Extracellular Vesicles from Ovarian Carcinoma Cells Display Specific Glycosignatures

Glycan Profiling in Small Extracellular Vesicles with a SERS Microfluidic Biosensor Identifies Early Malignant Development in Lung Cancer

Glycosylation is the most common post-translational modification of proteins and regulates a myriad of fundamental biological processes under normal, and pathological conditions. Altered protein glycosylation is linked to malignant transformation, showing distinct glycopatterns that are associated with cancer initiation and progression by regulating tumor proliferation, invasion, metastasis, and therapeutic resistance. The glycopatterns of small extracellular vesicles (sEVs) released by cancer cells are promising candidates for cancer monitoring since they exhibit glycopatterns similar to their cell-of-origin. However, the clinical application of sEV glycans is challenging due to the limitations of current analytical technologies in tracking the trace amounts of sEVs specifically derived from tumors in circulation. Herein, a sEV GLYcan PHenotype (EV-GLYPH) assay that utilizes a microfluidic platform integrated with surface-enhanced Raman scattering for multiplex profiling of sEV glycans in non-small cell lung cancer is clinically validated. For the first time, the EV-GLYPH assay effectively identifies distinct sEV glycan signatures between non-transformed and malignantly transformed lung cells. In a clinical study evaluated on 40 patients, the EV-GLYPH assay successfully differentiates patients with early-stage malignant lung nodules from benign lung nodules. These results reveal the potential to profile sEV glycans for noninvasive diagnostics and prognostics, opening up promising avenues for clinical applications and understanding the role of sEV glycosylation in lung cancer.

Exosomes in diagnostic and therapeutic applications of ovarian cancer

Ovarian cancer accounts for more deaths than any other female reproductive tract cancer. The major reasons for the high mortality rates include delayed diagnoses and drug resistance. Hence, improved diagnostic and therapeutic options for ovarian cancer are a pressing need. Extracellular vesicles (EVs), that include exosomes provide hope in both diagnostic and therapeutic aspects. They are natural lipid nanovesicles secreted by all cell types and carry molecules that reflect the status of the parent cell. This facilitates their potential use as biomarkers for an early diagnosis. Additionally, EVs can be loaded with exogenous cargo, and have features such as high stability and favorable pharmacokinetic properties. This makes them ideal for tumor-targeted delivery of biological moieties. The International Society of Extracellular Vesicles (ISEV) based on the Minimal Information for Studies on Extracellular Vesicles (MISEV) recommends the usage of the term "small extracellular vesicles (sEVs)" that includes exosomes for particles that are 30-200 nm in size. However, majority of the studies reported in the literature and relevant to this review have used the term "exosomes". Therefore, this review will use the term "exosomes" interchangeably with sEVs for consistency with the literature and avoid confusion to the readers. This review, initially summarizes the different isolation and detection techniques developed to study ovarian cancer-derived exosomes and the potential use of these exosomes as biomarkers for the early diagnosis of this devastating disease. It addresses the role of exosome contents in the pathogenesis of ovarian cancer, discusses strategies to limit exosome-mediated ovarian cancer progression, and provides options to use exosomes for tumor-targeted therapy in ovarian cancer. Finally, it states future research directions and recommends essential research needed to successfully transition exosomes from the laboratory to the gynecologic-oncology clinic.

High-throughput analysis of glycan sorting into extracellular vesicles

Extracellular vesicles (EVs) are cell-released vesicles that mediate intercellular communication by transferring bioactive cargo. Protein and RNA sorting into EVs has been extensively assessed, while selective enrichment of glycans in EVs remains less explored. In this study, a mass spectrometry-based approach, glycan node analysis (GNA), was applied to broadly assess the sorting of glycan features into EVs. Two metastatic variants (lung and bone) generated in mouse modes from the MDA-MB-231 human breast cancer cell line were assessed, as these EVs are known to contain distinct organotropic biomolecules. EVs were isolated from conditioned cell culture medium by tangential flow filtration and authenticated by standard techniques. GNA analysis revealed selective enrichment of several glycan features in EVs compared to the originating cells, particularly those associated with binding to the extracellular matrix, which was also observed in EVs from the parental MDA-MB-231 cell line (human pleural metastases). The bone-tropic variant displayed enrichment of distinct EV glycan features compared to the lung-tropic one. Additionally, the metastatic variants generated in mouse models displayed reduced EV glycan sorting compared to the parental metastatic cell line. This study represents the first comprehensive assessment of differences in glycan features between EVs and originating cells and provides evidence that the diversity of EV glycan sorting is reduced upon generation of variant cell lines in mouse models. Future research is likely to uncover novel mechanisms of EV glycan sorting, shed light on glycan features for EV authentication or biomarker purposes, and assess functional roles of the EV glycocode in (patho)physiology.

Recommendations for reproducibility of cerebrospinal fluid extracellular vesicle studies

Cerebrospinal fluid (CSF) is a clear, transparent fluid derived from blood plasma that protects the brain and spinal cord against mechanical shock, provides buoyancy, clears metabolic waste and transports extracellular components to remote sites in the brain. Given its contact with the brain and the spinal cord, CSF is the most informative biofluid for studies of the central nervous system (CNS). In addition to other components, CSF contains extracellular vesicles (EVs) that carry bioactive cargoes (e.g., lipids, nucleic acids, proteins), and that can have biological functions within and beyond the CNS. Thus, CSF EVs likely serve as both mediators of and contributors to communication in the CNS. Accordingly, their potential as biomarkers for CNS diseases has stimulated much excitement for and attention to CSF EV research. However, studies on CSF EVs present unique challenges relative to EV studies in other biofluids, including the invasive nature of CSF collection, limited CSF volumes and the low numbers of EVs in CSF as compared to plasma. Here, the objectives of the International Society for Extracellular Vesicles CSF Task Force are to promote the reproducibility of CSF EV studies by providing current reporting and best practices, and recommendations and reporting guidelines, for CSF EV studies. To accomplish this, we created and distributed a world-wide survey to ISEV members to assess methods considered 'best practices' for CSF EVs, then performed a detailed literature review for CSF EV publications that was used to curate methods and resources. Based on responses to the survey and curated information from publications, the CSF Task Force herein provides recommendations and reporting guidelines to promote the reproducibility of CSF EV studies in seven domains: (i) CSF Collection, Processing, and Storage; (ii) CSF EV Separation/Concentration; (iii) CSF EV Size and Number Measurements; (iv) CSF EV Protein Studies; (v) CSF EV RNA Studies; (vi) CSF EV Omics Studies and (vii) CSF EV Functional Studies.

Comprehensive Overview the Role of Glycosylation of Extracellular Vesicles in Cancers

Extracellular vesicles (EVs) are membranous structures secreted by various cells carrying diverse biomolecules. Recent advancements in EV glycosylation research have underscored their crucial role in cancer. This review provides a global overview of EV glycosylation research, covering aspects such as specialized techniques for isolating and characterizing EV glycosylation, advances on how glycosylation affects the biogenesis and uptake of EVs, and the involvement of EV glycosylation in intracellular protein expression, cellular metastasis, intercellular interactions, and potential applications in immunotherapy. Furthermore, through an extensive literature review, we explore recent advances in EV glycosylation research in the context of cancer, with a focus on lung, colorectal, liver, pancreatic, breast, ovarian, prostate, and melanoma cancers. The primary objective of this review is to provide a comprehensive update for researchers, whether they are seasoned experts in the field of EVs or newcomers, aiding them in exploring new avenues and gaining a deeper understanding of EV glycosylation mechanisms. This heightened comprehension not only enhances researchers' knowledge of the pathogenic mechanisms of EV glycosylation but also paves the way for innovative cancer diagnostic and therapeutic strategies.

