This study was supported by a K08 Award (DK090154-01) from the National Institutes of Health (NIH; to F.M.S.).

Obtaining the bile from patients by endoscopic retrograde cholangiopancreatography (ERCP) requires the approval of a human subjects study protocol by the Institutional Review Board. All work presented here was approved by the Johns Hopkins University Institutional Review Board.
1. Exosome Isolation from Bile
<ol>
	<li>Perform endoscopic retrograde cholangiopancreatography (ERCP). Place the patient in the supine position and intubate.
	<ol>
		<li>Pass a duodenoscope through the mouth of the p...

<ol>
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To reliably utilize exosomes isolated from bile, it is important to employ consistent high quality isolation methods to obtain high quality samples in return. The methodology defined in this paper is a well-established way to isolate exosomes and miRNA from human bile. It highlights several crucial steps in the characterization of the isolated exosomes which at a minimum should comprise electron microscopy or nanoparticle optical analysis and Western blots.
The most crucial step in the isolati...

Like other biological fluids, i.e., breast milk, plasma or urine, bile contains exosomes, lipid rich vesicles1-4. Exosomes can induce or alter biological functions in recipient cells5, 6, a form of cell-cell communication that might be part of their normal function4, 7-9. Exosomes can contain miRNA species which can provide a valuable source of biomarkers for diagnosis10. miRNAs profiles have gained substantial attention in recent years as diagnostic and prognostic markers for a variety of diseases11-14.
miRNA itself can be found in biological fluids, possibly released by dead cells and the amount of shed cells can be greatly influenced by an underlying disease. The miRNA profile of exosomes does not necessarily reflect the miRNA profile of the originating cell6, 10, 15-17, yet exosomes may carry miRNA signatures that might be characteristic for the parental cell like a tumor cell. Tumor-derived exosomes have been identified in the plasma of patients with lung adenocarcinoma, prostate cancer and other tumors8, 16, 18.
The goal of this method is the reliable and robust isolation of exosomes from human bile specimens, largely independent of their prior handling procedures. It was developed to utilize bile as a reliable source of miRNA for the potential diagnosis of diseases of the bile duct such as cholangiocarcinoma19. It consist of several steps of centrifugation with increasing speeds to isolate exosomes and might be applicable to other biological fluids.

<table border="0" cellpadding="0" cellspacing="0" width="752">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:305px;">0.2&#181;m Polyethersulfone (PES) membrane filter</td>
			<td style="width:161px;">Corning</td>
			<td align="right" style="width:119px;">431229</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">thinwall polyallomer ultracentrifuge tubes&#160;</td>
			<td style="width:161px;">Beckman Coulter</td>
			<td align="right" style="width:119px;">331374</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:305px;">SW40Ti rotor</td>
			<td style="width:161px;">Beckman Coulter</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:305px;">LM10-HS&#160;</td>
			<td style="width:161px;">Nanosight</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:305px;">Nanoparticle Tracking Analysis (NTA) software&#160;</td>
			<td style="width:161px;">Nanosight</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:305px;">mirVANA</td>
			<td style="width:161px;">Life Technologies</td>
			<td style="width:119px;">AM1560</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:305px;">cOmplete Protease Inhibitor</td>
			<td style="width:161px;">Roche distributed by Sigma-Aldrich</td>
			<td align="right" style="width:119px;">4693116001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:305px;">Immobilon PSQ</td>
			<td style="width:161px;">Millipore, Bedford MA</td>
			<td style="width:119px;">ISEQ00010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:305px;">Anti-CD63 antibody</td>
			<td style="width:161px;">Abcam</td>
			<td style="width:119px;">ab59479</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:305px;">Anti-Tsg101</td>
			<td style="width:161px;">Abcam</td>
			<td style="width:119px;">ab30871</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation and profiling of microrna-containing exosomes from human bile

Exosome research in the last three years has greatly extended the scope towards identification and characterization of biomarkers and their therapeutic uses.
Exosomes have recently been shown to contain microRNAs (miRs). MiRs themselves have arisen as valuable biomarkers for diagnostic purposes. As specimen collection in clinics and hospitals is quite variable, miRNA isolation from whole bile varies substantially. To achieve robust, accurate and reproducible miRNA profiles from collected bile samples in a simple manner required the development of a high-quality protocol to isolate and characterize exosomes from bile. The method requires several centrifugations and a filtration step with a final ultracentrifugation step to pellet the isolated exosomes. Electron microscopy, Western blots, flow cytometry and multi-parameter nanoparticle optical analysis, where available, are crucial characterization steps to validate the quality of the exosomes. For the isolation of miRNA from these exosomes, spiking the lysate with a non-specific, synthetic miRNA from a species like Caenorhabditis elegans, i.e., Cel-miR-39, is important for normalization of RNA extraction efficiency. The isolation of exosome from bile fluid following this method allows the successful miRNA profiling from bile samples stored for several years at -80 &#176;C.

Since exosomes are too small to be detected by regular microscopy or flow cytometry, electron microscopy or nanoparticle optical analysis has to be performed. The nanoparticle optical analysis has the advantage over electron microscopy that it is also quantitative and provides size distribution and concentration. The instrument introduces a finely focused laser beam through a glass prism into the sample. The Brownian motion of the isolated vesicles is captured via an EMCCD high sensitivit...

