The authors would like to thank Mr. Tam Po Leung, Mr. Wong Chi Kin and the technical staff of the Science Faculty Workshop, Hong Kong Baptist University, for their technical skills and advice in making the prototype of this wounder.

1. Introduction to the Parts of the Wounder (Figure 1)
<ol>
	<li>Prepare the pin holder by fixing the wounding pins at equal distances. Hold the pipette tips and adjust the tip height by moving the adjustable wounding pins up and down.</li>
	<li>Fit the adjustable guiding-bar on different brands of 96-well culture plates and ensure that the wounding area is in a fixed position.</li>
	<li>Fix the adjustable wounding pin by tightening the hex screw. Fix the guiding-bar in position by tightening the hex socket head caps on both ends.</li>
</ol>
2. Setting the Width of the Pin Holder (Figure 2)
<ol>
	<li>Loosen the hex socket head caps with the M5 hex wrench.</li>
	<li>Insert a suitable number of adjusting rings to both sides of the pin holder so that the guiding bars fit perfectly with the width of the 96-well culture plate. 
	NOTE: Corning and Iwaki plates requires 1 pair of large rings and 1 pair of small rings. Falcon and Nunc plates need 1 pair of large rings.</li>
	<li>Tighten the hex socket head caps to fix the guiding bar.</li>
</ol>
3. Adjusting the Guiding Bars (Figure 3)
<ol>
	<li>Fit the wounding pins with sterile 10-&#181;L plastic pipette tips.</li>
	<li>Loosen the hex socket head caps with the M5 hex wrench.</li>
	<li>Hold the wounder and dip the wounding pins into one column of a 96-well culture plate.</li>
	<li>Adjust the height of the guiding bars until all of the tips barely touch the bottom of the wells.</li>
	<li>Tighten the hex socket head caps. Ensure that the wounder now perfectly fits on the culture plate and that the pins are well-positioned in the middle of the wells.</li>
</ol>
4. Calibration of the Pins
<ol>
	<li>Hold the wounder perpendicular to a flat sterile surface (i.e. Petri dish) and loosen all the hex screws with the M3 hex wrench.</li>
	<li>Tap the wounder until all of the tips evenly touch the flat sterile surface.</li>
	<li>Tighten the hex screws again to lock the pins in position.</li>
	<li>Check the evenness of each tip by tapping the wounder gently on the flat sterile surface.</li>
</ol>
5. Scratching Cell Monolayer (Figure 4)
<ol>
	<li>Seed human umbilical vascular endothelial cells on a 0.1% gelatin-coated 96-well cell culture plate. Culture cells in Medium 199 supplemented with 20% heat-inactivated fetal bovine serum, 1% penicillin/streptomycin and 0.09 g/L heparin. Maintain cells in a humidified incubator with 5% carbon dioxide at 37 &#186;C overnight before being used. Cells should reach 100% confluency before wounding.</li>
	<li>Place the wounding tips at the leftmost (or the rightmost) side of each well within the same column of the culture plate. Slide the wounder across to the other side of the well; make sure the wounding tips are touching the bottom of the well.</li>
	<li>Repeat the scratching (Step 5.2) for all columns.</li>
	<li>After wounding, discard the medium in each well and replace with fresh medium containing testing compounds.</li>
</ol>
6. Data Acquisition and Image Analysis
<ol>
	<li>Image the whole well with the mechanical wound on the cell monolayer using a low-power microscope with digital camera (e.g. 10X objective) immediately after wounding (t=0 h).</li>
	<li>Add test compounds if desired and incubate for the desired length of time. Image the whole well with the wound area again after the desired incubation time (t=&#916;h).</li>
	<li>Using image analysis software such as ImageJ (<a href="https://imagej.nih.gov/ij/">https://imagej.nih.gov/ij/</a>), measure the wounded area on the image using the freehand tool.</li>
	<li>Calculate the percentage of wound closure: 
	<img alt="Equation" src="/files/ftp_upload/55411/55411eq1.jpg" /></li>
</ol>

