This study was supported by the National Natural Science Foundation of China (Grant No. 81670451, 81770430), the Shanghai Rising-Star Program (Grant No. 17QA1403000), and the Science Technology Committee of the Shanghai Municipal Government (Grant No. 14441903002, 15411963700).

All animal experiments were conducted in accordance with experimental protocols approved by the Committee on Animal Resources of Shanghai Jiao Tong University.
1. Perfusion of the mouse aorta
<ol>
	<li>Briefly, anesthetize 12-week-old C57BL/6 mice with intraperitoneal injections of sodium pentobarbital (50 mg/kg body weight). Confirm proper anesthetization by gently pinching the tail. 
	NOTE: If no movement is observed, the animal is sufficiently anesthetized to start the experiments.</li>
	<li>Tape the mouse&#39;s paws to a stack of paper towels with adhesive tapes.</li>
	<li>Hold up the skin of the mouse with forceps and cut the skin with a pair of scissors from the abdomen to the top of the thorax.</li>
	<li>Open the abdominal cavity below the ribcage with a sharp pair of scissors.</li>
	<li>Lift the sternum with forceps and cut the diaphragm; then, cut away the ribcage to expose the thoracic cavity.</li>
	<li>Cut off the vena cava just above the liver, with scissors.</li>
	<li>Pressure perfuse (100 mmHg) the arterial tree for 5 min with prechilled normal saline containing 40 units/mL heparin through the left ventricle until the lungs and liver become pale. Then, perfuse with prechilled 4% paraformaldehyde in phosphate-buffered saline (PBS, pH 7.4) for 3 min.</li>
	<li>Remove all the muscles, organs, and fat until the aorta is exposed.</li>
	<li>Place the mouse under a dissecting microscope.</li>
</ol>
2. Dissection and longitudinally opening of the aorta
<ol>
	<li>Expose the aorta clearly under a dissecting microscope and remove the connective tissues along the aorta as clean as possible, with delicate forceps and a pair of delicate scissors (Figure 1).</li>
	<li>Dissect the thoracic aorta from the heart to the celiac trunk with a pair of delicate scissors and put the aorta into a 6 cm cell culture dish with PBS. Cut open the aorta longitudinally, along the lesser curve, and along the greater curve until the straight segment is met. Cut open the three branches of the aortic arch, including the innominate, left common carotid and the left subclavian artery, with microscissors, as shown in Figure 2.</li>
</ol>
3. Pretreatment and immunostaining of the aorta
<ol>
	<li>Permeabilize the aorta with 0.1% polyoxyethylene octyl phenyl ether in PBS for 10 min and block it with 10% normal goat serum in Tris-buffered saline (TBS) containing 2.5% polysorbate 20 for 1 h at room temperature in a 12-well cell culture plate.</li>
	<li>Next, incubate the aorta with 5 g/mL rabbit anti-VCAM-1 and 5 g/mL rat anti-VE-cadherin in the blocking buffer, overnight at 4 &#176;C.</li>
	<li>After rinsing the sample 3x with washing solution (TBS containing 2.5% polysorbate 20), apply the fluorescence-conjugated secondary antibodies (1:1,000 dilution, Alexa Fluor 555-labeled anti-rabbit IgG and Alexa Fluor 488-labeled anti-rat IgG) for 1 h at room temperature. Rinse 3x in the washing solution.</li>
	<li>Counterstain the aorta with 4&#39;,6-diamidino-2-phenylindole (DAPI) (1 &#181;g/mL) for 10 min and rinse it 3x in the washing solution.</li>
</ol>
4. Mounting of the aorta on the glass slide
<ol>
	<li>Place the aorta on a coverslip with the luminal surface downward and move it slowly to the antifade mounting solution previously dropped on the coverslip. Gently stretch the aorta to keep the specimen flat.</li>
	<li>Inverse the coverslip and put it on the slide glass. Care must be taken not to allow any air bubbles to remain between the specimen and the glass.</li>
</ol>
5. Observation of the aorta
<ol>
	<li>Examine the aorta with a laser-scanning confocal microscope.</li>
	<li>Analyze color intensities of different channels from the desired region in the en face images with Image-Pro Plus software.</li>
</ol>

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The authors have nothing to disclose.

