The author wishes to thank Bhagawat Subramanian, Yi (Jason) Chang, Paul Randazzo, and Carole Parent for reading and commenting on the manuscript. This work was supported by the Intramural Research Program of the National Cancer Institute, National Institutes of Health.

1. Coating of Dishes (Day 1)
NOTE: Make sure not to leave fingerprints or dirt on the bottom of the plate when handling it.
<ol>
	<li>Thaw mouse collagen IV on ice, and dilute it with 50 mM HCl (pH 1.3) to prepare 3 mL of a 10 &#181;g/mL collagen IV solution. 
	NOTE: Collagen will precipitate at 37 &#176;C. It is therefore important to keep the collagen solution at a low temperature while thawing and working with it. Avoid repeated freeze-thaw cycles by preparing appropriately sized aliquots and storing them at -80 &#176;C.</li>
	<li>Add 250 &#181;L collagen IV solution to each well of 12-well glass bottom plates and place them into an appropriately sized, tight-closing plastic box. Place wet paper towel over and around the plates to manufacture a humid chamber and close the box. Incubate the plates overnight at room temperature. 
	Note: As only the growth area needs to be coated, it is sufficient to only cover the cover slip, which is attached to the bottom of the plate, with collagen solution (see Figure 1A, B for a schematic of plate).</li>
	<li>Next morning, rinse plates with deionized H2O twice to remove non-absorbed collagen and buffer. Direct the water to the edge of the plate well, not to the edge formed by the plate bottom and the coverslip (if water is pipetted into this area it will splash). Air-dry the plates in the laminar flow hood. Use plates immediately or store at 4 &#176;C for up to 5 days. 
	Note: Different cell lines might require different coating, such as fibronectin or collagen I.</li>
</ol>
2. Plating the Dot Assay (Day 2)
<ol>
	<li>Preparing the cell suspension
	<ol>
		<li>To prepare cell suspension, use cells that have been grown in a 60-mm tissue culture dish in DMEM/F12 medium supplemented with 5% horse serum to 80% confluence</li>
		<li>Rinse the cells with calcium- and magnesium-free Dulbecco&#39;s phosphate buffered saline (DPBS) once, add 500 &#181;L trypsin-EDTA (room temperature), and incubate the cells for 3 - 5 min in an incubator at 37 &#176;C, 5% CO2, humidified atmosphere.</li>
		<li>Suspend the detached cells in 4.5 mL culture medium to stop trypsin activity and count a 20 &#181;L aliquot of the cell suspension in a hemocytometer.</li>
		<li>Pellet the remaining cells in a 15 mL conical tube by centrifugation at 200 x g for 3 min, aspirate the supernatant, and resuspend the cells in culture medium to 3 x 106 cells/mL. 
		NOTE: For other coating substrates and/or cell lines, the optimal cell density must be established in a dilution series. 3 x 106 cell/mL is recommended as a starting point.</li>
	</ol>
	</li>
	<li>Plating cells
	<ol>
		<li>Place a 10 &#181;L drop of cell suspension at the center of each cover slip of the collagen IV coated 12-well glass bottom plate without touching or scratching the coating (Figure 1A, B). Incubate the plate for 30 min at 37 &#176;C, humidified atmosphere, to allow the cells to attach. Check in an inverted microscope that the cells are attached. 
		NOTE: This can be best seen at the edge of the drop, where formation of a monolayer can be observed (Figure 1C). If necessary, incubate the plate up to 3 h. Be sure that the humidity in the incubator is high enough as the drops can dry out quickly. If a reduction of the drop volume during this step is observed, add PBS to the spaces between the wells to increase humidity.</li>
