This work was supported by grants from the Natural Science Foundation of China (82070450 to C.T.and 82170466 to L.Z.) and the fellowship of China Postdoctoral Science Foundation (7121102223 to F.L.).

All animal procedures described below were approved by the Institutional Animal Care and Use Committee of Soochow University.
1. Reagents and materials preparation
<ol>
	<li>Utilize 1x PBS without calcium and magnesium and 2.5 U/mL heparin sodium salt to prepare the perfusion solution. Store at 4 &#176;C, and precool on ice when used.</li>
	<li>Prepare dissociation reagent A that contains 125 CDU/mL collagenase II and 60 U/mL DNase I by diluting 1250 CDU/mL collagenase II and 3000 U/mL DNase I with HBSS. Store at 4 &#176;C until use.</li>
	<li>Prepare dissociation reagent B that contains a final concentration of 0.12% trypsin by diluting 1 mL of 0.25% EDTA-free trypsin (without phenol red) into 1 mL of 1x PBS. Store at 4 &#176;C until use.</li>
	<li>Prepare 10 mL of 1.5% FBS and 10 mL of 5% FBS in 1x PBS. Use 1.5% FBS to pool carotid arteries and keep on ice before use. Use 5% FBS to neutralize digestion and store at room temperature (RT).</li>
	<li>Get the experimental materials, including 1 mL syringes, 20 mL syringes with 26-G needles, six-well cell culture plates, 1.5 mL centrifuge tubes, 40 &#181;m sterile cell strainers, and ice containers.</li>
</ol>
2. Equipment preparation
<ol>
	<li>Sterilize all the surgical equipment, including a stereoscopic microscope, dissecting scissors, micro-dissecting scissors, and fine-tip forceps.</li>
	<li>Turn on the automated cell counter and maintain it at RT.</li>
	<li>Turn on the water bath to 37 &#176;C in advance.</li>
	<li>Precool the microcentrifuge to 4 &#176;C before use.</li>
</ol>
3. Isolation of the mouse carotid artery
<ol>
	<li>Anesthetize the mouse using 1.25% tribromoethanol by intraperitoneal injection (0.24 mL for every 10 g of body weight) and flip the mouse to check if there is a righting reflex after 3 min. Then, euthanize the mouse by cervical dislocation and lay it on its back. Spray the mouse&#39;s skin with 75% alcohol.</li>
	<li>Use sterilized dissecting scissors to open up the skin and expose the chest cavity. Cut open the diaphragm.</li>
	<li>Continue cutting upward to the lower jaw and carefully remove excess connective tissues and fat, exposing the carotid artery.</li>
	<li>Cut the inferior vena cava of the mouse to make blood flow out of the closed circulation.</li>
	<li>Inject 20 mL of prechilled perfusion solution into the left ventricle with a syringe slowly and continuously. 
	NOTE: If perfusion is successful, blood-rich organs such as the liver, spleen, and kidneys will turn gray-white.</li>
	<li>Peel off all the fat and connective tissues around the carotid artery with micro-dissecting scissors under a stereoscopic microscope. 
	NOTE: This step should be done slowly and carefully to prevent damage to the carotid artery.</li>
	<li>Isolate the carotid artery from the mouse, wash with 1x PBS to flush the blood again, and transfer to six-well plates containing 1.5% FBS on ice.</li>
</ol>
4. Digestion of the carotid artery into single-cell suspension
<ol>
	<li>Use micro-dissecting scissors to dissect the carotid artery longitudinally and lay flat in another 6-well cell culture plate containing 1 mL of 1.5% FBS on ice.</li>
	<li>Flush the intima carefully with 1.5% FBS to remove the residual blood. 
	NOTE: Flushing should be gentle and slow to avoid injuring endothelial cells.</li>
	<li>Cut each carotid artery into approximately 2 mm2 tissue pieces using microdissecting scissors in 1.5% FBS.</li>
	<li>Transfer these tissue pieces into a 1.5 mL centrifuge tube with 1 mL wide bore tips, centrifuge at 400 x g for 5 min at 4 &#176;C to sink the tissues to the bottom.</li>
	<li>Discard the supernatant and resuspend the tissues in 500 &#181;L of dissociation reagent A.</li>
	<li>Place the tube in a 37 &#176;C water bath for 1 h. Pipette gently with a 1 mL pipette every 10 min.</li>
	<li>Add 500 &#181;L of 5% FBS into the tube and mix well with a 1 mL pipette.</li>
	<li>Filter the cell suspension through a 40 &#181;m sterile cell strainer into a new 1.5 mL centrifuge tube and centrifuge at 400 x g for 5 min at 4 &#176;C.</li>
	<li>Remove the supernatant carefully and resuspend the cell pellet in 200 &#181;L of dissociation reagent B.</li>
	<li>Place in a 37 &#176;C water bath and digest for another 5 min. Gently pipette every 2 min during digestion to fully dissociate into a single-cell suspension.</li>
	<li>Use 200 &#181;L of 5% FBS to terminate the digestion reaction, and centrifuge at 400 x g for 5 min at 4 &#176;C.</li>
	<li>Discard the supernatant and resuspend the cell pellet in 100 &#181;L of 1x PBS on ice.</li>
</ol>
5. Cell suspension examination and single-cell RNA sequencing
<ol>
	<li>Add 10 &#181;L of AO/PI solution into 10 &#181;L of single-cell suspension and gently mix with a 20 &#181;L pipette.</li>
	<li>Pipette 20 &#181;L of the mixture into the chamber slide and wait for 1 min.</li>
	<li>Load the slide into the automated cell counter instrument.</li>
	<li>Select the AO/PI Viability assay, then wait for the quality report.</li>
	<li>Use a single-cell 3&#697; reagent kit to generate single-cell gel beads in the emulsion on a single-cell controller and amplify the barcoded cDNA in a thermal cycler following the manufacturer&#39;s protocol. 
	NOTE: Here, Chromium Single Cell 3&#697;Reagent Kits v3 was used.</li>
	<li>Perform sequencing on a sequencer with a paired-end 150 bp (PE150) reading strategy. Use a software application (Cell Ranger) to convert raw base call files to fastq files using the mkfastq pipeline. Then, use the Count Pipeline of Cell Ranger for performing alignment, filtering, barcode counting, and unique molecular identifier (UMI) counting to generate feature-barcode matrices13.</li>
	<li>Perform data dimensionality reduction and visualization with the R package Seurat14.
	<ol>
		<li>First, the Read10X() function of Seurat reads in the output of the Cell Ranger pipeline and then uses the count matrix to create a Seurat object. Then, filter out the cells with expression of &#60;200 or &#62;4000 genes or a mitochondrial gene ratio that was more than 10% by the subset() function of Seurat.</li>
		<li>Use NormalizeData() and FindVariableFeatures() to normalize the data and identify 2000 highly variable features, respectively.</li>
		<li>Perform principal component analysis (PCA) on the scaled data, and cluster the cells with dims = 30 and resolution = 0.5. Finally, use the RunUMAP() function to visualize the single-cell datasets and FindAllMarkers() to find each cluster biomarker.</li>
	</ol>
	</li>
</ol>