The endothelium is exposed to numerous proatherogenic factors, including lipids, inflammatory mediators, and fluid shear stress1,11,12. Direct observation of endothelial cells in situ provides the special advantages to analyze changes in cell morphology, intercellular junctions, and molecule expression patterns in response to the injury stimuli.
Previous studies have provided two different en face imm...

The early changes in the vasculature primarily initiate in the endothelium, which functions as a selective barrier between the blood and the vessel wall with its intercellular tight junctional complexes1. Substantial evidence points to a critical role for the mechanical effects of blood flow in modulating endothelial function2. Fluid shear stress, a frictional force generated by blood flow, differentially shapes endothelial cell morphology and function, depending on the specific flow paradigms at different vascular sites2,3. Atherosclerotic lesions preferentially occur at sites of disturbed blood flow (d-flow), such as vessel curvatures, flow dividers, and branch points, as compared to regions of steady flow (s-flow), such as the straight segment of the artery. Therefore, direct observation of endothelial morphology and molecule expression patterns should provide important insights into the structural and functional phenotypes of endothelial cells under varying flow paradigms.
Cultured endothelial cells may not express the actual phenotype as they do in vivo partly due to the loss of impact of fluid shear stress, surrounding cytokines, and cell-cell or cell-extracellular matrix interactions. To aid this, the intact endothelial cell monolayer can be studied on transverse sections using classical immunohistochemistry. However, the endothelial monolayer is so thin and fragile that it usually cannot be observed clearly. En face immunohistochemistry has been used to observe the inner surface of the endothelium but is either complicated or erratic in its results because the endothelium is easily stripped from the underlying tissue, or just part of the arterial wall of rats or rabbits, whose walls are thick, is mounted4,5.
Mouse models have considerable advantages over other animals in many respects. Here, we employ a modified en face immunofluorescence technique to analyze endothelial cells of the aortic arch and thoracic aorta in C57BL/6 mouse. Such a technique has been widely used to study the endothelial pathophysiology in different flow patterns and in the development of atherosclerosis6,7,8,9,10. This method allows scientists to observe the entire surface of the endothelium clearly and to compare the expression patterns of a given protein in regions under different fluid shear stress.

<table border="0" cellpadding="0" cellspacing="0" style="width:655px;" width="655">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Antifade mountant</td>
			<td style="width:126px;">Servicebio</td>
			<td style="width:134px;">G1401</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Delicate Forceps</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">F11001-11</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Delicate Scissors</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">S12003-09</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Dissecting Forceps</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">F12005-10</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Mciro Spring Scissors</td>
			<td style="width:126px;">RWD Life Science</td>
			<td style="width:134px;">S11001-08</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Polyoxyethylene octyl phenyl ether (Triton X-100)</td>
			<td style="width:126px;">Amresco</td>
			<td style="width:134px;">M143</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Polysorbate 20 (Tween 20)</td>
			<td style="width:126px;">Amresco</td>
			<td style="width:134px;">0777</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">VCAM-1 antibody</td>
			<td style="width:126px;">Abcam</td>
			<td style="width:134px;">ab134047</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">VE-Cadherin antibody</td>
			<td style="width:126px;">BD Biosciences</td>
			<td style="width:134px;">555289</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Alexa Fluor 555 labeled anti-rabbit IgG</td>
			<td style="width:126px;">invitrogen</td>
			<td style="width:134px;">A-31572</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:223px;">Alexa Fluor 488 labeled anti-rat IgG</td>
			<td style="width:126px;">invitrogen</td>
			<td style="width:134px;">A-21208</td>
			<td style="width:174px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Laser Scanning Microscope&#160;</td>
			<td>Carl Zeiss</td>
			<td style="width:134px;"></td>
			<td style="width:174px;"></td>
		</tr>
	</tbody>
</table>

using en face immunofluorescence staining to observe vascular endothelial cells directly

Aberrant changes in endothelial phenotype and morphology are considered to be initial events in the pathogenesis of atherosclerosis. Direct observation of the intact endothelium will provide valuable information for understanding the cellular and molecular events in the dysfunctional endothelial cells. Here, we describe a modified en face immunofluorescence staining technique which enables scientists to obtain clear images of the intact endothelial surface and analyze the molecule expression patterns in situ. The method is simple and reliable for observing the entire endothelial monolayer at different sites of the aorta. This technique may be a promising tool for understanding the pathophysiology of atherosclerosis, especially at an early stage.

