This work was supported by grants from the National Natural Science Foundation of China (32000974, 81870796, 82170988, and 81930025) and the China Postdoctoral Science Foundation (2019M663986 and BX20190380). We are grateful for the assistance of the National Experimental Teaching Demonstration Center for Basic Medicine (AMFU).

The animal experiments were performed in accordance with the Guidelines of Institutional Animal Care and Use Committee of the Fourth Military Medical University and the ARRIVE guidelines. For the present study, 8-week-old C57Bl/6 mice (no preference for either females or males) were used. The steps involved in isolating plasma and tissue EVs are illustrated in Figure 1. The plasma is taken as a representative to describe the EV isolation procedure from body fluids. The maxillary bone is taken as a representative to explain the EV isolation procedure from the solid tissues.
1. Preparation of the plasma and the maxillary bone samples
<ol>
	<li>Prepare the plasma samples following the steps below.
	<ol>
		<li>Determine the body weight of the mouse using a standard laboratory balance.</li>
		<li>Add 20 &#181;L, 2 mg/mL of heparin to a 1.5 mL centrifuge tube and use the mixer device (see Table of Materials) to let the heparin attach to the wall of the tube. 
		NOTE: Anticoagulation tubes can also be used directly to collect the blood.</li>
		<li>Anesthetize the mouse by intraperitoneal injection of 50 mg/kg of pentobarbital sodium (see Table of Materials). Grab the neck of the mouse with the thumb and forefinger, then fix the tail and the left hind leg with the little finger and inject the pentobarbital sodium with a 1 mL injection syringe after exposing the belly.</li>
		<li>Confirm that the mouse is properly anesthetized based on the absence of corneal reflex and limb reaction when the footpad is pinched.</li>
		<li>Shave the hair on the face and eyelashes of the eyes with curved scissors.</li>
		<li>Grab the neck skin of the mouse and press the skin around the eyes to the back of the neck so that the eyeball protrudes. Use ophthalmic tweezers to quickly clamp the eyeball, and collect the outflow of blood with the 1.5 mL centrifuge tubes prepared in step 1.1.2. Sacrifice the mouse by dislocating the cervical vertebra. 
		CAUTION: Be careful with the hairs and eyelashes because they may cause hemolysis.</li>
		<li>Gently turn the tube upside down several times to prevent blood clotting. 
		CAUTION: Turn the tube upside down as soon as possible.</li>
		<li>Centrifuge the blood sample for 15 min at 1,200 x g at 4 &#176;C.</li>
		<li>Carefully transfer the supernatant to new and clean 1.5 mL centrifuge tubes, and use the plasma sample immediately or store it at 4 &#176;C for a few hours.</li>
		<li>Dilute the supernatant with an equal volume of 1x phosphate-buffered saline (PBS) and mix well. 
		&#8203;NOTE: The protocol provided above to collect the plasma is fatal. The blood can also be collected through subclavian vein puncture11 without sacrificing the mouse.</li>
	</ol>
	</li>
	<li>Prepare the maxillary bone samples following the steps below.
	<ol>
		<li>Isolate the maxillary bone with ophthalmic tweezers and scissors and wash them with PBS to get rid of soft tissues with tweezers.</li>
		<li>Put the maxillary bone into 1.5 mL centrifuge tubes and cut the bone into small pieces (the size must be less than 1 mm in diameter) with scissors. Add a certain amount of Liberase (5 &#181;g/mL, see Table of Materials) to cover the tissue (usually 1 mL for bone samples from an 8-week-old mouse), and then incubate for 30 min at 37 &#176;C.</li>
		<li>Centrifuge the sample at 800 x g for 10 min at 4 &#176;C.</li>
		<li>Carefully transfer the supernatant with a pipette to new and clean 1.5 mL centrifuge tubes.</li>
	</ol>
	</li>
</ol>
2. Extraction of EVs
<ol>
	<li>Centrifuge the samples (prepared in step 1.1.10 and step 1.2.4) for 15 min at 2,500 x g (4 &#176;C) to remove large cell debris and remaining platelets.</li>
	<li>Carefully transfer the supernatants to new and clean 1.5 mL centrifuge tubes and centrifuge for 30 min at 16,800 x g (4 &#176;C). 
	NOTE: The centrifugation speed can be set to over 10,000 x g to extract EVs12. The higher the speed of the centrifuge, the more quantity of EVs can be obtained. Because the speed limit of the centrifuge we used is 16,800 x g (see Table of Materials), we chose this speed in this protocol.</li>
	<li>Discard the supernatant and resuspend the pellets in each tube with 1 mL of PBS. Centrifuge for 30 min at 16,800 x g (4 &#176;C).</li>
	<li>Discard the supernatant and resuspend the pellets in each tube with 50 &#181;L of PBS. Store these samples at 4 &#176;C for only less than 24 h, or preferably use immediately for the following analyses (steps 3-5). 
	&#8203;CAUTION: Storage at -80 &#176;C is unacceptable, as this will reduce the concentration of EVs and increase the particle sizes of EVs13, thus influencing the following analysis of EVs.</li>
</ol>
3. Morphological identification of EVs
<ol>
	<li>Perform NTA analysis.
	<ol>
		<li>According to the amount of EVs (roughly judged by the size of pellets, the particles of 50 &#181;L plasma are the minimum), transfer 5-50 &#181;L of resuspension (step 2.4), dilute in 10 mL of buffer solution (PBS filtered with 0.22 &#181;m filter), and mix with 1 mL micro pipettor tips sufficiently. Use this final suspension for particle measurement.</li>
		<li>Use a sterile 1 mL syringe to inject at least 5 mL of distilled water with a moderate and constant speed until the number of particles displayed on the detection interface is less than five. 
