Name: Autor im Rampenlicht: Beschleunigung der Forschung zur Trennung und Heterogenität bakterieller extrazellulärer Vesikel
Uploaded: 2023-09-01T14:30:00
Description: Watch this Scientific Journal Video about Accelerating Research on Bacterial Extracellular Vesicles Separation and Heterogeneity at JoVE.com

Diese Arbeit wurde unterstützt durch den National Science Fund for Distinguished Young Scholars (82025024); das Schlüsselprojekt der National Natural Science Foundation of China (82230080); das National Key F&E-Programm Chinas (2021YFA1300604); die National Natural Science Foundation of China (81871735, 82272438 und 82002245); Guangdong Natural Science Fund for Distinguished Young Scholars (2023B1515020058); die Naturwissenschaftliche Stiftung der Provinz Guangdong (2021A1515011639); das Major State Basic Research Development Program der Natural Science Foundation der Provinz Shandong in China (ZR2020ZD11); die Postdoktoranden-Wissenschaftsstiftung (2022M720059); das Outstanding Youths Development Scheme des Nanfang Hospital, Southern Medical University (2022J001).

Die Ethikkommission des Nanfang Krankenhauses der Southern Medical University genehmigte diese Studie, die mit der informierten Zustimmung der Teilnehmer durchgeführt wurde. Alle hier verwendeten Methoden entsprechen den Standard-Betriebsrichtlinien der International Human Microbiome Standards (IHMS: http://www.microbiome-standards.org/). Alle nachfolgenden Liquid-Handling-Verfahren mussten in einer Biosicherheitswerkbank oder einer Reinstbank durchgeführt werden.
1. Entnahme und Aliqu...

Verbesserte Isolierung bakterieller extrazellulärer Vesikel für Mikrobiota-Multi-Omics

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Bakterielle extrazelluläre Vesikel (BEVs) sind Lipid-Doppelschicht-Nanopartikel, die von Bakterien abgesondert werden und eine Fülle von Proteinen, Lipiden, Nukleinsäuren und anderen bioaktiven Molekülen tragen, die zur Vermittlung der funktionellen Wirkungen von Bakterien beitragen20. Es wurde nachgewiesen, dass aus dem Darm gewonnene BEVs an der Entwicklung von Krankheiten wie entzündlichen Darmerkrankungen, Morbus Crohn und Darmkrebs beteiligt sind, den allgemeinen Stoffwechsel beeinflusse...