		<li>Gently wash the wells with 1 mL of culture medium twice to remove non-attached cells. Add 1 mL culture medium to each well. Check in an inverted microscope that no floating cells remain, otherwise wash the wells again. Incubate cells overnight at 37 &#176;C, 5% CO2, humidified atmosphere, to obtain well-defined cell sheets. 
		Note: Floating cells are likely to re-attach to the plate and to form undesired cell colonies.</li>
	</ol>
	</li>
</ol>
3. Stimulating Cells (Day 3)
<ol>
	<li>Check all wells using an inverse microscope to ensure that cell colonies have grown properly. If necessary, mark unsuitable wells and do not use them.</li>
	<li>Label each well of the plate appropriately for each condition investigated. Run each condition in duplicate or triplicate.</li>
	<li>Change the medium to starve the cells in DMEM/F12 containing 0.1% horse serum (starving medium) 3 h before cells are stimulated.</li>
	<li>Stimulate the cells by addition of EGF (5 ng/mL final concentration) or other desired mediators and gently mix the medium using a 1 mL micropipettor or by swirling the plate.</li>
	<li>Incubate the plate for 1 - 4 days to observe edge displacement and edge contour as described in section 4.1 or perform time-lapse imaging as described in section 4.2.</li>
</ol>
4. Visualization of Cell Colonies and Cell Migration
<ol>
	<li>Hematoxylin-eosin (HE) staining to measure colony growth (Day 4 - 7)
	<ol>
		<li>Fix cells in 70% ethanol (1 mL/well) for ~2 min.</li>
		<li>Stain nuclei with hematoxylin (1 mL/well), ~2 min.</li>
		<li>Wash cells with tap water (1 mL/well) until nuclei are blue, 5 - 10 min.</li>
		<li>Stain cytoplasm with eosin (1 mL/well), ~2 min.</li>
		<li>Rinse with deionized water (1 mL/well). 
		Note: Hematoxylin and eosin solutions can be collected and used multiple times until the staining becomes faint.</li>
		<li>Air-dry plate.</li>
		<li>Flip the plate and measure the dot diameter with a ruler. Alternatively, take pictures of the plate with a camera, and analyze the dot diameter in ImageJ.</li>
	</ol>
	</li>
	<li>Time-lapse microscopy (Day 3)
	<ol>
		<li>Switch on the incubator microscope and adjust the temperature to 37 &#176;C. Fill the humidifier with dH2O. Adjust the CO2 to 5%. Ensure that the incubator chamber is humidified and that the motorized stage can move freely. Close the incubator chamber and allow the microscope to adjust to 37 &#176;C. 
		NOTE: The microscope (see the Table of Materials) used here should be heated to 37 &#176;C for at least 3 h before the cells are imaged to avoid drifting of the focus.</li>
		<li>Place the plate on the stage of the incubator microscope and set up the stage list. Image two opposing edges and the center of each cell dot (Figure 1A).</li>
		<li>Take images every 3 min, for 15 - 24 h using the 10X&#160;objective. Download the data and proceed with image analysis in a program of choice, e.g., ImageJ or Matlab.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Liang, C. -. C., Park, A. Y., Guan, J. -. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+scratch+assay:+a+convenient+and+inexpensive+method+for+analysis+of+cell+migration+in+vitro.">In vitro scratch assay: a convenient and inexpensive method for analysis of cell migration in vitro.</a> Nat Protoc. 2 (2), 329-333 (2007).</li><li>Peplow, P. V., Chatterjee, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+the+influence+of+growth+factors+and+cytokines+in+in+vitro+human+keratinocyte+migration.">A review of the influence of growth factors and cytokines in in vitro human keratinocyte migration.