Name: isolation and analysis of traceable and functionalized extracellular vesicles from the plasma and solid tissues
Uploaded: 2022-10-17T14:00:00
Description: Watch this Scientific Journal Video about Isolation and Analysis of Traceable and Functionalized Extracellular Vesicles from the Plasma and Solid Tissues at JoVE.com

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 take...

<ol>
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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 ...

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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 ...

This protocol provides a feasible way to isolate and collect the right extracellular vesicles from most blood and solid tissues, especially analyze their source and the protein contents, which helps further functional experiments. Besides high yield and low contamination, the main advantage of this protocol is analysis of surface antigens and protein cargoes of EVs which is useful for physiological and pathological studies. It facilitates the diagnosis of cancers of diseases, such as inflammatory diseases and osteoporosis through the detection of surface markers of parental cells of extracellular vesicles with a flow cytometer.The quantity of tissue extracellular vesicle is critical for the following experiments. Make sure the concentration of extracellular vesicle is not high. Be patient to perform the dilution.To begin, prepare the maxillary bone samples by isolating the maxillary bone with ophthalmic tweezers and scissors and wash them with PBS to get rid of soft tissues with tweezers. Then put the maxillary bone into 1.5 milliliter centrifuge tubes and cut the bone into small pieces of one millimeter in diameter with scissors. Add a certain amount of Liberase to cover the tissue and incubate for 30 minutes at 37 degrees Celsius.Next, centrifuge the sample at 800 G for 10 minutes at four degrees Celsius and carefully transfer the supernatant with a pipette to a new and clean 1.5 milliliter centrifuge tubes. After centrifuging the prepared plasma and bone samples for 15 minutes at 2, 500 G and four degree Celsius to remove large cell debris and remaining platelets, carefully transfer the supernatants to new and clean 1.5 milliliter centrifuge tubes and centrifuge at 16, 800 G for 30 minutes at four degrees Celsius. Next, discard the supernatant and resuspend the pellets in each tube with one milliliter of PBS.After centrifuging and discarding the supernatant as demonstrated previously, again, resuspend the pellets in each tube with 50 microliters of PBS and store these samples at four degrees Celsius for less than 24 hours or preferably use them immediately for the analyses. Resuspend samples with 500 microliters of PBS and transfer 50 microliters into a new and clean 1.5 milliliter centrifuge tube as a blank control labeled as tube A and another 50 microliters into another clean 1.5 milliliter centrifuge tube as a simple staining tube for FITC, labeled as tube B.Add 0.5 microliters of membrane dye to the primary tube for membrane staining while incubating for five minutes at room temperature. After centrifuging the primary tube for 30 minutes at 16, 800 G and discarding the supernatant, resuspend the pellets with 200 microliters of PBS.Divide each 50 microliter sample into four 1.5 milliliter centrifuge tubes for simple staining tubes for PE labeled as tube C, surface marker staining labeled as tube D, and secondary antibody-only controls labeled as tube E.Add the primary antibody of osteoclast associated receptor and bone extracellular vesicle samples as well as CD-18 antibody and plasma extracellular vesicle samples to tube B and tube D separately, incubating for one hour at four degrees Celsius. Centrifuge the tubes and discard the supernatant as demonstrated previously and resuspend the pellets with 500 microliters of PBS. Again, centrifuge for 30 minutes at 16, 800 G and four degree Celsius to remove the extra primary antibodies.After discarding the supernatant resuspend the pellets with 50 microliters of PBS, followed by adding FITC conjugated secondary antibodies respectively in tube E.Incubate all the tubes for one hour at four degree Celsius in the dark. Dilute one drop of 0.2, 0.5, and one micrometer sized bead suspension respectively into one milliliter of PBS. Then run each size of beads to make sure of the gate chosen for extracellular vesicles and set the threshold of the flow cytometer to search for the beads and extracellular vesicle population using a suitable forward inside scatter.Set the terminal condition as calculating 100, 000 membrane dyed particles and analyze the sample via a flow cytometer as described in the manuscript. Resuspend the pellets in 50 microliters of RIPA-lysis buffer and incubate for 30 minutes on ice. To quantify the protein concentrations of all samples in the 96 well microplate by the BCA protein assay, dilute the two milligrams per milliliters of BSA with 0.9%of normal saline into 0.5 milligrams per milliliters.At 0.5 milligrams per milliliter of BSA and 0.9%of normal saline into three duplicated wells with certain volumes. Then drop two microliters of the samples and add 18 microliters of normal saline into three duplicated wells separately. After preparing a working solution by mixing BCA reagent A with reagent B, add 200 microliters of the working solution to each well and shake gently for 30 seconds.Then incubate the 96 well microplate for 20 to 25 minutes at 37 degrees Celsius and measure the optical density at 596 nanometers with the spectrophotometer. Next, export the data, draw a standard curve, and calculate the protein concentration of the samples. According to the results, dilute the samples to one microgram per microliter with 0.9%of normal saline and five times the concentration of SDS-PAGE loading buffer and seal the tubes with film tightly and heat for five minutes at 100 degrees Celsius.Load the samples in the protein ladder into a gradient concentration of four to 20%HEPy's tris gel. Run the gel in the running buffer at 80 volts until the proteins form a line. Then switch to 120 volts for one hour until the loading dye is at the bottom of the gel.Transfer the gel to the polyvinylidene fluoride membrane pre incubated in methyl alcohol for 20 seconds using a wet transfer system to transfer for one hour at 200 milliamperes. Prepare 5%BSA blocking buffer by adding 2.5 grams of BSA and 50 milliliters of TBST into a 50 milliliter centrifuge tube. Block the membranes in this buffer for two hours at room temperature with agitation.Incubate the membranes with specific primary antibodies diluted with TBST into proper concentration overnight at four degrees Celsius. Wash the membranes in the washing buffer four times and incubate the membranes with suitable secondary antibodies for one hour at room temperature with agitation. After washing the membranes in the washing buffer four times, image the membranes using the chemiluminescence kit in a gel imaging system.The transmission electron microscopy and nanoparticle tracking analysis revealed that the typical morphological characteristics of extracellular vesicles were round and cup shaped with a diameter ranging from 500 to 300 nanometers. Flow cytometry analysis shows the percentages of specific membrane markers expressed on extracellular vesicles that implies their origin from parent cells. Western blot analysis shows the expression of PGD and PKM2 respectively as a representative of protein content and plasma extracellular vesicles and bone extracellular vesicles, indicating the metabolic status.Negative expression of Golgin-84 in extracellular vesicles was detected with the presence of mitofilin, Alpha-actinin-4, Flotillin-1, Caveolin-1, and Beta-actin, along with vesicles marker CD9, while CD81 expression is low or absent with a lack of APO-A-1 existence in the plasma extracellular vesicles. Researchers, so keeping in mind that step 2.2, the preparation and the digestion of the tissue samples should be done sufficiently. Otherwise, the number of extracellular vesicles extracted from the tissues is limited.The marker labeled fluorescent stain of the extracellular vesicles can be injected into the mouth to treat the phase that linked to potential function.

