Deciphering the messages carried by extracellular vesicles in hematological malignancies

The role of the hematopoietic stem/progenitor cells-derived extracellular vesicles in hematopoiesis

Hematopoietic stem cells (HSCs) are tightly regulated by specific microenvironments called niches to produce an appropriate number of mature blood cell types. Self-renewal and differentiation are two hallmarks of hematopoietic stem and progenitor cells, and their balance is critical for proper functioning of blood and immune cells throughout life. In addition to cell-intrinsic regulation, extrinsic cues within the bone marrow niche and systemic factors also affect the fate of HSCs. Despite this, many paracrine and endocrine factors that influence the function of hematopoietic cells remain unknown. In hematological malignancies, malignant cells remodel their niche into a permissive environment to enhance the survival of leukemic cells. These events are accompanied by loss of normal hematopoiesis. It is well known that extracellular vehicles (EVs) mediate intracellular interactions under physiological and pathological conditions. In other words, EVs transfer biological information to surrounding cells and contribute not only to physiological functions but also to the pathogenesis of some diseases, such as cancers. Therefore, a better understanding of cell-to-cell interactions may lead to identification of potential therapeutic targets. Recent reports have suggested that EVs are evolutionarily conserved constitutive mediators that regulate hematopoiesis. Here, we focus on the emerging roles of EVs in normal and pathological conditions, particularly in hematological malignancies. Owing to the high abundance of EVs in biological fluids, their potential use as biomarkers and therapeutic tools is discussed.

EV-mediated intercellular communication in acute myeloid leukemia: Transport of genetic materials in the bone marrow microenvironment

Acute myeloid leukemia (AML) is a common hematological cancer. Cancer cells exchange information with the surrounding microenvironment, which can be transmitted by extracellular vesicles (EVs). In recent years, the genetic materials transported by EVs have attracted attention due to their important roles in different pathological processes. EV-derived ncRNAs (EV-ncRNAs) regulate physiological functions and maintain homeostasis, mainly including microRNAs, long noncoding RNAs, and circular RNAs. However, the mechanism of involvement and potential clinical application of EV-ncRNAs in AML have not been reported. Given the unique importance of the bone marrow microenvironment (BMME) for AML, a greater understanding of the communication between leukemic cells and the BMME is needed to improve the prognosis of patients and reduce the incidence of recurrence. Additionally, studies on leukemic EV-ncRNA transport guide the design of new diagnostic and therapeutic tools for AML. This review systematically describes intercellular communication in the BMME of AML and emphasizes the role of EVs. More importantly, we focus on the information transmission of EV-ncRNAs in the BMME to explore their clinical application as potential biomarkers and therapeutic targets.

Leukemogenesis occurs in a microenvironment enriched by extracellular microvesicles/exosomes: recent discoveries and questions to be answered

In single-cell organisms, extracellular microvesicles (ExMVs) were one of the first cell-cell communication platforms that emerged very early during evolution. Multicellular organisms subsequently adapted this mechanism. Evidence indicates that all types of cells secrete these small circular structures surrounded by a lipid membrane that may be encrusted by ligands and receptors interacting with target cells and harboring inside a cargo comprising RNA species, proteins, bioactive lipids, signaling nucleotides, and even entire organelles "hijacked" from the cells of origin. ExMVs are secreted by normal cells and at higher levels by malignant cells, and there are some differences in their cargo. On the one hand, ExMVs secreted from malignant cells interact with cells in the microenvironment, and in return, they are exposed by a "two-way mechanism" to ExMVs secreted by non-leukemic cells. Therefore, leukemogenesis occurs and progresses in ExMVs enriched microenvironments, and this biological fact has pathologic, diagnostic, and therapeutic implications. We are still trying to decipher this intriguing cell-cell communication language better. We will present a current point of view on this topic and review some selected most recent discoveries and papers.