Der Darm gilt weithin als das Organ, das die am häufigsten vorkommenden mikrobiellen Gemeinschaften im menschlichen Körper beherbergt, wobei über 90 % der Bakterien an der Besiedlung und Vermehrung beteiligt sind 1,2. Es gibt umfangreiche Belege dafür, dass die Darmmikrobiota die Darmmikroumgebung moduliert und gleichzeitig mit Funktionsstörungen in entfernten Organen interagiert, vor allem durch eine gestörte Darmbarriere 3,4. Es gibt immer mehr Hinweise auf einen Zusammenhang zwischen dem Ungleichgewicht der Darmmikrobiota und dem Fortschreiten von chronisch entzündlichen Darmerkrankungen (CED)5,6 sowie kognitiven Störungen über die Darm-Hirn-Achse 5,6,7,8. Bakterielle extrazelluläre Vesikel (BEVs), die von Bakterien produziert werden, spielen eine wichtige Rolle bei diesen pathologischen Prozessen.
BEVs sind nanoskalige Partikel, die bakterielle Derivate mit Durchmessern von 20 bis 400 nm verkapseln. Es wurde gezeigt, dass sie Interaktionen zwischen Bakterien und ihren Wirtsorganismen erleichtern 9,10. Trotz ihrer Unsichtbarkeit haben diese Partikel aufgrund ihrer potenziellen breiten Anwendung als diagnostische Biomarker, therapeutische Ziele und Vehikel zur Verabreichung von Medikamenten zunehmend die Aufmerksamkeit von Forschern auf sich gezogen11. Menschliche Fäkalien, die häufig als Bioproben für die Untersuchung von BEVs verwendet werden und überwiegend aus Darmbakterien stammen, enthalten unter anderem eine komplexe Mischung aus Wasser, Bakterien, Lipiden, Proteinen, unverdauten Nahrungsresten und abgeblätterten Epithelzellen. Die komplizierte Zusammensetzung der Fäkalien stellt eine Herausforderung für die Isolierung und Reinheit von BEVs dar und erschwert so eine umfassende, objektive und realistische Analyse von BEVs. Daher haben sich wirksame Strategien zur Minimierung von Störungen durch kontaminierende Komponenten und zur Steigerung der Ausbeute von BEVs als kritische Themen herausgestellt, die sofortige Aufmerksamkeit erfordern.
Bestehende Isolationsstrategien stützen sich weitgehend auf Techniken wie Ultrahochgeschwindigkeitszentrifugation (UC), Dichtegradientenzentrifugation (DGC) und Größenausschlusschromatographie (SEC)12,13,14,15,16,17. Derzeit ist DGC eine der am weitesten verbreiteten Methoden im Bereich der BEV-Trennung, die zwei Sedimentations-Schwimmmodi umfasst, "Top-down" und "Bottom-up", die durch die anfängliche Belastungsposition der Probe bestimmt werden. Diese Methoden unterscheiden extrazelluläre Vesikel (EVs) von anderen Komponenten auf der Grundlage von Größen- und Dichteunterschieden, was zu unterschiedlichen Reinheiten und Wiederfindungsraten führt. Frühere Forschungen haben gezeigt, dass Single-Approach-Strategien nicht ausreichen, um EVs angemessen von löslichen Proteinen in Körperflüssigkeitsproben wie Lipoprotein im Blut18 und Tamm-Horsfall-Protein im Urin19 zu trennen. Darüber hinaus überschneidet sich die Größenverteilung von eukaryotischen extrazellulären Vesikeln (EEVs) oft mit der von BEVs, was weitere methodische Verbesserungen zur Optimierung der BEV-Ausbeute erforderlich macht. Folglich hängt die Weiterentwicklung der Erforschung von BEVs von der Entwicklung effektiver Trenn- und Reinigungsmethoden ab. Bemerkenswert ist, dass Tulkens etal. 15 eine orthogonale biophysikalische Strategie zur Trennung von fäkalen BEVs von EEVs verwendeten, bei der die Zentrifugationszeit eines Bottom-up-DGC-Modus bis zu 18 h betrug. Im Gegensatz dazu reduzierte diese Studie sie auf 7 Stunden, was die Gradienten-Ultrazentrifugationszeit erheblich spart und den Prozess vereinfacht.
In der vorliegenden Studie haben wir fäkale BEVs unter Verwendung von zwei DGC-Modi unter optimierten Pufferbedingungen isoliert und gereinigt, nachdem wir BEVs mit einer Reihe von unterschiedlichen Zentrifugationsgeschwindigkeiten angereichert hatten, von niedriger bis extrem hoher Geschwindigkeit. Auswertungen auf der Grundlage von Morphologie, Partikelgröße und Konzentration zeigten eine lobenswerte Leistung dieser verbesserten Methode. Diese Studie könnte als Grundlage für zukünftige Forschungen dienen, ihre Anwendungen auf einen breiteren Bereich ausdehnen und Einblicke in die Heterogenität von BEVs im menschlichen Körper bieten. Es trägt auch zur Standardisierung von BEV-Trenn- und Analysetechniken bei.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1 % (w/v) glutaraldehyde (prepared from 2.5 % stock solution in deionized water)</td>
			<td>ACMEC</td>
			<td>AP1126</td>
			<td>Morphological observation for BEVs using TEM at Step 8.3.3</td>
		</tr>
		<tr>
			<td>1 % (w/v) methylcellulose (prepared from original powder in deionized water)</td>
			<td>Sigma-Aldrich</td>
			<td>M7027</td>
			<td>Morphological observation for BEVs using TEM at Step 8.3.6</td>
		</tr>
		<tr>
			<td>1.5 % (w/v) uranyl acetate (prepared from original powder in deionized water)</td>
			<td>Polysciences</td>
			<td>21447-25</td>
			<td>Morphological observation for BEVs using TEM at Step 8.3.5</td>
		</tr>
		<tr>
			<td>1000 &#956;L, 200 &#956;L, 10 &#956;L Pipette</td>
			<td>KIRGEN</td>
			<td>KG1313, KG1212, KG1011</td>
			<td>Transfer the solution</td>
		</tr>
		<tr>
			<td>5 % (w/v) bovine serum albumin solution (prepared from the original powder in TBST buffer)</td>
			<td>Fdbio science</td>
