Exosomal Fraction Research Articles

P2586Cardiac progenitor cell exosome-associated periostin triggers reentry of cardiomyocytes into cell cycle

Abstract Introduction Nanovesicles known as exosomes (Exo) from cardiac-derived progenitor cells (CPCs) are cardioprotective and improve cardiac function after myocardial infarction; however the mechanisms of benefit are incompletely understood, especially with respect to endogenous cardiomyocytes (CM) renewal. Periostin (POSTN), a secreted extracellular matrix protein, is emerging as a matricellular factor that can trigger CM proliferation. We have identified POSTN as a protein secreted by CPC and enriched in their exosomal fraction. Purpose We sought to determine whether Exo-CPC can induce proliferation of CM and to explore the role of exosomal POSTN in inducing reentry of CM into the cell cycle. Methods Exo were isolated from CPC condioned medium by density gradient ultracentrifugation. Fractions were analyzed by Western blotting for the presence of POSTN as well as specific Exo markers (TSG101, CD9). POSTN-depleted Exo (ExoCPC_SiPOSTN) were obtained by transfecting CPC with specific siRNA. Active DNA synthesis was assessed on primary cell culture of rat neonatal CM by EdU incorporation. H9C2 cardiomyocytic cells were used to assess by real-time RT-PCR the expression of downstream genes Hippo/Yes-associated protein (YAP) signaling pathway. Results Western blotting analysis allowed to specifically determining the presence of Exo markers and POSTN in the different fractions of secreted vesicles. Smaller fractions (f1-f3) have the highest amount of TSG101 and CD9 as well as POSTN, thus suggesting that CPC secrete POSTN associated with Exo. The silencing of POSTN in cells resulted in a 60% reduction of Exo-associated POSTN compared to naïve ExoCPC. ExoCPC but not ExoCPC_SiPOSTN, were able to increase phosporylation of AKT and ERK in H9C2 cells. YAP phosporylation and its degradation was decreased resulting in the activation of the downstream gene AurBKinase. By real-time PCR, AurBKinase expression was increased by 2.6 folds with ExoCPC and 1.5 folds with ExoCPC_SiPOSTN compared to cells not exposed to Exo. ExoCPC were able to increase 1.5 fold EdU incorporation in cardiac troponin-positive primary rat CM. ExoCPC_SiPSTN did not affect proliferation. Schematic figure Conclusion These results suggest that POSTN may promote cardiomyocyte proliferation through the direct activation of the AKT/ERK/Hippo-Yap pathway. Exosomes released by CPC are an important source of POSTN and may have a potential for promoting cardiac regeneration. Acknowledgement/Funding This work has been supported by The Swiss National Science Foundation under grant n° 310030_169194

Rasal2 suppresses breast cancer cell proliferation modulated by secretory autophagy.

Rasal2, a Ras-GTPase-activating protein (RasGAP), is a tumor suppressor in Luminal B breast cancer, frequently metastatic and recurrent. Exosomes (Exos) are small membrane vesicles secreted by various cell types, including tumor cells, recognized as vehicles for cell-to-cell communication. Our study aimed to investigate whether Rasal2 regulates breast cancer cell growth via affecting this process. In this paper, we described that Rasal2 knockout (KO) in MCF-7 cells enhanced exosomal release and increased autophagy-related proteins in exosomal fraction, while attenuated by exosome release inhibitor GW4869. Moreover, MCF-7 cells with chloroquine (CQ) treatment boosted Rasal2 KO-induced secretory autophagy. In addition, we presented that exosomes derived from KO MCF-7 cells (KO-exo) significantly promoted breast cancer cell proliferation compared to those from MCF-7 cells transfected with an empty crispr-cas9 plasmid serving as controls (sgNT-exo); however, exosomes purified from KO MCF-7 cells co-cultured with 3-methyladenine ((3-MA + KO)-exo)/CQ ((CQ + KO)-exo) dramatically inhibited/facilitated MCF-7 cell proliferation in contrast to KO-exo group, separately. In conclusion, our findings revealed a new mechanism of Rasal2 in the regulation of breast cancer cell proliferation via autophagy-exo-mediated pathway.

Inhibition of UCH-L1 Deubiquitinating Activity with Two Forms of LDN-57444 Has Anti-Invasive Effects in Metastatic Carcinoma Cells.