		NOTE: After injecting 1 mL of distilled water through the whole channel, the number of particles is directly shown on the detection interface. If the number is still over five, continue injecting 1 mL of distilled water until the criteria are met.</li>
		<li>Reconstitute 1 &#181;L of calibration solution in 1 mL of distilled water to generate a primary solution, and then take 100 &#181;L of the primary solution to 25 mL of distilled water to prepare a standard stock solution (1:250,000). Store this working reagent at 4 &#176;C for 1 week.</li>
		<li>Calibrate the NTA instrument with the standard stock solution (step 3.1.3). Inject 1-5 mL of the working calibration solution with a 1 mL sterile syringe to flush the machine channel until the number of particles displayed on the detection interface is between 50-400 (preferably around 300). Run the calibration program.</li>
		<li>Repeat step 3.1.2 to flush the machine channel before each sample measurement.</li>
		<li>Use a sterile 1 mL syringe to inject at least 2 mL of buffer solution to flush the machine channel at a constant speed until the number of particles displayed on the detection interface is less than 10.</li>
		<li>Inject 1 mL of the EV sample prepared in step 3.1.1 with a moderate and constant speed (the recommended speed is 0.5-1 mL/s). 
		NOTE: The optimal particle concentration is making the number of particles displayed on the detection interface range from 50-400, preferably around 300. If the number of particles is too high, repeat step 3.1.2 to flush the machine channel immediately to avoid particle retention at the channel wall and adjust the concentration of the EV sample with step 3.1.1, then repeat from step 3.1.5.</li>
		<li>Conduct the particle analysis and generate the analysis reports according to the manufacturer&#39;s instructions (see Table of Materials).</li>
		<li>If the sample is precious, pump back the EV sample with the 1 mL syringe and collect them in 1.5 mL centrifuge tubes. Repeat step 2.2 to extract the EVs.</li>
		<li>After detecting all samples, inject at least 2 mL of buffer solution to the machine channel and then inject at least 5 mL of distilled water until the number of particles displayed on the detection interface is less than five.</li>
		<li>Use a sterile 5 mL syringe to inject at least 10 mL of air at a constant speed (the recommended speed is 1 mL/s) to remove the water in the channel.</li>
	</ol>
	</li>
	<li>Perform TEM analysis. 
	NOTE: Perform the following steps with fresh EV resuspensions. The formvar-carbon coated electron microscope grid has two sides, with the working side being luminous in the center grids. The minimum volume of plasma to extract the EVs for the below procedure is 50 &#181;L.
	<ol>
		<li>Mix the EV sample (step 2.4) with an equal volume of 4% paraformaldehyde (PFA). Deposit 4 &#181;L of the EVs on one grid and incubate for 15 min at room temperature (RT).</li>
		<li>Put four drops of PBS (one drop is equal to 50 &#181;L) on a sheet of polyethylene film (see Table of Materials). Transfer the grids with clean microscopic tweezers and wash the working side of the grid in PBS from one drop to another.</li>
		<li>Use filter papers to remove extra PBS that remained in the grids.</li>
		<li>Incubate the working side of the grid into 1% phosphotungstic acid (see Table of Materials) for 2 min and then repeat step 3.2.2. 
		CAUTION: Since phosphotungstic acid is poisonous, this procedure needs to be operated in the fume hood, and redundant phosphotungstic acid needs to be specifically recycled rather than discarded directly.</li>
		<li>Put the grids face up in a 10 cm dish covered with filter papers. The grids can be stored at RT for several years.</li>
		<li>Observe the grids under an electron microscope following the manufacturer&#39;s instructions (see Table of Materials). 
		&#8203;NOTE: To ensure the single particles are observed, the concentration of the EVs must be adjusted, and the suspension needs to be clear without obvious turbidity. Before dropping, the sample should be well mixed. The representative TEM and NTA analyses are shown in Figure 2.</li>
	</ol>
	</li>
</ol>
4. Origin analysis of EVs
NOTE: The identification of the cellular origin of EVs requires the application of antibodies for typical cell membrane markers. The minimum plasma volume to extract the EVs for the below procedure is 300 &#181;L. Based on the lipid bilayer structures of EVs, membrane dye can be used to mark them. For blood plasma samples, CD18 for lymphocytes14 is chosen for representation. For maxillary bone samples, osteoclast-associated receptor (OSCAR) for osteoclasts15 is selected as an example. Before the FC, ensure the flow cytometer is adapted to the measurement of EVs16, as the lower size limit is largely different between distinct flow cytometers.
<ol>
	<li>Resuspend samples (step 2.4) with 500 &#181;L of PBS and transfer 50 &#181;L into a new and clean 1.5 mL centrifuge tube as a blank control (tube A) and another 50 &#181;L into a new and clean 1.5 mL centrifuge tube as a simple staining tube for FITC (tube B). Add 0.5 &#181;L of membrane dye to the primary tube for membrane staining. Incubate for 5 min at RT.</li>
	<li>Centrifuge the primary tube for 30 min at 16,800 x g (4 &#176;C). Discard the supernatant and resuspend the pellets with 200 &#181;L of PBS.</li>
	<li>Divide each 50 &#181;L sample into four 1.5 mL centrifuge tubes for simple staining tubes for PE (tube C), surface marker staining (tube D), and secondary antibody only controls (tube E).</li>
	<li>Add the primary antibody of OSCAR in bone EV samples as well as CD18 antibody in plasma EV samples (see Table of Materials) to tube B (step 4.1) and tube D (step 4.3) separately (diluted at 1:100). Incubate for 1 h at 4 &#176;C.</li>