A 12-week-old C57BL/6 mouse was euthanized and perfused with normal saline containing 40 units/mL heparin and, then, prechilled 4% paraformaldehyde. The mouse aorta was exposed under a dissecting microscope (Figure 1), dissected, and cut open longitudinally (Figure 2). En face immunofluorescence staining of the vascular endothelial cells was performed as illustrated in Figure 3 and Table 1</s...

Watch this Scientific Journal Video about Using En Face Immunofluorescence Staining to Observe Vascular Endothelial Cells Directly at JoVE.com

Using En Face Immunofluorescence Staining to Observe Vascular Endothelial Cells Directly

Here, we present a protocol for immunofluorescence staining to observe the endothelial cells of the mouse aorta directly. This technique is useful when studying the cellular and molecular phenotype of endothelial cells in different flow patterns and in the development of atherosclerosis.

Aberrant changes in endothelial phenotype and morphology are considered to be initial events in the pathogenesis of atherosclerosis. Direct observation of ...

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14.6K Views.  Shanghai Jiao Tong University School of Medicine. Here, we present a protocol for immunofluorescence staining to observe the endothelial cells of the mouse aorta directly. This technique is useful when studying the cellular and molecular phenotype of endothelial cells in different flow patterns and in the development of atherosclerosis.

Video: Using En Face Immunofluorescence Staining to Observe Vascular Endothelial Cells Directly

Transplantation of Cells Directly into the Kidney of Adult Zebrafish

Regenerative medicine based on the transplantation of stem or progenitor cells into damaged tissues has the potential to treat a wide range of chronic diseases1. However, most organs are not easily accessible, necessitating the need to develop surgical methods to gain access to these structures. In this video article, we describe a method for transplanting cells directly into the kidney of adult zebrafish, a popular model to study regeneration and disease2. Recipient fish are pre-conditioned by irradiation to suppress the immune rejection of the injected cells3. We demonstrate how the head kidney can be exposed by a lateral incision in the flank of the fish, followed by the injection of cells directly in to the organ. Using fluorescently labeled whole kidney marrow cells comprising a mixed population of renal and hematopoietic precursors, we show that nephron progenitors can engraft and differentiate into new renal tissue - the gold standard of any cell-based regenerative therapy. This technique can be adapted to deliver purified stem or progenitor cells and/or small molecules to the kidney as well as other internal organs and further enhances the zebrafish as a versatile model to study regenerative medicine.

Cell transplantation is an essential technique for studying tissue regeneration and for developing cell-based therapies of disease. We demonstrate here a microsurgical technique that permits the transplantation of genetically labeled cells directly into the kidney of adult zebrafish fish.

Regenerative medicine based on the transplantation of stem or progenitor cells into damaged tissues has the potential to treat a wide range of chronic ...

Isolation and Differentiation of Stromal Vascular Cells to Beige/Brite Cells

Brown adipocytes have the ability to uncouple the respiratory chain in mitochondria and dissipate chemical energy as heat. Development of UCP1-positive brown adipocytes in white adipose tissues (so called beige or brite cells) is highly induced by a variety of environmental cues such as chronic cold exposure or by PPAR&gamma; agonists, therefore, this cell type has potential as a therapeutic target for obesity treatment. Although most immortalized adipocyte lines cannot recapitulate the process of "browning" of white fat in culture, primary adipocytes isolated from stromal vascular fraction in subcutaneous white adipose tissue (WAT) provide a reliable cellular system to study the molecular control of beige/brite cell development. Here we describe a protocol for effective isolation of primary preadipocytes and for inducing differentiation to beige/brite cells in culture. The browning effect can be assessed by the expression of brown fat-selective markers such as UCP1.