<ol>
	<li>Friedl, P., Wolf, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumour-cell+invasion+and+migration:+diversity+and+escape+mechanisms.">Tumour-cell invasion and migration: diversity and escape mechanisms.</a> Nat Rev Cancer. 3 (5), 362-374 (2003).</li><li>Friedl, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prespecification+and+plasticity:+shifting+mechanisms+of+cell+migration.">Prespecification and plasticity: shifting mechanisms of cell migration.</a> Curr Opin Cell Biol. 16 (1), 14-23 (2004).</li><li>Lampugnani, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+migration+into+a+wounded+area+in+vitro.">Cell migration into a wounded area in vitro.</a> Methods Mol Biol. 96, 177-182 (1999).</li><li>Sholley, M. M., Gimbrone, M. A., Cotran, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+migration+and+replication+in+endothelial+regeneration:+a+study+using+irradiated+endothelial+cultures.">Cellular migration and replication in endothelial regeneration: a study using irradiated endothelial cultures.</a> Lab Invest. 36 (1), 18-25 (1977).</li><li>Gotlieb, A. I., Spector, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Migration+into+an+in+vitro+experimental+wound:+a+comparison+of+porcine+aortic+endothelial+and+smooth+muscle+cells+and+the+effect+of+culture+irradiation.">Migration into an in vitro experimental wound: a comparison of porcine aortic endothelial and smooth muscle cells and the effect of culture irradiation.</a> Am J Pathol. 103 (2), 271-282 (1981).</li><li>Chen, Y. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+migration+chip+for+chemotaxis-based+microfluidic+selection+of+heterogeneous+cell+populations.">Single-cell migration chip for chemotaxis-based microfluidic selection of heterogeneous cell populations.</a> Sci Rep. 18 (5), 9980 (2015).</li><li>Yarrow, J. C., Periman, Z. E., Westwood, N. J., Mitchison, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+high-throughput+cell+migration+assay+using+scratch+wound+healing,+a+comparsion+of+image-based+readout+methods.">A high-throughput cell migration assay using scratch wound healing, a comparsion of image-based readout methods.</a> BMC Biotechnol. 4, 21 (2004).</li><li>Lauder, H., Frost, E. E., Hiley, C. R., Fan, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+the+repair+process+involved+in+the+repair+of+a+cell+monolayer+using+an+in+vitro+model+of+mechanical+injury.">Quantification of the repair process involved in the repair of a cell monolayer using an in vitro model of mechanical injury.</a> Angiogenesis. 2 (1), 67-80 (1998).</li><li>Yue, P. Y. K., Leung, E. P. Y., Mak, N. K., Wong, R. N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simplified+method+for+quantifying+cell+migration/+wound+healing+in+96-well+plates.">A simplified method for quantifying cell migration/ wound healing in 96-well plates.</a> J. Biomol Screen. 15 (4), 427-433 (2010).</li><li>Yue, P. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elucidation+of+the+mechanisms+underlying+the+angiogenic+effects+of+ginsenoside+Rg(1)+in+vivo+and+in+vitro.">Elucidation of the mechanisms underlying the angiogenic effects of ginsenoside Rg(1) in vivo and in vitro.</a> Angiogenesis. 8 (3), 205-216 (2005).</li><li>Kwok, H. H., Chan, L. S., Poon, P. Y., Yue, P. Y., Wong, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ginsenoside-Rg1+induces+angiogenesis+by+the+inverse+regulation+of+MET+tyrosine+kinase+receptor+expression+through+miR-23a.">Ginsenoside-Rg1 induces angiogenesis by the inverse regulation of MET tyrosine kinase receptor expression through miR-23a.</a> Toxicol Appl Pharmacol. 287 (3), 276-283 (2015).</li></ol>

The authors declare that they have no competing financial interests.