	<li>Centrifuge the tubes for 30 min at 16,800 x g (4 &#176;C). Discard the supernatant, resuspend the pellets with 500 &#181;L of PBS, and then centrifuge again for 30 min at 16,800 x g (4 &#176;C) to remove the extra primary antibodies.</li>
	<li>Discard the supernatant and resuspend the pellets with 50 &#181;L of PBS, followed by adding FITC-conjugated secondary antibodies (see Table of Materials), respectively (diluted at 1:200) (tube E). Add the same secondary antibodies to tube B (step 4.1) and tube D (step 4.3). Incubate all the tubes for 1 h, at 4 &#176;C in the dark. 
	NOTE: Direct fluorescence-conjugated labeling antibodies can also be used to process the FC detection with proper isotype controls.</li>
	<li>Dilute one drop of 0.2, 0.5, and 1 &#181;m sized beads (see Table of Materials) suspension respectively into 1 mL of PBS, and run each size beads first to make sure of the gate chosen for EVs. Set the threshold of the flow cytometer to search for the beads and EV population by using a suitable forward scatter (FSC) and side scatter (SSC).
	<ol>
		<li>Set the terminal condition as calculating 100,000 membrane-dyed particles. Analyze the sample via a flow cytometer under the manufacturer&#39;s instructions (see Table of Materials). The representative results are shown in Figure 3. 
		&#8203;NOTE: NTA equipment with fluorescence channels can also be used for origin analysis, and the sample preparation is the same as FC.</li>
	</ol>
	</li>
</ol>
5. Protein content analysis of EVs
NOTE: The analysis of the protein content within EVs is performed via western blot. For example, the plasma and bone EVs were selected to analyze 6-phosphogluconate dehydrogenase (PGD) and pyruvate kinase M2 (PKM2) for metabolic status. Golgin84 (the Golgi organelle) was used as a negative control, and Flotillin (membrane protein), Caveolin (integral protein of caveolae), and &#946;-actin (the cytoskeleton)17 were used as a positive control in EVs compared to cell samples. Mitofilin and &#945;-Actinin-4 were chosen as large EV markers, while CD9 and CD81 were chosen as small EV markers to demonstrate the EV subpopulations18. Apoa1 was selected as a plasma lipoparticle marker19. For the respective reagent details, see Table of Materials.
<ol>
	<li>Resuspend the pellets (step 2.4) in 50 &#181;L of RIPA lysis buffer, and incubate for 30 min on ice.</li>
	<li>Quantify the protein concentrations of all samples in the 96-well microplate by the BCA protein assay following the manufacturer&#39;s instructions (see Table of Materials).
	<ol>
		<li>Dilute the 2 mg/mL of bovine serum albumin (BSA) with 0.9% of normal saline (NS) (containing 0.9% (w/v) of sodium chloride) into 0.5 mg/mL. Add the 0.5 mg/mL of BSA and 0.9% of NS into three duplicated wells with certain volumes, as shown in Table 1.</li>
		<li>Drop 2 &#181;L of the samples (step 5.1) and add 18 &#181;L of NS into three duplicated wells separately.</li>
		<li>Prepare a working solution by mixing BCA Reagent A with Reagent B (50:1 Reagent A:B). Add 200 &#181;L of the working solution to each well and shake gently for 30 s.</li>
		<li>Incubate the 96-well microplate for 20-25 min at 37 &#176;C.</li>
		<li>Measure the OD at 596 nm by the spectrophotometer (see Table of Materials).</li>
		<li>Export the data.</li>
		<li>Draw a standard curve and calculate the protein concentration of the samples.</li>
	</ol>
	</li>
	<li>According to the results, dilute the samples to 1 &#181;g/&#181;L with 0.9% of NS and 5x SDS-PAGE loading buffer (250 mM Tris&#183;HCl, pH 6.8, 10% SDS, 30% (v/v) Glycerol, 10 mM DTT, 0.05% (w/v) Bromophenol blue, see Table of Materials). Seal the tubes with film tightly and heat for 5 min at 100 &#176;C.</li>
	<li>Load the samples and the protein ladder into a gradient concentration of 4%-20% Hepes-Tris gel (see Table of Materials). 
	NOTE: Choose the gel percentage according to the molecular weight of the proteins of interest.</li>
	<li>Run the gel in the running buffer at 80 V until the proteins form a line, and then switch to 120 V for 1 h until the loading dye is at the bottom of the gel. 
	NOTE: The run time may vary according to the equipment used or the type and concentration of the gel.</li>
	<li>Transfer the gel to the polyvinylidene fluoride (PVDF) membrane (see Table of Materials), pre-incubated in methyl alcohol for 20 s. Use a wet transfer system to transfer for 1 h at 200 mA. 
	CAUTION: Ensure that there is no bubble inside the transfer system and keep the PVDF membrane wet. 
	NOTE: The transfer time may vary according to the molecular weight of the target protein; 1 KD usually needs 1 min.</li>
	<li>Prepare 5% BSA blocking buffer by adding 2.5 g of BSA (see Table of Materials) in 50 mL of Tris-buffered saline-Tween (TBST) (2 mL of Tween added in 2 L of PBS solution) into a 50 mL centrifuge tube. Agitate until the powder is dissolved. Block the membranes in this buffer for 2 h at RT with agitation.</li>
	<li>Incubate the membranes with specific primary antibodies diluted with TBST into proper concentration (Mitofilin, 1:1000; &#945;-Actinin-4, 1:1000; CD9, 1:1000; CD81, 1:1000; Apoa1, 1:1000; Golgin84, 1:1000; Flotillin-1, 1:1000; Caveolin-1, 1:1000; PGD, 1:1000; PKM2, 1:1000; &#946;-actin, 1:3000) overnight at 4 &#176;C.</li>
	<li>Wash the membranes in the washing buffer (2 mL of Tween added in 2 L of PBS solution) four times (15 min each time), and incubate the membranes with the suitable secondary antibodies at 1:4000 for 1 h at RT with agitation.</li>
	<li>Wash the membranes in the washing buffer four times (15 min each time), and image the membranes using the Chemiluminescence Kit and a gel imaging system (see Table of Materials).</li>
</ol>

