This work has been funded by Fondi di Ateneo to Luca Colucci-D&#39;Amato and VALERE Program funds to Maria Teresa Gentile and AIRC fund IG18999 to Maurizio Bifulco.

1. RGWE Preparation
<ol>
	<li>Collect R. graveolens leaves from plants during the spring/summer months under the supervision of a botanist. 
	NOTE: In this case, leaves were collected at the Experimental Section of Medicinal Plants in the Botanical Garden of Naples, Italy5. The plant is spontaneous, perennial, and is present in the Mediterranean regions (Figure 1).</li>
	<li>Weigh 250 g of leaves and finely chop them with scissors.</li>
	<li>Put the leaves in a conical flask and add 1 L of distilled water to 250 g of chopped leaves and bring that to a boil at 110 &#176;C for 60 min. Cover the flask with aluminum foil to avoid excessive evaporation.</li>
	<li>Use 3 mm-funnel filter paper to separate the boiled leaves from the liquid phase that represents the water extract.</li>
	<li>Filter the liquid phase through a 0.22 &#181;m filter, collecting it in a beaker. Cover the beaker with parafilm and freeze the extract at -80 &#176;C overnight.</li>
	<li>Make 10 - 15 holes with a needle in the parafilm and lyophilize the extract in a lyophilizer. Note that it can take a couple of days to obtain the powder.</li>
	<li>Weigh the powder obtained, divide it into aliquots, and store it at 4 &#176;C until necessary. It is possible to store it for a year.</li>
	<li>When necessary for the experiments, prepare a stock solution, diluting the powder with distilled water to a standard concentration of 50 mg/mL. Separate it into small-volume (e.g., 1 mL) aliquots. This preparation can be stored at -20 &#176;C until used but cannot be stored at 4 &#176;C for more than a couple of days because of the oxidations of the molecules. Avoid freeze and thaw.</li>
</ol>
2. Cell Culture
<ol>
	<li>Cultivate HUVECs in endothelial cell growth medium: endothelial basal medium supplemented with 1 &#956;g/mL hydrocortisone and 1 ng/mL epidermal growth factor, 10% FBS, and penicillin/streptomycin at 37 &#176;C in an atmosphere of 5% CO2.</li>
	<li>When 80% confluent, split the cells at the ratio of 1:3 every passage. Use cells from two to five passages, that do not show apparent differences in response to growth factors. After the sixth passage, cells become senescent and do not form tubes on the gelled basement matrix.</li>
</ol>
3. Transfection
<ol>
	<li>When the HUVECs are 70% confluent, transfect them with the desired gene.</li>
	<li>For a 100 mm plate, use 1 &#181;g of empty pCDNA3 vector as control and 1 &#181;g of pCDNA3 vector containing the gene of interest (constitutively active MEK [caMEK], in this case).</li>
	<li>Complex 1 &#181;g of DNA with 3 &#181;L of lipofectamine 2,000, diluted with reduced serum medium (see Table of Materials) to the final volume of 200 &#181;L. Remove the medium from the cells and replace it with 1 mL of fresh complete medium; then, add the transfecting solution to the cells. Incubate the cells in the incubator at 37 &#176;C, with 5% CO2. It is possible to also use other transfection agents different from lipofectamine 2,000, following the manufacturer&#8217;s instructions.</li>
	<li>Add 7 mL of complete fresh medium 3 h after the transfection and, then, further incubate the cells at 37 &#176;C for 24 - 48 h before proceeding with the next assays. The day after the transfection, replace the medium with fresh complete medium.</li>
</ol>
4. Tube Formation Assay
<ol>
	<li>Cool a 96-well plate and pipette tips at 4 &#176;C for 1 h before preparing the gelled basement.</li>
	<li>At the moment of the basement preparation, put the plate on ice (0 &#176;C) and add 50 &#956;L of cold matrix in each well while avoiding the formation of bubbles. Note that the matrix-containing vial should be kept on ice during the procedure since the matrix becomes solid at room temperature.</li>
	<li>Put the plate in the incubator at 37 &#176;C with 5% CO2 for at least 30 min to allow the basement to polymerize.</li>
	<li>In the meantime, harvest the cells. Wash the HUVECs with 1 mL of a 0.25% trypsin/0.53 mM EDTA solution; then, add 2 mL of the trypsin-EDTA solution and incubate at 37 &#176;C for 5 min. Observe the cells under an inverted microscope to verify that the cell layer is completely dispersed. Then, collect the medium in which the cells are suspended and harvest the detached cells by centrifugation at 264 x g for 3 min. Resuspend them in 1 mL of phosphate-buffered saline (PBS).</li>
	<li>To count the cells, add 0.2 mL of the cell suspension to 0.5 mL of PBS and 0.3 mL of 0.4% trypan blue solution. After 5 min at room temperature, count the cells in a B&#252;rker chamber.</li>
	<li>Resuspend the cells in complete medium at the concentration of 2 x 104 cells/50 &#181;L. Seed them onto the gelled basement at the concentration of 2 x 104 cells per well and let them settle on it.</li>
	<li>Pay attention to the number of the cells. Too many or too few cells may not form tubes in the right way on the gelled basement.</li>
	<li>Prepare increasing doses of RGWE (0.01, 0.1, and 1 mg/mL), diluting the stock solution in culture medium or rutin (12, 120, and 300 &#181;g/mL), all in the final volume of 50 &#181;L/well, and add them to 50 &#956;L/well of cell suspension. The final volume in each well will be 100 &#956;L. Prepare four to six wells for each experimental condition. As a control, dilute distilled water (vehicle) in the culture medium at a ratio of 1:50.</li>
	<li>Incubate the cells in the incubator at 37 &#176;C and 5% CO2 for a time ranging from 6 to 24 h.</li>
	<li>Observe the cells within a time range spanning from 6 to 24 h after seeding, using a phase-contrast microscope at a magnification of 10X. HUVECs are able to form tube-like structures within 6 h but it is possible to observe better results after 12 - 18 h. Photograph the tube-like structures on each well and image an average from three to five random fields in each well.</li>
	<li>After the image acquisition, the cells can be detached from the basement matrix and counted to evaluate the effect of the treatment on the number of cells. For each well, remove the medium, add dispase at a concentration of 24 U/mL, and put the plate at 37 &#176;C for 1 h. Then, from each well, collect the medium in which the cells are suspended and harvest the detached cells by centrifugation at 264 x g for 3 min. Resuspend them in 0.2 mL of PBS. To count the cells, add 0.2 mL of cell suspension to 0.5 mL of PBS and 0.3 mL of 0.4% trypan blue solution. After 5 min at room temperature, count the cells in the B&#252;rker chamber.</li>
	<li>To quantify the results of the tube formation assay, it is possible to count the number of branch points in which at least three tubes join. Using the appropriate image software, count for each field in each micrograph the number of branch points and calculate the mean &#177; the standard error (SE) for each experimental condition. Use a two-tailed t-test to evaluate statistical significance.</li>
</ol>