Our cell wounder has several unique features in solving the problems of traditional cell migration assays. The 8-channel mechanical cell wounder is made of high grade stainless steel (Steel 304) with a long lifespan that can be sterilized by autoclaving. Almost all commercial brands of 96-well culture plates available on the market can be used with this mechanical cell wounder because of the adjustable guiding bar. The design of the adjustable guiding bar also ensures that the scratching area is at the center of each well. The wound in a central position of the well can facilitate image capturing using a microscope. The images possess some variations while taken at different time points, but they do not affect data analysis because almost 90% of the well area can be viewed by the microscope with a low-magnification objective (i.e. 10X). Thus, a semi-high throughput analysis can be performed on 96-well culture plates7,8. However, this method still requires a large number of images, which require lengthy data analysis. This may be solved if an automatic image acquiring system is available.
The design of the individual adjustable pins of the wounder allows even contact with the 96-well plate surface to achieve identical, smooth and sharp wounds on the cell monolayer. The scratching pins are commercial plastic pipette tips, which can be sterilized and disposed after every single scratching, and can provide great elasticity to contact the well surface without mechanical damage. These advantages can further minimize cross contamination of samples during the experiment and the influence on cell movement across the denuded area. In the future, we will develop a spring-controlled pin which can eliminate the pin height adjustment step. The most critical step to use this device is the force applied on the cell monolayer during the scratching. The wounder must be held perpendicular against the culture plate, so that eight pipette tips are touching the bottom of the well. Indeed, the wounder provides a method to perform the cell migration assay without the use of expensive and complicated equipment. The protocol for this wounder is simple and straightforward.
In conclusion, our 8-channel mechanical wounder is a user-friendly device for cell migration assays that requires no special skills. Users can perform the cell migration assay in 96-well plates with a relatively large number of samples in a fast and simple manner9,10,11.

Cell migration plays an important role in cellular processes, such as embryogenesis, neurogenesis, angiogenesis, wound healing, mucosal repairing, epithelial-mesenchymal-transitions under normal development and disease situation1. It is a complicated process which involves the coordination of numerous inter- and intra-cellular events including signaling molecule interactions, cell polarization, cytoskeletal reorganization, matrix remodeling, membrane protrusion and dynamic cell-cell adhesion modulation2. By studying cell migration, the discovery and validation of chemicals or biomolecules leading to cell movement and its related biochemical pathways can be determined. This fundamental process can be used beneficially as a proxy for various applications, such as disease treatment and drug targeting.
The wounding assay is one of the cell migration assays3. Here, an individual sample of cells will be partially removed by mechanical means to produce a denuded area where cells will migrate to cover the area. The percentage of recovery at a particular time point will be monitored. When handling large number of samples, issues such as the experimental cost and cross-contamination within samples can be problematic. Although many commercial tools and assays are available for studying cell migration4,5,6, many of them required expensive and sophisticated equipment and improvements are still needed. For these reasons, an 8-channel mechanical cell wounder (Figure 1) is developed.
Our 8-channel mechanical cell wounder has incorporated several unique features in solving the above-mentioned problems. It provides the flexibility to perform cell migration/wounding assays in the 96-well culture plate format. The adjustable guiding bar design ensures that the scratch area is in the central position of each well. Also, the height of the guiding bars can be adjusted so that the wounder is applicable for various brands of culture plates. Finally, the adjustable wounding pin design enables an even contact of the pipette tips with the culture plate surface to achieve simultaneous and reproducible wounding7,8.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96-well cell culture plate</td>
			<td>Nunc</td>
			<td>167008</td>
			<td>Other brands of 96-well cell culture plate can also be used</td>
		</tr>
		<tr>
			<td>P10 pipette tips</td>
			<td>Axygen</td>
			<td>301-03-051</td>
			<td>Short P10 pipette tip is more easy to create a clear wound</td>
		</tr>
		<tr>
			<td>Wounder</td>
			<td>R&#38;P Technology Limited</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Medium 199</td>
			<td>Sigma</td>
			<td>M2520-1L</td>
			<td>For cell culture of human umbilical vein endothelial cells. 
			Use appropirate culture medium and condition for other type of cells.</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Gibco</td>
			<td>26140079</td>
			<td>For cell culture of human umbilical vein endothelial cells. 
			Use appropirate culture medium and condition for other type of cells.</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Gibco</td>
			<td>15140122</td>
			<td>For cell culture of human umbilical vein endothelial cells. 
			Use appropirate culture medium and condition for other type of cells.</td>
		</tr>
		<tr>
			<td>Heparin sodium salt from porcine intestinal mucosa</td>
			<td>Sigma</td>
			<td>H3393</td>
			<td>For cell culture of human umbilical vein endothelial cells. 
			Use appropirate culture medium and condition for other type of cells.</td>
		</tr>
		<tr>
			<td>Gelatin from bovine skin</td>
			<td>Sigma</td>
			<td>G9391</td>
			<td>For cell culture of human umbilical vein endothelial cells. 
			Use appropirate culture medium and condition for other type of cells.</td>
		</tr>
	</tbody>
</table>