Extracellular vesicle small RNA cargo discriminates non-cancer donors from pediatric B-lymphoblastic leukemia patients

Pediatric B-acute lymphoblastic leukemia (B-ALL) is a disease of abnormally growing B lymphoblasts. Here we hypothesized that extracellular vesicles (EVs), which are nanosized particles released by all cells (including cancer cells), could be used to monitor B-ALL severity and progression by sampling plasma instead of bone marrow. EVs are especially attractive as they are present throughout the circulation regardless of the location of the originating cell. First, we used nanoparticle tracking analysis to compare EVs between non-cancer donor (NCD) and B-ALL blood plasma; we found that B-ALL plasma contains more EVs than NCD plasma. We then isolated EVs from NCD and pediatric B-ALL peripheral blood plasma using a synthetic peptide-based isolation technique (Vn96), which is clinically amenable and isolates a broad spectrum of EVs. RNA-seq analysis of small RNAs contained within the isolated EVs revealed a signature of differentially packaged and exclusively packaged RNAs that distinguish NCD from B-ALL. The plasma EVs contain a heterogenous mixture of miRNAs and fragments of long non-coding RNA (lncRNA) and messenger RNA (mRNA). Transcripts packaged in B-ALL EVs include those involved in negative cell cycle regulation, potentially suggesting that B-ALL cells may use EVs to discard gene sequences that control growth. In contrast, NCD EVs carry sequences representative of multiple organs, including brain, muscle, and epithelial cells. This signature could potentially be used to monitor B-ALL disease burden in pediatric B-ALL patients via blood draws instead of invasive bone marrow aspirates.

Insight into extracellular vesicles in vascular diseases: intercellular communication role and clinical application potential

BACKGROUND

Cells have been increasingly known to release extracellular vesicles (EVs) to the extracellular environment under physiological and pathological conditions. A plethora of studies have revealed that EVs contain cell-derived biomolecules and are found in circulation, thereby implicating them in molecular trafficking between cells. Furthermore, EVs have an effect on physiological function and disease development and serve as disease biomarkers.

MAIN BODY

Given the close association  between EV circulation and vascular disease, this review aims to provide a brief introduction to EVs, with a specific focus on the EV cargoes participating in pathological mechanisms, diagnosis, engineering, and clinical potential, to highlight the emerging evidence suggesting promising targets in vascular diseases. Despite the expansion of research in this field, some noticeable limitations remain for clinical translational research.

CONCLUSION

This review makes a novel contribution to a summary of recent advances and a perspective on the future of EVs in vascular diseases. Video Abstract.

Feasibility of Leukemia-Derived Exosome Enrichment and Co-isolated dsDNA Sequencing in Acute Myeloid Leukemia Patients: A Proof of Concept for New Leukemia Biomarkers Detection

Simple Summary

The present pilot study aimed at investigating the feasibility of a leukemia-derived exosome enrichment approach followed by exosomal dsDNA target re-sequencing for adult Acute Myeloid Leukemias (AML) marker detection. To our knowledge, this is the first time that a proof-of-concept combining a leukemia-derived exosome enrichment strategy based on a commercial CE-IVD kit and next-generation sequencing was applied in a cohort of adult AML patients. The reported approach is easy, quick and user friendly and gives the possibility of obtaining a good quantity of exosomal dsDNA (composed of exosomal cargo and surrounding DNA) suitable for further analysis. The time-effective procedure opens up future effective clinical applications. This pilot study presents the potential of a proof-of-concept based on exosome analysis to be applied in clinical practice, as well as the feasibility of this kind of investigations using a certified kit, avoiding many additional analyses. It may encourage further studies regarding extracellular vesicles in myeloid neoplasia.

Abstract

Exosomes are extracellular vesicles playing a pivotal role in the intercellular communication. They shuttle different cargoes, including nucleic acids from their cell of origin. For this reason, they have been studied as carriers of tumor markers in different liquid biopsy approaches, in particular for solid tumors. Few data are available concerning exosomes as markers of myeloid neoplasia. To better understand their real potential and the best approach to investigate leukemic exosomes, we present the results of a pilot feasibility study evaluating the application of next-generation sequencing analysis of dsDNA derived from exosomes isolated in 14 adult patients affected by acute myeloid leukemias. In particular, leukemia-derived exosome fractions have been analyzed. The concentration of dsDNA co-extracted with exosomes and the number and types of mutations detected were considered and compared with ones identified in the Bone Marrow (BM) and Peripheral Blood (PB) cells. Exosomal DNA concentration, both considering the cargo and the DNA surrounding the lipid membrane resulted in a linear correlation with leukemic burden. Moreover, exosomal DNA mutation status presented 86.5% of homology with BM and 75% with PB. The results of this pilot study confirmed the feasibility of a leukemia-derived exosome enrichment approach followed by exosomal dsDNA NGS analysis for AML biomarker detection. These data point to the use of liquid biopsy in myeloid neoplasia for the detection of active leukemic cells resident in the BM via a painless procedure.