Lectins as potential tools for cancer biomarker discovery from extracellular vesicles

Extracellular vesicles (EVs) have considerable potential as diagnostic, prognostic, and therapeutic agents, in large part because molecular patterns on the EV surface betray the cell of origin and may also be used to "target" EVs to specific cells. Cancer is associated with alterations to cellular and EV glycosylation patterns, and the surface of EVs is enriched with glycan moieties. Glycoconjugates of EVs play versatile roles in cancer including modulating immune response, affecting tumor cell behavior and site of metastasis and as such, paving the way for the development of innovative diagnostic tools and novel therapies. Entities that recognize specific glycans, such as lectins, may thus be powerful tools to discover and detect novel cancer biomarkers. Indeed, the past decade has seen a constant increase in the number of published articles on lectin-based strategies for the detection of EV glycans. This review explores the roles of EV glycosylation in cancer and cancer-related applications. Furthermore, this review summarizes the potential of lectins and lectin-based methods for screening, targeting, separation, and possible identification of improved biomarkers from the surface of EVs.

Non-cell-autonomous regulation of interneuron specification mediated by extracellular vesicles

Disruption in neurogenesis and neuronal migration can influence the assembly of cortical circuits, affecting the excitatory-inhibitory balance and resulting in neurodevelopmental and neuropsychiatric disorders. Using ventral cerebral organoids and dorsoventral cerebral assembloids with mutations in the extracellular matrix gene LGALS3BP, we show that extracellular vesicles released into the extracellular environment regulate the molecular differentiation of neurons, resulting in alterations in migratory dynamics. To investigate how extracellular vesicles affect neuronal specification and migration dynamics, we collected extracellular vesicles from ventral cerebral organoids carrying a mutation in LGALS3BP, previously identified in individuals with cortical malformations and neuropsychiatric disorders. These results revealed differences in protein composition and changes in dorsoventral patterning. Proteins associated with cell fate decision, neuronal migration, and extracellular matrix composition were altered in mutant extracellular vesicles. Moreover, we show that treatment with extracellular vesicles changes the transcriptomic profile in neural progenitor cells. Our results indicate that neuronal molecular differentiation can be influenced by extracellular vesicles.

Comparison of different methods for isolating CD8+ T lymphocyte-derived extracellular vesicles and supramolecular attack particles

CD8+ T lymphocytes play vital roles in killing infected or deranged host cells, recruiting innate immune cells, and regulating other aspects of immune responses. Like any other cell, CD8+ T cells also produce extracellular particles. These include extracellular vesicles (EVs) and non-vesicular extracellular particles (NVEPs). T cell-derived EVs are proposed to mediate cell-to-cell signalling, especially in the context of inflammatory responses, autoimmunity, and infectious diseases. CD8+ T cells also produce supramolecular attack particles (SMAPs), which are in the same size range as EVs and mediate a component of T cell mediated killing. The isolation technique selected will have a profound effect on yield, purity, biochemical properties and function of T cell-derived particles; making it important to directly compare different approaches. In this study, we compared commonly used techniques (membrane spin filtration, ultracentrifugation, or size exclusion liquid chromatography) to isolate particles from activated human CD8+ T cells and validated our results by single-particle methods, including nanoparticle tracking analysis, flow cytometry, electron microscopy and super-resolution microscopy of the purified sample as well as bulk proteomics and lipidomics analyses to evaluate the quality and nature of enriched T cell-derived particles. Our results show that there is a trade-off between the yield and the quality of T cell-derived particles. Furthermore, the protein and lipid composition of the particles is dramatically impacted by the isolation technique applied. We conclude that from the techniques evaluated, size exclusion liquid chromatography offers the highest quality of T cell derived EVs and SMAPs with acceptable yields for compositional and functional studies.

The hidden potential of glycomarkers: Glycosylation studies in the service of cancer diagnosis and treatment

Changes in the glycosylation process appear early in carcinogenesis and evolve with the growth and spread of cancer. The correlation of the characteristic glycosylation signature with the tumor stage and the appropriate therapy choice is an important issue in translational medicine. Oncologists also pay attention to extracellular vesicles as reservoirs of new cancer glycomarkers that can be potent for cancer diagnosis/prognosis. In this review, we recall glycomarkers used in oncology and show their new glycoforms of improved clinical relevance. We summarize current knowledge on the biological functions of glycoepitopes in cancer-derived extracellular vesicles and their potential use in clinical practice. Is glycomics a future of cancer diagnosis? It may be, but in combination with other omics analyses than alone.

Glycoproteomic Analysis of Urinary Extracellular Vesicles for Biomarkers of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for the most common form of primary liver cancer cases and constitutes a major health problem worldwide. The diagnosis of HCC is still challenging due to the low sensitivity and specificity of the serum α-fetoprotein (AFP) diagnostic method. Extracellular vesicles (EVs) are heterogeneous populations of phospholipid bilayer-enclosed vesicles that can be found in many biological fluids, and have great potential as circulating biomarkers for biomarker discovery and disease diagnosis. Protein glycosylation plays crucial roles in many biological processes and aberrant glycosylation is a hallmark of cancer. Herein, we performed a comprehensive glycoproteomic profiling of urinary EVs at the intact N-glycopeptide level to screen potential biomarkers for the diagnosis of HCC. With the control of the spectrum-level false discovery rate ≤1%, 756 intact N-glycopeptides with 154 N-glycosites, 158 peptide backbones, and 107 N-glycoproteins were identified. Out of 756 intact N-glycopeptides, 344 differentially expressed intact N-glycopeptides (DEGPs) were identified, corresponding to 308 upregulated and 36 downregulated N-glycopeptides, respectively. Compared to normal control (NC), the glycoproteins LG3BP, PIGR and KNG1 are upregulated in HCC-derived EVs, while ASPP2 is downregulated. The findings demonstrated that specific site-specific glycoforms in these glycoproteins from urinary EVs could be potential and efficient non-invasive candidate biomarkers for HCC diagnosis.