</a> Cytokine. 62 (1), 1-21 (2013).</li><li>Hulkower, K. I., Herber, R. L. <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+and+invasion+assays+as+tools+for+drug+discovery.">Cell migration and invasion assays as tools for drug discovery.</a> Pharmaceutics. 3 (1), 107-124 (2011).</li><li>Weiger, M. C., Vedham, V., 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=Real-time+motion+analysis+reveals+cell+directionality+as+an+indicator+of+breast+cancer+progression.">Real-time motion analysis reveals cell directionality as an indicator of breast cancer progression.</a> PLOS ONE. 8 (3), 58859 (2013).</li><li>Poujade, M., Grasland-Mongrain, E., 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=Collective+migration+of+an+epithelial+monolayer+in+response+to+a+model+wound.">Collective migration of an epithelial monolayer in response to a model wound.</a> Proc Natl Acad Sci U S A. 104 (41), 15988-15993 (2007).</li><li>Sunyer, R., Conte, V., 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=Collective+cell+durotaxis+emerges+from+long-range+intercellular+force+transmission.">Collective cell durotaxis emerges from long-range intercellular force transmission.</a> Science. 353 (6304), 1157-1161 (2016).</li><li>Bazelli&#232;res, E., Conte, V., 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=Control+of+cell-cell+forces+and+collective+cell+dynamics+by+the+intercellular+adhesome.">Control of cell-cell forces and collective cell dynamics by the intercellular adhesome.</a> Nat Cell Biol. 17 (4), 409-420 (2015).</li><li>Stuelten, C. H., Busch, J. I., 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=Transient+tumor-fibroblast+interactions+increase+tumor+cell+malignancy+by+a+TGF-Beta+mediated+mechanism+in+a+mouse+xenograft+model+of+breast+cancer.">Transient tumor-fibroblast interactions increase tumor cell malignancy by a TGF-Beta mediated mechanism in a mouse xenograft model of breast cancer.</a> PLOS ONE. 5 (3), 9832 (2010).</li><li>Normanno, N., De Luca, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidermal+growth+factor+receptor+(EGFR)+signaling+in+cancer.">Epidermal growth factor receptor (EGFR) signaling in cancer.</a> Gene. 366 (1), 2-16 (2006).</li><li>Harrison, S. M. W., Knifley, T., Chen, M., O'Connor, K. L., HGF, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LPA,+HGF,+and+EGF+utilize+distinct+combinations+of+signaling+pathways+to+promote+migration+and+invasion+of+MDA-MB-231+breast+carcinoma+cells.">LPA, HGF, and EGF utilize distinct combinations of signaling pathways to promote migration and invasion of MDA-MB-231 breast carcinoma cells.</a> BMC Cancer. 13, 501 (2013).</li><li>Santner, S. J., Dawson, P. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Malignant+MCF10CA1+cell+lines+derived+from+premalignant+human+breast+epithelial+MCF10AT+cells.">Malignant MCF10CA1 cell lines derived from premalignant human breast epithelial MCF10AT cells.</a> Breast Cancer Research and Treatment. 65 (2), 101-110 (2001).</li><li>Tang, B., Vu, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGF-beta+switches+from+tumor+suppressor+to+prometastatic+factor+in+a+model+of+breast+cancer+progression.">TGF-beta switches from tumor suppressor to prometastatic factor in a model of breast cancer progression.</a> J Clin Invest. 112 (7), 1116-1124 (2003).</li><li>Lee, R. M., Stuelten, C. H., Parent, C. 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The author has nothing to disclose.