Two-Step Cell Digestion of Mouse Carotid Artery

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The authors have no conflicts of interest to disclose.

Here we provide a detailed protocol for the preparation of a high-quality single-cell suspension from the carotid artery of wild-type mice, in which a two-step digestion method integrating the digestion process of collagenase/DNase and trypsin was constructed. After the quality check of the single-cell suspension, we found that it satisfied the requirements for single-cell sequencing, with the viability of cells over 85% and a high cell concentration. Moreover, a variety of cell types in the carotid artery, including VSM...

Atherosclerosis is a chronic inflammatory disease associated with risk factors such as high blood pressure, hyperlipidemia, and hemodynamics1. Carotid artery bifurcations are prone to hemodynamic changes and lead to carotid plaque formation. The clinical presentation of carotid atherosclerosis can be acute such as stroke and transient cerebral ischemia, or chronic such as recurrent transient cerebral ischemia and vascular dementia2. Mechanically, carotid plaque is the outcome of the interaction between different vessel wall cells and various blood cells under pathological conditions. Therefore, revealing the single-cell atlas of carotid vessels under physiological and pathological conditions is particularly important for preventing and treating carotid plaque development.
Single-cell RNA sequencing is one of the most powerful technologies of biological research because of its ultrahigh resolution and detection of cell heterogeneity from the same cell type of organisms3,4. Researchers have used single-cell RNA sequencing to conduct research in many fields, such as cardiovascular disease5 and cancer6. However, quickly and accurately separating tissues into single cells is still one of the main challenges. Enzymatic dissociation is a commonly used method that dominantly includes collagenase, papain, trypsin, DNase, and hyaluronidase. Specifically, collagenases are the major enzyme species for single-cell digestion, mainly hydrolyzing collagen components in connective tissues. Different collagenase types are applicable for the dissociation of different tissues, such as the mammary gland7, glomerulus8, iridocorneal angle9, knee joint10, aorta11, and lung12. Due to the unique physiological properties of different tissues, dissociation using the same method may cause many troubles in acquiring single cells, such as low cell viability, low cell number, and large cell debris. Therefore, the invention of digestion methods for different tissues is essential for preparing high-quality single-cell suspensions.
This protocol aims to develop a two-step cell digestion method to prepare a single-cell suspension of the carotid artery of wild-type mice. According to the characteristics of the carotid artery, we combined collagenase/DNase with trypsin to obtain a high-quality single-cell suspension of the mouse carotid artery because collagenase can hydrolyze collagen of the carotid tissues, which was further digested by trypsin into a single-cell suspension. Acridine orange/propidium iodide (AO/PI) dual-fluorescence counting was used to detect cell viability and concentration, and it was found that the single-cell suspension satisfied the requirements for single-cell sequencing, with the viability of cells over 85% and a high cell concentration. After single-cell data processing, four cell types, including vascular smooth muscle cells (VSMCs), fibroblasts, endothelial cells (ECs), and macrophages and dendritic cells (M&#966;/DCs), were identified in normal mouse carotid arteries after digestion. The advantages of this protocol are that: 1) multiple cell types in the carotid artery can be identified, 2) cell viability is well preserved, and 3) it can be easily repeated without special equipment. This protocol is suitable for researchers who are interested in studying single-cell multiomics of the mouse carotid arteries. This protocol may also be helpful in the dissociation of other blood vessels with appropriate modifications.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.25% EDTA-free trypsin</td>