			<td>FD0030</td>
			<td>Used in western blotting for blocking at Step 8.5.6</td>
		</tr>
		<tr>
			<td>5 &#215; loading buffer</td>
			<td>Fdbio science</td>
			<td>FD006</td>
			<td>Used in western blotting and Coomassie brilliant blue stain at Step 8.5.1</td>
		</tr>
		<tr>
			<td>75 % (v/v) alcohol</td>
			<td>LIRCON</td>
			<td>LIRCON-500 mL</td>
			<td>Surface disinfection</td>
		</tr>
		<tr>
			<td>96-well plate</td>
			<td>Rar</td>
			<td>A8096</td>
			<td>Measure the absorbance values&#160;</td>
		</tr>
		<tr>
			<td>Anti-Calnexin antibody</td>
			<td>Abcam</td>
			<td>ab92573</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-CD63 antibody</td>
			<td>Abcam</td>
			<td>ab134045</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-CD9 antibody</td>
			<td>Abcam</td>
			<td>ab236630</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-Flagellin antibody</td>
			<td>Sino Biological</td>
			<td>40067-MM06</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-Integrin beta 1 antibody</td>
			<td>Abcam</td>
			<td>ab30394</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-LPS antibody</td>
			<td>Thermo Fisher</td>
			<td>MA1-83152</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-LTA antibody</td>
			<td>Thermo Fisher&#160;</td>
			<td>MA1-7402</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-OmpA antibody</td>
			<td>CUSABIO</td>
			<td>CSB-PA359226ZA01EOD, https://www.cusabio.com/</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-Syntenin antibody</td>
			<td>Abcam</td>
			<td>ab133267</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Anti-TSG101 antibody</td>
			<td>Abcam</td>
			<td>ab125011</td>
			<td>Western blotting (Primary Antibody)</td>
		</tr>
		<tr>
			<td>Autoclave</td>
			<td>ZEALWAY</td>
			<td>GR110DP</td>
			<td>Sterilization for supplies and mediums used in the experiment</td>
		</tr>
		<tr>
			<td>Balance</td>
			<td>Mettler Toledo</td>
			<td>AL104</td>
			<td>Balance the tube sample-loaded with PBS</td>
		</tr>
		<tr>
			<td>Bicinchoninic acid assay&#160;</td>
			<td>Fdbio science</td>
			<td>FD2001</td>
			<td>Measure protein content of BEVs at Step 8.2</td>
		</tr>
		<tr>
			<td>BioRender</td>
			<td>BioRender</td>
			<td>https://app.biorender.com</td>
			<td>Make the schematic workflow of BEVs isolation and purification showed in Figure 1</td>
		</tr>
		<tr>
			<td>Biosafety cabinet</td>
			<td>Haier</td>
			<td>HR1200- II B2</td>
			<td>Peform the procedures about feces sample handling</td>
		</tr>
		<tr>
			<td>Centrifuge 5810 R; Rotor F-34-6-38</td>
			<td>Eppendorf</td>
			<td>5805000092; 5804727002, adapter: 5804774000</td>
			<td>Preprocess for BEVs (Step 3)</td>
		</tr>
		<tr>
			<td>Chemiluminescence Apparatus</td>
			<td>BIO-OI</td>
			<td>OI600SE-MF</td>
			<td>Used in western blotting for signal detection at Step 8.5.12</td>
		</tr>
		<tr>
			<td>Cytation 5</td>
			<td>BioTek</td>
			<td>F01</td>
			<td>Microplate detector for measuring the absorbance (Step 8.1) and fluorescence (Figure 6) values&#160;</td>
		</tr>
		<tr>
			<td>Dil-labled low density lipoprotein</td>
			<td>ACMEC</td>
			<td>AC12038</td>
			<td>Definition of distribution of interfering components&#160;</td>
		</tr>
		<tr>
			<td>Electrophoresis equipment</td>
			<td>Bio-rad</td>
			<td>1658033</td>
			<td>Used in western blotting for protein separation and transfer at Step 8.5.2, 8.5.3, 8.5.5</td>
		</tr>
		<tr>
			<td>Enhanced Chemiluminescence kit HRP&#160;</td>
			<td>Fdbio science</td>
			<td>FD8020</td>
			<td>Used in western blotting for signal detection at Step 8.5.12</td>
		</tr>
		<tr>
			<td>Escherichia coli&#160;</td>
			<td>American Type Culture Collection</td>
			<td>ATCC8739</td>
			<td>Isolate BEVs as a positive control. Protocol: Dissolve 25 g of the LB powder in 1 L deionized water, and autoclave. Transfer the 800 &#956;L of preserved Escherichia coli into the medium. Cultivate at 37 &#176;C in the incubator shaker. Then centrifuge at 3, 000 &#215; g for 20 min at 4 &#176;C, 12, 000 &#215; g for 30 min at 4 &#176;C, filter the supernatant through 0.22 &#956;m membrane, and perform ultra-speed centrifugation at 160, 000 &#215; g for 70 min at 4 &#176;C. Pellet defined as crude BEVs from Escherichia coli was suspended in 1.2 mL PBS (Step 3, 4).&#160;&#160;&#160;&#160;</td>
		</tr>
		<tr>
			<td>Falcon tubes 50 mL</td>
			<td>KIRGEN</td>
			<td>KG2811</td>
			<td>Preprocess for BEVs (Step 3)</td>
		</tr>
		<tr>
			<td>Feto Protein Staining Buffer</td>
			<td>Absci</td>
			<td>ab.001.50</td>
			<td>Coomassie brilliant blue staining at Step 8.5.4</td>
		</tr>
		<tr>
			<td>Filter paper</td>
			<td>Biosharp</td>
			<td>BS-TFP-070B</td>
			<td>Morphological observation for BEVs using TEM at Step 8.3 (Blotting the solution)</td>
		</tr>
		<tr>
			<td>Formvar/Carbon supported copper grids&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>TEM-FCF200CU50</td>
			<td>Morphological observation for BEVs using TEM at Step 8.3</td>
		</tr>
		<tr>
			<td>HEPES powder</td>
			<td>Meilunbio</td>
			<td>MB6078</td>
			<td>Prepare iodixanol buffers with different concentrations for density gradient centrifugation</td>
		</tr>
		<tr>
			<td>HRP AffiniPure Goat Anti-Mouse IgG (H+L)</td>
			<td>Fdbio science</td>
			<td>FDM007</td>
