We thank Marleen De Meulemeester for demonstrating the assay technique in the video film. B. I. R. is a Postdoctoral Research Fellow of the Research Foundation &#8211; Flanders (FWO &#8211; Vlaanderen). L.M.M. is a recipient of an Emmanuel van der Schueren grant from the Flemish League against Cancer (Vlaamse Liga tegen Kanker).

<ol>
	<li>Mareel, M. M., Bracke, M. E., Van Roy, F. M., de Baetselier, P., JR, B. e. r. t. i. n. o. <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+of+cancer+invasion.">Molecular mechanisms of cancer invasion.</a> Encyclopedia of Cancer. 2, 1072-1083 (1997).</li><li>Mareel, M., Kint, J., Meyvisch, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+of+study+of+the+invasion+of+malignant+C3H+mouse+fibroblasts+into+embryonic+chick+heart+in+vitro.">Methods of study of the invasion of malignant C3H mouse fibroblasts into embryonic chick heart in vitro.</a> Virchows Arch. B. Cell Pathol. Incl. Mol. Pathol. 30 (1), 95-111 (1979).</li><li>Albini, A., Noonan, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+&#8216;chemoinvasion&#8217;+assay,+25+years+and+still+going+strong:+the+use+of+reconstituted+basement+membranes+to+study+cell+invasion+and+angiogenesis.">The &#8216;chemoinvasion&#8217; assay, 25 years and still going strong: the use of reconstituted basement membranes to study cell invasion and angiogenesis.</a> Curr. Opin. Cell Biol. 22 (5), 677-689 (2010).</li><li>De Wever, O., 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+and+spheroid+collagen+type+I+invasion+assay.">Single cell and spheroid collagen type I invasion assay.</a> Methods Mol. Biol. 1070, 12-35 (2014).</li><li>Wolff, E., Schneider, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=La+transplantation+prolong&#233;e+d&#8217;un+sarcome+de+souris+sur+des+organes+embryonnaires+de+poulet+cultiv&#233;s+in+vitro.">La transplantation prolong&#233;e d&#8217;un sarcome de souris sur des organes embryonnaires de poulet cultiv&#233;s in vitro.</a> C.R. Seances Soc. Biol. Fil. 151 (7), 1291-1292 (1957).</li><li>Easty, G. C., Easty, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+organ+culture+system+for+the+examination+of+tumor+invasion.">An organ culture system for the examination of tumor invasion.</a> Nature. 199, 1104-1105 (1963).</li><li>Schleich, A. B., Frick, M., Mayer, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patterns+of+invasive+growth+in+vitro.+Human+decidua+graviditatis+confronted+with+established+human+cell+lines+and+primary+human+explants.">Patterns of invasive growth in vitro. Human decidua graviditatis confronted with established human cell lines and primary human explants.</a> J. Natl. Cancer Inst. 56 (2), 221-237 (1976).</li><li>Sys, G. M. 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=The+In+ovo+CAM-assay+as+a+Xenograftodel+for+Sarcoma.">The In ovo CAM-assay as a Xenograftodel for Sarcoma.</a> J. Vis. Exp. (77), e50522 (2013).</li><li>Bracke, M. E., Van Larebeke, N. A., Vyncke, B. M., Mareel, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinoic+acid+modulates+both+invasion+and+plasma+membrane+ruffling+of+MCF-7+human+mammary+carcinoma+cells+in+vitro.">Retinoic acid modulates both invasion and plasma membrane ruffling of MCF-7 human mammary carcinoma cells in vitro.</a> Br. J. Cancer. 