Normally ubiquitin C-terminal hydrolase L1 (UCH-L1) is expressed in the central nervous and reproductive systems of adults, but its de novo expression has been detected in many human cancers. There is a growing body of evidence that UCH-L1 de-ubiquitinating (DUB) activity plays a major pro-metastatic role in certain carcinomas. Here we tested anti-metastatic effects of the small-molecule inhibitor of UCH-L1 DUB activity, LDN-57444, in cell lines from advanced oral squamous cell carcinoma (OSCC) as well as invasive nasopharyngeal (NP) cell lines expressing the major pro-metastatic gene product of Epstein–Barr virus (EBV) tumor virus, LMP1. To overcome the limited aqueous solubility of LDN-57444 we developed a nanoparticle formulation of LDN-57444 by incorporation of the compound in polyoxazoline micellear nanoparticles (LDN-POx). LDN-POx nanoparticles were equal in effects as the native compound in vitro. Our results demonstrate that inhibition of UCH-L1 DUB activity with LDN or LDN-POx inhibits secretion of exosomes and reduces levels of the pro-metastatic factor in exosomal fractions. Both forms of UCH-L1 DUB inhibitor suppress motility of metastatic squamous carcinoma cells as well as nasopharyngeal cells expressing EBV pro-metastatic Latent membrane protein 1 (LMP1) in physiological assays. Moreover, treatment with LDN and LDN-POx resulted in reduced levels of pro-metastatic markers, a decrease of carcinoma cell adhesion, as well as inhibition of extra-cellular vesicle (ECV)-mediated transfer of viral invasive factor LMP1. We suggest that soluble inhibitors of UCH-L1 such as LDN-POx offer potential forms of treatment for invasive carcinomas including EBV-positive malignancies.

Serum microRNA profiles in patients with autosomal dominant polycystic kidney disease show systematic dysregulation partially reversible by hemodialysis

IntroductionThe impact of autosomal dominant polycystic kidney disease (ADPKD) on serum microRNAs (miRNA) is unknown.Material and methodsFor profiling experiment we recruited 30 patients from three equinumerous groups: controls, ADPKD and ADPKD on hemodialysis. From the last group extra samples were collected for in pre-/postdialysis analysis. Additionally, 23 healthy volunteers were used for selected biomarker verification. Real-time PCR arrays were used for quantification of 752 miRNAs. Validation of selected miRNAs was performed in total RNA extracted from the serum and the exosomal fraction in pre-/postdialysis samples.ResultsIn total, 37 significant circulating miRNAs were found to differ between ADPKD patients and controls. In validation, 3 miRNAs with the highest fold change in comparison of dialyzed vs non-dialyzed patients (miR-532-3p, miR-320b, miR-144-5p) were not significantly altered by hemodialysis and from the top down-regulated ones, miR-27a-3p was significantly lower after dialysis in both total and exosomal fractions, miR-20a-5p was down-regulated in the exosomal fraction and miR-16-5p was unaltered by hemodialysis. MiR-16-5p was selected as the best circulating biomarker of ADPKD. Circulating representatives of the miR-17 family sharing the same seed region (miR-20a-5p, miR-93-5p and miR-106a-5p) showed significantly lower expression among dialyzed vs. non-dialyzed patients and their exosomal fraction dropped after hemodialysis.ConclusionsThe serum miRNAs among ADPKD patients differ substantially depending on the stage of CKD. The exosomal fraction of miRNA was more affected by dialysis than the total one. There was a common pattern of down-regulation for circulating miR-17 family members sharing the same seed region.

Abstract 3981: Exosomal microRNA profiles in peritoneal fluids as a therapeutic biomarker for peritoneal metastasis of gastric cancer

Abstract Objectives: Peritoneal metastasis (PM) frequently occurs in patients with gastric cancer and has poor prognosis even with systemic chemotherapy. Intraperitoneal chemotherapy (IPC) using paclitaxel (PTX) combined with systemic chemotherapy has demonstrated a remarkable clinical efficacy for gastric cancer with PM. However, there is no reliable biomarker to reflect the response of peritoneal lesions as well as to predict the outcome of the patients receiving IPC. Although peritoneal fluids are considered to contain many factors derived from disseminated tumor cells in peritoneal cavity, little information is available so far. In this study, we examined exosomal miRNA profiles derived from peritoneal fluids in patients with gastric cancer and explored possible biomarkers useful for IPC of the patients with PM. Methods: Peritoneal fluids were collected from 2 groups; with or without PM. Peritoneal fluids were obtained either laparoscopically, during open surgery or from subcutaneous infusion port connected to an intraperitoneal catheter. Exosomal fractions were isolated using ultracentrifuge method (150,000 xg, 70 min, 4°C) and the presence of exosome was confirmed with nanotracking analysis. Total RNA including small RNA was extracted from exosomal fractions and expression analyses of miRNAs were performed using RT-PCR. Results: At first, we comprehensively analyzed the expression of miRNAs between 11 samples with PM and 14 samples without PM and identified 11 miRNAs which showed particularly different expression pattern between the 2 groups. Among them, 4 miRNAs (miR-21-5p,miR-223-3p, miR-342-3p and miR-92a-3p) were selected and further analysed using 51 samples derived from the peritoneal fluids of gastric cancer. Expression of these 4 miRNAs were significantly up-regulated in samples with PM which was consistent with formeranalysis. Moreover, expression of miR-21-5p was significantly upregulated in in samples fromT4 tumor (invaded serosa or adjacent structure) as compared with those from T1 to T3 tumor. Conclusion: We identified several dysregulated exsosomal miRNAs derived from peritoneal fluids of the patients with PM from gastric cancer, which were supposed to reflect the tumor burden on peritoneum. Exosomal miRNA profiles might be useful biomarkers to determine the presence of PM as well as the response to IPC. Citation Format: Hideyuki Ohzawa, Akira Saito, Yuko Kumagai, Hironori Yamaguchi, Yoshinori Hosoya, Naohiro Sata, Joji Kitayama. Exosomal microRNA profiles in peritoneal fluids as a therapeutic biomarker for peritoneal metastasis of gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3981.