<ol>
	<li>Abels, E. R., Breakefield, X. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Introduction+to+extracellular+vesicles:+biogenesis,+RNA+cargo+selection,+content,+release,+and+uptake.">Introduction to extracellular vesicles: biogenesis, RNA cargo selection, content, release, and uptake.</a> Cellular and Molecular Neurobiology. 36 (3), 301-312 (2016).</li><li>Mathieu, M., Martin-Jaular, L., Lavieu, G., Th&#233;ry, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specificities+of+secretion+and+uptake+of+exosomes+and+other+extracellular+vesicles+for+cell-to-cell+communication.">Specificities of secretion and uptake of exosomes and other extracellular vesicles for cell-to-cell communication.</a> Nature Cell Biology. 21 (1), 9-17 (2019).</li><li>Van Niel, G., D'Angelo, G., Raposo, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shedding+light+on+the+cell+biology+of+extracellular+vesicles.">Shedding light on the cell biology of extracellular vesicles.</a> Nature Reviews Molecular Cell Biology. 19 (4), 213-228 (2018).</li><li>Witwer, K. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardization+of+sample+collection,+isolation+and+analysis+methods+in+extracellular+vesicle+research.">Standardization of sample collection, isolation and analysis methods in extracellular vesicle research.</a> Journal of Extracellular Vesicles. 2 (1), 20360 (2013).</li><li>Keshtkar, S., Azarpira, N., Ghahremani, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cell-derived+extracellular+vesicles:+novel+frontiers+in+regenerative+medicine.">Mesenchymal stem cell-derived extracellular vesicles: novel frontiers in regenerative medicine.</a> Stem Cell Research &amp; Therapy. 9 (1), 63 (2018).</li><li>Thietart, S., Rautou, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+vesicles+as+biomarkers+in+liver+diseases:+A+clinician's+point+of+view.">Extracellular vesicles as biomarkers in liver diseases: A clinician's point of view.</a> Journal of Hepatology. 73 (6), 1507-1525 (2020).</li><li>Xia, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Damaged+brain+accelerates+bone+healing+by+releasing+small+extracellular+vesicles+that+target+osteoprogenitors.">Damaged brain accelerates bone healing by releasing small extracellular vesicles that target osteoprogenitors.</a> Nature Communications. 12 (1), 6043 (2021).</li><li>In’t Veld, S. G. J. G., Wurdinger, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor-educated+pletelets.">Tumor-educated pletelets.</a> Blood. 133 (22), 2359-2364 (2019).</li><li>Schwager, S. C., Reinhart-King, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanobiology+of+microvesicle+release,+uptake,+and+microvesicle-mediated+activation.">Mechanobiology of microvesicle release, uptake, and microvesicle-mediated activation.</a> Current Topics in Membranes. 86, 255-278 (2020).</li><li>Brahmer, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=endothelial+cells+and+leukocytes+contribute+to+the+exercise-triggered+release+of+extracellular+vesicles+into+the+circulation.">endothelial cells and leukocytes contribute to the exercise-triggered release of extracellular vesicles into the circulation.</a> Journal of Extracellular Vesicles. 8 (1), 1615820 (2019).</li><li>Yang, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+collection+through+subclavian+vein+puncture+in+mice.">Blood collection through subclavian vein puncture in mice.</a> Journal of Visualized Experiments. (147), e59556 (2019).</li><li>Han, L., Lam, E. W., Sun, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+vesicles+in+the+tumor+microenvironment:+old+stories,+but+new+tales.">Extracellular vesicles in the tumor microenvironment: old stories, but new tales.</a> Molecular Cancer. 18 (1), 59 (2019).</li><li>Gelibter, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+storage+on+extracellular+vesicles:+A+systematic+study.">The impact of storage on extracellular vesicles: A systematic study.</a> Journal of Extracellular Vesicles. 11 (2), 12162 (2022).</li><li>Forsyth, C. B., Mathews, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lymphocytes+utilize+CD11b/CD18+for+adhesion+to+Candida+albicans.">Lymphocytes utilize CD11b/CD18 for adhesion to Candida albicans.</a> Cellular Immunology. 170 (1), 91-100 (1996).</li><li>Kodama, J., Kaito, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoclast+multinucleation:+review+of+current+literature.">Osteoclast multinucleation: review of current literature.</a> International Journal of Molecular Sciences. 21 (16), 5685 (2020).</li><li>Welsh, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MIFlowCyt-EV:+a+framework+for+standardized+reporting+of+extracellular+vesicle+flow+cytometry+experiments.">MIFlowCyt-EV: a framework for standardized reporting of extracellular vesicle flow cytometry experiments.</a> Journal of Extracellular Vesicles. 9 (1), 1713526 (2020).</li><li>Durcin, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterisation+of+adipocyte-derived+extracellular+vesicle+subtypes+identifies+distinct+protein+and+lipid+signatures+for+large+and+small+extracellular+vesicles.">Characterisation of adipocyte-derived extracellular vesicle subtypes identifies distinct protein and lipid signatures for large and small extracellular vesicles.</a> Journal of Extracellular Vesicles. 6 (1), 1305677 (2017).</li><li>Kowal, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+comparison+defines+novel+markers+to+characterize+heterogeneous+populations+of+extracellular+vesicle+subtypes.">Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes.</a> Proceedings of the National Academy of Sciences. 113 (8), 968-977 (2016).</li><li>Noren Hooten, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Association+of+extracellular+vesicle+protein+cargo+with+race+and+clinical+markers+of+mortality.">Association of extracellular vesicle protein cargo with race and clinical markers of mortality.</a> Scientific Reports. 9 (1), 17582 (2019).</li><li>Sidhom, K., Obi, P. O., Saleem, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+exosomal+isolation+methods:+is+size+exclusion+chromatography+the+best+option.">A review of exosomal isolation methods: is size exclusion chromatography the best option.</a> International Journal of Molecular Sciences. 21 (18), 6466 (2020).</li><li>Pietrowska, M., Wlosowicz, A., Gawin, M., Widlak, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MS-based+proteomic+analysis+of+serum+and+plasma:+problem+of+high+abundant+components+and+lights+and+shadows+of+albumin+removal.">MS-based proteomic analysis of serum and plasma: problem of high abundant components and lights and shadows of albumin removal.</a> Advances in Experimental Medicine and Biology. 1073, 57-76 (2019).</li><li>Coumans, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methodological+guidelines+to+study+extracellular+vesicles.">Methodological guidelines to study extracellular vesicles.</a> Circulation Research. 120 (10), 1632-1648 (2017).</li><li>Th&#233;ry, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimal+information+for+studies+of+extracellular+vesicles+2018+(MISEV2018):+a+position+statement+of+the+International+Society+for+Extracellular+Vesicles+and+update+of+the+MISEV2014+guidelines.">Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines.</a> Journal of Extracellular Vesicles. 7 (1), 1535750 (2018).</li><li>Witwer, K. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardization+of+sample+collection,+isolation+and+analysis+methods+in+extracellular+vesicle+research.">Standardization of sample collection, isolation and analysis methods in extracellular vesicle research.</a> Journal of Extracellular Vesicles. 2 (1), 20360 (2013).</li><li>Coumans, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methodological+guidelines+to+study+extracellular+vesicles.">Methodological guidelines to study extracellular vesicles.</a> Circulation Research. 120 (10), 1632-1648 (2017).</li><li>G&#246;rgens, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+storage+conditions+stabilizing+extracellular+vesicles+preparations.">Identification of storage conditions stabilizing extracellular vesicles preparations.</a> Journal of Extracellular Vesicles. 11 (6), 12238 (2020).</li><li>Maroto, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+storage+temperature+on+airway+exosome+integrity+for+diagnostic+and+functional+analyses.">Effects of storage temperature on airway exosome integrity for diagnostic and functional analyses.</a> Journal of Extracellular Vesicles. 6 (1), 1359478 (2017).</li><li>Zheng, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptotic+vesicles+restore+liver+macrophage+homeostasis+to+counteract+type+2+diabetes.">Apoptotic vesicles restore liver macrophage homeostasis to counteract type 2 diabetes.</a> Journal of Extracellular Vesicles. 10 (7), 12109 (2021).</li><li>Liu, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circulating+apoptotic+bodies+maintain+mesenchymal+stem+cell+homeostasis+and+ameliorate+osteopenia+via+transferring+multiple+cellular+factors.">Circulating apoptotic bodies maintain mesenchymal stem cell homeostasis and ameliorate osteopenia via transferring multiple cellular factors.</a> Cell Research. 28 (9), 918-933 (2018).</li><li>Vander Pol, E., van Gemert, M. J., Sturk, A., Nieuwland, R., van Leeuwen, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+vs.+swarm+detection+of+microparticles+and+exosomes+by+flow+cytometry.">Single vs. swarm detection of microparticles and exosomes by flow cytometry.</a> Journal of Thrombosis and Haemostasis. 10 (5), 919-930 (2012).</li><li>Dawson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+lipid+rafts+(detergent-resistant+microdomains)+and+comparison+to+extracellular+vesicles+(exosomes).">Isolation of lipid rafts (detergent-resistant microdomains) and comparison to extracellular vesicles (exosomes).</a> Methods in Molecular Biology. 2187, 99-112 (2021).</li><li>Zhang, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+vesicles:+Natural+liver-accumulating+drug+delivery+vehicles+for+the+treatment+of+liver+diseases.">Extracellular vesicles: Natural liver-accumulating drug delivery vehicles for the treatment of liver diseases.</a> Journal of Extracellular Vesicles. 10 (2), 12030 (2020).</li><li>Vella, L. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rigorous+method+to+enrich+for+exosomes+from+brain+tissue.">A rigorous method to enrich for exosomes from brain tissue.</a> Journal of Extracellular Vesicles. 6 (1), 1348885 (2017).</li></ol>