Primary white preadipocytes isolated from white adipose tissues in mice can be differentiated into beige/brite cells. Presented here is a reliable cellular model system to study the molecular regulation of "browning" of white fat.

Brown adipocytes have the ability to uncouple the  respiratory chain in mitochondria and dissipate chemical energy as heat.  Development of UCP1-positive ...

Robust 3D DNA FISH Using Directly Labeled Probes

3D DNA FISH has become a major tool for analyzing three-dimensional organization of the nucleus, and several variations of the technique have been published. In this article we describe a protocol which has been optimized for robustness, reproducibility, and ease of use. Brightly fluorescent directly labeled probes are generated by nick-translation with amino-allyldUTP followed by chemical coupling of the dye. 3D DNA FISH is performed using a freeze-thaw step for cell permeabilization and a heating step for simultaneous denaturation of probe and nuclear DNA. The protocol is applicable to a range of cell types and a variety of probes (BACs, plasmids, fosmids, or Whole Chromosome Paints) and allows for high-throughput automated imaging. With this method we routinely investigate nuclear localization of up to three chromosomal regions.

We describe a robust and versatile protocol for analyzing nuclear architecture by 3D DNA FISH using directly labeled fluorescent probes.

3D DNA FISH has become a major tool for  analyzing three-dimensional organization of the nucleus, and several variations  of the technique have been ...

Isolation and Primary Culture of Mouse Aortic Endothelial Cells

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an important model for cardiovascular disease research. This study demonstrates a simple method to isolate and culture endothelial cells from the mouse aorta without any special equipment. To isolate endothelial cells, the thoracic aorta is quickly removed from the mouse body, and the attached adipose tissue and connective tissue are removed from the aorta. The aorta is cut into 1 mm rings. Each aortic ring is opened and seeded onto a growth factor reduced matrix with the endothelium facing down. The segments are cultured in endothelial cell growth medium for about 4 days. The endothelial sprouting starts as early as day 2. The segments are then removed and the cells are cultured continually until they reach confluence. The endothelial cells are harvested using neutral proteinase and cultured in endothelial cell growth medium for another two passages before being used for experiments. Immunofluorescence staining indicated that after the second passage the majority of cells were double positive for Dil-ac-LDL uptake, Lectin binding, and CD31 staining, the typical characteristics of endothelial cells. It is suggested that cells at the second to third passages are suitable for in vitro and in vivo experiments to study the endothelial biology. Our protocol provides an effective means of identifying specific cellular and molecular mechanisms in endothelial cell physiopathology.

The vascular endothelial cells play a significant role in many important cardiovascular disorders. This article describes a simple method to isolate and expand endothelial cells from the mouse aorta without using any special equipment. Our protocol provides an effective means of identifying mechanisms in endothelial cell physiopathology.

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an ...

Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland

Indirect immunofluorescence is used to detect and locate proteins of interest in a tissue. The protocol presented here describes a complete and simple method for the immune detection of proteins, the mouse lactating mammary gland being taken as an example. A protocol for the preparation of the tissue samples, especially concerning the dissection of mouse mammary gland, tissue fixation and frozen tissue sectioning, are detailed. A standard protocol to perform indirect immunofluorescence, including an optional antigen retrieval step, is also presented. The observation of the labeled tissue sections as well as image acquisition and post-treatments are also stated. This procedure gives a full overview, from the collection of animal tissue to the cellular localization of a protein. Although this general method can be applied to other tissue samples, it should be adapted to each tissue/primary antibody couple studied.

The indirect immunofluorescence protocol described in this article allows the detection and the localization of proteins in the mouse mammary gland. A complete method is given to prepare mammary gland samples, to perform immunohistochemistry, to image the tissue sections by fluorescence microscopy, and to reconstruct images.