			<td>Western blotting (Secondary Antibody)</td>
		</tr>
		<tr>
			<td>HRP AffiniPure Goat Anti-Rabbit IgG (H+L)</td>
			<td>Fdbio science</td>
			<td>FDR007</td>
			<td>Western blotting (Secondary Antibody)</td>
		</tr>
		<tr>
			<td>Incubator shaker</td>
			<td>Qiangwen</td>
			<td>DHZ-L</td>
			<td>Cultivate Escherichia coli&#160;</td>
		</tr>
		<tr>
			<td>Kimwipes&#8482; Delicate Task Wipes</td>
			<td>Kimtech Science</td>
			<td>34155</td>
			<td>Wipe the inner wall of the ultracentrifuge tube at Step 4.15</td>
		</tr>
		<tr>
			<td>LB broth</td>
			<td>Hopebio</td>
			<td>HB0128</td>
			<td>Cultivate Escherichia coli&#160;</td>
		</tr>
		<tr>
			<td>Low temperature freezer (-80 &#176;C)</td>
			<td>Haier</td>
			<td>DW-86L338J</td>
			<td>Store the samples</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Alalddin</td>
			<td>M116118</td>
			<td>Used in western blotting for activating PVDF membrane at Step 8.5.5</td>
		</tr>
		<tr>
			<td>Micro tubes 1.5 mL</td>
			<td>KIRGEN</td>
			<td>KG2211</td>
			<td>Recover fractions after density gradient centrifugation</td>
		</tr>
		<tr>
			<td>Micro tubes 2 mL</td>
			<td>KIRGEN</td>
			<td>KG2911</td>
			<td>Recover fractions after density gradient centrifugation</td>
		</tr>
		<tr>
			<td>Micro tubes 5 mL</td>
			<td>BBI</td>
			<td>F610888-0001</td>
			<td>Recover fractions after density gradient centrifugation</td>
		</tr>
		<tr>
			<td>Microplate reader&#160;</td>
			<td>Thermo Fisher&#160;</td>
			<td>Multiskan MK3</td>
			<td>Measure protein content of BEVs at Step 8.2</td>
		</tr>
		<tr>
			<td>Millipore filter 0.22 &#956;m</td>
			<td>Merck millipore</td>
			<td>SLGP033RB</td>
			<td>Filtration sterilization; Material: polyethersulfone, PES</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>GHTECH</td>
			<td>1.01307.040</td>
			<td>Density gradient centrifugation solution</td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>GHTECH</td>
			<td>1.01394.068</td>
			<td>Density gradient centrifugation solution (pH adjustment)</td>
		</tr>
		<tr>
			<td>Optima&#8482; XPN-100</td>
			<td>Beckman Coulter</td>
			<td>A94469</td>
			<td>Ultracentrifugation for BEVs isolation at Step 4, 7</td>
		</tr>
		<tr>
			<td>OptiPrep&#8482;</td>
			<td>Serumwerk Bernburg AG</td>
			<td>1893</td>
			<td>Density gradient centrifugation stock solution</td>
		</tr>
		<tr>
			<td>Orbital Shaker</td>
			<td>Youning</td>
			<td>CS-100</td>
			<td>Dissolve feces at Step 2</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>Procell</td>
			<td>PB180327</td>
			<td>Dissolve feces at Step 2</td>
		</tr>
		<tr>
			<td>Pipettor</td>
			<td>Eppendorf</td>
			<td>3120000267, 3120000259</td>
			<td>Transfer the solution</td>
		</tr>
		<tr>
			<td>Plastic pasteur pipette</td>
			<td>ABCbio</td>
			<td>ABC217003-4</td>
			<td>Remove supernatant in preprocessing at Step 3.4</td>
		</tr>
		<tr>
			<td>Polyvinylidene difluoride (PVDF) membranes</td>
			<td>Millipore</td>
			<td>ISEQ00010, IPVH00010</td>
			<td>Used in western blotting for protein transfer at Step 8.5.5</td>
		</tr>
		<tr>
			<td>Prefabricated polyacrylamide gel, 4&#8211;20% 15 Wells</td>
			<td>ACE</td>
			<td>F15420Gel</td>
			<td>Used in western blotting for protein separation at Step 8.5.2, 8.5.3</td>
		</tr>
		<tr>
			<td>Primary antibody diluent</td>
			<td>Fdbio science</td>
			<td>FD0040</td>
			<td>Used in western blotting at Step 8.5.8</td>
		</tr>
		<tr>
			<td>Protein ladder</td>
			<td>Fdbio science</td>
			<td>FD0672</td>
			<td>Used in western blotting and Coomassie brilliant blue stain at Step 8.5</td>
		</tr>
		<tr>
			<td>Rapid protein blotting solution</td>
			<td>UBIO</td>
			<td>UW0500</td>
			<td>Used in western blotting for protein transfer at Step 8.5.5</td>
		</tr>
		<tr>
			<td>Rotor SW 32 Ti Swinging-Bucket Rotor</td>
			<td>Beckman Coulter</td>
			<td>369650</td>
			<td>Ultracentrifugation for BEVs isolation at Step 4, 7</td>
		</tr>
		<tr>
			<td>Syringe 20 mL, 50 mL&#160;</td>
			<td>Jetway</td>
			<td>ZSQ-20ML, YCXWJZSQ-50 mL</td>
			<td>Transfer buffers amd remove supernatant in preprocessing</td>
		</tr>
		<tr>
			<td>TBS powder</td>
			<td>Fdbio science</td>
			<td>FD1021</td>
			<td>Used in western blotting at Step 8.5</td>
		</tr>
		<tr>
			<td>Transmission electron microscope (TEM)</td>
			<td>Hitachi&#160;</td>
			<td>H-7650</td>
			<td>Morphological observation for BEVs at Step 8.3</td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Fdbio science</td>
			<td>FD0020</td>
			<td>Used in western blotting at Step 8.5</td>
		</tr>
		<tr>
			<td>Ultracentrifuge tube</td>
			<td>Beckman</td>
			<td>326823, 355642</td>
			<td>Ultracentrifugation for BEVs isolation at Step 4, 7</td>
		</tr>
		<tr>
			<td>Ultra-clean bench</td>
			<td>AIRTECH</td>
			<td>SW-CJ-2FD</td>
			<td>Peform the procedures about liquid handling</td>
		</tr>
		<tr>
			<td>Water bath</td>
			<td>Bluepard</td>
			<td>CU600</td>
			<td>Used for measuring protein content of BEVs at Step 8.2.5</td>
		</tr>
		<tr>
			<td>ZetaView</td>
			<td>Particle Metrix</td>
			<td>S/N 21-734, Software ZetaView (version 8.05.14 SP7)</td>
			<td>Nanoparticle tracking analysis (NTA) for measuring the particle size and concentrarion of BEVs at Step 8.4</td>
		</tr>
	</tbody>
</table>