During tumor progression cells migrate away from the tissue of origin to invade the surrounding tissue and metastasize to distant sites15. Migration of cells away from a cell colony can be observed in the dot assay. Here, the dot assay is illustrated by analyzing the migratory phenotype of human breast cancer cells in response to EGF.
To obtain accurate and replicable results several steps in the set-up of the dot assays are critical. First, the coating of the plate det...

Migration assays are widely used to evaluate the invasive and metastatic potential of tumor cells in vitro. Most commonly, the wound or scratch assay is used to assess migration of epithelial sheets into a cell cleared area1,2,3. To perform the scratch assay, cells are plated into a monolayer and a &#34;scratch&#34; or cell-free area is created with a pipette tip. The scratch assay is easy to set up with commonly available tissue culture supplies and can be performed in multi-well plates, allowing for processing of multiple samples. However, as the scratch is made, cells are physically removed from the monolayer and often undergo cell death. Furthermore, extracellular matrix attached to the plate is often damaged during the scratching process. Similarly, the use of silicon inserts (such as Ibidi chambers4) or of stencils5,6,7 can lead to mechanical disruption of the cells and the partial removal of matrix proteins used for coating the plates. Another disadvantage of assays monitoring closure of wounds or scratches is their limited time course, as cell migration can only be analyzed until the scratch is closed.
In performing the dot assay, cells are plated as a circular colony onto a coated or uncoated plate8. The rationale for this plating strategy is to obtain cell sheets with defined edges, that can migrate or invade into the surrounding cell-free areas without disturbing the culture by removal of cells or inserts. The overall goal of the dot assay is to observe migration of cell sheets as measured by edge displacement or colony diameter, as well as to perform time-lapse imaging to analyze the migratory phenotype of cells in higher spatio-temporal resolution.
Cell migration can be affected by a variety of microenvironmental cues like chemokines, cytokines, and growth factors such as EGF.&#160;EGF is a growth factor that exerts its biological effects via binding to its receptor, EGF receptor9, and increases invasive and metastatic behavior of tumor cells4,9,10. Here, the dot assay is used to study EGF stimulated cell migration in a human invasive, lung colony forming breast cancer cell line (MCF10CA1a)8,11,12.

<table><tbody><tr><td>MCF10CA1a cells</td><td>Karmanos Research Institute</td><td>N/A</td><td>cells used for assay</td></tr><tr><td>mouse collagen IV</td><td>BD Biosciences</td><td>354233</td><td>used to coat plates</td></tr><tr><td>trypsin / EDTA</td><td>Thermo Fisher</td><td>25300054</td><td>used to remove cells from tissue culture plates</td></tr><tr><td>DPBS&amp;nbsp;</td><td>Mediatech</td><td>21-031-CV</td><td>used to wash cells</td></tr><tr><td>DMEM / F12</td><td>Thermo Fisher</td><td>11320082</td><td>used as culture medium</td></tr><tr><td>horse serum</td><td>Thermo Fisher</td><td>26050088</td><td>used to supplement culture medium</td></tr><tr><td>12 well glass bottom plate</td><td>MatTek</td><td>P12G-1.5-14-F</td><td>used to grow cells for imaging</td></tr><tr><td>EGF (epidermal growth factor, human recombinant)</td><td>Peprotech</td><td>AF-100-15</td><td>used to stimulate cells</td></tr><tr><td>fatty acid free BSA</td><td>Sigma</td><td>A8806-1G</td><td>used to make buffer for EGF</td></tr><tr><td>hematoxylin</td><td>Sigma</td><td>HHS32</td><td>used to stain colonies</td></tr><tr><td>eosin</td><td>Electron Microscopy Sciences</td><td>26051-10</td><td>used to stain colonies</td></tr><tr><td>37 &amp;#176;C, 5% CO&lt;sub&gt;2&lt;/sub&gt; incubator</td><td>Sanyo</td><td>model MCO-18AIC (UV)</td><td></td></tr><tr><td>Zeiss AxioObserver with incubator chamber and motorized stage</td><td>Zeiss</td><td>model Axio Observer.Z1</td><td>used for time lapse imaging</td></tr><tr><td>ORCA Flash LT sCMOS camera</td><td>BioVision</td><td>C11440-42U-KIT</td><td>used for timelapse imaging in combination with Zeiss AxioObserver</td></tr><tr><td>Metamorph</td><td>BioVision</td><td>MMACQMIC</td><td>software used for time lapse imaging</td></tr><tr><td>inverted microscope</td><td>Olympus</td><td>model IX70</td><td>used to count cells and to check colonies in tissue culture</td></tr><tr><td>plastic box</td><td>Lock&amp;amp;Lock</td><td>N/A</td><td>used as humid chamber (any tight closing plastic box that fits the plates can be used)</td></tr></tbody></table>