Indirect immunofluorescence is used to detect and locate proteins of interest in a tissue. The protocol presented here describes a complete and simple ...

En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries

Endothelium-derived nitric oxide (NO) produced from endothelial NO-synthase (eNOS) is one of the most important vasoprotective molecules in cardiovascular physiology. Dysfunctional eNOS such as uncoupling of eNOS leads to decrease in NO bioavailability and increase in superoxide anion (O2.&#8722;) production, and in turn promotes cardiovascular diseases. Therefore, appropriate measurement of NO and O2.&#8722; levels in the endothelial cells are pivotal for research on cardiovascular diseases and complications. Because of the extremely labile nature of NO and O2.&#8722;, it is difficult to measure NO and O2.&#8722; directly in a blood vessel. Numerous methods have been developed to measure NO and O2.&#8722; production. It is, however, either insensitive, or non-specific, or technically demanding and requires special equipment. Here we describe an adaption of the fluorescence dye method for en face simultaneous detection and visualization of intracellular NO and O2.&#8722; using the cell permeable diaminofluorescein-2 diacetate (DAF-2DA) and dihydroethidium (DHE), respectively, in intact aortas of an obesity mouse model induced by high-fat-diet feeding. We could demonstrate decreased intracellular NO and enhanced O2.&#8722; levels in the freshly isolated intact aortas of obesity mouse as compared to the control lean mouse. We demonstrate that this method is an easy technique for direct detection and visualization of NO and O2.&#8722; in the intact blood vessels and can be widely applied for investigation of endothelial (dys)function under (physio)pathological conditions.

En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries

In this article we describe an adapted relatively easy method using the fluorescence dye diaminofluorescein-2 diacetate (DAF-2DA) and dihydroethidium (DHE) for en face simultaneous detection and visualization of intracellular nitric oxide (NO) and superoxide anion (O2.&#8722;) respectively, in freshly isolated intact aortas of an obesity mouse model.

Endothelium-derived nitric oxide (NO) produced from endothelial NO-synthase (eNOS) is one of the most important vasoprotective molecules in cardiovascular ...

A Simple Bioassay for the Evaluation of Vascular Endothelial Growth Factors

The analysis of receptor tyrosine kinases and their interacting ligands involved in vascular biology is often challenging due to the constitutive expression of families of related receptors, a broad range of related ligands and the difficulty of dealing with primary cultures of specialized endothelial cells. Here we describe a bioassay for the detection of ligands to the vascular endothelial growth factor receptor-2 (VEGFR-2), a key transducer of signals that promote angiogenesis and lymphangiogenesis. A cDNA encoding a fusion of the extracellular (ligand-binding) region of VEGFR-2 with the transmembrane and cytoplasmic regions of the erythropoietin receptor (EpoR) is expressed in the factor-dependent cell line Ba/F3. This cell line grows in the presence of interleukin-3 (IL-3) and withdrawal of this factor results in death of the cells within 24 hr. Expression of the VEGFR-2/EpoR receptor fusion provides an alternative mechanism to promote survival and potentially proliferation of stably transfected Ba/F3 cells in the presence of a ligand capable of binding and cross-linking the extracellular portion of the fusion protein (i.e., one that can cross-link the VEGFR-2 extracellular region). The assay can be performed in two ways: a semi-quantitative approach in which small volumes of ligand and cells permit a rapid result in 24 hr, and a quantitative approach involving surrogate markers of a viable cell number. The assay is relatively easy to perform, is highly responsive to known VEGFR-2 ligands and can accommodate extracellular inhibitors of VEGFR-2 signaling such as monoclonal antibodies to the receptor or ligands, and soluble ligand traps.

We describe a simple cell-based bioassay for detecting, quantifying and monitoring the activity of members of the vascular endothelial growth factor family of ligands. The assay uses chimeric receptors expressed in a factor-dependent cell line to provide a semi-quantitative or quantitative assessment of receptor binding and cross-linking by the ligand.

The analysis of receptor tyrosine kinases and their interacting ligands involved in vascular biology is often challenging due to the constitutive ...