isolation and purification of bacterial extracellular vesicles from human feces using density gradient centrifugation

Bakterielle extrazelluläre Vesikel (BEVs) sind Nanovesikel von Bakterien, die eine aktive Rolle bei der Kommunikation zwischen Bakterien und Bakterien spielen, indem sie bioaktive Moleküle wie Proteine, Lipide und Nukleinsäuren übertragen, die von den Mutterbakterien geerbt wurden. BEVs, die aus der Darmmikrobiota gewonnen werden, haben Wirkungen im Magen-Darm-Trakt und können entfernte Organe erreichen, was erhebliche Auswirkungen auf die Physiologie und Pathologie hat. Theoretische Untersuchungen, die die Arten, Mengen und Rollen von BEVs aus menschlichen Fäkalien untersuchen, sind entscheidend für das Verständnis der Sekretion und Funktion von BEVs aus der Darmmikrobiota. Diese Untersuchungen erfordern auch eine Verbesserung der aktuellen Strategie zur Isolierung und Reinigung von BEVs.
In dieser Studie wurde der Isolierungs- und Reinigungsprozess von BEVs optimiert, indem zwei Dichtegradientenzentrifugationsmodi (DGC) etabliert wurden: Top-down und Bottom-up. Die angereicherte Verteilung der BEVs wurde in den Fraktionen 6 bis 8 (F6-F8) bestimmt. Die Wirksamkeit des Ansatzes wurde anhand der Partikelmorphologie, der Größe, der Konzentration und des Proteingehalts bewertet. Die Partikel- und Proteinrückgewinnungsraten wurden berechnet und das Vorhandensein spezifischer Marker analysiert, um die Wiederfindung und Reinheit der beiden DGC-Modi zu vergleichen. Die Ergebnisse zeigten, dass der Top-down-Zentrifugationsmodus geringere Kontaminationswerte aufwies und eine ähnliche Rückgewinnungsrate und Reinheit wie der Bottom-up-Modus erreichte. Eine Zentrifugationszeit von 7 h war ausreichend, um eine fäkale BEV-Konzentration von 108/mg zu erreichen.
Abgesehen von Fäkalien kann diese Methode auch auf andere Arten von Körperflüssigkeiten angewendet werden, wobei die entsprechenden Modifikationen entsprechend den Unterschieden in den Komponenten und der Viskosität durchgeführt werden. Zusammenfassend lässt sich sagen, dass dieses detaillierte und zuverlässige Protokoll die standardisierte Isolierung und Aufreinigung von BEVs erleichtern und damit eine Grundlage für nachfolgende Multi-Omics-Analysen und funktionelle Experimente schaffen würde.