a device for performing cell migration/wound healing in a 96-well plate

The cell migration/wounding assay is a commonly used method to study cell migration and other biological processes, such as angiogenesis and tumor metastasis. In this assay, cells are grown to form a confluent monolayer and a mechanical wound is created by scratching with a device. Then the migration rate of the cells towards the denuded area can be monitored by imaging. Our 8-channel mechanical wounder is designed to tackle most of the problems associated with the cell migration assay. Firstly, our wounder can be easily sterilized by autoclaving or with common disinfectants. Secondly, the individual adjustable pins allow even contact with the cell culture plate so that sharp and reproducible wounds can be created. Thirdly, the guiding bars on both sides of the wounder ensure consistent wounding position in each well. The use of disposable plastic pipette tips for wounding can further provide better handling of the wounder as well as to minimize cross-contamination. In conclusion, our cell wounder can provide researchers with a user friendly and reproducible device for performing the cell migration assay using the standard 96-well culture plate.

This 8-channel mechanical wounder is constructed to scratch a cell monolayer in order to perform the cell migration assay. It is a user-friendly device that can carry out cell scratching assays in 96-well plates in less than a minute without special training. This wounder can introduce wound areas on cell monolayers with a uniform width of about 600 &#181;m and with sharp edges (Figures 5 and 6). The width of the wounds depends on the brand of pipette tips and the user&#39;s performance. This range of wound width is suitable for common image capturing under low-power magnification (Figure 7). After capturing the image, the percentage of wound closure can be calculated. This cell wounder has incorporated different strategies in solving problems encountered with the cell migration assay. Also, it provides flexibility in performing cell migration assays in various 96-well culture plate formats.
<img alt="Figure 1" src="/files/ftp_upload/55411/55411fig1.jpg" /> 
Figure 1: Eight-channel mechanical cell wounder. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55411/55411fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/55411/55411fig2.jpg" /> 
Figure 2: Adjust the width of the pin holder. Insert the adjusting rings in order to fit the 96-wells plate. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55411/55411fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/55411/55411fig3.jpg" /> 
Figure 3. Adjust the guiding bars to fit different plate formats. Slide the guiding bar up and down to fit the 96-wells plate. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55411/55411fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" src="/files/ftp_upload/55411/55411fig4.jpg" /> 
Figure 4: Scratching direction of the tip. Scratch the cells by sliding the wounder from the one side of the well bottom to the other side of the well bottom.
<img alt="Figure 5" src="/files/ftp_upload/55411/55411fig5.jpg" /> 
Figure 5: Overview of the 96-well plate after wounding. The cell monolayer is wounded by the wounder producing sharp edges with uniform width of about 600 &#181;m. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55411/55411fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" src="/files/ftp_upload/55411/55411fig6.jpg" /> 
Figure 6: Representative images of a row and a column of wells immediately after scratching. Quantitative analysis of the width of the each wound. Images are captured under a 10X objective. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55411/55411fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" src="/files/ftp_upload/55411/55411fig7.jpg" /> 
Figure 7: Captured wound images (10X objective) at t=0 h and t=&#916;h. The dotted line indicates the wound area and the solid line indicates the cell migration area. A) Human umbilical vein endothelial cells. B) Human dermal fibroblast. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55411/55411fig7large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about A Device for Performing Cell Migration/Wound Healing in a 96-Well Plate at JoVE.com

A Device for Performing Cell Migration/Wound Healing in a 96-Well Plate

Here, we present a protocol to perform a semi-high throughput cell migration assay on a 96-well cell culture plate. This protocol is a fast, simple and economical method to create consistent scratch wounds on a cell monolayer.

The cell migration/wounding assay is a commonly used method to study cell migration and other biological processes, such as angiogenesis and tumor ...

a-device-for-performing-cell-migrationwound-healing-in-a-96-well-plate

Nanyang Technological University

Research

JoVE Journal

Developmental Biology

10.4K Views.  Hong Kong Baptist University. Here, we present a protocol to perform a semi-high throughput cell migration assay on a 96-well cell culture plate. This protocol is a fast, simple and economical method to create consistent scratch wounds on a cell monolayer. 

Video: A Device for Performing Cell Migration/Wound Healing in a 96-Well Plate

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Understanding Early Organogenesis Using a Simplified In Situ Hybridization Protocol in Xenopus

The Xenopus laevis embryo continues to be exceptionally useful in the study of early development due to its large size and ease of manipulation. A simplified protocol for whole mount in situ hybridization protocol is provided that can be used in the identification of specific organs in this model system.