Classification of Extracellular Vesicles Based on Surface Glycan Structures by Spongy-like Separation Media

Extracellular vesicles (EVs) are lipid bilayer vesicles that enclose various biomolecules. EVs hold promise as sensitive biomarkers to detect and monitor various diseases. However, they have heterogeneous molecular compositions. The compositions of EVs from identical donor cells obtained using the same purification methods may differ, which is a significant obstacle for elucidating objective biological functions. Herein, the potential of a novel lectin-based affinity chromatography (LAC) method to classify EVs based on their glycan structures is demonstrated. The proposed method utilizes a spongy-like monolithic polymer (spongy monolith, SPM), which consists of poly(ethylene-co-glycidyl methacrylate) with continuous micropores and allows an efficient in situ protein reaction with epoxy groups. Two distinct lectins with different specificities, Sambucus sieboldiana agglutinin and concanavalin A, are effectively immobilized on SPM without impacting the binding activity. Moreover, high recovery rates of liposomal nanoparticles as a model of EVs are achieved due to the large flow-through pores (>10 μm) of SPM compared to a typical agarose gel. Finally, lectin-immobilized SPMs are employed to classify EVs based on the surface glycan structures and demonstrate different subpopulations by proteome profiling. This is the first approach to clarify the variation of protein contents in EVs by the difference of surface glycans via lectin immobilized media.

Lectin-Based Study Reveals the Presence of Disease-Relevant Glycoepitopes in Bladder Cancer Cells and Ectosomes

Bladder cancer is a malignancy that remains a therapeutic challenge and requires the identification of new biomarkers and mechanisms of progression. Several studies showed that extracellular vesicles promote angiogenesis, migration and metastasis, and inhibit apoptosis in bladder cancer. This effect may depend on their glycosylation status. Thus, the aim of this study was to compare glycosylation profiles of T-24 urothelial bladder cancer cells, HCV-29 normal ureter epithelial cells, and ectosomes released by both cell lines using lectin blotting and flow cytometry. Ectosomes displayed distinct total and surface glycosylation profiles with abundance of β-1,6-branched glycans and sialilated structures. Then, it was investigated whether the glycosylation status of the T-24 and HCV-29 cells is responsible for the effect exerted by ectosomes on the proliferation and migration of recipient cells. Stronger proproliferative and promigratory activity of T-24-derived ectosomes was observed in comparison to ectosomes from HCV-29 cells. When ectosomes were isolated from DMJ-treated cells, the aforementioned effects were diminished, suggesting that glycans carried by ectosomes were involved in modulation of recipient cell function. HCV-29- and T-24-derived ectosomes also increased the viability and motility of endothelial HUVEC cells and Hs27 fibroblasts. This supports the hypothesis that ectosomes can modulate the function of various cells present in the tumor microenvironment.

Extracellular vesicle contents as non-invasive biomarkers in ovarian malignancies

Ovarian cancer most commonly presents at an advanced stage where survival is approximately 30% compared with >80% if diagnosed and treated before disease spreads. Diagnostic capabilities have progressed from surgical staging via laparotomy to image-guided biopsies and immunohistochemistry staining, along with advances in technology and medicine. Despite improvements in diagnostic capabilities, population-level screening for ovarian cancer is not recommended. Extracellular vesicles (EVs) are 40–150 nm structures formed when the cellular lipid bilayer invaginates. These structures function in cell signaling, immune responses, cancer progression, and establishing the tumor microenvironment. EVs are found in nearly every bodily fluid, including serum, plasma, ascites, urine, and effusion fluid, and contain molecular cargo from their cell of origin. This cargo can be analyzed to yield information about a possible malignancy. In this review we describe how the cargo of EVs has been studied as biomarkers in ovarian cancer. We bring together studies analyzing evidence for various cargos as ovarian cancer biomarkers. Then, we describe the role of EVs in modulation of the tumor microenvironment. This review also summarizes the therapeutic and translational potential of EVs for their optimal utilization as non-invasive biomarkers for novel treatments against cancer.

Glycosylation and its research progress in endometrial cancer

Endometrial cancer (EC) is one of the most common tumors in the female reproductive system, which seriously threatens women's health, particularly in developed countries. 13% of the patients with EC have a poor prognosis due to recurrence and metastasis. Therefore, identifying good predictive biomarkers and therapeutic targets is critical to enable the early detection of metastasis and improve the prognosis. For decades, extensive studies had focused on glycans and glycoproteins in the progression of cancer. The types of glycans that are covalently attached to the polypeptide backbone, usually via nitrogen or oxygen linkages, are known as N‑glycans or O‑glycans, respectively. The degree of protein glycosylation and the aberrant changes in the carbohydrate structures have been implicated in the extent of tumorigenesis and reported to play a critical role in regulating tumor invasion, metabolism, and immunity. This review summarizes the essential biological role of glycosylation in EC, with a focus on the recent advances in glycomics and glycosylation markers, highlighting their implications in the diagnosis and treatment of EC.

Advances in the Immunomodulatory Properties of Glycoantigens in Cancer

Simple Summary

This work reviews the role of aberrant glycosylation in cancer cells during tumour growth and spreading, as well as in immune evasion. The interaction of tumour-associated glycans with the immune system through C-type lectin receptors can favour immune escape but can also provide opportunities to develop novel tumour immunotherapy strategies. This work highlights the main findings in this area and spotlights the challenges that remain to be investigated.

Abstract

Aberrant glycosylation in tumour progression is currently a topic of main interest. Tumour-associated carbohydrate antigens (TACAs) are expressed in a wide variety of epithelial cancers, being both a diagnostic tool and a potential treatment target, as they have impact on patient outcome and disease progression. Glycans affect both tumour-cell biology properties as well as the antitumor immune response. It has been ascertained that TACAs affect cell migration, invasion and metastatic properties both when expressed by cancer cells or by their extracellular vesicles. On the other hand, tumour-associated glycans recognized by C-type lectin receptors in immune cells possess immunomodulatory properties which enable tumour growth and immune response evasion. Yet, much remains unknown, concerning mechanisms involved in deregulation of glycan synthesis and how this affects cell biology on a major level. This review summarises the main findings to date concerning how aberrant glycans influence tumour growth and immunity, their application in cancer treatment and spotlights of unanswered challenges remaining to be solved.

L1CAM-associated extracellular vesicles: A systematic review of nomenclature, sources, separation, and characterization

When released into biological fluids like blood or saliva, brain extracellular vesicles (EVs) might provide a window into otherwise inaccessible tissue, contributing useful biomarkers of neurodegenerative and other central nervous system (CNS) diseases. To enrich for brain EVs in the periphery, however, cell-specific EV surface markers are needed. The protein that has been used most frequently to obtain EVs of putative neuronal origin is the transmembrane L1 cell adhesion molecule (L1CAM/CD171). In this systematic review, we examine the existing literature on L1CAM and EVs, including investigations of both neurodegenerative disease and cancer through the lens of the minimal information for studies of EVs (MISEV), specifically in the domains of nomenclature usage, EV sources, and EV separation and characterization. Although numerous studies have reported L1CAM-associated biomarker signatures that correlate with disease, interpretation of these results is complicated since L1CAM expression is not restricted to neurons and is also upregulated during cancer progression. A recent study has suggested that L1CAM epitopes are present in biofluids mostly or entirely as cleaved, soluble protein. Our findings on practices and trends in L1CAM-mediated EV separation, enrichment, and characterization yield insights that may assist with interpreting results, evaluating rigor, and suggesting avenues for further exploration.