<ol>
	<li>Carmeliet, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angiogenesis+in+life,+disease+and+medicine.">Angiogenesis in life, disease and medicine.</a> Nature. 438 (7070), 932-936 (2005).</li><li>Carmeliet, P., Jain, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanisms+and+clinical+applications+of+angiogenesis.">Molecular mechanisms and clinical applications of angiogenesis.</a> Nature. 473 (7347), 298-307 (2011).</li><li>Ferrara, N., Kerbel, 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=Angiogenesis+as+a+therapeutic+target.">Angiogenesis as a therapeutic target.</a> Nature. 438 (7070), 967-974 (2005).</li><li>Ravishankar, D., Rajora, A. K., Greco, F., Osborn, H. M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flavonoids+as+prospective+compounds+for+anti-cancer+therapy.">Flavonoids as prospective compounds for anti-cancer therapy.</a> The International Journal of Biochemistry &amp; Cell Biology. 45, 2821-2831 (2013).</li><li>Gentile, M. T., 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=Ruta+graveolens+water+extract+inhibits+cell-cell+network+formation+in+human+umbilical+endothelial+cells+via+MEK-ERK1/2+pathway.">Ruta graveolens water extract inhibits cell-cell network formation in human umbilical endothelial cells via MEK-ERK1/2 pathway.</a> Experimental Cell Research. 364 (1), 50-58 (2018).</li><li>Butler, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+products+to+drugs:+natural+product-derived+compounds+in+clinical+trials.">Natural products to drugs: natural product-derived compounds in clinical trials.</a> Natural Product Reports. 25, 475-516 (2008).</li><li>Sulaiman, R. S., Basavarajappa, H. D., Corson, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+product+inhibitors+of+ocular+angiogenesis.">Natural product inhibitors of ocular angiogenesis.</a> Experimental Eye Research. 129, 161-171 (2014).</li><li>Risau, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+angiogenesis.">Mechanisms of angiogenesis.</a> Nature. 386 (6626), 671-674 (1997).</li><li>Trung, N. X. <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+models+for+angiogenesis.">In vitro models for angiogenesis.</a> Journal of Science &amp; Development. 13 (4), 850-858 (2015).</li><li>Ucuzian, A. A., Greisler, H. P. <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+Models+of+Angiogenesis.">In vitro Models of Angiogenesis.</a> World Journal of Surgery. 31, 654-663 (2007).</li><li>Simons, 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=American+Heart+Association+Council+on+Basic+Cardiovascular+Sciences+and+Council+on+Cardiovascular+Surgery+and+Anaesthesia.+State-of-the-Art+Methods+for+Evaluation+of+Angiogenesis+and+Tissue+Vascularisation:+A+Scientific+Statement+From+the+American+Heart+Association.">American Heart Association Council on Basic Cardiovascular Sciences and Council on Cardiovascular Surgery and Anaesthesia. State-of-the-Art Methods for Evaluation of Angiogenesis and Tissue Vascularisation: A Scientific Statement From the American Heart Association.</a> Circulation Research. 116 (11), e99-e132 (2015).</li><li>Arnaoutova, I., Kleinman, H. K. <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+angiogenesis:+endothelial+cell+tube+formation+on+gelled+basement+membrane+extract.">In vitro angiogenesis: endothelial cell tube formation on gelled basement membrane extract.</a> Nature Protocols. 5 (4), 628-635 (2010).</li><li>DeCicco-Skinner, K. L., 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=Endothelial+cell+tube+formation+assay+for+the+in+vitro+study+of+angiogenesis.">Endothelial cell tube formation assay for the in vitro study of angiogenesis.</a> Journal of Visualized Experiments. (91), e51312 (2014).</li></ol>