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The threespine stickleback fish has emerged as a powerful system to study the genetic basis of a wide variety of morphological, physiological, and ...

Adenoviral Gene Therapy for Diabetic Keratopathy: Effects on Wound Healing and Stem Cell Marker Expression in Human Organ-cultured Corneas and Limbal Epithelial Cells

The goal of this protocol is to describe molecular alterations in human diabetic corneas and demonstrate how they can be alleviated by adenoviral gene therapy in organ-cultured corneas. The diabetic corneal disease is a complication of diabetes with frequent abnormalities of corneal nerves and epithelial wound healing. We have also documented significantly altered expression of several putative epithelial stem cell markers in human diabetic corneas. To alleviate these changes, adenoviral gene therapy was successfully implemented using the upregulation of c-met proto-oncogene expression and/or the downregulation of proteinases matrix metalloproteinase-10 (MMP-10) and cathepsin F. This therapy accelerated wound healing in diabetic corneas even when only the limbal stem cell compartment was transduced. The best results were obtained with combined treatment. For possible patient transplantation of normalized stem cells, an example is also presented of the optimization of gene transduction in stem cell-enriched cultures using polycationic enhancers. This approach may be useful not only for the selected genes but also for the other mediators of corneal epithelial wound healing and stem cell function.

An example of adenoviral gene therapy in the human diabetic organ-cultured corneas is presented towards the normalization of delayed wound healing and markedly reduced epithelial stem cell marker expression in these corneas. It also describes the optimization of this process in stem cell-enriched limbal epithelial cultures.

The goal of this protocol is to describe molecular alterations in human diabetic corneas and demonstrate how they can be alleviated by adenoviral gene ...

Rapid Isolation of BMPR-IB+ Adipose-Derived Stromal Cells for Use in a Calvarial Defect Healing Model

Invasive cancers, major injuries, and infection can cause bone defects that are too large to be reconstructed with preexisting bone from the patient's own body. The ability to grow bone de novo using a patient's own cells would allow bony defects to be filled with adequate tissue without the morbidity of harvesting native bone. There is interest in the use of adipose-derived stromal cells (ASCs) as a source for tissue engineering because these are obtained from an abundant source: the patient's own adipose tissue. However, ASCs are a heterogeneous population and some subpopulations may be more effective in this application than others. Isolation of the most osteogenic population of ASCs could improve the efficiency and effectiveness of a bone engineering process. In this protocol, ASCs are obtained from subcutaneous fat tissue from a human donor. The subpopulation of ASCs expressing the marker BMPR-IB is isolated using FACS. These cells are then applied to an in vivo calvarial defect healing assay and are found to have improved osteogenic regenerative potential compared with unsorted cells.

Adipose-derived stromal cells may be useful for engineering new tissue from a patient's own cells. We present a protocol for the isolation of a subpopulation of human adipose-derived stromal cells (ASCs) with increased osteogenic potential, followed by application of the cells in an in vivo calvarial healing assay.

Invasive cancers, major injuries, and infection can cause bone defects that are too large to be reconstructed with preexisting bone from the patient's own ...

A Novel Mammary Fat Pad Transplantation Technique to Visualize the Vessel Generation of Vascular Endothelial Stem Cells

Endothelial cells (ECs) are the fundamental building blocks of the vascular architecture and mediate vascular growth and remodeling to ensure proper vessel development and homeostasis. However, studies on endothelial lineage hierarchy remain elusive due to the lack of tools to gain access as well as to directly evaluate their behavior in vivo. To address this shortcoming, a new tissue model to study angiogenesis using the mammary fat pad has been developed. The mammary gland develops mostly in the postnatal stages, including puberty and pregnancy, during which robust epithelium proliferation is accompanied by extensive vascular remodeling. Mammary fat pads provide space, matrix, and rich angiogenic stimuli from the growing mammary epithelium. Furthermore, mammary fat pads are located outside the peritoneal cavity, making them an easily accessible grafting site for assessing the angiogenic potential of exogenous cells. This work also describes an efficient tracing approach using fluorescent reporter mice to specifically label the targeted population of vascular endothelial stem cells (VESCs) in vivo. This lineage tracing method, coupled with subsequent tissue whole-mount microscopy, enable the direct visualization of targeted cells and their descendants, through which the proliferation capability can be quantified and the differentiation commitment can be fate-mapped. Using these methods, a population of bipotent protein C receptor (Procr) expressing VESCs has recently been identified in multiple vascular systems. Procr+ VESCs, giving rise to both new ECs and pericytes, actively contribute to angiogenesis during development, homeostasis, and injury repair. Overall, this manuscript describes a new mammary fat pad transplantation and in vivo lineage tracing techniques that can be used to evaluate the stem cell properties of VESCs.

