Dataset Information

Non-reversible tissue fixation by EDC carbodiimide allows for imaging extracellular vesicles in situ

ABSTRACT: Extracellular vesicles (EVs) are secreted nanosized particles with many biological functions and a broad range of pathological associations. A major technical limitation to understanding the role of EVs in normal and diseased specimens has been the inability to visualize the spatial localization of EVs in tissue microenvironments. Here, we use bovine ocular tissue, the vitreous humor, as a model system to study EV imaging. We show that mammalian tissues crosslinked with conventional formaldehyde solutions result in significant EV loss, with subsequent reduced or negative EV signals; however, EV escape can be prevented by additional fixation with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) that permanently holds these nano-sized particles and allows for visualization of EVs in normal and cancer tissues in situ.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Bos Taurus (bovine)

SUBMITTER: henrik molina

LAB HEAD: Pena, John T.G.

PROVIDER: PXD015234 | Pride | 2019-11-18

REPOSITORIES: Pride

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Publications

Non-reversible tissue fixation retains extracellular vesicles for in situ imaging.

Gupta Mrinali P MP Tandalam Sangeetha S Ostrager Shariss S Lever Alexander S AS Fung Angus R AR Hurley David D DD Alegre Gemstonn B GB Espinal Jasmin E JE Remmel H Lawrence HL Mukherjee Sushmita S Levine Benjamin M BM Robins Russell P RP Molina Henrik H Dill Brian D BD Kenific Candia M CM Tuschl Thomas T Lyden David D D'Amico Donald J DJ Pena John T G JTG

Nature methods 20191111 12

Extracellular vesicles (EVs) are secreted nanosized particles with many biological functions and pathological associations. The inability to image EVs in fixed tissues has been a major limitation to understanding their role in healthy and diseased tissue microenvironments. Here, we show that crosslinking mammalian tissues with formaldehyde results in significant EV loss, which can be prevented by additional fixation with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for visualization of E ...[more]

PMID: 31712780

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Project description:Background: Acute coronary syndromes (ACS) are associated with aberrant gene expression and epigenetic mechanisms. In particular, de novo DNA methylation is typically linked to gene silencing, but its role in heart disease remains not fully understood. Extracellular vesicles (EVs) are active components in cellular communication for their ability to carry a plethora of signalling biomolecules, thus representing a promising new diagnostic/therapeutic approach in cardiovascular diseases (CVDs). Indeed, there is the need of novel biomarkers for ACS prediction and timely detection. Purpose: We hypothesized that specific epigenetic signals can be carried by EVs. In this regard, we isolated and characterized circulating EVs from ACS patients and evaluated their potential role to influence DNA methylation in target cells. Methods: Circulating EVs were recovered, by ultracentrifugation, from plasma samples of 19 ACS patients and 50 healthy subjects (HS). Nanoparticle tracking analysis (NTA) and western blot (WB) were used to confirm the EVs integrity and purity. Peripheral blood mononuclear cells (PBMCs) of volunteer donors were treated with both ACS and HS derived EVs and genomic DNA was extracted to perform epigenome wide analysis through Reduced Representation Bisulfite Sequencing. ShinyGO, PANTHER, and STRING tools were interrogated to perform GO and PPI network analyses. Flow Cytometry, qRT-PCR, and WB analysis were also performed to evaluate and validate both intra-vesicular and intra-cellular signals. Results: Plasma ACS-derived EVs showed a significant up-regulation of DNA methyltransferases (DNMTs) gene expression levels as compared to HS (P<0.001). Specifically, de novo methylation transcripts, as DNMT3A and DNMT3B were significantly increased in plasma ACS-EVs. DNA methylation analysis of PBMCs from volunteer donors treated with HS- and ACS-derived EVs showed that RNF166 and CCND3 genes resulted the most hyper- and hypo-methylated, respectively, after by ACS-EV treatment. In addition, PPI network analysis specifically evidenced the subnetwork with SRC, as a hub gene, connecting it to NOTCH1, FOXO3, CDC42, IKBKG, RXRA, DGKG, known as important genes already involved in the onset of CVDs. Surprising, other novel genes, BAIAP2, SYP, CHL1, and SHB, which were hypomethylated, were found significantly overexpressed in PBMCs (P<0.005), underlying the fundamental modulating properties of EV cargo in atherosclerosis. Conclusions: These findings support the significant role of ACS plasma-derived EVs, inducing de novo DNA methylation signals, and modulating specific signaling pathways in target cells.