Abstract 3091: Effects of melanoma cell-derived exosomes in melanoma patients’ plasma on immune cell functions

Abstract Background: Exosomes are a subset of small (30-150nm) extracellular vesicles (EVs) of the endocytic origin that mediate intercellular communication in health and disease. Exosomes are actively produced by tumor cells, circulate freely in body fluids and carry messages that alter functions of normal cells in the tumor microenvironment (TME), including immune cell functions. The ability of melanoma exosomes to reprogram immune cell functions might contribute to disease progression. Methods: To evaluate effects of melanoma cell-derived exosomes (MTEX) on human immune cell subsets, we isolated exosomes from plasma of 12 patients with melanoma and separated MTEX from non-MTEX by immune capture using anti-CSPG4 mAb on beads. These exosome fractions, and exosomes from plasma of 6 normal donors used as controls (NC), were studied by on-bead flow cytometry to quantify their surface protein profiles and in co-incubation assays with immune cell subsets for functional attributes. Phenotypic and functional profiles of MTEX and non-MTEX were compared. Results & Conclusion: MTEX were enriched (p<0.005)( in FasL and TRAIL, induced apoptosis of CD8+T cells, down-regulated CD69 expression levels on T cells and inhibited their proliferation (all p<0.0005). MTEX also interfered with NK cell functions (p<0.001). Non-MTEX were enriched (P<0.005) in co-stimulatory proteins, CD40L, OX40L, OX40 and, similar to exosomes of NC, were not immunosuppressive. Thus, MTEX, present in excess in plasma of patients with metastatic melanoma, mediate immune suppression and contribute to immune escape of the tumor. Citation Format: Priyanka Sharma, Brenda Diergaarde, Soldano Ferrone, John M. Kirkwood, Theresa L. Whiteside. Effects of melanoma cell-derived exosomes in melanoma patients’ plasma on immune cell functions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3091.

Exosomal Transport and Progression of Neurodegeneration in Amyotrophic Lateral Sclerosis

In recent years, increasing attention has been paid to the study of the communication between cells in the nervous system with extracellular vesicles, including exosomes, under physiological and pathological conditions. Exosomes are small extracellular vesicles ranging in size from 50 to 200 nm, which are secreted by most cell types and provide communication between cells by transporting proteins, lipids, and RNA to target cells. In addition, they perform antigen-presenting and signaling functions and can act as anti-inflammatory or pro-inflammatory agents. Data has been accumulated on the role of exosomes in the development of the pathological process in nervous system diseases, primarily brain tumors and neurodegenerative diseases. Amyotrophic lateral sclerosis (ALS) is a progressive fatal disease in which the selective death of motor neurons occurs. ALS inevitably leads to disruption of the functioning of muscles that perform vital functions and death of the patient in several years. The mechanisms that underlie the death of motor neurons and the spread of the pathological process are not clear. It is impossible to predict the rate of disease progression and the probable life expectancy of the patient. The most important mechanisms of AS development include the accumulation of aggregates of pathological proteins in neuronal bodies and impaired RNA metabolism. The possibility of transfer of pathological proteins and other molecules associated with the development of ALS through exosomes has been proven. This review provides an overview of studies on exosomes in different CNS diseases. The mechanisms of progression and spreading of the neurodegenerative process in ALS are discussed, focusing on the roles that exosomes and potential biomarkers of the disease in the exosomal fraction play.