The gut is widely recognized as the organ harboring the most abundant microbial communities in the human body, with over 90% of bacteria involved in colonization and multiplication1,2. Extensive evidence has demonstrated that the gut microbiota modulates the gut microenvironment and simultaneously interacts with dysfunction in distant organs, primarily through an impaired intestinal barrier3,4. Mounting evidence indicates a correlation between the imbalance of gut microbiota and the progression of inflammatory bowel disease (IBD)5,6, as well as cognitive disorders through the gut-brain axis5,6,7,8. Bacterial extracellular vesicles (BEVs) produced by bacteria play significant roles in these pathological processes.
BEVs are nanoscale particles encapsulating bacterial derivatives, with diameters ranging from 20 to 400 nm. They have been demonstrated to facilitate interactions between bacteria and their host organisms9,10. Despite their invisibility, these particles have garnered increasing attention from researchers due to their prospective broad applications as diagnostic biomarkers, therapeutic targets, and drug delivery vehicles11. Human feces, often used as biospecimens for studying BEVs, predominantly sourced from gut bacteria, contain a complex mixture of water, bacteria, lipids, proteins, undigested food residue, and exfoliated epithelial cells among others. The intricate fecal composition poses challenges to the isolation and purity of BEVs, thereby impeding a comprehensive, objective, and realistic analysis of BEVs. Hence, effective strategies to minimize interference from contaminating components and enhance the yield of BEVs have emerged as critical issues warranting immediate attention.
Existing isolation strategies largely rely on techniques such as ultra-high-speed centrifugation (UC), density gradient centrifugation (DGC), and size exclusion chromatography (SEC)12,13,14,15,16,17. Currently, DGC is one of the most widely applied methods in the field of BEV separation, encompassing two sedimentation-floating modes, &#34;Top-down&#34; and &#34;Bottom-up&#34;, which are determined by the initial loading position of the sample. These methodologies differentiate extracellular vesicles (EVs) from other components based on size and density disparities, yielding variable purity and recovery rates. Prior research has indicated that single-approach strategies are insufficient for adequately separating EVs from soluble proteins in body fluid samples, such as lipoprotein in blood18 and Tamm-Horsfall protein in urine19. Additionally, the size distribution of eukaryotic extracellular vesicles (EEVs) often overlaps with that of BEVs, thereby necessitating further methodological enhancements to optimize BEV yield. Consequently, advancing the study of BEVs hinges on the development of effective separation and purification methodologies. Notably, Tulkens et al15 employed an orthogonal biophysical strategy to separate fecal BEVs from EEVs, in which the centrifugation time of a Bottom-up DGC mode was up to 18 h. In contrast, this study reduced it to 7 h, greatly saving the gradient-ultracentrifugation time and simplifying the process.
In the present study, we isolated and purified fecal BEVs employing two DGC modes under optimized buffer conditions, after enriching BEVs with a range of differential centrifugation speeds, from low to extremely high velocity. Evaluations based on morphology, particle size, and concentration indicated a commendable performance by this enhanced method. This study could serve as the foundation for future research, extending its applications to a broader domain, and offering insights into the heterogeneity of BEVs within the human body. It also contributes to the standardization of BEV separation and analysis techniques.

