrent chronic conditions, which require an integrative management approach, there is a need to greater understand the shared disease mechanisms contributing to multimorbidity. The intercellular transfer of extracellular vesicles (EVs) has recently been proposed as an important method of local and distal cell-to-cell communication mediating both homeostatic and pathological conditions. EVs have been identified in many biological fluids and provide a stable capsule for the transfer of cargo including proteins, lipids and nucleic acids. Of these cargo, microRNAs (miRNAs), which are short 17-24 nucleotide non-coding RNA molecules, have been amongst the most extensively studied. There is evidence to support that miRNA are selectively packaged into EVs and can regulate recipient cell gene expression including major pathways involved in inflammation, apoptosis and fibrosis. Furthermore changes in EV cargo including miRNA have been reported in many chronic diseases and in response to risk factors including respiratory infections, noxious stimuli and ageing. In this review, we discuss the potential of EVs and EV-associated miRNA to modulate shared pathological processes in chronic diseases. Further delineating these may lead to the identification of novel biomarkers and therapeutic targets for patients with COPD and multimorbidities.

Establishment Genes Present on pLS20 Family of Conjugative Plasmids Are Regulated in Two Different Ways

During conjugation, a conjugative DNA element is transferred from a donor to a recipient cell via a connecting channel. Conjugation has clinical relevance because it is the major route for spreading antibiotic resistance and virulence genes. The conjugation process can be divided into different steps. The initial steps carried out in the donor cell culminate in the transfer of a single DNA strand (ssDNA) of the conjugative element into the recipient cell. However, stable settlement of the conjugative element in the new host requires at least two additional events: conversion of the transferred ssDNA into double-stranded DNA and inhibition of the hosts’ defence mechanisms to prevent degradation of the transferred DNA. The genes involved in this late step are historically referred to as establishment genes. The defence mechanisms of the host must be inactivated rapidly and—importantly—transiently, because prolonged inactivation would make the cell vulnerable to the attack of other foreign DNA, such as those of phages. Therefore, expression of the establishment genes in the recipient cell has to be rapid but transient. Here, we studied regulation of the establishment genes present on the four clades of the pLS20 family of conjugative plasmids harboured by different Bacillus species. Evidence is presented that two fundamentally different mechanisms regulate the establishment genes present on these plasmids. Identification of the regulatory sequences were critical in revealing the establishment regulons. Remarkably, whereas the conjugation genes involved in the early steps of the conjugation process are conserved and are located in a single large operon, the establishment genes are highly variable and organised in multiple operons. We propose that the mosaical distribution of establishment genes in multiple operons is directly related to the variability of defence genes encoded by the host bacterial chromosomes.

Bracovirus sneaks into apoptotic bodies transmitting immunosuppressive signaling driven by integration-mediated eIF5A hypusination

The typical characteristic of polydnavirus (PDV) infection is persistent immunosuppression, governed by the viral integration and expression of virulence genes. Recently, how Microplitis bicoloratus bracovirus (MbBV) activates caspase-3 to cleave Innexins, gap junction proteins, has been highlighted, further promoting apoptotic cell disassembly and apoptotic body (AB) formation. However, little is known about how inserted viral fragments interact with host cells to drive apoptosis and the role MbBV-mediated extracellular vesicles play in immune suppression. Herein, we show that ABs transmitted immunosuppressive signaling, causing recipient cell apoptosis and dismigration. Overall, viral host integrated motif sites insertion damaged host genome stimulating eIF5A nucleocytoplasmic transport, activating the eIF5A-hypusination translation pathway. Functionally, translated apoptosis-related host proteins, such as P53, CypD, CypJ, and CypA, drive a broken dsDNA cellular apoptosis. Furthermore, translated viral proteins, vank86, 92, and 101, known to complex with transcription factor Dip3, positively regulated DHYS and DOHH transcription maintaining the activation of the eIF5A-hypusination translation pathway. Mechanistically, MbBV-mediated extracellular vesicles contained inserted viral fragments that re-integrated into recipients, potentially via the homologous recombinant repair system. Meanwhile, this stimulation regulated activated caspase-3 level via pI3K/Akt 308 and 473 dephosphorylation to promote recipients cell apoptosis; pI3K/Akt 473 phosphorylation inhibited caspase-3 activation leading to recipient cell dismigration. In conclusion, our results suggest that integration-mediated eIF5A hypusination drives extracellular vesicles for continues immunosuppressive.

Ischaemia reperfusion induces the release of donor derived Passenger Leukocytes (PLs) during normothermic machine perfusion (NMP) of the liver- a new opportunity for ex situ graft leukodepletion?