63 (6), 867-872 (1991).</li><li>Vermeulen, S. 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=Transition+from+the+noninvasive+to+the+invasive+phenotype+and+loss+of+alpha-catenin+in+human+colon+cancer+cells.">Transition from the noninvasive to the invasive phenotype and loss of alpha-catenin in human colon cancer cells.</a> Cancer Res. 55 (20), 4722-4728 (1995).</li><li>Parmar, V. S., 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=Anti-invasive+activity+of+3,7-dimethoxyflavone+in+vitro.">Anti-invasive activity of 3,7-dimethoxyflavone in vitro.</a> J. Pharma. Sci. 83 (9), 1217-1221 (1994).</li><li>Parmar, V. S., 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=Anti-invasive+activity+of+alkaloids+and+polyphenolics+in+vitro.">Anti-invasive activity of alkaloids and polyphenolics in vitro.</a> Bioorg. Med. Chem. 5 (8), 1609-1619 (1997).</li><li>Gaillard, P. J., MB, V. i. s. s. e. r. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organ+culture+technique+using+embryologic+watch+glasses.">Organ culture technique using embryologic watch glasses.</a> Methods in Medical Research. 2, 241-24 (1951).</li><li>Romeis, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Das+mikrotom.">Das mikrotom.</a> Mikroskopische Technik. 15 Verb. Aufl. Kapitel. 7, 114-120 (1948).</li><li>Van Marck, 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=P-cadherin+promotes+cell-cell+adhesion+and+counteracts+invasion+in+human+melanoma.">P-cadherin promotes cell-cell adhesion and counteracts invasion in human melanoma.</a> Cancer Res. 65 (19), 8774-8783 (2005).</li><li>Attia, M. A., Weiss, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunology+of+spontaneous+mammary+carcinomas+in+mice.+V.+Acquired+tumor+resistance+and+enhancement+in+strain+A+mice+infected+with+mammary+tumor+virus.">Immunology of spontaneous mammary carcinomas in mice. V. Acquired tumor resistance and enhancement in strain A mice infected with mammary tumor virus.</a> Cancer Res. 26 (8), 1787-1800 (1966).</li><li>Katritzky, A. R., 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=QSAR+modeling+of+anti-invasive+activity+of+organic+compounds+using+structural+descriptors.">QSAR modeling of anti-invasive activity of organic compounds using structural descriptors.</a> Bioorg. Med. Chem. 14 (20), 6933-6939 (2006).</li><li>McKinnell, R. G., Bruyneel, E. A., Mareel, M. M., Seppanen, E. D., Mekala, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Invasion+in+vitro+by+explants+of+Lucke+renal+carcinoma+cocultered+with+normal+tissue+is+temperature+dependent.">Invasion in vitro by explants of Lucke renal carcinoma cocultered with normal tissue is temperature dependent.</a> Clin. Exp. Metastasis. 4 (4), 237-243 (1986).</li><li>Wanson, J. C., de Ridder, L., Mosselmans, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Invasion+of+hyperplastic+nodule+cells+from+diethylnitrosamine+treated+cells.">Invasion of hyperplastic nodule cells from diethylnitrosamine treated cells.</a> Cancer Res. 41 (12 Pt 1), 5162-5175 (1981).</li><li>Mareel, M. 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=Effect+of+temperature+on+invasion+of+MO4+mouse+fibrosarcoma+cells+in+organ+culture.">Effect of temperature on invasion of MO4 mouse fibrosarcoma cells in organ culture.</a> Clin. Exp. Metastasis. 