The authors have nothing to disclose.

Natural compounds are characterized by a high chemical diversity and biochemical specificity and represent a source of potentially therapeutic molecules. Here, we show how to obtain water extract from the plant R. graveolens and&#160;propose the tube formation assay as an easy-to-perform, reliable, and quantitative method useful to investigate RGWE&#39;s effects on angiogenesis. It is important to boil the R. graveolens leaves for 1 h to be sure to obtain the complete water extract. Boiling for less tha...

Angiogenesis is a physiological process that leads to the formation of new blood vessels from preexisting ones and occurs during embryogenesis and organ growth. In adulthood, angiogenesis is activated only in the cycling ovary, in the placenta during pregnancy, and during wound healing and repair. Angiogenesis depends on the ability of endothelial cells to proliferate, differentiate, and migrate to form an intact vascular network1. However, in several disorders, such as inflammatory, metabolic, and rheumatic diseases, angiogenic processes are altered and angiogenesis becomes excessive. Moreover, uncontrolled angiogenic processes also stimulate tumor progression and metastasis1. For these reasons, in the last decade, research studies are focused on the development of new therapeutic strategies aimed at the inhibition of excessive angiogenesis in cancer, ocular, joint, or skin disorders2,3.
Vascular endothelial growth factor (VEGF) represents the main target of current antiangiogenic therapies4, and several anti-VEGF monoclonal antibodies have been developed and synthesized to prevent excessive angiogenesis. However, these synthetic drugs show severe side effects and have an unfavorable cost-to-benefit ratio5,6. Therefore, it is imperative to find new therapeutic strategies to limit excessive angiogenesis with minimal side effects to complement and combine with currently used drugs. These new drugs can be found among natural products that are characterized by a high chemical diversity and biochemical specificity.
In this article, we propose a simple method to evaluate the impact of the RGWE on the ability of HUVECs to form tubules on a gelled basement matrix in vitro5. Indeed, RGWE is a mixture of secondary metabolites such as flavonoids and polyphenols among which rutin is the major component5. Many of them have been already tested as anti-inflammatory and vasoprotective agents7,8,9,10,11. Moreover, we have recently demonstrated that RGWE, but not rutin, is able to inhibit the HUVEC ability to form tubules on a gelled basement matrix and that this phenomenon is mediated by the MEK-ERK pathway, indicating RGWE as a potential therapeutic tool able to prevent excessive new blood vessel formation5.