Role of microRNAs in B-Cell Compartment: Development, Proliferation and Hematological Diseases

B-cell development is a very orchestrated pathway that involves several molecules, such as transcription factors, cytokines, microRNAs, and also different cells. All these components maintain the ideal microenvironment and control B-cell differentiation. MicroRNAs are small non-coding RNAs that bind to target mRNA to control gene expression. These molecules could circulate in the body in a free form, protein-bounded, or encapsulated into extracellular vesicles, such as exosomes. The comprehension of the role of microRNAs in the B-cell development was possible based on microRNA profile of each B-cell stage and functional studies. Herein, we report the knowledge about microRNAs in the B-cell the differentiation, proliferation, and also in hematological malignancies.

Characterizing Extracellular Vesicles Using Nanoparticle-Tracking Analysis

Extracellular vesicles (EVs) are nanosized lipid bound particles secreted by cells. EVs transfer biologic material and can be found in all body fluids. Accurately characterizing the size and concentration of EVs is difficult because of the nanoscale size of EVs. An evolving solution to this problem is tracking the Brownian motion of EVs in suspension, a technique known as nanoparticle-tracking analysis (NTA). This technique is used by many researchers in the EV field. The ability to accurately replicate data between studies and laboratories is critical to advancing the knowledge surrounding EVs for use in liquid biopsy and cancer studies, in general. Thus, this chapter provides a step-by-step guide on isolating EVs using a variety of methods, for characterizing EVs using the NS300 NTA instrument, troubleshooting tips, and a robust guide to reporting key parameters that will help improve cross-lab reproducibility of NTA data.

Multiple Myeloma-Derived Extracellular Vesicles Impair Normal Hematopoiesis by Acting on Hematopoietic Stem and Progenitor Cells

Multiple myeloma (MM) is characterized by the abnormal proliferation of clonal plasma cells (PCs) in bone marrow (BM). MM-PCs progressively occupy and likely alter BM niches where reside hematopoietic stem and progenitor cells (HSPCs) whose viability, self-renewal, proliferation, commitment, and differentiation are essential for normal hematopoiesis. Extracellular vesicles (EVs) are particles released by normal and neoplastic cells, such as MM cells. They are important cell-to-cell communicators able to modify the phenotype, genotype, and the fate of the recipient cells. Investigation of mechanisms and mediators underlying HSPC-MM-PC crosstalk is warranted to better understand the MM hematopoietic impairment and for the identification of novel therapeutic strategies against this incurable malignancy. This study is aimed to evaluate whether EVs released by MM-PCs interact with HSPCs, what effects they exert, and the underlying mechanisms involved. Therefore, we investigated the viability, cell cycle, phenotype, clonogenicity, and microRNA profile of HSPCs exposed to MM cell line-released EVs (MM-EVs). Our data showed that: (i) MM cells released a heterogeneous population of EVs; (ii) MM-EVs caused a dose-dependent reduction of HSPCs viability; (iii) MM-EVs caused a redistribution of the HSPC pool characterized by a significant increase in the frequency of stem and early precursors accompanied by a reduction of late precursor cells, such as common myeloid progenitors (CMPs), megakaryocyte erythroid progenitors (MEPs), B and NK progenitors, and a slight increase of granulocyte macrophage progenitors (GMPs); (iv) MM-EVs caused an increase of stem and early precursors in S phase with a decreased number of cells in G₀/G₁ phase in a dose-dependent manner; (v) MM-EVs reduced the HSPC colony formation; and (vi) MM-EVs caused an increased expression level of C-X-C motif chemokine receptor type 4 (CXCR4) and activation of miRNAs. In conclusion, MM cells through the release of EVs, by acting directly on normal HSPCs, negatively dysregulate normal hematopoiesis, and this could have important therapeutic implications.