Autor im Rampenlicht: Beschleunigung der Forschung zur Trennung und Heterogenität bakterieller extrazellulärer Vesikel 

Isolierung und Aufreinigung bakterieller extrazellulärer Vesikel aus menschlichen Fäkalien mittels Dichtegradientenzentrifugation

Our study isolates, purifies, and characterize bacterial extracellular vesicles from physicists using density gradient centrifugation. We aim to address the separation of BEVs from contaminants and provide a reliable method for researchers. Our protocol reduces centrifugation time from 18 to 7 hours.Top down mode improves BEV separation and reduces contamination from liver proteins. Our method simplifies the separation of BEVs, setting a standard for future studies. It can be applied to other body fluids with appropriate modification, enhancing our understanding and facilitating the study of BEVs revealing their inherent heterogeneity within the human body.

Bestimmung der Verteilung von BEV-angereicherten Fraktionen Um die Verteilung der mit bakteriellen extrazellulären Vesikeln (BEVs) angereicherten Fraktionen zu bestimmen, wurde eine Blindkontrolle zur Messung der Absorptionswerte bei OD 340 nm etabliert und die Dichte jeder Fraktion basierend auf den Messungen und den Iodixanol-Richtlinien berechnet (Schritt 8.1). Tabelle 2 zeigt die Dichteergebnisse, die zeigen, dass die Fraktionen F4 bis F9 Dichten innerhalb des Bereichs aufwiesen,...

Watch this Scientific Journal Video about Accelerating Research on Bacterial Extracellular Vesicles Separation and Heterogeneity at JoVE.com

Diese Studie beschreibt eine Methode zur Isolierung und Reinigung bakterieller extrazellulärer Vesikel (BEVs), die aus menschlichen Fäkalien mittels Dichtegradientenzentrifugation (DGC) angereichert wurden, identifiziert die physikalischen Eigenschaften von BEVs anhand von Morphologie, Partikelgröße und Konzentration und diskutiert die potenziellen Anwendungen des DGC-Ansatzes in der klinischen und wissenschaftlichen Forschung.

Bacterial extracellular vesicles (BEVs) are nanovesicles derived from bacteria that play an active role in bacteria-bacteria and bacteria-host ...

Unsere Studie isoliert, reinigt und charakterisiert bakterielle extrazelluläre Vesikel von Physikern mittels Dichtegradientenzentrifugation. Unser Ziel ist es, die Trennung von BEVs von Verunreinigungen zu verbessern und Forschern eine zuverlässige Methode zur Verfügung zu stellen. Unser Protokoll reduziert die Zentrifugationszeit von 18 auf 7 Stunden.Der Top-Down-Modus verbessert die BEV-Trennung und reduziert die Kontamination durch Leberproteine. Unsere Methode vereinfacht die Trennung von BEVs und setzt damit einen Standard für zukünftige Studien. Es kann mit entsprechender Modifikation auf andere Körperflüssigkeiten angewendet werden, was unser Verständnis verbessert und die Untersuchung von BEVs erleichtert, die ihre inhärente Heterogenität im menschlichen Körper aufdecken.

isolation-purification-bacterial-extracellular-vesicles-from-human

Research

JoVE Journal

Biology

Isolation and Purification of Bacterial Extracellular Vesicles from Human Feces Using Density Gradient Centrifugation

Bacterial extracellular vesicles (BEVs) are nanovesicles derived from bacteria that play an active role in bacteria-bacteria and bacteria-host communication, transferring bioactive molecules such as proteins, lipids, and nucleic acids inherited from the parent bacteria. BEVs derived from the gut microbiota have effects within the gastrointestinal tract and can reach distant organs, resulting in significant implications for physiology and pathology. Theoretical investigations that explore the types, quantities, and roles of BEVs derived from human feces are crucial for understanding the secretion and function of BEVs from the gut microbiota. These investigations also necessitate an improvement in the current strategy for isolating and purifying BEVs.
This study optimized the isolation and purification process of BEVs by establishing two density gradient centrifugation (DGC) modes: Top-down and Bottom-up. The enriched distribution of BEVs was determined in fractions 6 to 8 (F6-F8). The effectiveness of the approach was evaluated based on particle morphology, size, concentration, and protein content. The particle and protein recovery rates were calculated, and the presence of specific markers was analyzed to compare the recovery and purity of the two DGC modes. The results indicated that the Top-down centrifugation mode had lower contamination levels and achieved a recovery rate and purity similar to that of the Bottom-up mode. A centrifugation time of 7 h was sufficient to achieve a fecal BEV concentration of 108/mg.
Apart from feces, this method could be applied to other body fluid types with proper modification according to the differences in components and viscosity. In conclusion, this detailed and reliable protocol would facilitate the standardized isolation and purification of BEVs and thus, lay a foundation for subsequent multi-omics analysis and functional experiments.

This study describes a method to isolate and purify bacterial extracellular vesicles (BEVs) enriched from human feces via density gradient centrifugation (DGC), identifies the physical characteristics of BEVs from morphology, particle size, and concentration, and discusses the potential applications of the DGC approach in clinical and scientific research.