Assessment of Surface Glycan Diversity on Extracellular Vesicles by Lectin Microarray and Glycoengineering Strategies for Drug Delivery Applications

Extracellular vesicles (EVs) are released by all types of mammalian cells for cell-cell communication. In this study, surface glycans on EVs are compared in terms of their cell type, size, and isolation method to examine whether EV glycan profiles by lectin microarray can be used to define EV subpopulations. Moreover, EVs are glycoengineered with four distinctive surface glycan patterns and evaluated their cellular uptake efficiencies for potential drug delivery applications. Both similarities and differences in glycan patterns are identified on EVs obtained under each experimental condition. EV size- and isolation method-dependent lectin-binding patterns are observed. Moreover, cellular uptake behaviors of EVs are affected by EV glycan profiles and acceptor cells. The in vivo biodistribution of EVs is also dependent on their glycan profile. These results suggest that EV surface glycans are a potential novel indicator of EV heterogeneity, and glycoengineering is a useful approach to regulate cell-EV interactions for biomedical applications.

Sialic acids in gynecological cancer development and progression: Impact on diagnosis and treatment

Gynecological cancers are in the top 10 of most common cancers in women. Survival and outcome are strongly related to the stage at diagnosis. Therefore, early diagnosis is essential in reducing morbidity and mortality. The high mortality rate of gynecological cancers can mainly be attributed to ovarian cancer (OC). OC is commonly diagnosed at an advanced stage due to a lack of proper screening tools allowing early detection. Endometrial cancer (EC) on the contrary, is mostly diagnosed at an early stage and has, in general, better outcomes. The incidence of nonendometrioid EC has increased in the last decade, displaying a shared tumor biology with OC and consequently significantly worse outcome. New approaches allowing detection of gynecological cancers in an early stage are therefore desired. Recent studies on cancer biology have shown the relevance of altered glycosylation in the occurrence and progression of cancer. The aberrant expression of sialic acid, a specific carbohydrate terminating glycoproteins and glycolipids on the cell‐surface, is frequently correlated with malignancy. We aimed to determine the current understanding of sialic acid function in different gynecological cancers to identify the gaps in knowledge and its potential use for new diagnostic and therapeutic avenues. Therefore we performed a review on current literature focusing on studies where sialylation was linked to gynecological cancers. The identified studies showed elevated levels of sialic acid in serum, tissue and sialylated antigens in most patients with gynecological cancers, underlining its potential for diagnosis.

What's new?

Recent studies have shown the relevance of altered glycosylation in the occurrence and progression of cancer. In this review, the authors found elevated levels of sialic acid in serum and tissue and high levels of sialylated antigens in most patients with gynaecological cancers, underlining the potential of sialic acid for diagnosis. Elevated levels of sialylation were related with tumour growth, poor differentiation, inhibition of apoptosis, and chemoresistance. Taken together, the studies suggest that sialylation levels could be used to discriminate healthy and benign samples from cancer samples and even early and advanced stages in ovarian, cervical, and endometrial cancer.

Extracellular Vesicle Proteomes Shed Light on the Evolutionary, Interactive, and Functional Divergence of Their Biogenesis Mechanisms

Extracellular vesicles (EVs) are membranous structures containing bioactive molecules, secreted by most cells into the extracellular environment. EVs are classified by their biogenesis mechanisms into two major subtypes: ectosomes (enriched in large EVs; lEVs), budding directly from the plasma membrane, which is common in both prokaryotes and eukaryotes, and exosomes (enriched in small EVs; sEVs) generated through the multivesicular bodies via the endomembrane system, which is unique to eukaryotes. Even though recent proteomic analyses have identified key proteins associated with EV subtypes, there has been no systematic analysis, thus far, to support the general validity and utility of current EV subtype separation methods, still largely dependent on physical properties, such as vesicular size and sedimentation. Here, we classified human EV proteomic datasets into two main categories based on distinct centrifugation protocols commonly used for isolating sEV or lEV fractions. We found characteristic, evolutionarily conserved profiles of sEV and lEV proteins linked to their respective biogenetic origins. This may suggest that the evolutionary trajectory of vesicular proteins may result in a membership bias toward specific EV subtypes. Protein-protein interaction (PPI) network analysis showed that vesicular proteins formed distinct clusters with proteins in the same EV fraction, providing evidence for the existence of EV subtype-specific protein recruiters. Moreover, we identified functional modules enriched in each fraction, including multivesicular body sorting for sEV, and mitochondria cellular respiration for lEV proteins. Our analysis successfully captured novel features of EVs embedded in heterogeneous proteomics studies and suggests specific protein markers and signatures to be used as quality controllers in the isolation procedure for subtype-enriched EV fractions.

Extracellular Vesicles and Glycosylation

Extracellular vesicles (EVs), a generic term for any vesicles or particles that are released from cells, play an important role in modulating numerous biological and pathological events, including development, differentiation, aging, thrombus formation, immune responses, neurodegenerative diseases, and tumor progression. During the biogenesis of EVs, they encapsulate biologically active macromolecules (i.e., nucleotides and proteins) and transmit signals for delivering them to neighboring or cells that are located some distance away. In contrast, there are receptor molecules on the surface of EVs that function to mediate EV-to-cell and EV-to-matrix interactions. A growing body of evidence indicates that the EV surface is heavily modified with glycans, the function of which is to regulate the biogenesis and extracellular behaviors of EVs. In this chapter, we introduce the current status of our knowledge concerning EV glycosylation and discuss how it influences EV biology, highlighting the potential roles of EV glycans in clinical applications.

Determining The Role of Surface Glycans in The Pharmacokinetics of Small Extracellular Vesicles

Small extracellular vesicles (sEVs) are important mediators of intercellular communication and are thereby expected to be promising carriers for drug delivery. Understanding the factors that affect sEV pharmacokinetics is crucial for its application as a drug delivery carrier. In this study, the role of sEV surface glycans was investigated by evaluating the effects of enzymatic deglycosylation treatment on sEV pharmacokinetics. First, control glycoprotein fetuin was used to optimize the glycosidase treatment conditions. B16-BL6-derived sEVs labeled with fusion proteins comprising Gag protein and Gaussia luciferase (gLuc) (Gag-gLuc) were then treated with glycosidases, Peptide-N-Glycosidase F or O-glycosidase, which cleaves N- and O-glycans, respectively. Glycosidase-treated sEVs showed physicochemical characteristics comparable to those of the untreated sEVs. However, removal of N-glycans from B16-BL6 sEVs enhanced cellular uptake by the peritoneal macrophages, while the removal of O-glycans had minimal impact, as evaluated by flow cytometry. To determine the effect of surface glycans on the sEV pharmacokinetics, Gag-gLuc labeled B16-BL6 sEVs treated with or without glycosidases were then intravenously administered to mice. Glycosidase-treated sEVs showed almost identical clearance from the blood circulation as that of the untreated sEVs. These results suggest minimal impact of surface glycans on sEV pharmacokinetics, despites its effect on cellular uptake.