			<td>Beyotime</td>
			<td>C0205</td>
			<td>Dilute 1 mL of 0.25% EDTA-free trypsin into 1 mL of 1x PBS.</td>
		</tr>
		<tr>
			<td>0.9% NaCl saline solution</td>
			<td>Beyotime</td>
			<td>ST341</td>
			<td>Dilute the heparin sodium solution into a final concentration of 10 mg/mL</td>
		</tr>
		<tr>
			<td>1 mL syringes</td>
			<td>&#160;SKJYLEAN</td>
			<td>sk-r009</td>
			<td>To perform cardiac perfusion</td>
		</tr>
		<tr>
			<td>1.5 mL centrifuge tubes</td>
			<td>KIRGEN</td>
			<td>KG2211W</td>
			<td>To centrifuge the tissue piece and cell suspension</td>
		</tr>
		<tr>
			<td>20 mL syringes</td>
			<td>SKJYLEAN</td>
			<td>sk-r013</td>
			<td>To perform cardiac perfusion</td>
		</tr>
		<tr>
			<td>40 &#181;m cell strainer</td>
			<td>JETBIOFIL</td>
			<td>css010040</td>
			<td>To filter undigested tissue fragments</td>
		</tr>
		<tr>
			<td>AO/PI kit</td>
			<td>Hengrui Biological</td>
			<td>RE010212</td>
			<td>To identify whether the cell is alive or dead</td>
		</tr>
		<tr>
			<td>Automated cell counter</td>
			<td>Countstar</td>
			<td>Mira FL</td>
			<td>To analyze the cell morphology and cell viability of digested carotid vascular cells</td>
		</tr>
		<tr>
			<td>Cell Ranger software</td>
			<td>10&#215; Genomics</td>
			<td>3.0.2</td>
			<td>To process Chromium single-cell RNA-seq output and perform clustering and gene expression analysis</td>
		</tr>
		<tr>
			<td>Chromium Single Cell 3&#39;Reagent Kits v3</td>
			<td>10&#215; Genomics</td>
			<td>1000075</td>
			<td>To prepare single-cell RNA-seq libraries of single-cell suspension</td>
		</tr>
		<tr>
			<td>Collagenase II</td>
			<td>Sigma-Aldrich</td>
			<td>C6885</td>
			<td>Dilute with HBSS to a final concentration of 125 CDU/mL</td>
		</tr>
		<tr>
			<td>Deoxyribonuclease I</td>
			<td>Worthington</td>
			<td>LS002140</td>
			<td>Dilute with HBSS to a final concentration of 60 U/mL</td>
		</tr>
		<tr>
			<td>Fetal bovine serum&#160;</td>
			<td>HyClone</td>
			<td>SH30088.03</td>
			<td>Termination of the digestion reaction</td>
		</tr>
		<tr>
			<td>Hank&#39;s balanced salt solution&#160;</td>
			<td>Gibco</td>
			<td>14175095</td>
			<td>Store at the room temperture</td>
		</tr>
		<tr>
			<td>Heparin sodium salt</td>
			<td>Solarbio Life Science</td>
			<td>H8060</td>
			<td>Dilute with 0.9% NaCl to a final concentration of 10 mg/mL</td>
		</tr>
		<tr>
			<td>Microcentrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>75002560</td>
			<td>Applied for spining down the tissues and cell pellets</td>
		</tr>
		<tr>
			<td>NovaSeq 6000&#160;</td>
			<td>Illumina</td>
			<td>N/A</td>
			<td>Sequencer</td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline</td>
			<td>Solarbio Life Science</td>
			<td>P1000</td>
			<td>Used for cardiac perfusion and resuspension of cells</td>
		</tr>
		<tr>
			<td>Seurat package- R</td>
			<td>Satija Lab</td>
			<td>3.1.2</td>
			<td>To performed dimensionality reduction, visualization, and analysis of scRNA-sequencing data</td>
		</tr>
		<tr>
			<td>Six-well cell culture plates</td>
			<td>NEST</td>
			<td>703002</td>
			<td>Place the vascular tissue</td>
		</tr>
		<tr>
			<td>Water bath</td>
			<td>Jinghong</td>
			<td>DK-S22</td>
			<td>Keep the digestion temperature at 37 &#176;C</td>
		</tr>
	</tbody>
</table>