2 (2), 107-125 (1984).</li><li>Laerum, O. D., Steinsvag, S., Bjerkvig, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+and+tissue+culture+of+the+central+nervous+system:+recent+developments+and+current+applications.">Cell and tissue culture of the central nervous system: recent developments and current applications.</a> Acta Neurol. Scand. 72 (6), 529-549 (1985).</li><li>Schroyens, W., Mareel, M. M., Dragonetti, C. <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+invasiveness+of+human+bladder+cancer+from+cell+lines+and+biopsy+specimens.">In vitro invasiveness of human bladder cancer from cell lines and biopsy specimens.</a> Clin. Exp. Metastasis. 1 (2), 153-162 (1983).</li><li>Mareel, M. M., De Bruyne, G. K., Vandesande, F., Dragonetti, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunohistochemical+study+of+embryonic+chick+heart+invaded+by+malignant+cells+in+three+dimensional+culture.">Immunohistochemical study of embryonic chick heart invaded by malignant cells in three dimensional culture.</a> Invasion Metastasis. 1 (3), 195-204 (1981).</li><li>Bjerkvig, R., Laerum, O. D., Mella, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glioma+cell+interactions+with+fetal+rat+brain+aggregates+in+vitro+and+with+brain+tissue+in+vivo.">Glioma cell interactions with fetal rat brain aggregates in vitro and with brain tissue in vivo.</a> Cancer Res. 46 (8), 4071-4079 (1986).</li><li>Bracke, M. 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=Confrontation+of+an+invasive+(MO4)+and+a+non-invasive+(MDCK)+cell+line+with+embryonic+chick+heart+fragments+in+serum-free+culture+media.">Confrontation of an invasive (MO4) and a non-invasive (MDCK) cell line with embryonic chick heart fragments in serum-free culture media.</a> In Vitro Cell Dev. Biol. 22 (9), 508-514 (1986).</li><li>Mareel, M. M., Bracke, M. E., Storme, G. A., Grundmann, E. <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+tumor+spread:+a+brief+overview.">Mechanisms of tumor spread: a brief overview.</a> Cancer Campaign. 9: The Cancer Patient. , 59-64 (1985).</li><li>De Neve, W. J., Storme, G. A., De Bruyne, G. K., Mareel, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+image+analysis+system+for+the+quantification+of+invasion+in+vitro.">An image analysis system for the quantification of invasion in vitro.</a> Clin. Exp. Metast. 3 (2), 87-101 (1985).</li><li>Smolle, 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=Quantitative+evaluation+of+melanoma+cell+invasion+in+three-dimensional+confrontation+cultures+in+vitro+using+automated+image+analysis.">Quantitative evaluation of melanoma cell invasion in three-dimensional confrontation cultures in vitro using automated image analysis.</a> J. Invest. Dermatol. 94 (1), 114-119 (1990).</li><li>Bracke, M. 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=flavonoid+effect+on+tumor+invasion+and+metastasis.">flavonoid effect on tumor invasion and metastasis.</a> Food Technol. 48 (11), 121-124 (1994).</li><li>Bracke, M. 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=The+influence+of+tangeretin+on+tamoxifen&#8217;s+therapeutic+benefit+in+mammary+cancer.">The influence of tangeretin on tamoxifen&#8217;s therapeutic benefit in mammary cancer.</a> J. Natl. Cancer Inst. 91 (4), 354-359 (1999).</li></ol>