The authors have no conflicts of interest to disclose.

When studying the features, the fate, and the function of EVs, it is crucial to isolate EVs with high yield and low contamination. Various methods exist to extract EVs, such as density gradient centrifugation (DGC), size-exclusion chromatography (SEC), and immunocapture assays4,20. Here, one of the most commonly used methods, differential centrifugation, was used; the advantages of this are that it is not time consuming, it generates a high yield of EVs with easy...

Extracellular vesicles (EVs) have been proposed to define cell-released lipid bilayer-enclosed extracellular structures1, which play important roles in various physiological and pathological events2. EVs released by healthy cells can be broadly divided into two main categories, namely exosomes (or small EVs) formed through an intracellular endocytic trafficking pathway3 and microvesicles (or large EVs) developed by the outward budding of the plasma membrane of the cell4. While many studies focus on the function of EVs collected from cultured cells in vitro5, EVs derived from the circulation or tissues are more complex and heterogeneous, which have the advantage of reflecting the true state of the organism in vivo6. Furthermore, nearly all kinds of tissues can produce EVs in vivo, and these EVs can act as messengers within the tissue or be transferred by various body fluids, especially the peripheral blood, to facilitate systemic communication7. EVs in the circulation and tissues are also targets for disease diagnosis and treatment8.
Whereas exosomes have been intensively studied in recent years, microvesicles also have important biological functions, which can be easily extracted without ultracentrifugation, thus promoting basic and clinical research9. Notably, a critical issue regarding EVs isolated from the circulation and tissues is that they are derived from different cell types10. Since microvesicles are blebbed from the plasma membrane and featured by an abundance of cell surface molecules9, using parent cell membrane markers to identify the cellular origin of these EVs is feasible. Specifically, the flow cytometry (FC) technique can be applied to detect membrane markers. Moreover, researchers can isolate the EVs and make further analyses based on the functional cargos.
The present protocol provides a thorough procedure for extracting and characterizing EVs from in vivo samples. The EVs are isolated via differential centrifugation, and the characterization of EVs includes morphological identification via nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM), origin analysis via FC, and protein cargo analysis via western blot. The blood plasma and maxillary bone of mice are used as representatives. Researchers can refer to this protocol for EVs from other sources and make corresponding modifications.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>4% paraformaldehyde&#160;</td>
			<td>Biosharp</td>
			<td>143174</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>Alexa fluor 488 anti-goat secondary antibody</td>
			<td>Yeason</td>
			<td>34306ES60</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Alexa fluor 488 anti-rabbit secondary antibody</td>
			<td>Invitrogen</td>
			<td>A11008</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Anti-CD18 antibody</td>
			<td>Abcam</td>
			<td>ab131044</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Anti-CD81 antibody</td>
			<td>Abcam</td>
			<td>ab109201</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>anti-CD9 antibody</td>
			<td>Huabio</td>
			<td>ET1601-9</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Anti-Mitofilin antibody</td>
			<td>Abcam</td>
			<td>ab110329</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>APOA1 Rabbit pAb</td>
			<td>Abclone</td>
			<td>A14211</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>BCA protein assay kit</td>
			<td>TIANGEN</td>
			<td>PA115</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>BLUeye Prestained Protein Ladder</td>
			<td>Sigma-Aldrich</td>
			<td>94964-500UL</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Bovine serum albumin</td>
			<td>MP Biomedical</td>
			<td>218072801</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Caveolin-1 antibody</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-53564</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>CellMask Orange plasma membrane stain</td>
			<td>Invitrogen</td>
			<td>C10045</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Chemiluminescence</td>
			<td>Amersham Biosciences</td>
			<td>N/A</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Curved operating scissor</td>
			<td>JZ Surgical Instrument</td>
			<td>J21040</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>Electronic balance</td>
			<td>Zhi Ke</td>
			<td>ZK-DST</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>Epoch spectrophotometer</td>
			<td>BioTek</td>
			<td>N/A</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Eppendorf tubes</td>
			<td>Eppendorf</td>
			<td>3810X</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>Flotillin-1 antibody</td>
			<td>PTM BIO</td>
			<td>PTM-5369</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Gel imaging system</td>
			<td>Tanon</td>
			<td>4600</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Golgin84</td>
			<td>Novus</td>
			<td>nbp1-83352</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Grids - Formvar/Carbon Coated - Copper 200 mesh</td>
			<td>Polysciences</td>
			<td>24915</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>Heparin Solution</td>
			<td>StemCell&#160;</td>
			<td>7980</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>Liberase Research Grade</td>
			<td>Sigma-Aldrich</td>
			<td>5401127001</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>Microscopic tweezer</td>
			<td>JZ Surgical Instrument</td>
			<td>JD1020</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>NovoCyte flow cytometer</td>
			<td>ACEA</td>
			<td>N/A</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Omni-PAGE Hepes-Tris Gels Hepes 4~20%, 10 wells</td>
			<td>Epizyme</td>
			<td>LK206</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>OSCAR(D-19) antibody</td>
			<td>Santa Cruz Biotechnology</td>
			<td>SC-34235</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>PBS (2x)</td>
			<td>ZHHC</td>
			<td>PW013</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Pentobarbital sodium</td>
			<td>Sigma-Aldrich</td>
			<td>57-33-0</td>
			<td>Anesthetization</td>
		</tr>
		<tr>
			<td>Peroxidase AffiniPure Goat Anti-Mouse IgG (H+L)</td>
			<td>Jacson</td>
			<td>115-035-003</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Peroxidase AffiniPure Goat Anti-Rabbit IgG (H+L)</td>
			<td>Jacson</td>
			<td>111-035-003</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Phosphotungstic acid</td>
			<td>RHAWN</td>
			<td>12501-23-4</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>PKM2(d78a4) xp rabbit&#160; mab&#160;</td>
			<td>Cell Signaling</td>
			<td>4053t</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Polyethylene (PE) film</td>
			<td>Xiang yi</td>
			<td>200150055</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>Polyvinylidene fluoride membranes&#160;</td>
			<td>Roche</td>
			<td>3010040001</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Protease inhibitors</td>
			<td>Roche</td>
			<td>4693132001</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Recombinant anti-PGD antibody</td>
			<td>Abcam</td>
			<td>ab129199</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>RIPA lysis buffer</td>
			<td>Beyotime</td>
			<td>P0013</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>SDS-PAGE loading buffer (5x)</td>
			<td>Cwbio</td>
			<td>CW0027S</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Size beads</td>
			<td>Invitrogen</td>
			<td>F13839</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Tabletop High-Speed Micro Centrifuges</td>
			<td>Hitachi</td>
			<td>CT15E</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>Transmission electron microscope</td>
			<td>HITACHI</td>
			<td>H-7650</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>MP Biomedicals</td>
			<td>19472</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Vortex Mixer Genie</td>
			<td>Scientific Industries</td>
			<td>SI0425</td>
			<td>EV isolation</td>
		</tr>
		<tr>
			<td>ZetaView BASIC NTA - Nanoparticle Tracking Video Microscope PMX-120</td>
			<td>Particle Metrix</td>
			<td>N/A</td>
			<td>Nanoparticle tracking analysis</td>
		</tr>
		<tr>
			<td>&#945;-Actinin-4 Rabbit mAb</td>
			<td>Abclone</td>
			<td>A3379</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>&#946;-actin</td>
			<td>Cwbio</td>
			<td>CW0096M</td>
			<td>Western blot</td>
		</tr>
	</tbody>
</table>