Fungai Dengu1, Tamsyn Clark1,3, Hussain Abbas1, Etohan Ann Ogbemudia1, Faysal El Gilani1,David Nasralla1, Peter Friend1, James Fildes2 1. Oxford Organ Perfusion Lab, Nuffield Department of Surgical Sciences and Oxford Biomedical ResearchCentre, University of Oxford, Oxford, UK2. The Ex-Vivo Lab, Division of Cell Matrix Biology and Regenerative Medicine, School of BiologicalSciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester AcademicHealth Science Centre, Manchester, UK3. Institute of Biomedical Engineering, University of Oxford, Oxford, UK Background Passenger Leukocytes (PLs) are implicated in both the direct and semi-direct pathways of allorecognition which is the process that underpins acute allograft rejection1. The majority of liver-derived PLs are short lived and predominantly impact early recipient immune responses2. Removal of PLs has been shown in kidney, lung and vascularised composite allografts to reduce early allograft damage and abrogate ejection3. We aimed to assess the use normothermic machine perfusion (NMP) to investigate PL kinetics and explore PL depletion strategies in donor livers. Methods Porcine livers (N=4) procured in a donation after circulatory death (DCD) model were preserved with sequential static cold storage then NMP. During NMP, livers were subjected to repeated 20 min warm ischaemic hits (IH) followed by 30mins of NMP using a leukocyte depleted autologous RBC based perfusate. Leukocytes were quantified using the Sysmex® cell counter system and samples stored for flow cytometric analysis. Results In total, 3.4x106 PLs are effluxed into the circuit immediately after initiation of NMP, this falls rapidly to 1.35x106 by 30 mins. Following the first IH, a further efflux of occurs with a peak of 3.74x106 occurring. The second IH also induced an efflux of cells (1.61x106) with lymphocytes representing the predominant leukocyte sub-type in each efflux. Discussion During NMP, there is an inducible and reproducible efflux of graft derived PLs into the circuit that is composed of predominantly lymphocytes with unexpectedly low numbers of monocytes. Removal of these PLs from the perfusate during NMP may therefore be feasible using an in-line leukocyte-filter. References 1. Alsughayyir, J., Motallebzadeh, R. & Pettigrew, G. J. Are donor lymphocytes a barrier to transplantation tolerance? Curr. Opin. Organ Transplant. 23, 90–96 (2018).2. Mastoridis, S. et al. Impact of donor extracellular vesicle release on recipient cell “cross-dressing” following clinical liver and kidney transplantation. Am. J. Transplant. ajt.16123 (2020). doi:10.1111/ajt.161233. Stone, J. P. et al. Mechanical removal of dendritic cell–generating non-classical monocytes via ex vivo lung perfusion. J. Hear. Lung Transplant. 33, 864–869 (2014).

Extracellular Vesicles Taken up by Astrocytes

Extracellular vesicles (EVs) are composed of lipid bilayer membranes and contain various molecules, such as mRNA and microRNA (miRNA), that regulate the functions of the recipient cell. Recent studies have reported the importance of EV-mediated intercellular communication in the brain. The brain contains several types of cells, including neurons and glial cells. Among them, astrocytes are the most abundant glial cells in the mammalian brain and play a wide range of roles, from structural maintenance of the brain to regulation of neurotransmission. Furthermore, since astrocytes can take up EVs, it is possible that EVs originating from inside and outside the brain affect astrocyte function, which in turn affects brain function. However, it has not been fully clarified whether the specific targeting mechanism of EVs to astrocytes as recipient cells exists. In recent years, EVs have attracted attention as a cell-targeted therapeutic approach in various organs, and elucidation of the targeting mechanism of EVs to astrocytes may pave the way for new therapies for brain diseases. In this review, we focus on EVs in the brain that affect astrocyte function and discuss the targeting mechanism of EVs to astrocytes.

Abstract P404: Membrane Composition Of Cardiac-derived Extracellular Vesicles Changes With Vesicle Origin And Determines Uptake

Introduction: Myocardial infarction (MI) is a leading cause of mortality worldwide. The potency of cell-based therapies for MI is increasingly attributed to the release of extracellular vesicles (EVs) which consist of a lipid/protein membrane and encapsulate RNA cargo. Specifically, EVs from ckit+ progenitor cells (CPCs) and mesenchymal stromal cells (MSCs) are shown to be pro-reparative, with clinical trials ongoing. Despite copious research into EV cargo, the role of donor cell type on EV membrane composition and its effects on EV uptake mechanism by recipient cells remain unclear. This is crucial for designing EV-based therapeutics as uptake mechanism dictates the functionality of the cargo. Thus, we hypothesized that (1) EV membrane composition varies by donor cell type and (2) this variation covaries with the mechanism of uptake. Methods: EVs were isolated using differential ultracentrifugation from four cardiac cell types: CPCs, MSCs, cardiac endothelial cells (CECs) and rat cardiac fibroblasts (RCFs) grown in normoxia (18% O 2 ) or hypoxia (1% O 2 ) to mimic ischemic conditions. EVs were characterized for size and concentration. EV lipid membrane profile was assessed through LC/MS/MS. Donor cell’s role on EV uptake mechanism was determined by inhibiting known uptake pathways (clathrin, dynamin, macropinocytosis and caveolae/lipid raft) with small molecules and quantifying CEC/RCF endocytosis of EVs with flow cytometry. Finally, partial least squares regression was used to determine the most important lipids involved in EV uptake mechanism. Results: EVs were successfully isolated and characterized. The EV membrane lipid profiles clustered by donor cell type. Uptake mechanism of EVs varied based on both donor and recipient cell type with dynamin mediated endocytosis being the most common. Further, the uptake mechanism was independent of normoxic/hypoxic conditioning. Finally, supervised learning methods revealed specific lipid classes (sphingolipids and glycerophospholipids) covaried with EV uptake mechanism. Conclusion: This work highlights the importance of the understudied EV membrane and its role in delivering therapeutic cargo. Active donor cell selection for efficient EV uptake will allow for more potent EV-based MI therapies.