preparation of a single-cell suspension from mouse carotid arteries for single-cell sequencing

Carotid arteries are major blood vessels in the neck that supply blood and oxygen to the brain, but carotid stenosis occurs when carotid arteries are clogged by plaque. Revealing the cellular composition of the carotid artery at the single-cell level is essential for treating carotid atherosclerosis. However, there is no ready-to-use protocol for the preparation of single-cell suspensions from carotid arteries. To obtain a suitable protocol for the dissociation of normal carotid arteries at the single-cell level with less damage to cells, we designed a two-step digestion method by integrating the digestion process of collagenase/DNase and trypsin. Acridine orange/propidium iodide (AO/PI) dual-fluorescence counting was used to detect cell viability and concentration, and it was found that the single-cell suspension satisfied the requirements for single-cell sequencing, with the viability of cells over 85% and a high cell concentration. After single-cell data processing, a median of ~2500 transcripts per cell were detected in each carotid artery cell. Notably, a variety of cell types of the normal carotid artery, including vascular smooth muscle cells (VSMCs), fibroblasts, endothelial cells (ECs), and macrophages and dendritic cells (M&#966;/DCs), were concurrently detectable. This protocol may be applied to prepare a single-cell suspension of blood vessels from other tissues with appropriate modifications.

This protocol describes a two-step cell digestion method for preparing a single-cell suspension of mouse carotid arteries (Figure 1). This two-step cell digestion method combines collagenase/DNase with trypsin to effectively dissociate the mouse carotid vascular wall to obtain high-quality single-cell suspensions for single-cell sequencing. After dissociation, the cell concentration and cell viability were calculated by an automated cell counter. The bright field showed the morphology of car...

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Here we describe a two-step cell digestion protocol for preparing a single-cell suspension of mouse carotid arteries.

