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Ultrafiltration combined with size exclusion chromatography efficiently isolates extracellular vesicles from cell culture media for compositional and functional studies.

ABSTRACT: Appropriate isolation methods are essential for unravelling the relative contribution of extracellular vesicles (EVs) and the EV-free secretome to homeostasis and disease. We hypothesized that ultrafiltration followed by size exclusion chromatography (UF-SEC) provides well-matched concentrates of EVs and free secreted molecules for proteomic and functional studies. Conditioned media of BEAS-2B bronchial epithelial cells were concentrated on 10?kDa centrifuge filters, followed by separation of EVs and free protein using sepharose CL-4B SEC. Alternatively, EVs were isolated by ultracentrifugation. EV recovery was estimated by bead-coupled flow cytometry and tuneable resistive pulse sensing. The proteomic composition of EV isolates and SEC protein fractions was characterized by nano LC-MS/MS. UF-SEC EVs tended to have a higher yield and EV-to-protein rate of purity than ultracentrifugation EVs. UF-SEC EVs and ultracentrifugation EVs showed similar fold-enrichments for biological pathways that were distinct from those of UF-SEC protein. Treatment of BEAS-2B cells with UF-SEC protein, but not with either type of EV isolate increased the IL-8 concentration in the media whereas EVs, but not protein induced monocyte adhesion to endothelial cells. Thus, UF-SEC is a useful alternative for ultracentrifugation and allows comparing the proteomic composition and functional effects of EVs and free secreted molecules.

SUBMITTER: Benedikter BJ

PROVIDER: S-EPMC5681555 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Ultrafiltration combined with size exclusion chromatography efficiently isolates extracellular vesicles from cell culture media for compositional and functional studies.

Benedikter Birke J BJ Bouwman Freek G FG Vajen Tanja T Heinzmann Alexandra C A ACA Grauls Gert G Mariman Edwin C EC Wouters Emiel F M EFM Savelkoul Paul H PH Lopez-Iglesias Carmen C Koenen Rory R RR Rohde Gernot G U GGU Stassen Frank R M FRM

Scientific reports 20171110 1

Appropriate isolation methods are essential for unravelling the relative contribution of extracellular vesicles (EVs) and the EV-free secretome to homeostasis and disease. We hypothesized that ultrafiltration followed by size exclusion chromatography (UF-SEC) provides well-matched concentrates of EVs and free secreted molecules for proteomic and functional studies. Conditioned media of BEAS-2B bronchial epithelial cells were concentrated on 10 kDa centrifuge filters, followed by separation of EV ...[more]

PMID: 29127410

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Project description:Extracellular vesicles (EVs) exert important functions in the extracellular space and in cell-to-cell communication. Ultracentrifugation, the most frequently used EV isolation technique, requires specialized equipment and provides relatively low purity and yield. A more recently applied and easily accessible EV isolation technique is size exclusion chromatography (SEC). Here, we hypothesized that EVs isolated from dilute cell culture media by concentration on a 10 kDa filter followed by SEC are suitable for proteomic and functional studies. We also hypothesized that the protein-rich SEC fractions are suitable controls to assess biological effects of the non-EV associated secretome. Cell-depleted medium from BEAS-2B bronchial epithelial cells (60 ml) was 0.22 µm filtered, concentrated to 0.5 ml by 10 kDa UF and run over a sepharose CL-4B column. Fractions were assessed for protein and EV content. EV-rich and protein-rich fractions were concentrated by 10 kDa UF. EV concentrates were characterized by tuneable resistive pulse sensing, cryo transmission electron microscopy and nanoLC-MS/MS. Finally, we assessed the effect of EVs or free secreted protein from unexposed cells or cells exposed to 1% (v/v) cigarette smoke extract (CSE) on IL-8 release by naïve BEAS-2B cells or on adhesion of THP-1 monocytes to endothelial cells. UF concentrated the EVs with approximately 100% recovery. Most of EVs eluted in SEC fractions 6-11, while protein became detectable at fraction 12. The final EV recovery was 40 ± 4%, as compared to 27 ± 8% by ultracentrifugation. Mass Spectrometry of the EV fractions identified 388 different proteins, including various EV markers. Only the protein, but not the EV fractions from media of CSE-exposed cells induced IL-8 release by naïve bronchial epithelial cells, whereas only EVs, but not the protein fractions induced THP-1 adhesion to endothelial cells. Thus, UF followed by SEC provides EV isolates with sufficient yield and purity for proteomic studies and allows directly comparing the functional effects of EVs and the non-EV associated secretome.