Protein glycosylation in extracellular vesicles: Structural characterization and biological functions

Extracellular vesicles (EVs) are lipid bilayer-enclosed particles involved in intercellular communication, delivery of biomolecules from donor to recipient cells, cellular disposal and homeostasis, potential biomarkers and drug carriers. The content of EVs includes DNA, lipids, metabolites, proteins, and microRNA, which have been studied in various diseases, such as cancer, diabetes, pregnancy, neurodegenerative, and cardiovascular disorders. EVs are enriched in glycoconjugates and exhibit specific glycosignatures. Protein glycosylation is a co- and post-translational modification (PTM) that plays an important role in the expression and function of exosomal proteins. N- and O-linked protein glycosylation has been mapped in exosomal proteins. The purpose of this review is to highlight the importance of glycosylation in EVs proteins. Initially, we describe the main PTMs in EVs with a focus on glycosylation. Then, we explore glycan-binding proteins describing the main findings of studies that investigated the glycosylation of EVs in cancer, pregnancy, infectious diseases, diabetes, mental disorders, and animal fluids. We have highlighted studies that have developed innovative methods for studying the content of EVs. In addition, we present works related to lipid glycosylation. We explored the content of studies deposited in public databases, such as Exocarta and Vesiclepedia. Finally, we discuss analytical methods for structural characterization of glycoconjugates and present an overview of the critical points of the study of glycosylation EVs, as well as perspectives in this field.

The role of O-glycosylation in human disease

O-glycosylation is a highly frequent post-translation modification of proteins, with important functional implications in both physiological and disease contexts. The biosynthesis of O-glycans depends on several layers of regulation of the cellular glycosylation machinery, being organ-, tissue- and cell-specific. This review provides insights on the molecular mechanism underlying O-glycan biosynthesis and modification, and highlights illustrative examples of diseases that are triggered or modulated by aberrant cellular O-glycosylation. Particular relevance is given to genetic disorders of glycosylation, infectious diseases and cancer. Finally, we address the potential of O-glycans and their biosynthetic pathways as targets for novel therapeutic strategies.

Glycosylation of Cancer Extracellular Vesicles: Capture Strategies, Functional Roles and Potential Clinical Applications

Glycans are major constituents of extracellular vesicles (EVs). Alterations in the glycosylation pathway are a common feature of cancer cells, which gives rise to de novo or increased synthesis of particular glycans. Therefore, glycans and glycoproteins have been widely used in the clinic as both stratification and prognosis cancer biomarkers. Interestingly, several of the known tumor-associated glycans have already been identified in cancer EVs, highlighting EV glycosylation as a potential source of circulating cancer biomarkers. These particles are crucial vehicles of cell–cell communication, being able to transfer molecular information and to modulate the recipient cell behavior. The presence of particular glycoconjugates has been described to be important for EV protein sorting, uptake and organ-tropism. Furthermore, specific EV glycans or glycoproteins have been described to be able to distinguish tumor EVs from benign EVs. In this review, the application of EV glycosylation in the development of novel EV detection and capture methodologies is discussed. In addition, we highlight the potential of EV glycosylation in the clinical setting for both cancer biomarker discovery and EV therapeutic delivery strategies.

The "sugar-coated bullets" of cancer: Tumor-derived exosome surface glycosylation from basic knowledge to applications

Scientific interest in exosomes has exploded in recent decades. In 1990 only three articles were published on exosomes, while over 1,700 have already been published half-way into 2020.1 While researchers have shown much interest in exosomes since being discovered in 1981, an appreciation of the potential role of glycans in exosome structure and function has emerged only recently. Glycosylation is one of the most common post-translational modification, which functions in many physiological and pathological aspects of cellular function. Many components of exosomes are heavily glycosylated including proteins, lipids, among others. Thus, glycosylation undoubtedly has a great impact on exosome biosynthesis and function. Despite the importance of glycosylation in exosomes and the recent recognition of them as biomarkers for not only malignancies but also other system dysfunction and disease, the characterization of exosome glycans remains understudied. In this review, we discuss glycosylation patterns of exosomes derived from various tissues, their biological features, and potential for various clinical applications. We highlight state-of-the-art knowledge about the fine structure of exosomes, which will allow researchers to reconstruct them by surface modification. These efforts will likely lead to novel disease-related biomarker discovery, purification tagging, and targeted drug transfer for clinical applications in the future.

The Delivery of Extracellular Vesicles Loaded in Biomaterial Scaffolds for Bone Regeneration

Extracellular vesicles (EVs) are heterogeneous nanoparticles actively released by cells that comprise highly conserved and efficient systems of intercellular communication. In recent years, numerous studies have proven that EVs play an important role in the field of bone tissue engineering (BTE) due to several advantages, such as good biosafety, stability and efficient delivery. However, the application of EVs therapies in bone regeneration has not been widely used. One of the major challenges for the application of EVs is the lack of sufficient scaffolds to load and control the release of EVs. Thus, in this review, we describe the most advanced current strategies for delivering EVs with various biomaterials for the use in bone regeneration, the role of EVs in bone regeneration, the distribution of EVs mediated by biomaterials and common methods of promoting EVs delivery efficacy with a focus on biomaterial properties.

Progress in exosome associated tumor markers and their detection methods

Exosomes are secreted by cells and are widely present in body fluids. Exosomes contain various molecular constituents of their cells of origin such as proteins, mRNA, miRNAs, DNA, lipid and glycans which are very similar as the content in tumor cells. These contents play an important role in various stages of tumor development, and make the tumor-derived exosome as a hot and emerging biomarker for various cancers diagnosis and management in non-invasive manner. The present problems of exosome isolation and detection hinder the application of exosomes. With the development of exosome isolation and detection technology, the contents of exosomes can be exploited for early cancer diagnosis. This review summarizes the recent progress on exosome-associated tumor biomarkers and some new technologies for exosome isolation and detection. Furthermore, we have also discussed the future development direction in exosome analysis methods.

The Impact of Small Extracellular Vesicles on Lymphoblast Trafficking across the Blood-Cerebrospinal Fluid Barrier In Vitro

Central nervous System (CNS) disease in pediatric acute lymphoblastic leukemia (ALL) is a major concern, but still, cellular mechanisms of CNS infiltration are elusive. The choroid plexus (CP) is a potential entry site, and, to some extent, invasion resembles CNS homing of lymphocytes during healthy state. Given exosomes may precondition target tissue, the present work aims to investigate if leukemia-derived exosomes contribute to a permissive phenotype of the blood-cerebrospinal fluid barrier (BCSFB). Leukemia-derived exosomes were isolated by ultracentrifugation from the cell lines SD-1, Nalm-6, and P12-Ichikawa (P12). Adhesion and uptake to CP epithelial cells and the significance on subsequent ALL transmigration across the barrier was studied in a human BCSFB in vitro model based on the HiBCPP cell line. The various cell lines markedly differed regarding exosome uptake to HiBCPP and biological significance. SD-1-derived exosomes associated to target cells unspecifically without detectable cellular effects. Whereas Nalm-6 and P12-derived exosomes incorporated by dynamin-dependent endocytosis, uptake in the latter could be diminished by integrin blocking. In addition, only P12-derived exosomes led to facilitated transmigration of the parental leukemia cells. In conclusion, we provide evidence that, to a varying extent, leukemia-derived exosomes may facilitate CNS invasion of ALL across the BCSFB without destruction of the barrier integrity.