Project description:Introduction: Cell-derived extracellular vesicles ([EVs], i.e., exosomes and microparticles) have been reported to mediate the cardioprotective effects of stem cells. However, a head-to-head comparison of their effects with those of the cells from which they derive has not been reported. Hypothesis: The effects of the EV content of human embryonic stem cell (hESC)-derived cardiac progenitors may be equivalent to those of the parent cells. Methods: Two series of immunodeficient (nude) mice underwent permanent coronary artery ligation. Three weeks later, those with an echocardiographically-determined LV ejection fraction â¤ 50% were randomly allocated to receive transcutaneous echo-guided peri-infarct injections of alpha-MEM media (controls), hESC-derived SSEA-1+ cardiac progenitors (500000 cells in 30 Î¼L), or total EV secreted by those 500000 cells in 48 hours in an equivalent volume. The second series also included sham-operated animals for which the needle was inserted into the myocardium in three places without injection. EVs were collected from the cell-secreted medium by ultracentrifugation and characterized by flow cytometry, and nanosight NTS. Outcomes were assessed after 6 weeks by echocardiography, taking LV end-systolic volume (ESV) as the primary end point. Hearts were processed for the assessment of fibrosis and angiogenesis. Total RNA was extracted from carefully selected animals for gene expression analysis by Affymetrix chip. Only animals with similar VTS at baseline were used for this analysis. All data were collected and analyzed blindly. Results: Cardiac progenitors were successfully generated by exposure of the pluripotent ESC to bone morphogenetic protein-2, purified by anti-CD15 immunomagnetic sorting and then cultured on vitronectin for 48 hours, after which cells or EVs derived from the same cell batch were injected. After 6 weeks in the first series, LVESV [mÂ±SEM] in controls did not significantly differ from the pre-injection value (difference: -2.64 Â± 1.54 ÂµL, p=0.12, n= 12). Conversely, in the cell-treated group, LVESV significantly decreased by -4.20 Â± 0.96 ÂµL (p=0.0007, n=16). A similar decrease was seen in the EV-treated group: -5.73 Â± 1.21 ÂµL (p=0.0003, n=15). Similar patterns were seen for LV end-diastolic volumes: controls (-2.46 Â± 1.19 ÂµL, p=NS), cells (-4.48 Â± 1.47 ÂµL, p=0.009), EV (-4.29 Â± 1.31 ÂµL, p=0.005). For the second series, the VTD of cell- and EV-treated animals remained stable (cell: -1.85 Â± 3.27 ÂµL, p=NS, n= 4; EV: +0.05 Â± 1.53 ÂµL, p=NS, n = 4), whereas sham- and control-treated animals deteriorated significantly (sham: +2.20 Â± 0.35 ÂµL, p = 0.003, n = 5; control: +3.27 Â± 0.87 ÂµL, p = 0.03, n = 4). The trend held for VTS, though differences were not significant. Analysis of gene expression data revealed interesting pathways that were more highly expressed in cell- and EV-treated animals than in controls and sham-operated animals. Conclusions: These data support the hypothesis that EVs may be critical mediators of the paracrine effects of cell therapy, and for the sake of streamlining translational processes, deserve to be considered as potential alternatives to stem cell transplantation. Gene expression levels were compared between mouse hearts.

Dataset Information

Non-reversible tissue fixation by EDC carbodiimide allows for imaging extracellular vesicles in situ

Publications

Non-reversible tissue fixation retains extracellular vesicles for in situ imaging.

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