using the dot assay to analyze migration of cell sheets

Although complex organisms appear static, their tissues are under a continuous turnover. As cells age, die, and are replaced by new cells, cells move within tissues in a tightly orchestrated manner. During tumor development, this equilibrium is disturbed, and tumor cells leave the epithelium of origin to invade the local microenvironment, to travel to distant sites, and to ultimately form metastatic tumors at distant sites. The dot assay is a simple, two-dimensional unconstrained migration assay, to assess the net movement of cell sheets into a cell-free area, and to analyze parameters of cell migration using time-lapse imaging. Here, the dot assay is demonstrated using a human invasive, lung colony forming breast cancer cell line, MCF10CA1a, to analyze the cells' migratory response to epidermal growth factor (EGF), which is known to increase malignant potential of breast cancer cells and to alter the migratory phenotype of cells.

The dot assay presented here (Figure 1) was performed using invasive, lung colony forming breast cancer cells (MCF10CA1a) as a model system. The dot assay yields highly reproducible cell dots even in the hand of beginners, making it a convenient and easy to execute assay (Figure 1D). The dot assay combined with HE staining, or time-lapse imaging and subsequent particle image velocimetry (PIV) allows the&#160;stud...

Watch this Scientific Journal Video about Using the Dot Assay to Analyze Migration of Cell Sheets at JoVE.com

Using the Dot Assay to Analyze Migration of Cell Sheets

Cell migration is essential for development, tissue maintenance and repair, and tumorigenesis, and is regulated by growth factors, chemokines, and cytokines. This protocol describes the dot assay, a two-dimensional, unconstrained migration assay to assess the migratory phenotype of attached, cohesive cell sheets in response to microenvironmental cues.

Although complex organisms appear static, their tissues are under a continuous turnover. As cells age, die, and are replaced by new cells, cells move ...

using-the-dot-assay-to-analyze-migration-of-cell-sheets

Universidad San Sebastian

Research

JoVE Journal

Cancer Research

6.8K Views.  National Institutes of Health. Cell migration is essential for development, tissue maintenance and repair, and tumorigenesis, and is regulated by growth factors, chemokines, and cytokines. This protocol describes the dot assay, a two-dimensional, unconstrained migration assay to assess the migratory phenotype of attached, cohesive cell sheets in response to microenvironmental cues.

Video: Using the Dot Assay to Analyze Migration of Cell Sheets

Assessment of Endothelial Cell Migration After Exposure to Toxic Chemicals

Exposure to chemical substances (including alkylating chemical warfare agents like sulfur and nitrogen mustards) cause a plethora of clinical symptoms including wound healing disorder. The physiological process of wound healing is highly complex. The formation of granulation tissue is a key step in this process resulting in a preliminary wound closure and providing a network of new capillary blood vessels &#8211; either through vasculogenesis (novel formation) or angiogenesis (sprouting of existing vessels). Both vasculo- and angiogenesis require functional, directed migration of endothelial cells. Thus, investigation of early endothelial cell (EEC) migration is important to understand the pathophysiology of chemical induced wound healing disorders and to potentially identify novel strategies for therapeutic intervention.
We assessed impaired wound healing after alkylating agent exposure and tested potential candidate compounds for treatment. We used a set of techniques outlined in this protocol. A modified Boyden chamber to quantitatively investigate chemokinesis of EEC is described. Moreover, the use of the wound healing assay in combination with track analysis to qualitatively assess migration is illustrated. Finally, we demonstrate the use of the fluorescent dye TMRM for the investigation of mitochondrial membrane potential to identify underlying mechanisms of disturbed cell migration. The following protocol describes basic techniques that have been adapted for the investigation of EEC.

Investigation of early endothelial cell (EEC) migration is important to understand the pathophysiology of certain illnesses and to potentially identify novel strategies for therapeutic intervention. The following protocol describes techniques to assess cell migration that have been adapted for the investigation of EEC.

Exposure to chemical substances (including alkylating chemical warfare agents like sulfur and nitrogen mustards) cause a plethora of clinical symptoms ...