CD24 and IgM Stimulation of B Cells Triggers Transfer of Functional B Cell Receptor to B Cell Recipients Via Extracellular Vesicles

Extracellular vesicles (EVs) are membrane-encapsulated nanoparticles that carry bioactive cargo, including proteins, lipids, and nucleic acids. Once taken up by target cells, EVs can modify the physiology of the recipient cells. In past studies, we reported that engagement of the glycophosphatidylinositol-anchored receptor CD24 on B lymphocytes (B cells) causes the release of EVs. However, a potential function for these EVs was not clear. Thus, we investigated whether EVs derived from CD24 or IgM-stimulated donor WEHI-231 murine B cells can transfer functional cargo to recipient cells. We employed a model system where donor cells expressing palmitoylated GFP (WEHI-231-GFP) were cocultured, after stimulation, with recipient cells lacking either IgM (WEHI-303 murine B cells) or CD24 (CD24 knockout mouse bone marrow B cells). Uptake of lipid-associated GFP, IgM, or CD24 by labeled recipient cells was analyzed by flow cytometry. We found that stimulation of either CD24 or IgM on the donor cells caused the transfer of lipids, CD24, and IgM to recipient cells. Importantly, we found that the transferred receptors are functional in recipient cells, thus endowing recipient cells with a second BCR or sensitivity to anti-CD24-induced apoptosis. In the case of the BCR, we found that EVs were conclusively involved in this transfer, whereas in the case in the CD24 the involvement of EVs is suggested. Overall, these data show that extracellular signals received by one cell can change the sensitivity of neighboring cells to the same or different stimuli, which may impact B cell development or activation.

Mycosis fungoides-derived exosomes promote cell motility and are enriched with microRNA-155 and microRNA-1246, and their plasma-cell-free expression may serve as a potential biomarker for disease burden

BACKGROUND

Literature regarding exosomes as mediators in intercellular communication to promote progression in mycosis fungoides (MF) is lacking.

OBJECTIVES

To characterize MF-derived exosomes and their involvement in the disease.

METHODS

Exosomes were isolated by ultracentrifugation from cutaneous T-cell lymphoma (CTCL) cell lines, and from plasma of patients with MF and controls (healthy individuals). Exosomes were confirmed by electron microscopy, NanoSight and CD81 staining. Cell-line exosomes were profiled for microRNA array. Exosomal microRNA (exomiRNA) expression and uptake, and plasma-cell-free microRNA (cfmiRNA) were analysed by reverse-transcriptase quantitative polymerase chain reaction. Exosome uptake was monitored by fluorescent labelling and CD81 immunostaining. Migration was analysed by transwell migration assay.

RESULTS

MyLa- and MJ-derived exosomes had a distinctive microRNA signature with abundant microRNA (miR)-155 and miR-1246. Both microRNAs were delivered into target cells, but only exomiR-155 was tested, demonstrating a migratory effect on target cells. Plasma levels of cfmiR-1246 were significantly highest in combined plaque/tumour MF, followed by patch MF, and were lowest in controls (plaque/tumour > patch > healthy), while cfmiR-155 was upregulated only in plaque/tumour MF vs. controls. Specifically, exomiR-1246 (and not exomiR-155) was higher in plasma of plaque/tumour MF than in healthy controls. Plasma exosomes from MF but not from controls increased cell migration.

CONCLUSIONS

Our findings show that MF-derived exosomes promote cell motility and are enriched with miR-155, a well-known microRNA in MF, and miR-1246, not previously reported in MF. Based on their plasma expression we suggest that they may serve as potential biomarkers for tumour burden.

Circulating Exosomal MiR-107 Restrains Tumorigenesis in Diffuse Large B-Cell Lymphoma by Targeting 14-3-3η

Exosomes, nanometer-sized membranous vesicles in body fluids, have emerged as promising non-invasive biomarkers for cancer diagnosis. However, the function of exosomes in diffuse large B-cell lymphoma (DLBCL) remains elusive. This study aimed to investigate the role of exosomal miR-107 in lymphomagenesis and explore its clinical significance. In this study, decreased exosomal miR-107, miR-375-3p, and upregulated exosomal miR-485-3p were detected in the plasma of DLBCL patients and showed potential diagnostic value. Downregulated miR-107 expression was associated with advanced Ann Arbor stage, high IPI score, LDH, and β₂-MG level in DLBCL patients. Overexpression of miR-107 by miR-107 Agomir significantly abrogated cell proliferation, induced apoptosis, and inhibited cell invasion in vitro, and repressed tumor growth in vivo. Moreover, the downregulation of miR-107 went in the opposite direction. The target genes of miR-107 were mainly enriched in the PI3K-Akt, Hippo, and AMPK signaling pathways. Notably, upregulated 14-3-3η (YWHAH) was suppressed by miR-107 in DLBCL, suggesting that miR-107 may restrain tumorigenesis by targeting 14-3-3η. In summary, this study unveils the function of miR-107 in lymphomagenesis, highlighting its potential as a diagnostic and prognostic indicator and as a new therapeutic target in the management of DLBCL.