isolation and analysis of traceable and functionalized extracellular vesicles from the plasma and solid tissues

Circulating and tissue-resident extracellular vesicles (EVs) represent promising targets as novel theranostic biomarkers, and they emerge as important players in the maintenance of organismal homeostasis and the progression of a wide spectrum of diseases. While the current research focuses on the characterization of endogenous exosomes with the endosomal origin, microvesicles blebbing from the plasma membrane have gained increasing attention in health and sickness, which are featured by an abundance of surface molecules recapitulating the membrane signature of parent cells. Here, a reproducible procedure is presented based on differential centrifugation for extracting and characterizing EVs from the plasma and solid tissues, such as the bone. The protocol further describes subsequent profiling of surface antigens and protein cargos of EVs, which are thus traceable for their derivations and identified with components related to potential function. This method will be useful for correlative, functional, and mechanistic analysis of EVs in biological, physiological, and pathological studies.

According to the experimental workflow, EVs can be extracted from the peripheral blood and solid tissues (Figure 1). The maxillary bone of a mouse aged 8 weeks is approximately 0.1 &#177; 0.05 g, and about 300 &#181;L of plasma can be collected from the mouse. Following the protocol steps, 0.3 mg and 3 &#181;g of EVs can be collected, respectively. As analyzed by TEM and NTA, the typical morphological characteristics of EVs are round cup-shaped membrane vesicles with a diameter ranging from ...

Watch this Scientific Journal Video about Isolation and Analysis of Traceable and Functionalized Extracellular Vesicles from the Plasma and Solid Tissues at JoVE.com

Isolation and Analysis of Traceable and Functionalized Extracellular Vesicles from the Plasma and Solid Tissues

The present protocol describes a method to extract extracellular vesicles from the peripheral blood and solid tissues with subsequent profiling of surface antigens and protein cargos.

Circulating and tissue-resident extracellular vesicles (EVs) represent promising targets as novel theranostic biomarkers, and they emerge as important ...

isolation-analysis-traceable-functionalized-extracellular-vesicles

Research

JoVE Journal

Biology

1.8K Views.  The Fourth Military Medical University. The present protocol describes a method to extract extracellular vesicles from the peripheral blood and solid tissues with subsequent profiling of surface antigens and protein cargos.

Video: Isolation and Analysis of Traceable and Functionalized Extracellular Vesicles from the Plasma and Solid Tissues

Solid Phase Synthesis of a Functionalized Bis-Peptide Using "Safety Catch" Methodology

In 1962, R.B. Merrifield published the first procedure using solid-phase peptide synthesis as a novel route to efficiently synthesize peptides. This technique quickly proved advantageous over its solution-phase predecessor in both time and labor. Improvements concerning the nature of solid support, the protecting groups employed and the coupling methods employed over the last five decades have only increased the usefulness of Merrifield's original system. Today, use of a Boc-based protection and base/nucleophile cleavable resin strategy or Fmoc-based protection and acidic cleavable resin strategy, pioneered by R.C. Sheppard, are most commonly used for the synthesis of peptides1.
Inspired by Merrifield's solid supported strategy, we have developed a Boc/tert-butyl solid-phase synthesis strategy for the assembly of functionalized bis-peptides2, which is described herein. The use of solid-phase synthesis compared to solution-phase methodology is not only advantageous in both time and labor as described by Merrifield1, but also allows greater ease in the synthesis of bis-peptide libraries. The synthesis that we demonstrate here incorporates a final cleavage stage that uses a two-step "safety catch" mechanism to release the functionalized bis-peptide from the resin by diketopiperazine formation.
Bis-peptides are rigid, spiro-ladder oligomers of bis-amino acids that are able to position functionality in a predictable and designable way, controlled by the type and stereochemistry of the monomeric units and the connectivity between each monomer. Each bis-amino acid is a stereochemically pure, cyclic scaffold that contains two amino acids (a carboxylic acid with an &alpha;-amine)3,4. Our laboratory is currently investigating the potential of functional bis-peptides across a wide variety of fields including catalysis, protein-protein interactions and nanomaterials.

Solid Phase Synthesis of a Functionalized Bis-Peptide Using &quot;Safety Catch&quot; Methodology

The efficient solid-phase peptide synthesis of a functionalized bis-peptide trimer utilizing a "safety catch" cleavage procedure from HMBA resin is described.

In 1962, R.B. Merrifield published the first procedure using solid-phase peptide synthesis as a novel route to efficiently synthesize peptides. This ...

Techniques for the Analysis of Extracellular Vesicles Using Flow Cytometry

Extracellular Vesicles (EVs) are small, membrane-derived vesicles found in bodily fluids that are highly involved in cell-cell communication and help regulate a diverse range of biological processes. Analysis of EVs using flow cytometry (FCM) has been notoriously difficult due to their small size and lack of discrete populations positive for markers of interest. Methods for EV analysis, while considerably improved over the last decade, are still a work in progress. Unfortunately, there is no one-size-fits-all protocol, and several aspects must be considered when determining the most appropriate method to use. Presented here are several different techniques for processing EVs and two protocols for analyzing EVs using either individual detection or a bead-based approach. The methods described here will assist with eliminating the antibody aggregates commonly found in commercial preparations, increasing signal&#8211;to-noise ratio, and setting gates in a rational fashion that minimizes detection of background fluorescence. The first protocol uses an individual detection method that is especially well suited for analyzing a high volume of clinical samples, while the second protocol uses a bead-based approach to capture and detect smaller EVs and exosomes.