Forschung

Biologie

Bacterial Extracellular Vesicles (BEVs) Enrichment from Human Faeces Using Differential Centrifugation Speeds

To begin, take the prepared human fecal samples. Cool the high speed refrigerated centrifuge to 4 degrees Celsius. Use PBS to adjust the weight of the sample tubes to 0.1 grams, and centrifuge them at 3, 000 G for 20 minutes at 4 degrees Celsius.Using a plastic pipette, transfer the supernatant into two 50 milliliter tubes, leaving 1 milliliter behind. Then, centrifuge the supernatant at 12, 000 G for 30 minutes at 4 degrees Celsius. Using a 20 milliliter syringe, aspirate the supernatant, and remove the needle from the syringe.Filter the liquid through 0.22 micrometer filters into 50 milliliter tubes. Next, wipe the bucket with 75%alcohol to eliminate any remaining contamination. Transfer approximately 30 milliliters of the filtered fecal supernatant into the ultracentrifuge tube.Fill the tube with approximately 8 milliliters of PBS, leaving a 3 millimeter gap from the tube's opening. Place the two ultracentrifuge tubes in opposing ultracentrifugation buckets, and equalize the weight of the two buckets using PBS. Load all buckets onto the rotor, irrespective of whether they are loaded with tubes.Place the samples in the centrifuge, initiate the vacuum and spin them at 160, 000 G for 70 minutes at 4 degrees Celsius. As soon as the centrifugation completes, release the chamber vacuum and open the door of the ultra centrifuge. Then, promptly remove the rotor.Transfer the buckets from the rotor to the rack, and pick up the tubes using a nipper. Discard the supernatant, and save the visible brown pellets. Add 1 milliliter of pre-chilled PBS to resuspend the pellets completely.Fill the tube with approximately 37 milliliters of PBS, leaving a 3 millimeter gap from the opening. After performing another round of ultracentrifugation, discard the supernatant and leave the tube inverted for 5 minutes. Remove any remaining solution on the inner wall with wipers.Using a 1, 000 microliter pipette, add 1.2 milliliters of pre-chilled PBS to resuspend pellets, and mix them by pipetting. Transfer 1.2 milliliters of the PBS BEV solution from one ultracentrifuge tube to a clean 1.5 milliliter micro tube.

Anreicherung bakterieller extrazellulärer Vesikel (BEVs) aus menschlichen Fäkalien mit unterschiedlichen Zentrifugationsgeschwindigkeiten

Establishment of a Density Gradient Centrifugation System to Isolate and Purify Bacterial Extracellular Vesicles (BEVs) from Human Faeces

To begin, take 500 microliters of the prepared PBS/BEV solution. Combine it with three milliliters of PBS and mix gently using a 1, 000 microliter pipette. Place a 31 milliliter ultracentrifuge tube on a foam plate with holes, and label the tube with a downward arrow.Then hold a 1, 000 microliter pipette vertically and add three milliliters of the 50%iodixanol solution to the bottom of the tube. Place a tube holder slightly above the level of the foam plate below the tube opening, and tilt the tube to an angle of 70 degrees. Using a 1, 000 microliter pipette, add three milliliters of 40%iodixanol solution on top of the 50%iodixanol solution.Then layer three milliliters of 20%iodixanol solution on the 40%iodixanol solution. Using a 1, 000 microliter pipette, add three milliliters of a 10%iodixanol solution on top of the prepared 20%iodixanol solution. Next, add 3.5 milliliters of the PBS/BEV solution on top of the 10%iodixanol solution, and gently return the tubes to an upright position.Now, position a 31 milliliter ultracentrifuge tube on a foam plate with holes, and label it with an upward arrow. Using a 1, 000 microliter pipette, vertically add 2.5 milliliters of the 60%iodixanol stock solution into the bottom of the tube, and combine it with 500 microliters of PBS/BEV solution to get three milliliters of 50%iodixanol BEV solution. Mix the solution thoroughly by pipetting.Then after layering 40, 20 and 10%iodixanol solution in sequence, use a 1, 000 microliter pipette to add 3.5 milliliters of PBS on top of the 10%iodixanol solution. Adjust the weight of the two tubes with PBS to a total weight within plus minus 0.005 grams. Next, position the tubes in the buckets and centrifuge them at 160, 000 G for seven hours at four degrees Celsius.Using a pipetter, collect the fractions obtained from a gradient ultracentrifugation mode sequentially from top to bottom against the sidewall into 10 separate 38.5 milliliter ultracentrifuge tubes. Then ultracentrifuge the fractions at 160, 000 G for 70 minutes at four degrees Celsius. Remove the supernatant, and invert the ultracentrifuge tubes for five minutes.Next, resuspend the pellets in 200 microliters of pre-chilled PBS using a 200 microliter pipette. Transfer the PBS/BEV solution into a clean 1.5 milliliter microtube. Label the fractions from F1 to F10 as obtained from one gradient ultracentrifugation mode, and proceed for analysis.