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Research

JoVE Journal

Biology

Isolation and Analysis of Hematopoietic Stem Cells from the Placenta

Hematopoietic stem cells (HSCs) have the ability to self-renew and generate all cell types of the blood lineages throughout the lifetime of an individual. All HSCs emerge during embryonic development, after which their pool size is maintained by self-renewing cell divisions. Identifying the anatomical origin of HSCs and the critical developmental events regulating the process of HSC development has been complicated as many anatomical sites participate during fetal hematopoiesis. Recently, we identified the placenta as a major hematopoietic organ where HSCs are generated and expanded in unique microenvironmental niches (Gekas, et al 2005, Rhodes, et al 2008). Consequently, the placenta is an important source of HSCs during their emergence and initial expansion.
In this article, we show dissection techniques for the isolation of murine placenta from E10.5 and E12.5 embryos, corresponding to the developmental stages of initiation of HSCs and the peak in the size of the HSC pool in the placenta, respectively. In addition, we present an optimized protocol for enzymatic and mechanical dissociation of placental tissue into single-cell suspension for use in flow cytometry or functional assays. We have found that use of collagenase for single-cell suspension of placenta gives sufficient yields of HSCs. An important factor affecting HSC yield from the placenta is the degree of mechanical dissociation prior to, and duration of, enzymatic treatment.
We also provide a protocol for the preparation of fixed-frozen placental tissue sections for the visualization of developing HSCs by immunohistochemistry in their precise cellular niches. As hematopoietic specific antigens are not preserved during preparation of paraffin embedded sections, we routinely use fixed frozen sections for localizing placental HSCs and progenitors.

We have identified the placenta as a major hematopoietic organ during development. We found that hematopoietic stem cells (HSCs) are both generated and expanded in the placenta in unique microenvironmental niches. Here, we describe experimental techniques required for isolation and visualization of HSCs in the mouse placenta.

Hematopoietic stem cells (HSCs) have the ability to self-renew and generate all cell types of the blood lineages throughout the lifetime of an individual. ...

Vampiric Isolation of Extracellular Fluid from Caenorhabditis elegans

The genetically tractable model organism C. elegans has provided insights into a myriad of biological questions, enabled by its short generation time, ease of growth and small size. This small size, though, has disallowed a number of technical approaches found in other model systems. For example, blood transfusions in mammalian systems and grafting techniques in plants enable asking questions of circulatory system composition and signaling. The circulatory system of the worm, the pseudocoelom, has until recently been impossible to assay directly. To answer questions of intercellular signaling and circulatory system composition C. elegans researchers have traditionally turned to genetic analysis, cell/tissue specific rescue, and mosaic analysis. These techniques provide a means to infer what is happening between cells, but are not universally applicable in identification and characterization of extracellular molecules. Here we present a newly developed technique to directly assay the pseudocoelomic fluid of C. elegans. The technique begins with either genetic or physical manipulation to increase the volume of extracellular fluid. Afterward the animals are subjected to a vampiric reverse microinjection technique using a microinjection rig that allows fine balance pressure control. After isolation of extracellular fluid, the collected fluid can be assayed by transfer into other animals or by molecular means. To demonstrate the effectiveness of this technique we present a detailed approach to assay a specific example of extracellular signaling molecules, long dsRNA during a systemic RNAi response. Although characterization of systemic RNAi is a proof of principle example, we see this technique as being adaptable to answer a variety of questions of circulatory system composition and signaling.

Vampiric Isolation of Extracellular Fluid from Caenorhabditis elegans

The model organism C. elegans uses pseudocoelomic fluid as a passive circulatory system. Direct assay of this fluid has not been previously possible. Here we present a novel technique to directly assay the extracellular space, and use systemic silencing signals during an RNAi response as a proof of principle example.

The genetically tractable model organism C. elegans has provided insights into a myriad of biological questions, enabled by its short generation time, ...

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.

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 ...