Many different methods exist for the measurement of extracellular vesicles (EVs) using flow cytometry (FCM). Several aspects should be considered when determining the most appropriate method to use. Two protocols for measuring EVs are presented, using either individual detection or a bead-based approach.

Extracellular Vesicles (EVs) are small, membrane-derived vesicles found in bodily fluids that are highly involved in cell-cell communication and help ...

Enrichment of Extracellular Matrix Proteins from Tissues and Digestion into Peptides for Mass Spectrometry Analysis

The extracellular matrix (ECM) is a complex meshwork of cross-linked proteins that provides biophysical and biochemical cues that are major regulators of cell proliferation, survival, migration, etc. The ECM plays important roles in development and in diverse pathologies including cardio-vascular and musculo-skeletal diseases, fibrosis, and cancer. Thus, characterizing the composition of ECMs of normal and diseased tissues could lead to the identification of novel prognostic and diagnostic biomarkers and potential novel therapeutic targets. However, the very nature of ECM proteins (large in size, cross-linked and covalently bound, heavily glycosylated) has rendered biochemical analyses of ECMs challenging. To overcome this challenge, we developed a method to enrich ECMs from fresh or frozen tissues and tumors that takes advantage of the insolubility of ECM proteins. We describe here in detail the decellularization procedure that consists of sequential incubations in buffers of different pH and salt and detergent concentrations and that results in 1) the extraction of intracellular (cytosolic, nuclear, membrane and cytoskeletal) proteins and 2) the enrichment of ECM proteins. We then describe how to deglycosylate and digest ECM-enriched protein preparations into peptides for subsequent analysis by mass spectrometry.

This protocol describes a procedure for enriching ECM proteins from tissues or tumors and deglycosylating and digesting the ECM-enriched preparations into peptides to analyze their protein composition by mass spectrometry.

The extracellular matrix (ECM) is a complex meshwork of cross-linked proteins that provides biophysical and biochemical cues that are major regulators of ...

Analysis of Cell Suspensions Isolated from Solid Tissues by Spectral Flow Cytometry

Flow cytometry has been used for the past 40 years to define and analyze the phenotype of lymphoid and other hematopoietic cells. Initially restricted to the analysis of a few fluorochromes, currently there are dozens of different fluorescent dyes, and up to 14-18 different dyes can be combined at a time. However, several limitations still impair the analytical capabilities. Because of the multiplicity of fluorescent probes, data analysis has become increasingly complex due to the need of large, multi-parametric compensation matrices. Moreover, mutant mouse models carrying fluorescent proteins to detect and trace specific cell types in different tissues have become available, so the analysis (by flow cytometry) of auto-fluorescent cell suspensions obtained from solid organs is required. Spectral flow cytometry, which distinguishes the shapes of emission spectra along a wide range of continuous wavelengths, addresses some of these problems. The data is analyzed with an algorithm that replaces compensation matrices and treats auto-fluorescence as an independent parameter. Thus, spectral flow cytometry should be capable of discriminating fluorochromes with similar emission peaks and can provide a multi-parametric analysis without compensation requirements.
This protocol describes the spectral flow cytometry analysis, allowing for a 21-parameter (19 fluorescent probes) characterization and the management of an auto-fluorescent signal, providing high resolution in minor population detection. The results presented here show that spectral flow cytometry presents advantages in the analysis of cell populations from tissues difficult to characterize in conventional flow cytometry, such as the heart and the intestine. Spectral flow cytometry thus demonstrates the multi-parametric analytical capacity of high-performing conventional flow cytometry without the requirement for compensation and enables auto-fluorescence management.

This article describes spectral cytometry, a new approach in flow cytometry that uses the shapes of emission spectra to distinguish fluorochromes. An algorithm replaces compensations and can treat auto-fluorescence as an independent parameter. This new approach allows for the proper analysis of cells isolated from solid organs.

Flow cytometry has been used for the past 40 years to define and analyze the phenotype of lymphoid and other hematopoietic cells. Initially restricted to ...

Flow Cytometric Analysis of Extracellular Vesicles from Cell-conditioned Media

Flow cytometry (FC) is the method of choice for semi-quantitative measurement of cell-surface antigen markers. Recently, this technique has been used for phenotypic analyses of extracellular vesicles (EV) including exosomes (Exo) in the peripheral blood and other body fluids. The small size of EV mandates the use of dedicated instruments having a detection threshold around 50-100 nm. Alternatively, EV can be bound to latex microbeads that can be detected by FC. Microbeads, conjugated with antibodies that recognize EV-associated markers/Cluster of Differentiation CD63, CD9, and CD81 can be used for EV capture. Exo isolated from CM can be analyzed with or without pre-enrichment by ultracentrifugation. This approach is suitable for EV analyses using conventional FC instruments. Our results demonstrate a linear correlation between Mean Fluorescence Intensity (MFI) values and EV concentration. Disrupting EV through sonication dramatically decreased MFI, indicating that the method does not detect membrane debris. We report an accurate and reliable method for the analysis of EV surface antigens, which can be easily implemented in any laboratory.

The protocol describes a reproducible method designed for use with cell culture supernatants to detect surface epitopes on small extracellular vesicles (EV). It utilizes specific EV immunoprecipitation using beads coupled with antibodies that recognize surface antigen CD9, CD63, and CD81. The method is optimized for downstream flow cytometry analysis.

Flow cytometry (FC) is the method of choice for semi-quantitative measurement of cell-surface antigen markers. Recently, this technique has been used for ...

Purification and Analysis of Caenorhabditis elegans Extracellular Vesicles

The secretion of small membrane-bound vesicles into the external environment is a fundamental physiological process of all cells. These extracellular vesicles (EVs) function outside the cell to regulate global physiological processes by transferring proteins, nucleic acids, metabolites, and lipids between tissues. EVs reflect the physiological state of their cells of origin. EVs are implicated to have fundamental roles in virtually every aspect of human health. Thus, EV protein and genetic cargos are being increasingly analyzed for biomarkers of health and disease. However, the EV field still lacks a tractable invertebrate model system that permits the study of EV cargo composition. C. elegans is well suited for EV research because it actively secretes EVs outside of its body into its external environment, permitting facile isolation. This article provides all the necessary information for generating, purifying, and quantifying these environmentally secreted C. elegans EVs including how to work quantitatively with very large populations of age-synchronized worms, purifying EVs, and a flow cytometry protocol that directly measures the number of intact EVs in the purified sample. Thus, the large library of genetic reagents available for C. elegans research can be tapped into for investigating the impacts of genetic pathways and physiological processes on EV cargo composition.

Purification and Analysis of Caenorhabditis elegans Extracellular Vesicles

This article presents methods for generating, purifying, and quantifying Caenorhabditis elegans extracellular vesicles.