Developmental Biology

Evaluation of the Cell Invasion and Migration Process: A Comparison of the Video Microscope-based Scratch Wound Assay and the Boyden Chamber Assay

The invasion and migration abilities of tumor cells are main contributors to cancer progression and recurrence. Many studies have explored the migration and invasion abilities to understand how cancer cells disseminate, with the aim of developing new treatment strategies. Analysis of the cellular and molecular basis of these abilities has led to the characterization of cell mobility and the physicochemical properties of the cytoskeleton and cellular microenvironment. For many years, the Boyden chamber assay and the scratch wound assay have been the standard techniques to study cell invasion and migration. However, these two techniques have limitations. The Boyden chamber assay is difficult and time consuming, and the scratch wound assay has low reproducibility. Development of modern technologies, especially in microscopy, has increased the reproducibility of the scratch wound assay. Using powerful analysis systems, an &#34;in-incubator&#34; video microscope can be used to provide automatic and real-time analysis of cell migration and invasion. The aim of this paper is to report and compare the two assays used to study cell invasion and migration: the Boyden chamber assay and an optimized in vitro video microscope-based scratch wound assay.

This study reports two different methods for the analysis of cell invasion and migration: the Boyden chamber assay and the in vitro video microscope-based wound-healing assay. The protocols for these two experiments are described, and their benefits and disadvantages are compared.

The invasion and migration abilities of tumor cells are main contributors to cancer progression and recurrence. Many studies have explored the migration ...

A Simple Migration/Invasion Workflow Using an Automated Live-cell Imager

Cancer cell mobility is crucial for the initiation of metastasis. Therefore, investigation of the cell movement and invasive capacity is of great significance. Migration assays provide basic insight of cell movement at a 2D level, whereas invasion assays are more physiologically relevant, mimicking in vivo cancer cell dislodgment from the original site and invading through the extracellular matrix. The current protocol provides a single workflow for migration and invasion assays. Together with the integrated automated microscopic camera for real-time HD images and built-in analysis module, it gives researchers a time-efficient, simple and reproducible experimental option. This protocol also includes substitutions for the consumables and alternative analysis methods for users to choose from.

The current protocol describes an integrated method investigating cancer cell migration and invasion on a single platform in real-time, providing an easily reproducible and time-efficient option to study cell mobility and morphology.

Cancer cell mobility is crucial for the initiation of metastasis. Therefore, investigation of the cell movement and invasive capacity is of great ...

Study of Cell Migration in Microfabricated Channels

The method described here allows the study of cell migration under confinement in one dimension. It is based on the use of microfabricated channels, which impose a polarized phenotype to cells by physical constraints. Once inside channels, cells have only two possibilities: move forward or backward. This simplified migration in which directionality is restricted facilitates the automatic tracking of cells and the extraction of quantitative parameters to describe cell movement. These parameters include cell velocity, changes in direction, and pauses during motion. Microchannels are also compatible with the use of fluorescent markers and are therefore suitable to study localization of intracellular organelles and structures during cell migration at high resolution. Finally, the surface of the channels can be functionalized with different substrates, allowing the control of the adhesive properties of the channels or the study of haptotaxis. In summary, the system here described is intended to analyze the migration of large cell numbers in conditions in which both the geometry and the biochemical nature of the environment are controlled, facilitating the normalization and reproducibility of independent experiments.

A quantitative method to study spontaneous migration of cells in a one-dimensional confined microenvironment is described. This method takes advantage of microfabricated channels and can be used to study migration of large number of cells under different conditions in single experiments.

The method described here allows the study of cell migration under confinement in one dimension. It is based on the use of microfabricated channels, which ...