Abstract 2225: Exosomes in plasma for protein based cancer biomarkers: A clinical research tool using UHPLC-MS

Abstract Introduction: Exosomes have been used as a source of biomarkers in diagnostics for many diseases, including cancer, and are now being used as therapeutic delivery systems. To date, the most efficient method for isolating exosomes from serum or plasma samples has been to use a size exclusion, chromatography (SEC) based isolation. The conditions of the SEC separation can be modified to yield extracellular vesicles of different sizes and diagnostic value. Apoptotic bodies, 50-5000nm, microvesicles, 50-1000nm, and exosomes, 30-120nm, all have different diagnostic and targeted applications. Here, we show a routine and robust method for the isolation and monitoring of proteins in exosomes isolated from plasma samples. The methods and conditions used here are focused on rapidly providing a high yield of exosome vesicles in a monodisperse 40nm size range from a plasma sample. Materials and methods: K2EDTA plasma samples from donor disease and control groups were collected with IRB approval. All SEC columns and reagents for exosome isolation were obtained as a kit (NX Prenatal, Houston, TX). The 40nm exosome fraction from the column was lysed, the proteins reduced, alkylated and digested with trypsin; the subsequent peptides were analyzed by ultra-high performance liquid chromatography (Vanquish Horizon, ThermoFisher Scientific), tandem mass spectrometry (Q-Exactive, ThermoFisher Scientific), to quantify and identify greater than 500 proteins from exosomes, isolated from a single plasma sample, in a 1 hour method. Subsequent isolations of 40nm exosome fractions were labeled with a sulfo-NHS-biotin linker, followed by lysis and enrichment with streptavidin columns, and an identical LC-MS analysis to obtain quantitative analysis of the surface membrane protein contents on the exosomes. Results: Raw data was analyzed using the label-free quantitation module in Proteome Discoverer (Thermofisher Scientific). Peptide peak areas from three technical replicate runs were used to ascertain the reproducibility of the method across both normal and disease samples. Membrane protein extracts LC-MS data was further grouped by Protein Center (ThermoFisher Scientific) by cell type and tissue of origin. Conclusions: The methods shown here provide a robust and efficient platform for 40nm exosome isolation from human plasma samples, and quantitative analysis of the protein content thereof for the purposes of biomarker discovery, quantification and screening purposes. Citation Format: David A. Sarracino, Xiaolei Xie, Courtney E. Martel, Shen Luan, Kevin Rosenblatt. Exosomes in plasma for protein based cancer biomarkers: A clinical research tool using UHPLC-MS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2225.

Elevated exosomal lysyl oxidase like 2 is a potential biomarker for head and neck squamous cell carcinoma.

The secretory enzyme lysyl oxidase like 2 (LOXL2) is speculated to contribute to tumor progression through its functions in the remodeling of extracellular matrix and epithelial-mesenchymal transition. We previously identified elevated expression of LOXL2 in metastatic human head and neck squamous cell carcinoma (HNSCC) cells in a mouse lymph node metastases model. Here we performed a case series study examining LOXL2 expression levels in human serum from HNSCC patients to evaluate whether LOXL2 is worth evaluation in a large cohort study. LOXL2 protein levels in three serum samples from HNSCC patients were assessed by immunoblotting and LOXL2 tissue expression was examined in one human tongue squamous cell carcinoma (SCC) tissue by immunohistochemistry as a representative of HNSCC tissue. Serum samples were further fractionated in exosomes and supernatants by ultracentrifugation, which were then subjected to immunoblot and in vitro LOX activity analyses. Exosomal LOXL2 levels of 36 serum samples from HNSCC patients and seven healthy volunteers were measured using polymer sedimentation exosome preparation followed by ELISA measurement and subjected to statistical analyses. Immunoblot analyses revealed that LOXL2 was present in serum exosomal fractions from three HNSCC patients, and we observed approximately threefold higher levels of LOXL2 in HNSCC patients compared with three healthy volunteers. Immunohistochemical LOXL2 staining was detected in HNSCC cells in addition to non-cancerous lipid tissues and some muscles in human tongue HNSCC tissue. Further measurements of exosomal LOXL2 by ELISA showed over ninefold higher mean LOXL2 levels in patients compared with controls. Statistical analysis revealed a correlation between elevated serum exosomal LOXL2 levels and low-grade, but not high-grade, HNSCC. Our case series study that elevated serum exosomal LOXL2 levels exhibited a correlation with low-grade HNSCCs. A follow-up large cohort clinical study will be required to determine the potential clinical utility of LOXL2 as a new biomarker and/or therapy target for HNSCCs. 4 Laryngoscope, 130:E327-E334, 2020.

Mesenchymal Stem/Stromal Cell Therapy for Bronchopulmonary Dysplasia in the Neonatal Intensive Care Unit

Clinical trials of mesenchymal stem/stromal cell (MSC) therapy for bronchopulmonary dysplasia (BPD) are already underway. A thorough understanding of the preclinical work that underpins these trials is critical for neonatal practitioners to properly evaluate them. The more significant advances have been in investigating the mechanisms of action by which MSCs are thought to ameliorate BPD, and the recognition that this therapeutic effect is largely contained within the non-cellular exosome fraction of MSCs. In rodent hyperoxia models of BPD, MSCs have a pro-angiogenic effect mediated largely by vascular endothelial growth factor (VEGF) and shift the balance of endogenous lung cells from a pro-inflammatory to a pro-healing phenotype. MSC-derived exosomes can recapitulate these effects.