Project description:Extracellular vesicles (EVs) are a heterogeneous population of biological particles released by cells. They represent an attractive source of potential biomarkers for early detection of diseases such as cancer. However, it is critical that sufficient amounts of EVs can be isolated and purified in a robust and reproducible manner. Several isolation methods that seem to produce distinct populations of vesicles exist, making data comparability difficult. While some methods induce cellular stress that may affect both the quantity and function of the EVs produced, others involve expensive reagents or equipment unavailable for many laboratories. Thus, there is a need for a standardized, feasible and cost-effective method for isolation of EVs from cell culture supernatants. Here we present the most common obstacles in the production and isolation of small EVs, and we suggest a combination of relatively simple strategies to avoid these. Three distinct cell lines were used (human oral squamous cell carcinoma (PE/CA-PJ49/E10)), pancreatic adenocarcinoma (BxPC3), and a human melanoma brain metastasis (H3). The addition of 1% exosome-depleted FBS to Advanced culture media enabled for reduced presence of contaminating bovine EVs while still ensuring an acceptable cell proliferation and low cellular stress. Cells were gradually adapted to these new media. Furthermore, using the Integra CELLine AD1000 culture flask we increased the number of cells and thereby EVs in 3D-culture. A combination of ultrafiltration with different molecular weight cut-offs and size-exclusion chromatography was further used for the isolation of a heterogeneous population of small EVs with low protein contamination. The EVs were characterized by nanoparticle tracking analysis, immunoaffinity capture, flow cytometry, Western blot and transmission electron microscopy. We successfully isolated a significant amount of small EVs compatible with exosomes from three distinct cell lines in order to demonstrate reproducibility with cell lines of different origin. The EVs were characterized as CD9 positive with a size between 60-140 nm. We conclude that this new combination of methods is a robust and improved strategy for the isolation of EVs, and in particular small EVs compatible with exosomes, from cell culture media without the use of specialized equipment such as an ultracentrifuge.

Project description:Extracellular vesicles (EVs) are involved in a wide range of physiological and pathological processes by shuttling material out of and between cells. Tissue EVs may thus lend insights into disease mechanisms and also betray disease when released into easily accessed biological fluids. Since brain-derived EVs (bdEVs) and their cargo may serve as biomarkers of neurodegenerative diseases, we evaluated modifications to a published, rigorous protocol for separation of EVs from brain tissue and studied effects of processing variables on quantitative and qualitative outcomes. To this end, size exclusion chromatography (SEC) and sucrose density gradient ultracentrifugation were compared as final separation steps in protocols involving stepped ultracentrifugation. bdEVs were separated from brain tissues of human, macaque. Effects of post-mortem interval (PMI) before final bdEV separation were probed. MISEV2018-compliant EV characterization was performed, and both small RNA and protein profiling were done. We conclude that the modified, SEC-employing protocol achieves EV separation efficiency roughly similar to a protocol using gradient density ultracentrifugation, while decreasing operator time and, potentially, variability. The protocol appears to yield bdEVs of higher purity for human tissues compared with macaque, suggesting opportunities for optimization. The interval between death/tissue storage/processing and final bdEV separation can also affect bdEV populations and composition and should thus be recorded for rigorous reporting. Different populations of EVs obtained through the modified method reported herein display characteristic RNA and protein content that hint at biomarker potential. To conclude, this study finds that the automatable and increasingly employed technique of SEC can be applied to tissue EV separation, and also reveals more about the importance of species-specific and technical considerations when working with tissue EVs. These results are expected to enhance the use of bdEVs in revealing and understanding brain disease.

Dataset Information

Ultrafiltration combined with size exclusion chromatography efficiently isolates extracellular vesicles from cell culture media for compositional and functional studies.

Publications

Ultrafiltration combined with size exclusion chromatography efficiently isolates extracellular vesicles from cell culture media for compositional and functional studies.

Similar Datasets

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