En Face Preparation of Mouse Blood Vessels

Sections of paraffin embedded tissues are routinely used for studying tissue histology and histopathology. However, it is difficult to determine what the three-dimensional tissue morphology is from such sections. In addition, the sections of tissues examined may not contain the region within the tissue that is necessary for the purpose of the ongoing study. This latter limitation hinders histopathological studies of blood vessels since vascular lesions develop in a focalized manner. This requires a method that enables us to survey a wide area of the blood vessel wall, from its surface to deeper regions. A whole mount en face preparation of blood vessels fulfills this requirement. In this article, we will demonstrate how to make en face preparations of the mouse aorta and carotid artery and to immunofluorescently stain them for confocal microscopy and other types of fluorescence-based imaging.

En Face Preparation of Mouse Blood Vessels

A procedure for making en face preparations of the mouse carotid artery and aorta is described. Such preparations, when immunofluorescently stained with specific antibodies, enable us to study localization of proteins and identification of cell types within the entire vascular wall by confocal microscopy.

Sections of paraffin embedded tissues are routinely used for studying tissue histology and histopathology. However, it is difficult to determine what the ...

Measuring Proliferation of Vascular Smooth Muscle Cells Using Click Chemistry

The ability of a cell to proliferate is integral to the normal function of most cells, and dysregulation of proliferation is at the heart of many disease processes. For these reasons, measuring proliferation is a common tool used to assess cell function. Cell proliferation can be measured simply by counting; however, this is an indirect means of measuring proliferation. One common means of directly detecting cells preparing to divide is by incorporation of labeled nucleoside analogs. These include the radioactive nucleoside analog 3H-thymidine plus non-radioactive nucleoside analogs such as 5-bromo-2&#8217; deoxyuridine (BrdU) and 5-ethynyl-2&#8242;-deoxyuridine (EdU). Incorporation of EdU is detected by click chemistry, which has several advantages when compared to BrdU. In this report, we provide a protocol for measuring proliferation by the incorporation of EdU. This protocol includes options for various readouts, along with the advantages and disadvantages of each. We also discuss places where the protocol can be optimized or altered to meet the specific needs of the experiment planned. Finally, we touch on the ways that this basic protocol can be modified for measuring other cell metabolites.

Proliferation is a critical part of cellular function, and a common readout used to assess potential toxicity of new drugs. Measuring proliferation is, therefore, a frequently used assay in cell biology. Here we present a simple, versatile method of measuring proliferation that can be used in adherent and non-adherent cells.

The ability of a cell to proliferate is integral to the normal function of most cells, and dysregulation of proliferation is at the heart of many disease ...

Staining and High-Resolution Imaging of Three-Dimensional Organoid and Spheroid Models

In vitro three-dimensional (3D) cell culture models, such as organoids and spheroids, are valuable tools for many applications including development and disease modeling, drug discovery, and regenerative medicine. To fully exploit these models, it is crucial to study them at cellular and subcellular levels. However, characterizing such in vitro 3D cell culture models can be technically challenging and requires specific expertise to perform effective analyses. Here, this paper provides detailed, robust, and complementary protocols to perform staining and subcellular resolution imaging of fixed in vitro 3D cell culture models ranging from 100 &#181;m to several millimeters. These protocols are applicable to a wide variety of organoids and spheroids that differ in their cell-of-origin, morphology, and culture conditions. From 3D structure harvesting to image analysis, these protocols can be completed within 4-5 days. Briefly, 3D structures are collected, fixed, and can then be processed either through paraffin-embedding and histological/immunohistochemical staining, or directly immunolabeled and prepared for optical clearing and 3D reconstruction (200 &#181;m depth) by confocal microscopy.

Here, we provide detailed, robust, and complementary protocols to perform staining and subcellular resolution imaging of fixed three-dimensional cell culture models ranging from 100 &#181;m to several millimeters, thus enabling the visualization of their morphology, cell-type composition, and interactions.

In vitro three-dimensional (3D) cell culture models, such as organoids and spheroids, are valuable tools for many applications including development and ...