<table>
	<tbody>
		<tr>
			<td>HUVEC cells</td>
			<td>Clontech</td>
			<td>C2519A</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Invitrogen</td>
			<td>10270106</td>
			<td></td>
		</tr>
		<tr>
			<td>EBM-2 basal medium</td>
			<td>Clontech</td>
			<td>cc3156</td>
			<td></td>
		</tr>
		<tr>
			<td>Single quot kit- supplemets and growth factors</td>
			<td>clontech</td>
			<td>cc4147</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>Corning</td>
			<td>354234</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well plates</td>
			<td>Thermo Scientific</td>
			<td>167008</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL conical tubes</td>
			<td>Sarstedt</td>
			<td>62,554,502</td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL disposable serological pipette</td>
			<td>Sarstedt</td>
			<td>861,254,001</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL disposable serological pipette</td>
			<td>Sarstedt</td>
			<td>861,253,001</td>
			<td></td>
		</tr>
		<tr>
			<td>1000 &#956;L pipette</td>
			<td>Gilson</td>
			<td>Pipetman classic</td>
			<td></td>
		</tr>
		<tr>
			<td>100 &#956;L pipette</td>
			<td>Gilson</td>
			<td>Pipetman classic</td>
			<td></td>
		</tr>
		<tr>
			<td>20 &#956;L pipette</td>
			<td>Gilson</td>
			<td>Pipetman classic</td>
			<td></td>
		</tr>
		<tr>
			<td>p1000 pipette tips</td>
			<td>Sarstedt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>p20-200 pipette tips</td>
			<td>Sarstedt</td>
			<td>70,760,502</td>
			<td></td>
		</tr>
		<tr>
			<td>Burker chamber</td>
			<td>Fortuna</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan blu stain</td>
			<td>Gibco</td>
			<td>15250-061</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS</td>
			<td>Gibco</td>
			<td>14190-094</td>
			<td></td>
		</tr>
		<tr>
			<td>mill-ex 0.22 um filters</td>
			<td>Millipore</td>
			<td>SLGS033SS</td>
			<td></td>
		</tr>
		<tr>
			<td>Lyophilizer</td>
			<td>VirTis-SP Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CO2</td>
			<td>AirCos</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pen-Strep</td>
			<td>Gibco</td>
			<td>15070-063</td>
			<td></td>
		</tr>
		<tr>
			<td>100 mm dish</td>
			<td>Sarstedt</td>
			<td>833,902</td>
			<td></td>
		</tr>
		<tr>
			<td>pcDNA3</td>
			<td>Invitrogen</td>
			<td>v79020</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipofectamine-2000</td>
			<td>Invitrogen</td>
			<td>11668027</td>
			<td></td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Gibco</td>
			<td>31985070</td>
			<td>Reduced serum medium</td>
		</tr>
		<tr>
			<td>Rutin</td>
			<td>Sigma-Aldrich</td>
			<td>R5143-50G</td>
			<td></td>
		</tr>
		<tr>
			<td>Axiovert 25 microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AmScope MD500 camera</td>
			<td>AmScope</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dispase</td>
			<td>Thermo Scientific</td>
			<td>D4818</td>
			<td></td>
		</tr>
		<tr>
			<td>Lab heater</td>
			<td>Falc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ParaFilm</td>
			<td>American National Can</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

huvec tube-formation assay to evaluate the impact of natural products on angiogenesis

Angiogenesis is a phenomenon that includes different processes, such as endothelial cell proliferation, differentiation, and migration, that lead to the formation of new blood vessels and involve several signal transduction pathways. Here we show that the tube formation assay is a simple in vitro method to evaluate the impact of natural products on angiogenesis and to investigate the molecular mechanisms involved. In particular, in the presence of the water extract of Ruta graveolens (RGWE), endothelial cells are no longer able to form a cell-cell network and that the RGWE effects on human umbilical vein endothelial cell (HUVEC) tube formation is abolished by the constitutive activation of MEK.

To evaluate the influence of RGWE on angiogenesis, we carried out a tube formation assay on a gelled basement matrix. When cultivated on it, HUVECs form tube-like structures that originate from cells that appear elongated and that connect each other to form a cell-cell network (Figure 2). In Figure 3, we show that the number of branches in HUVECs treated with RGWE was significantly lower as compared to the control conditions. Not...