The secretion of small membrane-bound vesicles into the external environment is a fundamental physiological process of all cells. These extracellular ...

Nanoparticle Tracking Analysis for the Quantification and Size Determination of Extracellular Vesicles

The physiological and pathophysiological roles of extracellular vesicles (EVs) have become increasingly recognized, making the EV field a quickly evolving area of research. There are many different methods for EV isolation, each with distinct advantages and disadvantages that affect the downstream yield and purity of EVs. Thus, characterizing the EV prep isolated from a given source by a chosen method is important for interpretation of downstream results and comparison of results across laboratories. Various methods exist for determining the size and quantity of EVs, which can be altered by disease states or in response to external conditions. Nanoparticle tracking analysis (NTA) is one of the prominent technologies used for high-throughput analysis of individual EVs. Here, we present a detailed protocol for quantification and size determination of EVs isolated from mouse perigonadal adipose tissue and human plasma using a breakthrough technology for NTA representing major advances in the field. The results demonstrate that this method can deliver reproducible and valid total particle concentration and size distribution data for EVs isolated from different sources using different methods, as confirmed by transmission electron microscopy. The adaptation of this instrument for NTA will address the need for standardization in NTA methods to increase rigor and reproducibility in EV research.

We demonstrate how to use a novel nanoparticle tracking analysis instrument to estimate the size distribution and total particle concentration of extracellular vesicles isolated from mouse perigonadal adipose tissue and human plasma.

The physiological and pathophysiological roles of extracellular vesicles (EVs) have become increasingly recognized, making the EV field a quickly evolving ...

Scalable Isolation and Purification of Extracellular Vesicles from Escherichia coli and Other Bacteria

Diverse bacterial species secrete ~20-300 nm extracellular vesicles (EVs), comprised of lipids, proteins, nucleic acids, glycans, and other molecules derived from the parental cells. EVs function as intra- and inter-species communication vectors while also contributing to the interaction between bacteria and host organisms in the context of infection and colonization. Given the multitude of functions attributed to EVs in health and disease, there is a growing interest in isolating EVs for in vitro and in vivo studies. It was hypothesized that the separation of EVs based on physical properties, namely size, would facilitate the isolation of vesicles from diverse bacterial cultures. 
The isolation workflow consists of centrifugation, filtration, ultrafiltration, and size-exclusion chromatography (SEC) for the isolation of EVs from bacterial cultures. A pump-driven tangential flow filtration (TFF) step was incorporated to enhance scalability, enabling the isolation of material from liters of starting cell culture. Escherichia coli was used as a model system expressing EV-associated nanoluciferase and non-EV-associated mCherry as reporter proteins. The nanoluciferase was targeted to the EVs by fusing its N-terminus with cytolysin A. Early chromatography fractions containing 20-100 nm EVs with associated cytolysin A - nanoLuc were distinct from the later fractions containing the free proteins. The presence of EV-associated nanoluciferase was confirmed by immunogold labeling and transmission electron microscopy. This EV isolation workflow is applicable to other human gut-associated gram-negative and gram-positive bacterial species. In conclusion, combining centrifugation, filtration, ultrafiltration/TFF, and SEC enables scalable isolation of EVs from diverse bacterial species. Employing a standardized isolation workflow will facilitate comparative studies of microbial EVs across species.

Scalable Isolation and Purification of Extracellular Vesicles from Escherichia coli and Other Bacteria

Bacteria secrete nanometer-sized extracellular vesicles (EVs) carrying bioactive biological molecules. EV research focuses on understanding their biogenesis, role in microbe-microbe and host-microbe interactions and disease, as well as their potential therapeutic applications. A workflow for scalable isolation of EVs from various bacteria is presented to facilitate standardization of EV research.

Diverse bacterial species secrete ~20-300 nm extracellular vesicles (EVs), comprised of lipids, proteins, nucleic acids, glycans, and other molecules ...

Isolation and Characterization of Cyanobacterial Extracellular Vesicles

Cyanobacteria are a diverse group of photosynthetic, Gram-negative bacteria that play critical roles in global ecosystems and serve as essential biotechnology models. Recent work has demonstrated that both marine and freshwater cyanobacteria produce extracellular vesicles -&#160;small membrane-bound structures released from the outer surface of the microbes. While vesicles likely contribute to diverse biological processes, their specific functional roles in cyanobacterial biology remain largely unknown. To encourage and advance research in this area, a detailed protocol is presented for isolating, concentrating, and purifying cyanobacterial extracellular vesicles. The current work discusses methodologies that have successfully isolated vesicles from large cultures of Prochlorococcus, Synechococcus, and Synechocystis. Methods for quantifying and characterizing vesicle samples from these strains are presented. Approaches for isolating vesicles from aquatic field samples are also described. Finally, typical challenges encountered with cyanobacterial vesicle purification, methodological considerations for different downstream applications, and the trade-offs between approaches are also discussed.

The present protocol providesdetailed descriptions for isolation, concentration,and characterization of extracellular vesicles from cyanobacterial cultures. Approaches for purifying vesicles from cultures at different scales, trade-offs among methodologies, and considerations for working with field samples are also discussed.

Cyanobacteria are a diverse group of photosynthetic, Gram-negative bacteria that play critical roles in global ecosystems and serve as essential ...

Isolation of microRNAs from Tick Ex Vivo Salivary Gland Cultures and Extracellular Vesicles

Ticks are important ectoparasites that can vector multiple pathogens. The salivary glands of ticks are essential for feeding as their saliva contains many effectors with pharmaceutical properties that can diminish host immune responses and enhance pathogen transmission. One group of such effectors are microRNAs (miRNAs). miRNAs are short non-coding sequences that regulate host gene expression at the tick-host interface and within the organs of the tick. These small RNAs are transported in the tick saliva via extracellular vesicles (EVs), which serve inter-and intracellular communication. Vesicles containing miRNAs have been identified in the saliva of ticks. However, little is known about the roles and profiles of the miRNAs in tick salivary vesicles and glands. Furthermore, the study of vesicles and miRNAs in tick saliva requires tedious procedures to collect tick saliva. This protocol aims to develop and validate a method for isolating miRNAs from purified extracellular vesicles produced by ex vivo organ cultures. The materials and methodology needed to extract miRNAs from extracellular vesicles and tick salivary glands are described herein.

Isolation of microRNAs from Tick Ex Vivo Salivary Gland Cultures and Extracellular Vesicles

The present protocol describes the isolation of microRNAs from tick salivary glands and purified extracellular vesicles. This is a universal procedure that combines commonly used reagents and supplies. The method also allows the use of a small number of ticks, resulting in quality microRNAs that can be readily sequenced.

Ticks are important ectoparasites that can vector multiple pathogens. The salivary glands of ticks are essential for feeding as their saliva contains many ...