The Essential Functions and Detection of Bisecting GlcNAc in Cell Biology

The N-glycans of mammalian glycoproteins vary greatly in structure, and the biological importance of these variations is mostly unknown. It is widely acknowledged that the bisecting N-acetylglucosamine (GlcNAc) structure, a β1,4-linked GlcNAc attached to the core β-mannose residue, represents a special type of N-glycosylated modification, and it has been reported to be involved in various biological processes, such as cell adhesion, fertilization and fetal development, neuritogenesis, and tumor development. In particular, the occurrence of N-glycans with a bisecting GlcNAc modification on proteins has been proven, with many implications for immune biology. Due to the essential functions of bisecting GlcNAc structures, analytical approaches to this modification are highly required. The traditional approach that has been used for bisecting GlcNAc determinations is based on the lectin recognition of Phaseolus vulgaris erythroagglutinin (PHA-E); however, poor binding specificity hinders the application of this method. With the development of mass spectrometry (MS) with high resolution and improved sensitivity and accuracy, MS-based glycomic analysis has provided precise characterization and quantification for glycosylation modification. In this review, we first provide an overview of the bisecting GlcNAc structure and its biological importance in neurological systems, immune tolerance, immunoglobulin G (IgG), and tumor metastasis and development and then summarize approaches to its determination by MS for performing precise functional studies. This review is valuable for those readers who are interested in the importance of bisecting GlcNAc in cell biology.

Altered biodistribution of deglycosylated extracellular vesicles through enhanced cellular uptake

Extracellular vesicles (EVs) from cancer are delivered both proximal and distal organs. EVs are highly glycosylated at the surface where EVs interact with cells and therefore has an impact on their properties and biological functions. Aberrant glycosylation in cancer is associated with cancer progression and metastasis. However, the biological function of glycosylation on the surface of EV is uncovered. We first demonstrated differential glycosylation profiles of EVs and their originated cells, and distinct glycosylation profiles in a brain-metastatic subline BMD2a from its parental human breast cancer cell line, MDA-MB-231-luc-D3H2LN by lectin blot. We then investigated the roles of surface glycoconjugates on EV uptake. N- and/or O-glycosylation removal of fluorescent-labelled BMD2a EVs enhanced cellular uptake to endothelial cells, suggesting that surface glycosylation has inhibitory effects on cellular uptake. Biodistribution of glycosylation-deprived BMD2a EVs administrated intravenously into mice was further analysed ex vivo using near-infrared lipophilic dye. EVs treated with O-deglycosylation enzymes enhanced the accumulation of EVs to the lungs after 24 h from the injection, while N-deglycosylation did not markedly alter biodistribution. As the lungs are first organs in which intravenous blood flows, we suggest that surface glycosylation of cancer-derived EVs avoid promiscuous adhesion to proximal tissues to be delivered to distant organs.

Prognostic relevance of the Golgi mannosidase MAN1A1 in ovarian cancer: impact of N-glycosylation on tumour cell aggregation

Background

Maturation of complex N-glycans involves the action of Golgi mannosidases and plays a major role in cancer progression. We recently showed a favourable prognostic role of α-mannosidase MAN1A1 in breast cancer mainly caused by alteration of certain adhesion molecules.

Methods

We analysed the protein expression of MAN1A1 in ovarian cancer (n = 204) using western blot and studied the impact of MAN1A1 itself and of MAN1A1-related glycosylation on the prognostic relevance of two adhesion molecules. Functional consequences of mannosidase inhibition using kifunensine and MAN1A1 knock out were investigated in ovarian cancer cells in vitro.

Results

Patients with high MAN1A1 expression in tumours showed significantly shorter RFS than those with low-MAN1A1 levels. Moreover, high MAN1A1 expression correlated significantly with advanced stage, lymph node involvement and distant metastasis. Further, the glycosylated adhesion molecule ALCAM reveals a significant adverse prognostic effect only in the presence of high MAN1A1 expression. In spheroid-formation assays, mannosidase inhibition and especially MAN1A1 knock out led to strong reduction of tumour cell aggregation.

Conclusions

Our study demonstrates the unfavourable prognostic role of MAN1A1 in ovarian cancer, probably caused by an altered ability of spheroid formation, and the strong influence of this glycosylation enzyme on the prognostic impact of ALCAM.

Glycan modification of glioblastoma-derived extracellular vesicles enhances receptor-mediated targeting of dendritic cells

Glioblastoma is the most prevalent and aggressive primary brain tumour for which total tumour lysate-pulsed dendritic cell vaccination is currently under clinical evaluation. Glioblastoma extracellular vesicles (EVs) may represent an enriched cell-free source of tumour-associated (neo-) antigens to pulse dendritic cells (DCs) for the initiation of an anti-tumour immune response. Capture and uptake of EVs by DCs could occur in a receptor-mediated and presumably glycan-dependent way, yet the glycan composition of glioblastoma EVs is unknown. Here, we set out to characterize the glycocalyx composition of glioblastoma EVs by lectin-binding ELISA and comprehensive immunogold transmission electron microscopy (immuno-TEM). The surface glycan profile of human glioblastoma cell line-derived EVs (50-200 nm) was dominated by α-2,3- and α-2,6 linked sialic acid-capped complex N-glycans and bi-antennary N-glycans. Since sialic acids can trigger immune inhibitory sialic acid-binding Ig-like lectin (Siglec) receptors, we screened for Siglec ligands on the EVs. Glioblastoma EVs showed significant binding to Siglec-9, which is highly expressed on DCs. Surprisingly, however, glioblastoma EVs lack glycans that could bind Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209), a receptor that mediates uptake and induction of CD4+ and CD8+ T cell activation. Therefore, we explored whether modification of the EV glycan surface could reduce immune inhibitory Siglec binding, while enhancing EV internalization by DCs in a DC-SIGN dependent manner. Desialylation with a pan-sialic acid hydrolase led to reduction of sialic acid expression on EVs. Moreover, insertion of a high-affinity ligand (LewisY) for DC-SIGN resulted in a four-fold increase of uptake by monocyte-derived DCs. In conclusion, we show that the glycocalyx composition of EVs is a key factor of efficient DC targeting and that modification of the EV glycocalyx potentiates EVs as anti-cancer vaccine.

Exosome surface glycans reflect osteogenic differentiation of mesenchymal stem cells: Profiling by an evanescent field fluorescence-assisted lectin array system

Extracellular vesicles (EVs) carry information between cells in the form of biomolecules. Such molecules have been found to serve as biomarkers. Glycans attached to surface molecules on EVs are involved in their cellular uptake. In this study, we examined glycan profiles of small EVs which are generally termed exosomes before and after osteogenic differentiation of adipose-derived mesenchymal stem cells (MSCs) by an evanescent field fluorescence-assisted (EFF)-lectin array system to discover glycan biomarkers for osteogenic differentiation. We found few differences between exosomes before and after osteogenic differentiation of MSCs in terms of fundamental characteristics such as size, morphology, and exosomal marker proteins. However, specific lectins bound strongly to exosomes from differentiated cells. Exosomes from osteogenically differentiated MSCs bound strongly to fucose- and mannose-binding lectins, especially at a high concentration of exosomes. In summary, we found that several lectins bound to exosomes from differentiated MSCs more strongly than to those from undifferentiated cells using an EFF-lectin array system, indicating that monitoring exosomal surface glycans may identify predictive indexes of osteogenic differentiation.