Watch this Scientific Journal Video about HUVEC Tube-formation Assay to Evaluate the Impact of Natural Products on Angiogenesis at JoVE.com

HUVEC Tube-formation Assay to Evaluate the Impact of Natural Products on Angiogenesis

Here, we evaluate the effects of the water extract of Ruta graveolens on vessel network formation by using a tube formation assay on a gelled basement matrix.

Angiogenesis is a phenomenon that includes different processes, such as endothelial cell proliferation, differentiation, and migration, that lead to the ...

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16.4K Views.  University of Campania "Luigi Vanvitelli". Here, we evaluate the effects of the water extract of Ruta graveolens on vessel network formation by using a tube formation assay on a gelled basement matrix.

Video: HUVEC Tube-formation Assay to Evaluate the Impact of Natural Products on Angiogenesis

Alginate Encapsulation of Pluripotent Stem Cells Using a Co-axial Nozzle

Pluripotent stem cells (PS cells) are the focus of intense research due to their role in regenerative medicine and drug screening. However, the development of a mass culture system would be required for using PS cells in these applications. Suspension culture is one promising culture method for the mass production of PS cells, although some issues such as controlling aggregation and limiting shear stress from the culture medium are still unsolved. In order to solve these problems, we developed a method of calcium alginate (Alg-Ca) encapsulation using a co-axial nozzle. This method can control the size of the capsules easily by co-flowing N2 gas. The controllable capsule diameter must be larger than 500 &#181;m because too high a flow rate of N2 gas causes the breakdown of droplets and thus heterogeneous-sized capsules. Moreover, a low concentration of Alg-Na and CaCl2 causes non-spherical capsules. Although an Alg-Ca capsule without a coating of Alg-PLL easily dissolves enabling the collection of cells, they can also potentially leak out from capsules lacking an Alg-PLL coating. Indeed, an alginate-PLL coating can prevent cellular leakage but is also hard to break. This technology can be used to research the stem cell niche as well as the mass production of PS cells because encapsulation can modify the micro-environment surrounding cells including the extracellular matrix and the concentration of secreted factors.

We established a method of encapsulating pluripotent stem cells (PS cells) into alginate hydrogel capsules using a co-axial nozzle. This prevents cells from aggregating excessively and limits the shear stress experienced by cells in suspension culture. The technique is applicable to the mass production of PS cells as well as research on stem cell niche.

Pluripotent stem cells (PS cells) are the focus of intense research due to their role in regenerative medicine and drug screening.  However, the ...

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is the formation of fibroblastic foci, which is associated with the disease severity. Mesenchymal cells consisting of the fibroblastic foci are proposed to be derived from several cell sources, including originally resident intrapulmonary fibroblasts and circulating fibrocytes from bone marrow. Recently, mesenchymal cells that underwent epithelial-mesenchymal transition (EMT) have been also supposed to contribute to the pathogenesis of fibrosis. In addition, EMT can be induced by transforming growth factor &#946;, and EMT can be enhanced by pro-inflammatory cytokines like tumor necrosis factor &#945;. The gel contraction assay is an ideal in vitro model for the evaluation of contractility, which is one of the characteristic functions of fibroblasts and contributes to wound repair and fibrosis. Here, the development of a gel contraction assay is demonstrated for evaluating contractile ability of mesenchymal cells that underwent EMT.

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Here, we describe the development and application of a gel contraction assay for evaluating contractile function in mesenchymal cells that underwent epithelial-mesenchymal transition.

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is ...

Competitive Transplants to Evaluate Hematopoietic Stem Cell Fitness

The gold standard definition of a hematopoietic stem cell (HSC) is a cell that when transferred into an irradiated recipient will have the ability to reestablish blood cell production for the lifespan of the recipient. This protocol explains how to set up a functional assay to compare the HSC capacities of two different populations of cells, such as bone marrow from mice of two different genotypes, and how to analyze the recipient mice by flow cytometry. The protocol uses HSC equivalents rather than cell sorting for standardization and discusses the advantages and disadvantages of both approaches. We further discuss different variations to the basic protocol, including serial transplants, limiting dilution assays, homing assays and non-competitive transplants, including the advantages and preferred uses of these varied approaches. These assays are central for the study of HSC function and could be used not only for the investigation of fundamental HSC intrinsic aspects of biology but also for the development of preclinical assays for bone marrow transplant and HSC expansion in culture.

This protocol provides step-by-step guidelines for setting up competitive mouse bone marrow transplant experiments to study hematopoietic stem/progenitor cell function without prior purification of stem cells by cell sorting.