The authors declare that they have no competing financial interests.

During the preparation of PHFs, the fragments may not stay in suspension but adhere to the vessel wall; this can be overcome by increasing the volume of the culture medium. If the number of PHFs is too low and their size is too big, decrease the volume of the culture medium. Failure of the test cells to aggregate may be due to fluctuations in the temperature or to microbial infection. Alternatively, an inability to aggregate may be an intrinsic characteristic of the cells. During attachment of the aggregates to PHF, poor...

Invasion is the hallmark of malignant tumors. This activity not only leads to the destruction of surrounding tissues, but is also implicated in metastasis formation. Since cancer patients die from invasion and metastasis, and efficient anti-invasive treatments are still scarce, laboratory assays that mimic the invasion of tumor cells have been developed. The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish between invasive and non-invasive cells, and allows to study the effects of test compounds on tumor invasion.
The rationale behind the use of the assay is the actual concept that tumors are ecosystems where the neoplastic cells continuously interact with their stroma (host cells and extracellular matrix), and that through these molecular interactions invasion is fine-tuned1. So, in the assay tumor cells are confronted with living embryonic chick heart fragments2, which serve not only as substrates for invasion by the tumor cells, but also as a source of different types of stromal cells and matrix elements. The chick heart contains myocytes, fibroblasts and endothelial cells, and the extracellular matrix is composed of laminin, fibronectin and different types of collagen. In this way, the three-dimensional organ culture technique covers many cellular and molecular interactions implicated in invasion of patient tumors.
The main advantage of the chick heart assay is the implementation of stromal effects. This aspect is more complete than in other invasion assays in vitro that are based on tumor cell invasion into non-living gels composed of basement membrane3 or interstitial matrix4 molecules. The concept of confrontation between tumor cells and normal living host tissue as found in organ culture experimentation has been introduced by several authors including Wolff and Schneider in France5, Easty and Easty in the United Kingdom6, and Schleich in Germany7. Two technical advantages of the chick heart invasion assay over the cited methods is that the volume of the fragments can easily be standardized, and that they remain contractile, which allows functional integrity monitoring during organ culture. Furthermore, avian embryos are preferred, because they can easily be dissected from the sterile content of the egg. The assay has conceptual resemblance to the chick chorioallantois membrane assay8 by offering a complex stromal surrounding to the tumor cells.
The assay has successfully been applied to distinguish between invasive and non-invasive cell variants from the same human tumors such as in the MCF-7 (mammary)9 and HCT-8 (colonic)10 cell line families. The technique is useful to test potentially anti-invasive compounds as well11,12. As further explained, it can be used for the establishment of structure-activity relations of small organic molecules. The assay does, however, not take into account the contribution of immunological cells to cancer invasion. It should be stressed that the technique cannot be considered as a high-throughput analysis system, because of the high number of manipulations, the limited numbers of assay runs (maximum 30 cultures) and the long turn-around time (about 1 month).

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Ringer&#39;s salt solution</td>
			<td>Braun</td>
			<td>CEO123</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto-agar</td>
			<td>Becton Dickinson</td>
			<td>214010</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-(hydroxymethyl)-aminomethaan Analar</td>
			<td>VWR</td>
			<td>103157P</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA : albumin from bovine serum, cohn V fract.</td>
			<td>Sigma</td>
			<td>A4503-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM-Rega 3</td>
			<td>Life Technologies&#160;</td>
			<td>19993013</td>
			<td></td>
		</tr>
		<tr>
			<td>Gyrotory shakers</td>
			<td>New Brunswick Scientific</td>
			<td>G10 and G33</td>
			<td></td>
		</tr>
		<tr>
			<td>Erlenmeyer flasks 50 ml</td>
			<td>Novolab</td>
			<td>92717</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Petri dishes</td>
			<td>Novolab</td>
			<td>68516</td>
			<td></td>
		</tr>
		<tr>
			<td>Iridectomy scissors</td>
			<td>Rumex</td>
			<td>11-0625</td>
			<td></td>
		</tr>
		<tr>
			<td>Macroscope with calibrated ocular grid</td>
			<td>Wild</td>
			<td>157702</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffin wax</td>
			<td>International Medical products</td>
			<td>8599956</td>
			<td></td>
		</tr>
		<tr>
			<td>Eosin Y</td>
			<td>Sigma</td>
			<td>230251-25g</td>
			<td></td>
		</tr>
		<tr>
			<td>Harris&#39; hematoxylin</td>
			<td>Sigma</td>
			<td>HHS32-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>Coverslipping resin (Tissue-Tek)</td>
			<td>Sakura</td>
			<td>4494</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffin melting apparatus</td>
			<td>GFL</td>
			<td>1052</td>
			<td></td>
		</tr>
		<tr>
			<td>Microtome for paraffin sectioning</td>
			<td>Reichert</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stppers for Erlemeyer flasks with gas in- and outlets</td>
			<td>Novolab</td>
			<td>2602421 and 260243</td>
			<td></td>
		</tr>
		<tr>
			<td>Diaminobenzidine</td>
			<td>Sigma</td>
			<td>D8001</td>
			<td></td>
		</tr>
		<tr>
			<td>REAX rocking table</td>
			<td>Heidolph</td>
			<td>54131</td>
			<td></td>
		</tr>
		<tr>
			<td>24-well tissue dishes</td>
			<td>VWR</td>
			<td>NUNC142475</td>
			<td></td>
		</tr>
		<tr>
			<td>Ophtalmological enucleation spoon</td>
			<td>Rumex</td>
			<td>16-060</td>
			<td></td>
		</tr>
		<tr>
			<td>Sharp forceps</td>
			<td>Rumex</td>
			<td>4-111T</td>
			<td></td>
		</tr>
		<tr>
			<td>Blunt forceps</td>
			<td>Nickel-Electro LTD</td>
			<td>7112</td>
			<td></td>
		</tr>
		<tr>
			<td>Erlenmeyer flasks 5 ml</td>
			<td>Novolab</td>
			<td>211901</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope slides washed and degreased</td>
			<td>International Medical products</td>
			<td>8613908</td>
			<td></td>
		</tr>
	</tbody>
</table>