Bioengineering

From a 2DE-Gel Spot to Protein Function: Lesson Learned From HS1 in Chronic Lymphocytic Leukemia

The identification of molecules involved in tumor initiation and progression is fundamental for understanding disease&#8217;s biology and, as a consequence, for the clinical management of patients. In the present work we will describe an optimized proteomic approach for the identification of molecules involved in the progression of Chronic Lymphocytic Leukemia (CLL). In detail, leukemic cell lysates are resolved by 2-dimensional Electrophoresis (2DE) and visualized as &#8220;spots&#8221; on the 2DE gels. Comparative analysis of proteomic maps allows the identification of differentially expressed proteins (in terms of abundance and post-translational modifications) that are picked, isolated and identified by Mass Spectrometry (MS). The biological function of the identified candidates can be tested by different assays (i.e. migration, adhesion and F-actin polymerization), that we have optimized for primary leukemic cells.

Here we describe a protocol that couples two proteomic techniques, namely 2-dimensional Electrophoresis (2DE) and Mass Spectrometry (MS), to identify differentially expressed/post-translational modified proteins among two or more groups of primary samples. This approach, together with functional experiments, allows the identification and characterization of prognostic markers/therapeutic targets.

The identification of molecules involved in tumor initiation and progression is fundamental for understanding disease&#8217;s biology and, as a ...

Medicine

Migration, Chemo-Attraction, and Co-Culture Assays for Human Stem Cell-Derived Endothelial Cells and GABAergic Neurons

Role of brain vasculature in nervous system development and etiology of brain disorders is increasingly gaining attention. Our recent studies have identified a special population of vascular cells, the periventricular endothelial cells, that play a critical role in the migration and distribution of forebrain GABAergic interneurons during embryonic development. This, coupled with their cell-autonomous functions, alludes to novel roles of periventricular endothelial cells in the pathology of neuropsychiatric disorders like schizophrenia, epilepsy, and autism. Here, we have described three different in vitro assays that collectively evaluate the functions of periventricular endothelial cells and their interaction with GABAergic interneurons. Use of these assays, particularly in a human context, will allow us to identify the link between periventricular endothelial cells and brain disorders. These assays are simple, low cost, and reproducible, and can be easily adapted to any adherent cell type.

We present three simple in vitro assays-the long-distance migration assay, the co-culture migration assay, and chemo-attraction assay-that collectively evaluate the functions of human stem cell derived periventricular endothelial cells and their interaction with GABAergic interneurons.

Role of brain vasculature in nervous system development and etiology of brain disorders is increasingly gaining attention. Our recent studies have ...

Neuroscience

Quantifying Three-Dimensional Cell Migration Within and Into Granular Hydrogel Biomaterials

Granular hydrogel scaffolds hold significant potential in regenerative medicine, functioning either as carriers for cell delivery or as interfaces for tissue integration. This article introduces two novel approaches for quantifying cell migration within and into granular hydrogels, highlighting the distinct applications of these scaffolds. First, a cell monolayer interface assay that simulates tissue growth into granular hydrogels for integration purposes is presented. Second, a spheroid-based assay is described, designed to track cell movement within the hydrogel matrix, specifically suited for applications involving cell delivery. Both methods enable precise and controlled measurements of cell migration, providing a comprehensive toolkit for researchers utilizing granular hydrogel scaffolds. The motivation for these methods stems from the need for tailored control over cell migration within the scaffold to align with specific applications. By optimizing and standardizing these quantification techniques, researchers can iteratively refine granular hydrogel properties, ensuring their effectiveness in diverse regenerative medicine contexts. This robust set of quantitative tools offers new opportunities to enhance granular hydrogel scaffolds, advancing their use in both cell delivery and tissue integration applications.

A protocol for the quantitative evaluation of 3D cell migration within and into the interface of granular hydrogels is presented here.

Granular hydrogel scaffolds hold significant potential in regenerative medicine, functioning either as carriers for cell delivery or as interfaces for ...