A High Efficient Method to Isolate Exosomes from Small Intestinal Epithelium.

The intestinal epithelium is an important receptor that is not only exposed to nutrients but also to pathogens, such as ingested toxins, bacterial flora, and their metabolites. The sensory information is communicated to extensive endocrine, neural, immune systems, and the exosomes acts as carriers of communication from cell-to-cell. Isolation of exosomes from small intestinal epithelium remains more complex to obtain as a source of exosomes, as it contains varying proportions of exosomes derived from many different cells. Current studies on exosomes have been largely performed using supernatants of cultured cells. This is because, in a cell culture, the origin of exosomes can be determined and isolation of exosomes devoid of 'contaminating' proteins, lipids, and sugars involves relatively simple composition of most culture media facilitates. However, this is hard to achieve in intestinal epithelial cells (IECs) due to several technical issues, including recapitulation of in vivo physiology, operational simplicity, culture stability over time, and assay throughput. Meanwhile, separation of exosomes from a specific cell type remains to be a considerable problem, as the isolated supernatant exosomal fraction may represent only a small fraction of the total instead of reflecting the overall situation. Herein, we proposed an efficient protocol for enrichment of exosomes from the interstitial space of small intestinal epithelium. This method maintains the integrity of the vesicles as well as their contents. Also, it may help to better understand the properties of exosomes and explore their role in cell-to-cell communication of small intestinal epithelium.

Circulating exosomal and Argonaute-bound microRNAs in preeclampsia

IntroductionmicroRNAs (miRNAs) play important role in the regulation of placental development, and abnormal miRNA expression is associated with preeclampsia (PE). miRNAs are released from trophoblast cells to maternal blood flow, where they are highly stable, being encapsulated inside extracellular vesicles, like exosomes or bound to Argonaute proteins. In PE, placental dysfunction leads to aberrant extracellular miRNA secretion. hsa-miR-210 is a hypoxia-sensitive miRNA found to be upregulated in PE; however, it is unknown whether it is the cause or the consequence of the disease. ObjectiveOur aim was to analyze the expression of several miRNAs, including hsa-miR-210 in placenta, exosome and Ago-bound fractions comparing normal (N) and PE pregnancies. We performed in vitro analyses of extracellular hsa-miR-210 secretion of trophoblast cell cultures (of villous and extravillous origin) under hypoxic condition. MethodsPE and N placenta samples were collected from C-sections, and blood samples were drawn from each pregnant woman in the third trimester. HTR-8 and JAR cell lines were cultured in exosome-free media and treated with hypoxia-mimetic agents. Exosome and Ago-bound fractions were isolated by membrane affinity spin column method from plasma and cell media. Short RNAs were extracted from exosomes and vesicle-free fractions, and total-RNA was isolated from the placenta samples. The RNA purity and concentration were measured by spectrophotometry. Expression analysis was carried out by qPCR with specific primers to target and reference miRNAs. ResultsThe level of hsa-miR-210 was significantly higher in PE placentas, which could cause a minor increase of exosomal and a high elevation of Ago-bound miR-210 in circulation. Hypoxia lead to intracellular hsa-miR-210 upregulation in trophoblast cell lines. In extravillous cell (HTR-8) media, only the level of exosomal hsa-miR-210 was increased but no change in Ago-bound hsa-miR-210 level was observed. In contrast, in villous cell (JAR) media, the level of exosomal hsa-miR-210 was increased and enhanced release of Ago-bound hsa-miR-210 was also observed. ConclusionBased on our data, we postulate that in PE, exosomal hsa-miR-210 is secreted actively from the trophoblast, and by intercellular communication, it may have a role in disease etiology. In addition, there is a passive release of Ago-bound hsa-miR-210 into the circulation, which may represent by-products of cell-death and is thereby a possible consequence of the disease.

Characterization of single microvesicles in plasma from glioblastoma patients.