The gold standard definition of a hematopoietic stem cell (HSC) is a cell that when transferred into an irradiated recipient will have the ability to ...

Acute and Chronic Models of Hyperglycemia in Zebrafish: A Method to Assess the Impact of Hyperglycemia on Neurogenesis and the Biodistribution of Radiolabeled Molecules

Hyperglycemia is a major health issue that leads to cardiovascular and cerebral dysfunction. For instance, it is associated with increased neurological problems after stroke and is shown to impair neurogenic processes. Interestingly, the adult zebrafish has recently emerged as a relevant and useful model to mimic hyperglycemia/diabetes and to investigate constitutive and regenerative neurogenesis. This work provides methods to develop zebrafish models of hyperglycemia to explore the impact of hyperglycemia on brain cell proliferation under homeostatic and brain repair conditions. Acute hyperglycemia is established using the intraperitoneal injection of D-glucose (2.5 g/kg bodyweight) into adult zebrafish. Chronic hyperglycemia is induced by immersing adult zebrafish in D-glucose (111 mM) containing water for 14 days. Blood-glucose-level measurements are described for these different approaches. Methods to investigate the impact of hyperglycemia on constitutive and regenerative neurogenesis, by describing the mechanical injury of the telencephalon, dissecting the brain, paraffin embedding and sectioning with a microtome, and performing immunohistochemistry procedures, are demonstrated. Finally, the method of using zebrafish as a relevant model for studying the biodistribution of radiolabeled molecules (here,[18F]-FDG) using PET/CT is also described.

This work describes methods to establish acute and chronic hyperglycemia models in zebrafish. The aim is to investigate the impact of hyperglycemia on physiological processes, such as constitutive and injury-induced neurogenesis. The work also highlights the use of zebrafish to follow radiolabeled molecules (here, [18F]-FDG) using PET/CT.

Hyperglycemia is a major health issue that leads to cardiovascular and cerebral dysfunction. For instance, it is associated with increased neurological ...

A 5-mC Dot Blot Assay Quantifying the DNA Methylation Level of Chondrocyte Dedifferentiation In Vitro

The dedifferentiation of hyaline chondrocytes into fibroblastic chondrocytes often accompanies monolayer expansion of chondrocytes in vitro. The global DNA methylation level of chondrocytes is considered to be a suitable biomarker for the loss of the chondrocyte phenotype. However, results based on different experimental methods can be inconsistent. Therefore, it is important to establish a precise, simple, and rapid method to quantify global DNA methylation levels during chondrocyte dedifferentiation.
Current genome-wide methylation analysis techniques largely rely on bisulfite genomic sequencing. Due to DNA degradation during bisulfite conversion, these methods typically require a large sample volume. Other methods used to quantify global DNA methylation levels include high-performance liquid chromatography (HPLC). However, HPLC requires complete digestion of genomic DNA. Additionally, the prohibitively high cost of HPLC instruments limits HPLC&#39;s wider application.
In this study, genomic DNA (gDNA) was extracted from human chondrocytes cultured with varying number of passages. The gDNA methylation level was detected using a methylation-specific dot blot assay. In this dot blot approach, a gDNA mixture containing the methylated DNA to be detected was spotted directly onto an N+ membrane as a dot inside a previously drawn circular template pattern. Compared with other gel electrophoresis-based blotting approaches and other complex blotting procedures, the dot blot method saves significant time. In addition, dot blots can detect overall DNA methylation level using a commercially available 5-mC antibody. We found that the DNA methylation level differed between the monolayer subcultures, and therefore could play a key role in chondrocyte dedifferentiation. The 5-mC dot blot is a reliable, simple, and rapid method to detect the general DNA methylation level to evaluate chondrocyte phenotype.

A 5-mC Dot Blot Assay Quantifying the DNA Methylation Level of Chondrocyte Dedifferentiation In Vitro

We present a method to quantify DNA methylation based on the 5-methylcytosine (5-mC) dot blot. We determined the 5-mC levels during chondrocyte dedifferentiation. This simple technique could be used to quickly determine the chondrocyte phenotype in ACI treatment.

The dedifferentiation of hyaline chondrocytes into fibroblastic chondrocytes often accompanies monolayer expansion of chondrocytes in vitro. The global ...