An Insight into the Proteome of Uveal Melanoma-Derived Ectosomes Reveals the Presence of Potentially Useful Biomarkers

Cancer cells are known to release extracellular vesicles that often promote disease development and progression. The present study investigated the protein content and glycosylation pattern of ectosomes released in vitro by a human primary uveal melanoma Mel202 cell line. Ectosomes released by Mel202 cells were isolated from conditioned media using sequential centrifugation, and a nano-LC-MS/MS approach was used to determine their protein content. Subsequently, proteins from ectosomes, the whole cell extracts, and the membrane fractions were probed with a panel of lectins using Western blotting and flow cytometry to reveal characteristic glycan structures. As many as 2527 unique proteins were identified, and many of them are known to be involved in cancer cell proliferation and altered metabolism, tumor invasion, metastasis, or drug resistance. Lectin-based studies revealed a distinct glycosylation pattern between Mel202-derived ectosomes and the parental cell membranes. Selective enrichment of ectosomal proteins with bisected complex type N-glycans and α2,6-linked sialic acids may be significant for ectosome formation and sequestration. Differences in the surface glycosylation of Mel202 cells and ectosomes supports recent findings that the budding of ectosomes occurs within strictly determined fragments of the plasma membrane, and thus ectosomes contain a unique protein and glycan composition.

Exosomes, metastases, and the miracle of cancer stem cell markers

Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.

Systems biology approaches to investigating the roles of extracellular vesicles in human diseases

Extracellular vesicles (EVs) are membrane-enclosed structures secreted by cells. In the past decade, EVs have attracted substantial attention as carriers of complex intercellular information. They have been implicated in a wide variety of biological processes in health and disease. They are also considered to hold promise for future diagnostics and therapy. EVs are characterized by a previously underappreciated heterogeneity. The heterogeneity and molecular complexity of EVs necessitates high-throughput analytical platforms for detailed analysis. Recently, mass spectrometry, next-generation sequencing and bioinformatics tools have enabled detailed proteomic, transcriptomic, glycomic, lipidomic, metabolomic, and genomic analyses of EVs. Here, we provide an overview of systems biology experiments performed in the field of EVs. Furthermore, we provide examples of how in silico systems biology approaches can be used to identify correlations between genes involved in EV biogenesis and human diseases. Using a knowledge fusion system, we investigated whether certain groups of proteins implicated in the biogenesis/release of EVs were associated with diseases and phenotypes. Furthermore, we investigated whether these proteins were enriched in publicly available transcriptomic datasets using gene set enrichment analysis methods. We found associations between key EV biogenesis proteins and numerous diseases, which further emphasizes the key role of EVs in human health and disease.

Tumor-Derived Apoptotic Vesicles: With Death They Do Part

Tumor cells release lipid particles known as extracellular vesicles (EV) that contribute to cancer metastasis, to the immune response, and to thrombosis. When tumors are exposed to radiation or chemotherapy, apoptotic vesicles (ApoVs) are released in abundance as the plasma membrane delaminates from the cytoskeleton. Recent studies have suggested that ApoVs are distinct from the EVs released from living cells, such as exosomes or microvesicles. Depending on their treatment conditions, tumor-released ApoV have been suggested to either enhance or suppress anti-cancer immunity. In addition, tumor-derived ApoV possess procoagulant activity that could increase the thrombotic state in cancer patients undergoing chemotherapy or radiotherapy. Since ApoVs are one of the least appreciated type of EVs, we focus in this review on the distinctive characterization of tumor ApoVs and their proposed mechanistic effects on cancer immunity, coagulation, and metastasis.

Glycosylation of extracellular vesicles: current knowledge, tools and clinical perspectives

It is now acknowledged that extracellular vesicles (EVs) are important effectors in a vast number of biological processes through intercellular transfer of biomolecules. Increasing research efforts in the EV field have yielded an appreciation for the potential role of glycans in EV function. Indeed, recent reports show that the presence of glycoconjugates is involved in EV biogenesis, in cellular recognition and in the efficient uptake of EVs by recipient cells. It is clear that a full understanding of EV biology will require researchers to focus also on EV glycosylation through glycomics approaches. This review outlines the major glycomics techniques that have been applied to EVs in the context of the recent findings. Beyond understanding the mechanisms by which EVs mediate their physiological functions, glycosylation also provides opportunities by which to engineer EVs for therapeutic and diagnostic purposes. Studies characterising the glycan composition of EVs have highlighted glycome changes in various disease states, thus indicating potential for EV glycans as diagnostic markers. Meanwhile, glycans have been targeted as molecular handles for affinity-based isolation in both research and clinical contexts. An overview of current strategies to exploit EV glycosylation and a discussion of the implications of recent findings for the burgeoning EV industry follows the below review of glycomics and its application to EV biology.

Janus-Faced Myeloid-Derived Suppressor Cell Exosomes for the Good and the Bad in Cancer and Autoimmune Disease

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells originally described to hamper immune responses in chronic infections. Meanwhile, they are known to be a major obstacle in cancer immunotherapy. On the other hand, MDSC can interfere with allogeneic transplant rejection and may dampen autoreactive T cell activity. Whether MDSC-Exosomes (Exo) can cope with the dangerous and potentially therapeutic activities of MDSC is not yet fully explored. After introducing MDSC and Exo, it will be discussed, whether a blockade of MDSC-Exo could foster the efficacy of immunotherapy in cancer and mitigate tumor progression supporting activities of MDSC. It also will be outlined, whether application of native or tailored MDSC-Exo might prohibit autoimmune disease progression. These considerations are based on the steadily increasing knowledge on Exo composition, their capacity to distribute throughout the organism combined with selectivity of targeting, and the ease to tailor Exo and includes open questions that answers will facilitate optimizing protocols for a MDSC-Exo blockade in cancer as well as for strengthening their therapeutic efficacy in autoimmune disease.

Exploring functional pairing between surface glycoconjugates and human galectins using programmable glycodendrimersomes

Cells are decorated with charged and uncharged carbohydrate ligands known as glycans, which are responsible for several key functions, including their interactions with proteins known as lectins. Here, a platform consisting of synthetic nanoscale vesicles, known as glycodendrimersomes, which can be programmed with cell surface-like structural and topological complexity, is employed to dissect design aspects of glycan presentation, with specificity for lectin-mediated bridging. Aggregation assays reveal the extent of cross-linking of these biomimetic nanoscale vesicles—presenting both anionic and neutral ligands in a bioactive manner—with disease-related human and other galectins, thus offering the possibility of unraveling the nature of these fundamental interactions.