Extracellular vesicles (EV) are shed by tumor cells but little is known about their individual molecular phenotypes and heterogeneity. While exosomes have received considerable attention, much less is known about larger microvesicles. Here we profile single microvesicles (MV) and exosomes from glioblastoma (GB) cells and MV from the plasma of patients. EV secreted from mouse glioma GL261 and human primary GBM8 cell lines as well as from the plasma of 8 patients with diagnoses of GB and 2 healthy controls were isolated and processed for single vesicle analysis. EV were immobilized on glass slides and the heterogeneity of vesicle and tumor markers were analyzed at the single vesicle level. We show that (i) MV are abundant, (ii) only a minority of MV expresses putative MV markers, and (iii) MV share tetraspanin biomarkers previously thought to be diagnostic of exosomes. Using MV capture and staining techniques that allow differentiation of host cell and GB-derived MV we further demonstrate that (i) tumoral MV often present as <10% of all MV in GB patient plasma, and (ii) there is extensive heterogeneity in tumor marker expression in these tumor-derived MV. These results indicate that single MV analysis is likely necessary to identify rare tumoral MV populations and the single vesicle analytical technique used here can be applied to both MV and exosome fractions without the need for their separation from each other. These studies form the basis for using single EV analyses for cancer diagnostics.

Extracellular Microvesicle Cytokines Secreted from Bone Marrow Mesenchymal Cells Mediate Proliferative and Survival Advantage in Acute Myeloid Leukaemia

BackgroundHaematopoietic stem cell transplantation is still the most effective anti-leukaemic therapy for AML treatment for a large number of patients, but a significant proportion of these will relapse post-transplant and the probability of long term survival is low.The bone marrow microenvironment has been implicated as a major contributor to chemotherapy resistance and relapse through mediating interactions between residual haematopoietic stem cells (HSC), leukaemic stem cells (LSC) and mesenchymal stem cells (MSC) which have been shown to support and maintain the leukaemic niche.Interactions within this malignant niche can be facilitated by exosomes, microvesicles secreted by multiple cell types that function as delivery vehicles of cargo consisting of mRNA, DNA, miRNA, enzymes and cytokines. Exosomes have become the focus of much interest in recent years as there is increasing evidence that they are involved in cancer progression and resistance to therapy, however the role of secreted exosomes in mediating cell communication in the post-transplant microenvironment is relatively unknown.ResultsStromal MSC cultures were derived from diagnostic, post-allogeneic bone marrow transplant (BMT) AML patients (AML-MSC, n=20) and normal bone marrow donors (NBM-MSC, n=5). MSC supernatants were collected from monolayers at passage 3 and exosome preparations were extracted and quantified using NanoSight analysis and western blotting for CD81 and CD63 exosome membrane proteins.Results show that exosome particle number and protein content was significantly increased in diagnostic AML-MSCs samples compared to normal and post-BMT samples (p=0.0028). miRNA yield was also found to be significantly higher in diagnostic samples compared to normal and post-BMT marrow MSC production (p=0.0017).Ex vivo co-culture assays using sucrose cushion derived functional exosome preparations from primary AML-MSCs revealed an exosome induced proliferative effect when cultured with primary AML blasts (p<0.05) and a significant protection against TKI treated co-cultures (n=7, p<0.001) confirming the pro-leukaemic effects of AML-MSC derived exosomes, these effects were absent in NBM-MSC derived exosome preparations. Within stromal co-cultures the addition of exosomes exerted a significantly increased proliferative effect compared to stroma alone demonstrating the additional support exosomes provide (p=0.0079)Secreted cytokine profiling was undertaken using a Luminex bead capture array panel of more than 100 secreted targets in paired AML-MSC exosome and total supernatants.AML-MSC exosome profiles were compared to NBM-MSC fractions and contained significantly higher levels of several inflammatory/angiogenic chemokines including MMP-1 (p=0.0286), CXCL2 (p= 0.0497) and CXCL8 IL-8 (p=0.0284) all of which have been previously associated with poor prognosis in AML. This observation was also reflected in the total supernatant cytokine profile.Within the exosomal fractions the following targets showed increased levels compared to their corresponding supernatant; MMP-3 involved in chemokine signalling, IL-1ra and TRAIL both involved in immunological response and implicated in AML blast proliferation. Profiles of the post-BMT exosomal fraction followed the signature of diagnostic-MSC fractions, indicating the persistence of a diseased phenotype.These results demonstrate significant differences in the exosome production and content of AML-MSC compared to NBM-MSC and whilst both NBM and AML derived MSC exosomes are capable of protecting against drug resistance in co-culture, AML-MSC exosomes produce a considerably stronger proliferative drive and this in part may be mediated through a leukaemic specific MMP/pro-angiogenic signalling axis which has the potential to remodel the surrounding microenvironment. Targeting these pathways warrants further investigation to determine whether suppression of the leukaemic microenvironment may influence transplant outcome for these patients. DisclosuresOttmann:Amgen: Consultancy; Celgene: Consultancy, Research Funding; Fusion Pharma: Consultancy, Research Funding; Pfizer: Consultancy; Incyte: Consultancy, Research Funding; Takeda: Consultancy; Novartis: Consultancy.