Preparation of a Single-Cell Suspension from Mouse Carotid Arteries for Single-Cell Sequencing

Carotid arteries are major blood vessels in the neck that supply blood and oxygen to the brain, but carotid stenosis occurs when carotid arteries are ...

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2.7K Views.  Soochow University. Here we describe a two-step cell digestion protocol for preparing a single-cell suspension of mouse carotid arteries.

Video: Author Spotlight: Vascular Tissue Dissociation and Exploring Single-Cell Subclusters for Targeted Therapy 

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Generation of Single-Cell Suspensions from Mouse Neural Tissue

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Within the nervous system, hundreds of neuronal and glial cell types have been described. Each specific cell type in the brain or spinal cord has a ...

Single-cell Suction Recordings from Mouse Cone Photoreceptors

Rod and cone photoreceptors in the retina are responsible for light detection. In darkness, cyclic nucleotide-gated (CNG) channels in the outer segment are open and allow cations to flow steadily inwards across the membrane, depolarizing the cell. Light exposure triggers the closure of the CNG channels, blocks the inward cation current flow, and thus results in cell hyperpolarization. Based on the polarity of photoreceptors, a suction recording method was developed in 1970s that, unlike the classic patch-clamp technique, does not require penetrating the plasma membrane 1. Drawing the outer segment into a tightly-fitting glass pipette filled with extracellular solution allows recording the current changes in individual cells upon test-flash exposure. However, this well-established "outer-segment-in (OS-in)" suction recording is not suitable for mouse cone recordings, because of the low percentage of cones in the mouse retina (3%) and the difficulties in identifying the cone outer segments. Recently, an inner-segment-in (IS-in) recording configuration was developed to draw the inner segment/nuclear region of the photoreceptor into the recording pipette 2,3. In this video, we will show how to record from individual mouse cone photoresponses using single-cell suction electrode.

We will show how to record flash responses from single mouse cones using a suction electrode.

Rod and cone photoreceptors in the retina are responsible for light detection. In darkness, cyclic nucleotide-gated (CNG) channels in the outer segment ...

Single Cell Transcriptional Profiling of Adult Mouse Cardiomyocytes

While numerous studies have examined gene expression changes from homogenates of heart tissue, this prevents studying the inherent stochastic variation between cells within a tissue. Isolation of pure cardiomyocyte populations through a collagenase perfusion of mouse hearts facilitates the generation of single cell microarrays for whole transcriptome gene expression, or qPCR of specific targets using nanofluidic arrays. We describe here a procedure to examine single cell gene expression profiles of cardiomyocytes isolated from the heart. This paradigm allows for the evaluation of metrics of interest which are not reliant on the mean (for example variance between cells within a tissue) which is not possible when using conventional whole tissue workflows for the evaluation of gene expression (Figure 1). We have achieved robust amplification of the single cell transcriptome yielding micrograms of double stranded cDNA that facilitates the use of microarrays on individual cells. In the procedure we describe the use of NimbleGen arrays which were selected for their ease of use and ability to customize their design. Alternatively, a reverse transcriptase - specific target amplification (RT-STA) reaction, allows for qPCR of hundreds of targets by nanofluidic PCR. Using either of these approaches, it is possible to examine the variability of expression between cells, as well as examining expression profiles of rare cell types from within a tissue. Overall, the single cell gene expression approach allows for the generation of data that can potentially identify idiosyncratic expression profiles that are typically averaged out when examining expression of millions of cells from typical homogenates generated from whole tissues.

Single cell expression profiling allows the detailed gene expression analysis of individual cells. We describe methods for the isolation of cardiomyocytes, and preparing the resulting lysates for either whole transcriptome microarray or qPCR of specific targets.

While numerous studies have examined gene expression changes from homogenates of heart tissue, this prevents studying the inherent stochastic variation ...