A Customizable Chamber for Measuring Cell Migration

Cell migration is a vital part of immune responses, growth, and wound healing. Cell migration is a complex process that involves interactions between cells, the extracellular matrix, and soluble and non-soluble chemical factors (e.g., chemoattractants). Standard methods for measuring the migration of cells, such as the Boyden chamber assay, work by counting cells on either side of a divider. These techniques are easy to use; however, they offer little geometric modification for different applications. In contrast, microfluidic devices can be used to observe cell migration with customizable concentration gradients of soluble factors1,2. However, methods for making microfluidics based assays can be difficult to learn.
Here, we describe an easy method for creating cell culture chambers to measure cell migration in response to chemical concentration gradients. Our cell migration chamber method can create different linear concentration gradients in order to study cell migration for a variety of applications. This method is relatively easy to use and is typically performed by undergraduate students.
The microchannel chamber was created by placing an acrylic insert in the shape of the final microchannel chamber well into a Petri dish. After this, poly(dimethylsiloxane) (PDMS) was poured on top of the insert. The PDMS was allowed to harden and then the insert was removed. This allowed for the creation of wells in any desired shape or size. Cells may be subsequently added to the microchannel chamber, and soluble agents can be added to one of the wells by soaking an agarose block in the desired agent. The agarose block is added to one of the wells, and time-lapse images can be taken of the microchannel chamber in order to quantify cell migration. Variations to this method can be made for a given application, making this method highly customizable.

This protocol details a customizable method to measure cell migration in response to chemoattractants that may also be used to determine the diffusion rate of a drug out of a polymer matrix.

Cell migration is a vital part of immune responses, growth, and wound healing. Cell migration is a complex process that involves interactions between ...

Biology

Single Cell Durotaxis Assay for Assessing Mechanical Control of Cellular Movement and Related Signaling Events

Durotaxis is the process by which cells sense and respond to gradients of tension. In order to study this process in vitro, the stiffness of the substrate underlying a cell must be manipulated. While hydrogels with graded stiffness and long-term migration assays have proven useful in durotaxis studies, immediate, acute responses to local changes in substrate tension allow focused study of individual cell movements and subcellular signaling events. To repeatably test the ability of cells to sense and respond to the underlying substrate stiffness, a modified method for application of acute gradients of increased tension to individual cells cultured on deformable hydrogels is used which allows for real time manipulation of the strength and direction of stiffness gradients imparted upon cells in question. Additionally, by fine tuning the details and parameters of the assay, such as the shape and dimensions of the micropipette or the relative position, placement, and direction of the applied gradient, the assay can be optimized for the study of any mechanically sensitive cell type and system. These parameters can be altered to reliably change the applied stimulus and expand the functionality and versatility of the assay. This method allows examination of both long term durotactic movement as well as more immediate changes in cellular signaling and morphological dynamics in response to changing stiffness.

Mechanical forces are important for controlling cell migration. This protocol demonstrates the use of elastic hydrogels that can be deformed using a glass micropipette and a micromanipulator to stimulate cells with a local stiffness gradient to elicit changes in cell structure and migration.

Durotaxis is the process by which cells sense and respond to gradients of tension. In order to study this process in vitro, the stiffness of the substrate ...

The Transwell Migration Assay

Cells migration in response to chemical cues is crucial to development, immunity and disease states such as cancer. To quantify cell migration, a simple assay was developed in 1961 by Dr. Stephen Boyden, which is now known as the transwell migration assay or Boyden chamber assay. This set-up consists an insert which separates the wells of a multiwell plate into top and bottom compartments. Cells whose migration is to be studied are seeded into the top compartment and the chemoattractant solution is placed in the bottom compartment. After incubation, counting the cells in the bottom compartment allows quantification of migration induced by chemoattractants.
This video will review the commonly used experimental set-up for cell migration studies. Then we'll highlight a few key considerations, and outline a generalized protocol for running an experiment involving adherent cells. Lastly, we'll review various adaptations of this set-up currently being used to study different factors that affect migration.

The Transwell Migration Assay and Chemo-attractants

Cells migration in response to chemical cues is crucial to development, immunity and disease states such as cancer.  To quantify cell migration, a simple ...