This work demonstrates a novel approach to assess the proliferation, differentiation, and vessel-forming potential of vascular endothelial stem cells (VESCs) through mammary fat pad transplantation followed by whole-mount tissue preparation for microscopic observation. A lineage tracing strategy to investigate the behavior of VESCs in vivo is also presented.

Endothelial cells (ECs) are the fundamental building blocks of the vascular architecture and mediate vascular growth and remodeling to ensure proper ...

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell types include enzyme-secreting acinar cells, an arborized ductal system responsible for the transportation of enzymes to the gut, and hormone-producing endocrine cells. 
Endocrine beta-cells are the sole cell type in the body that produce insulin to lower blood glucose levels. Diabetes, a disease characterized by a loss or the dysfunction of beta-cells, is reaching epidemic proportions. Thus, it is essential to establish protocols to investigate beta-cell development that can be used for screening purposes to derive the drug and cell-based therapeutics. While the experimental investigation of mouse development is essential, in vivo studies are laborious and time-consuming. Cultured cells provide a more convenient platform for screening; however, they are unable to maintain the cellular diversity, architectural organization, and cellular interactions found in vivo. Thus, it is essential to develop new tools to investigate pancreatic organogenesis and physiology.
Pancreatic epithelial cells develop in the close association with mesenchyme from the onset of organogenesis as cells organize and differentiate into the complex, physiologically competent adult organ. The pancreatic mesenchyme provides important signals for the endocrine development, many of which are not well understood yet, thus difficult to recapitulate during the in vitro culture. Here, we describe a protocol to culture three-dimensional, cellular complex mouse organoids that retain mesenchyme, termed pancreatoids. The e10.5 murine pancreatic bud is dissected, dissociated, and cultured in a scaffold-free environment. These floating cells self-assemble with mesenchyme enveloping the developing pancreatoid and a robust number of endocrine beta-cells developing along with the acinar and the duct cells. This system can be used to study the cell fate determination, structural organization, and morphogenesis, cell-cell interactions during organogenesis, or for the drug, small molecule, or genetic screening.

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

Here, we present a protocol to generate insulin expressing 3D murine pancreatoids from free-floating e10.5 dissociated pancreatic progenitors and the associated mesenchyme.

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell ...

Visualizing the Node and Notochordal Plate In Gastrulating Mouse Embryos Using Scanning Electron Microscopy and Whole Mount Immunofluorescence

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is the formation of the transient organizers, the node and notochordal plate, from cells that have passed through the primitive streak. The proper formation of these signaling centers is essential for the development of the body plan and techniques to visualize them are of high interest to mouse developmental biologists. The node and notochordal plate lie on the ventral surface of gastrulating mouse embryos around embryonic day (E) 7.5 of development. The node is a cup-shaped structure whose cells possess a single slender cilium each. The proper subcellular localization and rotation of the cilia in the node pit determines left-right asymmetry. The notochordal plate cells also possess single cilia albeit shorter than those of the node cells. The notochordal plate forms the notochord which acts as an important signaling organizer for somitogenesis and neural patterning. Because the cells of the node and notochordal plate are transiently present on the surface and possess cilia, they can be visualized using scanning electron microscopy (SEM). Among other techniques used to visualize these structures at the cellular level is whole mount immunofluorescence (WMIF) using the antibodies against the proteins that are highly expressed in the node and notochordal plate. In this report, we describe our optimized protocols to perform SEM and WMIF of the node and notochordal plate in developing mouse embryos to help in the assessment of tissue shape and cellular organization in wild-type and gastrulation mutant embryos.

The node and notochordal plate are transient signaling organizers in developing mouse embryos that can be visualized using several techniques. Here, we describe in detail how to perform two of the techniques to study their structure and morphogenesis: 1) scanning electron microscopy (SEM); and 2) whole mount immunofluorescence (WMIF).

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is ...