Single-cell Microinjection for Cell Communication Analysis

Gap junctions are intercellular channels that allow the communication of neighboring cells. This communication depends on the contribution of a hemichannel by each neighboring cell to form the gap junction. In mammalian cells, the hemichannel is formed by six connexins, monomers with four transmembrane domains and a C and N terminal within the cytoplasm. Gap junctions permit the exchange of ions, second messengers, and small metabolites. In addition, they have important roles in many forms of cellular communication within physiological processes such as synaptic transmission, heart contraction, cell growth and differentiation. We detail how to perform a single-cell microinjection of Lucifer Yellow to visualize cellular communication via gap-junctions in living cells. It is expected that in functional gap junctions, the dye will diffuse from the loaded cell to the connected cells. It is a very useful technique to study gap junctions since you can evaluate the diffusion of the fluorescence in real time. We discuss how to prepare the cells and the micropipette, how to use a micromanipulator and inject a low molecular weight fluorescent dye in an epithelial cell line.

We describe here how to perform a single-cell microinjection of Lucifer Yellow to visualize cellular communication via gap-junctions in living cells, and provide some useful tips. We expect that this paper will help everyone to evaluate the degree of cellular coupling due to functional gap junctions. Everything described here could be, in principle, adapted to other fluorescent dyes with molecular weight below 1,000 Daltons.

Gap junctions are intercellular channels that allow the communication of neighboring cells. This communication depends on the contribution of a ...

Single Cell Collection of Trophoblast Cells in Peri-implantation Stage Human Embryos

Human implantation, the apposition and adhesion to the uterine surface epithelia and subsequent invasion of the blastocyst into the maternal decidua, is a critical yet enigmatic biological event that has been historically difficult to study due to technical and ethical limitations. Implantation is initiated by the development of the trophectoderm to early trophoblast and subsequent differentiation into distinct trophoblast sublineages. Aberrant early trophoblast differentiation may lead to implantation failure, placental pathologies, fetal abnormalities, and miscarriage. Recently, methods have been developed to allow human embryos to grow until day 13 post-fertilization in vitro in the absence of maternal tissues, a time-period that encompasses the implantation period in humans. This has given researchers the opportunity to investigate human implantation and recapitulate the dynamics of trophoblast differentiation during this critical period without confounding maternal influences and avoiding inherent obstacles to study early embryo differentiation events in vivo. To characterize different trophoblast sublineages during implantation, we have adopted existing two-dimensional (2D) extended culture methods and developed a procedure to enzymatically digest and isolate different types of trophoblast cells for downstream assays. Embryos cultured in 2D conditions have a relatively flattened morphology and may be suboptimal in modeling in vivo three-dimensional (3D) embryonic architectures. However, trophoblast differentiation seems to be less affected as demonstrated by anticipated morphology and gene expression changes over the course of extended culture. Different trophoblast sublineages, including cytotrophoblast, syncytiotrophoblast and migratory trophoblast can be separated by size, location, and temporal emergence, and used for further characterization or experimentation. Investigation of these early trophoblast cells may be instrumental in understanding human implantation, treating common placental pathologies, and mitigating the incidence of pregnancy loss.

Here, we describe a method for warming vitrified human blastocysts, culturing them through the implantation period in vitro, digesting them into single cells and collecting early trophoblast cells for further investigation.

Human implantation, the apposition and adhesion to the uterine surface epithelia and subsequent invasion of the blastocyst into the maternal decidua, is a ...

Isolation of Endothelial Cells from the Lumen of Mouse Carotid Arteries for Single-Cell Multi-Omics Experiments

Atherosclerosis is an inflammatory disease of the arterial regions exposed to disturbed blood flow (d-flow). D-flow regulates the expression of genes in the endothelium at the transcriptomic and epigenomic levels, resulting in proatherogenic responses. Recently, single-cell RNA sequencing (scRNAseq) and single-cell Assay for Transposase Accessible Chromatin sequencing (scATACseq) studies were performed to determine the transcriptomic and chromatin accessibility changes at a single-cell resolution using the mouse partial carotid ligation (PCL) model. As endothelial cells (ECs) represent a minor fraction of the total cell populations in the artery wall, a luminal digestion method was used to obtain EC-enriched single-cell preparations. For this study, mice were subjected to PCL surgery to induce d-flow in the left carotid artery (LCA) while using the right carotid artery (RCA) as a control. The carotid arteries were dissected out two days or two weeks post PCL surgery. The lumen of each carotid was subjected to collagenase digestion, and endothelial-enriched single cells or single nuclei were obtained. These single-cell and single-nuclei preparations were subsequently barcoded using a 10x Genomics microfluidic setup. The barcoded single-cells and single-nuclei were then utilized for RNA preparation, library generation, and sequencing on a high-throughput DNA sequencer. Post bioinformatics processing, the scRNAseq and scATACseq datasets identified various cell types from the luminal digestion, primarily consisting of ECs. Smooth muscle cells, fibroblasts, and immune cells were also present. This EC-enrichment method aided in understanding the effect of blood flow on the endothelium, which could have been difficult with the total artery digestion method. The EC-enriched single-cell preparation method can be used to perform single-cell omics studies in EC-knockouts and transgenic mice where the effect of blood flow on these genes has not been studied. Importantly, this technique can be adapted to isolate EC-enriched single cells from human artery explants to perform similar mechanistic studies.