Exosomal proteins constitute an essential part of the human adipose tissue secretome

Adipose tissue is an endocrine organ, secreting various adipokines, either directly or via extracellular vesicles, including exosomes. Exosomes are vesicles of 40–150 nm size that represent a novel concept of biomolecule release. We purified exosomes from isolated primary human preadipocytes differentiated to mature adipocytes. The analyses of these exosomal preparations by LC-MS identified 884 proteins, so called exoadipokines. The comparison of exoadipokines with previously identified human exosome-associated proteins in ExoCarta database show an overlap of 817 proteins, but also revealed 67 proteins not assigned to human exosomes, yet. We further compared all exoadipokines to our previously reported reference secretome of human adipose tissue (http://diabesityprot.org/), finding 212 common proteins, whereas 672 proteins were specific for the exosomal fraction. Bioinformatic analyses revealed that the 212 common proteins can be assigned to all major functions of adipose tissue secreted proteins e.g. molecules involved in fibrotic processes or inflammation. In contrast, the exosome-specific proteins were rather assigned to signaling pathways and membrane-mediated processes. In conclusion, the isolation of exosomes allows to further specify the functionality of adipokines and exoadipokines as part of the adipocyte secretome in signaling and interorgan crosstalk.

Early Exposure to a High-Fat Diet Impacts on Hippocampal Plasticity: Implication of Microglia-Derived Exosome-like Extracellular Vesicles.

Adolescence is a transitional period from childhood to adulthood characterized by puberty and brain maturation involving behavioral changes and environmental vulnerability. Diet is one of the factors affecting brain health, potentially leading to long-lasting effects. Hence, we studied the impact of early exposure (P21-60) to a high-fat diet (HFD) on mouse hippocampus, analyzing inflammation, adult neurogenesis, dendritic spine plasticity, and spatial memory. Glycemia and seric pro-inflammatory IL1β were higher in HFD mice without differences on body weight. In the HFD hippocampus, neuroinflammation was evidenced by Iba1+ cells reactivity together with a higher expression of TNFα and IL1β while the neurogenic capability in the dentate gyrus was strongly reduced. We found a predominance of immature Dil-labeled dendritic spines from CA1 neurons along with diminished levels of the scaffold protein Shank2, suggesting a defective connectivity. Moreover, the HFD group exhibited spatial memory alterations. To elucidate whether microglia could be mediating HFD-associated neuronal changes, the lipotoxic context was emulated by incubating primary microglia with palmitate, a saturated fatty acid present in HFD. Palmitate induced a pro-inflammatory profile as shown by secreted cytokine levels. The isolated exosome fraction from palmitate-stimulated microglia induced an immature dendritic spine phenotype in primary GFP+ hippocampal neurons, in line with the in vivo findings. These results provide novel data concerning microglia to neuron communication and highlight that fat excess during a short and early period of life could negatively impact on cognition and synaptic plasticity in a neuroinflammatory context, where microglia-derived exosomes could be implicated. Graphical Abstract ᅟ.

Molecular mechanisms of biogenesis of apoptotic exosome-like vesicles and their roles as damage-associated molecular patterns

Recent research has led to contradictory notions regarding the conventional theory that apoptotic cell death can evoke inflammatory or immunogenic responses orchestrated by released damage-associated patterns (DAMPs). By inducing IL-1β from bone marrow-derived macrophages in an effort to determine the inflammatory mediators released from apoptotic cells, we found that exosomal fractions called "apoptotic exosome-like vesicles" (AEVs) prepared from apoptotic-conditioned medium were the main inflammatory factors. These AEVs showed characteristics of exosomes in their size, density, morphology, and protein expression but had unique marker proteins, sphingosine-1-phosphate receptors 1 and 3 (S1PR1 and 3). Their biogenesis was completely dependent on cellular sphingosine-1-phosphate (S1P)/S1PRs signaling from multiple fine spindles of plasma membrane accompanied by F-actin, S1PR1, S1PR3, and CD63 at the early apoptotic phase and progressing to the maturation of F-actin-guided multivesicular endosomes mediated by Gβγ subunits of S1PRs downstream. S1P-loaded S1PRs on AEVs were critical factors for inducing IL-1β via NF-κB transcriptional factor and p38 MAPK, possibly through the RHOA/NOD2 axis, in differentiating macrophages. The AEVs induced genes of proinflammatory cytokines, chemokines, and mediators in both in vitro and in vivo models. In conclusion, AEVs could be key inflammatory mediators, acting as DAMPs that could explain the pathogeneses of various chronic inflammations, autoimmune diseases, or cancers in the future.

Plasma Derived Exosomal Biomarkers of Exposure to Ionizing Radiation in Nonhuman Primates.