chick heart invasion assay for testing the invasiveness of cancer cells and the activity of potentially anti-invasive compounds

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish between invasive and non-invasive cells, and enables study of the effects of test compounds on tumor invasion. Cancer cells - either as aggregates or single cells - are confronted with fragments of embryonic chick heart. After organ culture in suspension for a few days or weeks the confronting cultures are fixed and embedded in paraffin for histological analysis. The three-dimensional interaction between the cancer cells and the normal tissue is then reconstructed from serial sections stained with hematoxylin-eosin or after immunohistochemical staining for epitopes in the heart tissue or the confronting cancer cells. The assay is consistent with the recent concept that cancer invasion is the result of molecular interactions between the cancer cells and their neighbouring stromal host elements (myofibroblasts, endothelial cells, extracellular matrix components, etc.). Here, this stromal environment is offered to the cancer cells as a living tissue fragment. Supporting aspects to the relevance of the assay are multiple. Invasion in the assay is in accordance with the criteria of cancer invasion: progressive occupation and replacement in time and space of the host tissue, and invasiveness and non-invasiveness in vivo of the confronting cells generally correlates with the outcome of the assay. Furthermore, the invasion pattern of cells in vivo, as defined by pathologists, is reflected in the histological images in the assay. Quantitative structure-activity relation (QSAR) analysis of the results obtained with numerous potentially anti-invasive organic congener compounds allowed the study of structure-activity relations for flavonoids and chalcones, and known anti-metastatic drugs used in the clinic (e.g., microtubule inhibitors) inhibit invasion in the assay as well. However, the assay does not take into account immunological contributions to cancer invasion.

&#160; The histological sections as presented in Figure 5 show the end result of a number of successful assays. The sound histology of the cultures indicates viable cells and allows to interpret the interaction between tumor cells and normal tissue. Furthermore, no immune reaction from the normal tissue can be observed, which confirms the correct age of the chick embryos used e.g.,&#160;before the immune rejection system is developed. There are no bacteria visible, which indicates absence of (gross) contaminatio...

Watch this Scientific Journal Video about Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds at JoVE.com

Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds

Here, we present a protocol to study the invasion of tumor cells into living normal tissue fragments in three dimensions. This organ culture technique is mainly applied to test potentially anti-invasive drugs in vitro.

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish ...

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9.0K 次观看.  University of Ghent. 在这里，我们提出了一个协议入侵肿瘤细胞研究到生活的正常组织碎片在三个方面。这种器官培养技术主要应用于体外测试潜在抗侵袭药物。 