We present a method for isolating endothelial cells and nuclei from the lumen of mouse carotid arteries exposed to stable or disturbed flow conditions to perform single-cell omics experiments.

Atherosclerosis is an inflammatory disease of the arterial regions exposed to disturbed blood flow (d-flow). D-flow regulates the expression of genes in ...

Real-Time Detection of Reactive Oxygen Species Production in Immune Response in Rice with a Chemiluminescence Assay

Reactive oxygen species (ROS) play vital roles in a variety of biological processes, including the sensing of abiotic and biotic stresses. Upon pathogen infection or challenge with pathogen-associated chemicals (pathogen-associated molecular patterns [PAMPs]), an array of immune responses, including a ROS burst, are quickly induced in plants, which is called PAMP-triggered immunity (PTI). A ROS burst is a hallmark PTI response, which is catalyzed by a group of plasma membrane-localized NADPH oxidases-the RBOH family proteins. The vast majority of ROS comprise hydrogen peroxide (H2O2), which can be easily and steadily detected by a luminol-based chemiluminescence method. Chemiluminescence is a photon-producing reaction in which luminol, or its derivative (such as L-012), undergoes a redox reaction with ROS under the action of a catalyst. This paper describes an optimized L-012-based chemiluminescence method to detect apoplast ROS production in real-time upon PAMP elicitation in rice tissues. The method is easy, steady, standardized, and highly reproducible under firmly controlled conditions.

Here, we describe a method for the real-time detection of apoplastic reactive oxygen species (ROS) production in rice tissues in pathogen-associated molecular pattern-triggered immune response. This method is simple, standardized, and generates highly reproducible results under controlled conditions.

Reactive oxygen species (ROS) play vital roles in a variety of biological processes, including the sensing of abiotic and biotic stresses. Upon pathogen ...

Single-Cell Proteomics Preparation for Mass Spectrometry Analysis Using Freeze-Heat Lysis and an Isobaric Carrier

Single-cell proteomics analysis requires sensitive, quantitatively accurate, widely accessible, and robust methods. To meet these requirements, the Single-Cell ProtEomics (SCoPE2) protocol was developed as a second-generation method for quantifying hundreds to thousands of proteins from limited samples, down to the level of a single cell. Experiments using this method have achieved quantifying over 3,000 proteins across 1,500 single mammalian cells (500-1,000 proteins per cell) in 10 days of mass spectrometer instrument time. SCoPE2 leverages a freeze-heat cycle for cell lysis, obviating the need for clean-up of single cells and consequently reducing sample losses, while expediting sample preparation and simplifying its automation. Additionally, the method uses an isobaric carrier, which aids protein identification and reduces sample losses.
This video protocol provides detailed guidance to enable the adoption of automated single-cell protein analysis using only equipment and reagents that are widely accessible. We demonstrate critical steps in the procedure of preparing single cells for proteomic analysis, from harvesting up to injection to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Additionally, viewers are guided through the principles of experimental design with the isobaric carrier, quality control for both isobaric carrier and single-cell preparations, and representative results with a discussion of limitations of the approach.

In this protocol, we describe how to prepare mammalian cells for single-cell proteomics analysis via mass spectrometry using commercially available reagents and equipment, with options for both manual and automatic pipetting.

Single-cell proteomics analysis requires sensitive, quantitatively accurate, widely accessible, and robust methods. To meet these requirements, the ...