Visualization and Quantitative Analysis of Embryonic Angiogenesis in Xenopus tropicalis

Blood vessels supply oxygen and nutrients throughout the body, and the formation of the vascular network is under tight developmental control. The efficient in vivo visualization of blood vessels and the reliable quantification of their complexity are key to understanding the biology and disease of the vascular network. Here, we provide a detailed method to visualize blood vessels with a commercially available fluorescent dye, human plasma acetylated low density lipoprotein DiI complex (DiI-AcLDL), and to quantify their complexity in Xenopus tropicalis. Blood vessels can be labeled by a simple injection of DiI-AcLDL into the beating heart of an embryo, and blood vessels in the entire embryo can be imaged in live or fixed embryos. Combined with gene perturbation by the targeted microinjection of nucleic acids and/or the bath application of pharmacological reagents, the roles of a gene or of a signaling pathway on vascular development can be investigated within one week without resorting to sophisticated genetically engineered animals. Because of the well-defined venous system of Xenopus and its stereotypic angiogenesis, the sprouting of pre-existing vessels, vessel complexity can be quantified efficiently after perturbation experiments. This relatively simple protocol should serve as an easily accessible tool in diverse fields of cardiovascular research.

Visualization and Quantitative Analysis of Embryonic Angiogenesis in Xenopus tropicalis

This protocol demonstrates a fluorescence-based method to visualize the vasculature and to quantify its complexity in Xenopus tropicalis. Blood vessels can be imaged minutes after the injection of a fluorescent dye into the beating heart of an embryo after genetic and/or pharmacological manipulations to study cardiovascular development in vivo.

Blood vessels supply oxygen and nutrients throughout the body, and the formation of the vascular network is under tight developmental control. The ...

Methods for Analyzing the Impacts of Natural Uranium on In Vitro Osteoclastogenesis

Uranium has been shown to interfere with bone physiology and it is well established that this metal accumulates in bone. However, little is known about the effect of natural uranium on the behavior of bone cells. In particular, the impact of uranium on osteoclasts, the cells responsible for the resorption of the bone matrix, is not documented. To investigate this issue, we have established a new protocol using uranyl acetate as a source of natural uranium and the murine RAW 264.7 cell line as a model of osteoclast precursors. Herein, we detailed all the assays required to test uranium cytotoxicity on osteoclast precursors and to evaluate its impact on the osteoclastogenesis and on the resorbing function of mature osteoclasts. The conditions we have developed, in particular for the preparation of uranyl-containing culture media and for the seeding of RAW 264.7 cells allow to obtain reliable and highly reproductive results. Moreover, we have optimized the use of software tools to facilitate the analysis of various parameters such as the size of osteoclasts or the percentage of resorbed matrix.

Methods for Analyzing the Impacts of Natural Uranium on In Vitro Osteoclastogenesis

Uranium is known to affect bone metabolism. Here, we present a protocol aimed at investigating the effect of natural uranium exposure on the viability, the differentiation, and the function of osteoclasts, the cells in charge of bone resorption.

Uranium has been shown to interfere with bone physiology and it is well established that this metal accumulates in bone. However, little is known about ...

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the Notch receptor with ligands from neighboring cells induces activation of the signaling pathway (trans-activation), while interaction with ligands from the same cell inhibits signaling (cis-inhibition). Proper balance between trans-activation and cis-inhibition helps establish optimal levels of Notch signaling in some contexts during animal development. Because of the overlapping expression domains of Notch and its ligands in many cell types and the existence of feedback mechanisms, studying the effects of a given post-translational modification on trans- versus cis-interactions of Notch and its ligands in vivo is difficult. Here, we describe a protocol for using Drosophila S2 cells in cell-aggregation assays to assess the effects of knocking down a Notch pathway modifier on the binding of Notch to each ligand in trans and in cis. S2 cells stably or transiently transfected with a Notch-expressing vector are mixed with cells expressing each Notch ligand (S2-Delta or S2-Serrate). Trans-binding between the receptor and ligands results in the formation of heterotypic cell aggregates and is measured in terms of the number of aggregates per mL composed of &#62;6 cells. To examine the inhibitory effect of cis-ligands, S2 cells co-expressing Notch and each ligand are mixed with S2-Delta or S2-Serrate cells and the number of aggregates is quantified as described above. The relative decrease in the number of aggregates due to the presence of cis-ligands provides a measure of cis-ligand-mediated inhibition of trans-binding. These straightforward assays can provide semi-quantitative data on the effects of genetic or pharmacological manipulations on the binding of Notch to its ligands, and can help deciphering the molecular mechanisms underlying the in vivo effects of such manipulations on Notch signaling.