The "Vesicular Intelligence" Strategy of Blood Cancers

Blood cancers are a heterogeneous group of disorders including leukemia, multiple myeloma, and lymphoma. They may derive from the clonal evolution of the hemopoietic stem cell compartment or from the transformation of progenitors with immune potential. Extracellular vesicles (EVs) are membrane-bound nanovesicles which are released by cells into body fluids with a role in intercellular communication in physiology and pathology, including cancer. EV cargos are enriched in nucleic acids, proteins, and lipids, and these molecules can be delivered to target cells to influence their biological properties and modify surrounding or distant targets. In this review, we will describe the “smart strategy” on how blood cancer-derived EVs modulate tumor cell development and maintenance. Moreover, we will also depict the function of microenvironment-derived EVs in blood cancers and discuss how the interplay between tumor and microenvironment affects blood cancer cell growth and spreading, immune response, angiogenesis, thrombogenicity, and drug resistance. The potential of EVs as non-invasive biomarkers will be also discussed. Lastly, we discuss the clinical application viewpoint of EVs in blood cancers. Overall, blood cancers apply a ‘vesicular intelligence’ strategy to spread signals over their microenvironment, promoting the development and/or maintenance of the malignant clone.

Clinical relevance of extracellular vesicles in hematological neoplasms: from liquid biopsy to cell biopsy

In the era of precision medicine, liquid biopsy is becoming increasingly important in oncology. It consists in the isolation and analysis of tumor-derived biomarkers, including extracellular vesicles (EVs), in body fluids. EVs are lipid bilayer-enclosed particles, heterogeneous in size and molecular composition, released from both normal and neoplastic cells. In tumor context, EVs are valuable carriers of cancer information; in fact, their amount, phenotype and molecular cargo, including proteins, lipids, metabolites and nucleic acids, mirror nature and origin of parental cells rendering EVs appealing candidates as novel biomarkers. Translation of these new potential diagnostic tools into clinical practice could deeply revolutionize the cancer field mainly for solid tumors but for hematological neoplasms, too.

Characterization of miRNAs in Extracellular Vesicles Released From Atlantic Salmon Monocyte-Like and Macrophage-Like Cells

Cell-derived extracellular vesicles (EVs) participate in cell-cell communication via transfer of molecular cargo including genetic material like miRNAs. In mammals, it has previously been established that EV-mediated transfer of miRNAs can alter the development or function of immune cells, such as macrophages. Our previous research revealed that Atlantic salmon head kidney leukocytes (HKLs) change their morphology, phagocytic ability and miRNA profile from primarily “monocyte-like” at Day 1 to primarily “macrophage-like” at Day 5 of culture. Therefore, we aimed to characterize the miRNA cargo packaged in EVs released from these two cell populations. We successfully isolated EVs from Atlantic salmon HKL culture supernatants using the established Vn96 peptide-based pull-down. Isolation was validated using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. RNA-sequencing identified 19 differentially enriched (DE) miRNAs packaged in Day 1 versus Day 5 EVs. Several of the highly abundant miRNAs, including those that were DE (e.g. ssa-miR-146a, ssa-miR-155 and ssa-miR-731), were previously identified as DE in HKLs and are associated with macrophage differentiation and immune response in other species. Interestingly, the abundance relative of the miRNAs in EVs, including the most abundant miRNA (ssa-miR-125b), was different than the miRNA abundance in HKLs, indicating selective packaging of miRNAs in EVs. Further study of the miRNA cargo in EVs derived from fish immune cells will be an important next step in identifying EV biomarkers useful for evaluating immune cell function, fish health, or response to disease.