Precise translation of glycan-encoded information into cellular activity depends critically on highly specific functional pairing between glycans and their human lectin counter receptors. Sulfoglycolipids, such as sulfatides, are important glycolipid components of the biological membranes found in the nervous and immune systems. The optimal molecular and spatial design aspects of sulfated and nonsulfated glycans with high specificity for lectin-mediated bridging are unknown. To elucidate how different molecular and spatial aspects combine to ensure the high specificity of lectin-mediated bridging, a bottom-up toolbox is devised. To this end, negatively surface-charged glycodendrimersomes (GDSs), of different nanoscale dimensions, containing sulfo-lactose groups are self-assembled in buffer from a synthetic sulfatide mimic: Janus glycodendrimer (JGD) containing a 3′-O-sulfo-lactose headgroup. Also prepared for comparative analysis are GDSs with nonsulfated lactose, a common epitope of human membranes. These self-assembled GDSs are employed in aggregation assays with 15 galectins, comprising disease-related human galectins, and other natural and engineered variants from four families, having homodimeric, heterodimeric, and chimera architectures. There are pronounced differences in aggregation capacity between human homodimeric and heterodimeric galectins, and also with respect to their responsiveness to the charge of carbohydrate-derived ligand. Assays reveal strong differential impact of ligand surface charge and density, as well as lectin concentration and structure, on the extent of surface cross-linking. These findings demonstrate how synthetic JGD-headgroup tailoring teamed with protein engineering and network assays can help explain how molecular matchmaking operates in the cellular context of glycan and lectin complexity.

A detection and quantification label-free tool to speed up downstream processing of model mucins

Mucins are high-molecular weight glycoproteins (0.25-20 MDa) containing one or more domains that are heavily O-glycosylated. Their implications as targets for cancer treatment have increased the interest in these glycoproteins, mainly in the fields of vaccines and antibodies. However, mucins present high heterogeneity, posing challenges that affect purification processes and quality control analysis. In that sense, it is necessary to develop and improve downstream processes and analytical methods to characterize these products. Here a tool based on biolayer interferometry analysis to improve mucin's detection and quantification in a fast, simple and label free-way is presented. Taking advantage of lectin recognition of mucins' carbohydrate structures, several lectins were evaluated and immobilized on streptavidin biosensors. Different assay conditions were optimized and the most suitable lectin, Aleuria aurantia lectin (AAL), was selected. Bovine Submaxillary Gland and human MUC5B mucins were used as proof of concept and were successfully detected and quantified at different stages of purification. High sensitivity levels were achieved with LOD and LOQ of 3.8 μg mL-1 and 11.7 μg mL-1 for BSM, and 0.2 μg mL-1 and 0.6 μg mL-1 for MUC5B. AAL binding specificity was also confirmed with fucose competition assays. Our method represents an advance on mucins detection and quantification since the existing methods present several disadvantages for process development. Hereafter, it can be applied to the optimization of new or already established downstream processes for mucins' purification.

Tumor-derived exosomes in ovarian cancer - liquid biopsies for early detection and real-time monitoring of cancer progression

Ovarian cancer usually has a poor prognosis because it predominantly presents as high stage disease. New approaches are required to develop more effective early detection strategies and real-time treatment response monitoring. Nano-sized extracellular vesicles (EVs, including exosomes) may provide an approach to enrich tumor biomarker detection and address this clinical need. Exosomes are membranous extracellular vesicles of approximately 100 nm in diameter that have potential to be used as biomarkers and therapeutic delivery tools for ovarian cancer. Exosomal content (proteins and miRNA) is often parent cell specific thus providing an insight or "fingerprint" of the intracellular environment. Furthermore, exosomes can aid cell-cell communication and have the ability to modify target cells by transferring their content. Additionally, via the capacity to evade the immune system and remain stable over long periods in circulation, exosomes have potential as natural drug agents. This review examines the potential role of exosomes in diagnosis, drug delivery and real-time monitoring in ovarian cancer.

A Perspective on Extracellular Vesicles Proteomics

Increasing attention has been given to secreted extracellular vesicles (EVs) in the past decades, especially in the portrayal of their molecular cargo and role as messengers in both homeostasis and pathophysiological conditions. This review presents the state-of-the-art proteomic technologies to identify and quantify EVs proteins along with their PTMs, interacting partners and structural details. The rapid growth of mass spectrometry-based analytical strategies for protein sequencing, PTMs and structural characterization has improved the level of molecular details that can be achieved from limited amount of EVs isolated from different biological sources. Here we will provide a perspective view on the achievements and challenges on EVs proteome characterization using mass spectrometry. A detailed bioinformatics approach will help us to picture the molecular fingerprint of EVs and understand better their pathophysiological function.

Glycan profiling analysis using evanescent-field fluorescence-assisted lectin array: Importance of sugar recognition for cellular uptake of exosomes from mesenchymal stem cells

Studies involving the functional analysis of exosomal contents including proteins, DNA, and RNA have been reported. Most membrane proteins and lipids are glycosylated, which controls their physical properties and functions, but little is known about glycans on exosomes owing to the difficulty of analysing them. To shed light on these issues, we collected exosomes from mesenchymal stem cells (MSCs) derived from human adipose tissue for glycan profiling using evanescent-field fluorescence-assisted lectin array as well as analysis of their uptake in vivo. Initial analyses showed that the mean diameter of the collected exosomes was 178 nm and they presented with typical exosomal and MSC markers. Regarding the glycan profiling, exosomes interacted more strongly than the membrane of the original MSCs did with a range of lectins, especially sialic acid-binding lectins. The findings also showed that cellular exosome uptake involved recognition by HeLa cell-surface-bound sialic acid-binding immunoglobulin (Ig)-like lectins (siglecs). Confirming this siglec-related uptake, in vivo experiments involving subcutaneous injection of the fluorescently labelled exosomes into mice showed their transport into lymph nodes and internalization by antigen-presenting cells, particularly those expressing CD11b. Closer analysis revealed the colocalization of the exosomes with siglecs, indicating their involvement in the uptake. These findings provide us with an improved understanding of the importance of exosomal transport and targeting in relation to glycans on exosomal surfaces, potentially enabling us to standardize exosomes when using them for therapeutic purposes.

Epigenetic Regulation of the Biosynthesis & Enzymatic Modification of Heparan Sulfate Proteoglycans: Implications for Tumorigenesis and Cancer Biomarkers

Emerging evidence suggests that the enzymes in the biosynthetic pathway for the synthesis of heparan sulfate moieties of heparan sulfate proteoglycans (HSPGs) are epigenetically regulated at many levels. As the exact composition of the heparan sulfate portion of the resulting HSPG molecules is critical to the broad spectrum of biological processes involved in oncogenesis, the epigenetic regulation of heparan sulfate biosynthesis has far-reaching effects on many cellular activities related to cancer progression. Given the current focus on developing new anti-cancer therapeutics focused on epigenetic targets, it is important to understand the effects that these emerging therapeutics may have on the synthesis of HSPGs as alterations in HSPG composition may have profound and unanticipated effects. As an introduction, this review will briefly summarize the variety of important roles which HSPGs play in a wide-spectrum of cancer-related cellular and physiological functions and then describe the biosynthesis of the heparan sulfate chains of HSPGs, including how alterations observed in cancer cells serve as potential biomarkers. This review will then focus on detailing the multiple levels of epigenetic regulation of the enzymes in the heparan sulfate synthesis pathway with a particular focus on regulation by miRNA and effects of epigenetic therapies on HSPGs. We will also explore the use of lectins to detect differences in heparan sulfate composition and preview their potential diagnostic and prognostic use in the clinic.