Exposure to ionizing radiation induces a cascade of molecular events that ultimately impact endogenous metabolism. Qualitative and quantitative characterization of metabolomic profiles is a pragmatic approach to studying the risks of radiation exposure since it provides a phenotypic readout. Studies were conducted in irradiated nonhuman primates (NHP) to investigate metabolic changes in plasma and plasma-derived exosomes. Specifically, rhesus macaques (Macaca mulatta) were exposed to cobalt-60 gamma-radiation and plasma samples were collected prior to and after exposure to 5.8 Gy or 6.5 Gy radiation. Exosomes were isolated using ultracentrifugation and analyzed by untargeted profiling via ultra-performance liquid chromatography mass spectrometry (UPLC-MS) based metabolomic and lipidomic analyses, with the goal of identifying a molecular signature of irradiation. The enrichment of an exosomal fraction was confirmed using quantitative ELISA. Plasma profiling showed markers of dyslipidemia, inflammation and oxidative stress post-irradiation. Exosomal profiling, on the other hand, enabled detection and identification of low abundance metabolites that comprise exosomal cargo which would otherwise get obscured with plasma profiling. We discovered enrichment of different classes of metabolites including N-acyl-amino acids, Fatty Acid ester of Hydroxyl Fatty Acids (FAHFA’s), glycolipids and triglycerides as compared to the plasma metabolome composition with implications in mediation of systemic response to radiation induced stress signaling.

Novel finding of caveolin-2 in apical membranes of proximal tubule and first detection of caveolin-2 in urine: A promising biomarker of renal disease.

Caveolin-2 (Cav-2) is expressed in a variety of cell tissue, and it has also been found in renal tissue. The expression of Cav-2 in proximal tubules is still unclear. The aim of this study was to carry out a complete evaluation of the expression pattern of Cav-2 in rat renal cortex to clarify and deepen the knowledge about the localization of Cav-2 in the proximal tubules and also to evaluate its presence in urine. Male Wistar rats were used to assess Cav-2 expression by Western blot analysis in homogenates, apical, and basolateral membranes from kidney cortex, in lysates and total plasma membranes from renal cortical cell suspensions, in urine, and in urinary exosomes. Cav-2 was clearly expressed in renal cortex homogenates and in both apical and basolateral membranes isolated from kidney cortex, with a greater expression on the former membranes. It was also observed in lysates and in plasma membranes from cortical cell suspensions. Moreover, Cav-2 was found in urine and in its exosomal fraction. These results confirmed the presence of Cav-2 in proximal tubule cells in the kidney of healthy rats, and showed for the first time its expression at the apical membrane of these cells and in urine. Besides, urinary exosomal pathway could be involved in Cav-2 urinary excretion under normal conditions. We observed an increase in the urinary abundance of Cav-2 in two models of acute kidney injury, and thus we proposed the urinary excretion of Cav-2 as a potential biomarker of kidney injury.

194. Connections between circulating argonaute-bound, exosomal and placental miR-210 expression patterns in preeclampsia

Introduction Placenta-specific miRNAs play important role in the regulation of pregnancy, and altered miRNA expression is associated with preeclampsia (PE). In PE, the placental dysfunction causes the abnormal release of extracellular miRNAs to the maternal circulation. These are highly stable, being encapsulated inside vesicles (e.g. exosomes) or bound to Argonaute (Ago) proteins. Previously we showed that the hypoxia-sensitive hsa-mir-210 is elevated in exosome fractions in case of PE. Objective Our aim was to analyze the expression of miR-210 in placenta, exosome and Ago-bound fractions comparing normal (N) and PE pregnancies. We investigated the Ago-bound/exosomal miRNA ratio and compared the expression profiles of the two fractions to the placental miRNA expression. Methods PE and N placenta samples were collected from C-sections and blood samples were drawn from each pregnant in the third trimester. Plasma was separated, and exosomes were isolated by membrane affinity spin column method. Short RNAs were extracted from exosomes and vesicle-free fractions, and total-RNA was isolated from the placenta samples. Expression analysis was carried out by qPCR with specific primers to target and reference miRNAs. Results The level of placental miR-210 was significantly higher in affected samples versus the control group. We found that miR-210 was overrepresented in the Ago-bound fractions compared to exosomal fractions in both groups. The ratio of Ago-bound/exosomal miR-210 was relatively higher in PE compared to N group. The placental miR-210 excess in PE samples could be associated with higher levels of miR-210 in the Ago-fraction. Discussion We investigated placental, exosomal and Ago-bound miR-210 expression profile in PE vs N groups. The level of miR-210 was significantly higher in PE placentas, which could be related to the increase of circulating Ago-bound miR-210. In PE, apart from active exosomal secretion, there is also a large-scale passive release of Ago-bound miRNAs.