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Complexity of in vivo systems makes it difficult to distinguish between the activation and inhibition of Notch receptor by trans- and cis-ligands, respectively. Here, we present a protocol based on in vitro cell-aggregation assays for qualitative and semi-quantitative evaluation of the binding of Drosophila Notch to trans-ligands vs cis-ligands.

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the ...

In Vitro Assays to Evaluate the Migration, Invasion, and Proliferation of Immortalized Human First-trimester Trophoblast Cell Lines

Cell movement is a critical property of trophoblasts during placental development and early pregnancy. The significance of proper trophoblast migration and invasion is demonstrated by pregnancy disorders such as pre-eclampsia and intrauterine growth restriction, which are associated with inadequate trophoblast invasion of the maternal vasculature. Unfortunately, our understanding of the mechanisms by which the placenta develops from migrating trophoblasts is limited. In vitro analysis of cell migration via the scratch assay is a useful tool in identifying factors that regulate trophoblast migratory capacity. However, this assay alone does not define the cellular changes that can result in altered cell migration. This protocol describes three different in vitro assays that are used collectively to evaluate trophoblast cell movement: the scratch assay, the invasion assay, and the proliferation assay. The protocols described here may also be modified for use in other cell lines to quantify cell movement in response to stimuli. These methods allow investigators to identify individual factors that contribute to the cell movement and provide a thorough examination of potential mechanisms underlying apparent changes in cell migration.

Here, we present a highly accessible protocol for evaluating the cell movement in human trophoblast cells using three in vitro assays: the scratch assay, the transwell invasion assay, and the cell proliferation assay.

Cell movement is a critical property of trophoblasts during placental development and early pregnancy. The significance of proper trophoblast migration ...

Assessment of Oxidative Damage in the Primary Mouse Ocular Surface Cells/Stem Cells in Response to Ultraviolet-C (UV-C) Damage

The ocular surface is subjected to regular wear and tear due to various environmental factors. Exposure to UV-C radiation constitutes an occupational health hazard. Here, we demonstrate the exposure of primary stem cells from the mouse ocular surface to UV-C radiation. Reactive oxygen species (ROS) formation is the readout of the extent of oxidative stress/damage. In an experimental in vitro setting, it is also essential to assess the percentage of dead cells generated due to oxidative stress. In this article, we will demonstrate the 2&#39;,7&#39;-Dichlorofluoresceindiacetate (DCFDA) staining of UV-C exposed mouse primary ocular surface stem cells and their quantification based on the fluorescent images of DCFDA staining. DCFDA staining directly corresponds to ROS generation. We also demonstrate the quantification of dead and live cells by simultaneous staining with propidium iodide (PI) and Hoechst 3332 respectively and the percentage of DCFDA (ROS positive) and PI positive cells.

Assessment of Oxidative Damage in the Primary Mouse Ocular Surface Cells/Stem Cells in Response to Ultraviolet-C UV-C Damage

This protocol demonstrates the simultaneous detection of reactive oxygen species (ROS), live cells, and dead cells in live primary cultures from mouse ocular surface cells. 2&#39;,7&#39;-Dichlorofluoresceindiacetate, propidium iodide, and Hoechst staining are used to assess the ROS, dead cells, and live cells, respectively, followed by imaging and analysis.

The ocular surface is subjected to regular wear and tear due to various environmental factors. Exposure to UV-C radiation constitutes an occupational ...

HUVEC Tube-formation Assay to Evaluate the Impact of Natural Products on Angiogenesis

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Acute and Chronic Models of Hyperglycemia in Zebrafish: A Method to Assess the Impact of Hyperglycemia on Neurogenesis and the Biodistribution of Radiolabeled Molecules

A 5-mC Dot Blot Assay Quantifying the DNA Methylation Level of Chondrocyte Dedifferentiation In Vitro

Visualization and Quantitative Analysis of Embryonic Angiogenesis in Xenopus tropicalis

Methods for Analyzing the Impacts of Natural Uranium on In Vitro Osteoclastogenesis

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

In Vitro Assays to Evaluate the Migration, Invasion, and Proliferation of Immortalized Human First-trimester Trophoblast Cell Lines

Assessment of Oxidative Damage in the Primary Mouse Ocular Surface Cells/Stem Cells in Response to Ultraviolet-C (UV-C) Damage