Watch this Scientific Journal Video about Isolation and Profiling of MicroRNA-containing Exosomes from Human Bile at JoVE.com

Isolation and Profiling of MicroRNA-containing Exosomes from Human Bile

Bile fluid is a valuable source of extracellular vesicles/exosomes that contain potentially important biomarkers. This protocol represents a robust method to isolate exosomes from human bile for further analyses including miRNA profiling.

Exosome research in the last three years has greatly extended the scope towards identification and characterization of biomarkers and their therapeutic ...

The overall goal of this method is to isolate exosomes from human bile for further analyses including microRNA profiling. This method can help answer key questions in the liver disease field such as detection of a particular bile marker for cholangiocarcinomas or other biliary diseases. The main advantage of this technique is that this is robust and repeatable.To perform endoscopic retrograde cholangiopancreatography, or ERCP, begin by placing the patient in a supine position. After intubating and passing a duodenoscope through the mouth of the patient, insert it into the second part of the duodenum and identify the major papilla. Selectively cannulate the common bile duct by inserting a triple lumen sphincterotome preloaded with a 0.35-inch or a 0.9-millimeter hydrophilic guidewire.Under fluoroscopic guidance, advance the guidewire to the left hepatic duct then advance the sphincterotome five centimeters into the bile duct to acquire a stable position. After removing the guidewire, attach a 10-millimeter syringe to the guidewire port through the lower lock and use 10 milliliters of negative pressure to aspirate the bile. Remove the syringe containing the bile and after reinserting the guidewire, inject contrast agent through the injection port to opacify the biliary tree.Then, transfer the collected bile into a 15-milliliter tube on ice and if storing for a later time, centrifuge the sample at 500 times g and four degrees Celsius for 10 minutes before freezing at minus 80 degrees Celsius. To immediately proceed with exosome isolation, transfer 400 microliters of bile into a microcentrifuge tube and centrifuge at 300 times g and four degrees Celsius for 10 minutes to collect cells and cell debris. To further clear the supernatant, transfer the solution to fresh microcentrifuge tubes and centrifuge the samples at 16, 500 times g and four degrees Celsius for 20 minutes.Then in a biosafety cabinet, collect the supernatant into a syringe and filter it through a 0.2-micrometer polyethersulfone membrane filter to remove any remaining particles larger than 200 nanometers. Transfer the filtered supernatant to ultracentrifuge tubes and use PBS to bring the tubes up to at least two-thirds full to prevent the tubes from collapsing during centrifugation. Pellet the exosomes through ultracentrifugation at 120, 000 times g and four degrees Celsius for 70 minutes.A small, yellow pellet will contain the exosomes. Discard the supernatant by carefully decanting and disinfect the waste by adding bleach to a final concentration of 10%volume per volume. Then let it stand for 20 minutes.For downstream experiments, either process the pellets in a small volume of appropriate solution or re-suspend them in 50 to 100 microliters of PBS and store at minus 80 degrees Celsius for future use. After preparing grids of contrast-stained extracellular vesicles, or EVs, according to the text protocol, acquire images with an electron microscope using an acceleration voltage of 80 kilovolts starting at magnifications of 20, 000 X, and increasing to 100, 000 X, when determining the size of the particles. Exosomes are too small to be detected by regular microscopy or flow cytometry;however, this figure shows the results of a typical nanoparticle tracking analysis, or NTA, of exosomes that measure the concentration and size distribution, which averaged 97 nanometers in this isolated human bile sample.Electron microscopy can also be used to confirm the size of the isolated particles in human bile and this figure shows a typical transmission EM result. These western blots were probed for proteins enriched in exosomes such as the tetraspanin CD63 and Tsg101. This real-time amplification plot shows a variety of microRNA species extracted from exosomes of human bile.Since exosomes lack reliable standards like 18S or 28S ribosomal RNA or housekeeping genes, the spiking of a synthetic microRNA is important for normalization. the exos isolation technique can be done in three hours if it is performed properly. After watching this video, you should have a good understanding of how to obtain and process bile from patients or animals to isolate and analyze extracellular vesicles.While recanting this procedure, it is important to remember to centrifuge the sample at 500 G and four degrees before freezing at minus 80, if you can't proceed with ultracentrifugation. Following this procedure, other methods like microRNA studies can be performed in order to answer additional questions like microRNA profiles. Don't forget that working with bile can be extremely hazardous since it could contain hepatitis, and precautions such as wearing gloves and safety glasses should always be taken while performing this procedure.After its development, the technique paved the way for research in the field of cholangiocarcinoma research to explore extracellular vesicles as potential biomarker in bile from patients with biliary problems such as obstruction of PSA.

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10.2K vistas.  Johns Hopkins University School of Medicine. The overall goal of this method is to isolate exosomes from human bile for further analyses including microRNA profiling. This method can help answer key questions in the liver disease field such as detection of a particular bile marker for cholangiocarcinomas or other biliary diseases. The main advantage of this technique is that this is robust and repeatable.To perform endoscopic retrograde cholangiopancreatography, or ERCP, begin by placing the patient in a supine position. After in...