视频: Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds

Modeling and Imaging 3-Dimensional Collective Cell Invasion

A defining characteristic of cancer malignancy is invasion and metastasis 1. In some cancers (e.g. glioma 2), local invasion into surrounding healthy tissue is the root cause of disease and death. For other cancers (e.g. breast, lung, etc.), it is the process of metastasis, in which tumor cells move from a primary tumor mass, colonize distal sites and ultimately contribute to organ failure, that eventually leads to morbidity and mortality 3. It has been estimated that invasion and metastasis are responsible for 90&#37; of cancer deaths 4. As a result, there has been intense interest in identifying the molecular processes and critical protein mediators of invasion and metastasis for the purposes of improving diagnosis and treatment 5.
A challenge for cancer scientists is to develop invasion assays that sufficiently resemble the in vivo situation to enable accurate disease modeling 6. Two-dimensional cell motility assays are only informative about one aspect of invasion and do not take into account extracellular matrix (ECM) protein remodeling which is also a critical element. Recently, research has refined our understanding of tumor cell invasion and revealed that individual cells may move by elongated or rounded modes 7. In addition, there has been greater appreciation of the contribution of collective invasion, in which cells invade in strands, sheets and clusters, particularly in highly differentiated tumors that maintain epithelial characteristics, to the spread of cancer 8.
We present a refined method 9 for examining the contributions of candidate proteins to collective invasion 10. In particular, by engineering separate pools of cells to express different fluorescent proteins, it is possible to molecularly dissect the activities and proteins required in leading cells versus those required in following cells. The use of RNAi provides the molecular tool to experimentally disassemble the processes involved in individual cell invasion as well as in different positions of collective invasion. In this procedure, mixtures of fluorescently-labeled cells are plated on the bottom of a Transwell insert previously filled with Matrigel ECM protein, then allowed to invade "upwards" through the filter and into the Matrigel. Reconstruction of z-series image stacks, obtained by confocal imaging, into three-dimensional representations allows for visualization of collectively invading strands and analysis of the representation of fluorescently-labeled cells in leading versus following positions.

Models of tumor cell invasion into three-dimensional extracellular matrix better reflect the in vivo situation than two-dimensional motility assays. Using matrix invasion assays combined with confocal imaging of fluorescently-labeled cells, detailed information on invasion modes and the distinct contributions of leading versus following cells can be obtained.

A defining characteristic of cancer malignancy is invasion and metastasis 1. In some cancers (e.g. glioma 2), local invasion into surrounding healthy ...

Minimal Erythema Dose (MED) Testing

Ultraviolet radiation (UV) therapy is sometimes used as a treatment for various common skin conditions, including psoriasis, acne, and eczema. The dosage of UV light is prescribed according to an individual's skin sensitivity. Thus, to establish the proper dosage of UV light to administer to a patient, the patient is sometimes screened to determine a minimal erythema dose (MED), which is the amount of UV radiation that will produce minimal erythema (sunburn or redness caused by engorgement of capillaries) of an individual's skin within a few hours following exposure. This article describes how to conduct minimal erythema dose (MED) testing. There is currently no easy way to determine an appropriate UV dose for clinical or research purposes without conducting formal MED testing, requiring observation hours after testing, or informal trial and error testing with the risks of under- or over-dosing. However, some alternative methods are discussed.

Minimal Erythema Dose MED Testing

This article describes how to conduct minimal erythema dose (MED) testing in order to determine the lowest dose of ultraviolet radiation that will cause erythema (burning) when administered to an individual.

Ultraviolet radiation (UV) therapy is  sometimes used as a treatment for various common skin conditions, including  psoriasis, acne, and eczema. The ...

Quantification of Breast Cancer Cell Invasiveness Using a Three-dimensional (3D) Model

It is now well known that the cellular and tissue microenvironment are critical regulators influencing tumor initiation and progression. Moreover, the extracellular matrix (ECM) has been demonstrated to be a critical regulator of cell behavior in culture and homeostasis in vivo. The current approach of culturing cells on two-dimensional (2D), plastic surfaces results in the disturbance and loss of complex interactions between cells and their microenvironment. Through the use of three-dimensional (3D) culture assays, the conditions for cell-microenvironment interaction are established resembling the in vivo microenvironment. This article provides a detailed methodology to grow breast cancer cells in a 3D basement membrane protein matrix, exemplifying the potential of 3D culture in the assessment of cell invasion into the surrounding environment. In addition, we discuss how these 3D assays have the potential to examine the loss of signaling molecules that regulate epithelial morphology by immunostaining procedures. These studies aid to identify important mechanistic details into the processes regulating invasion, required for the spread of breast cancer.

Quantification of Breast Cancer Cell Invasiveness Using a Three-dimensional 3D Model

This article provides detailed methodologies for the use of three-dimensional (3D) assays to quantify breast cancer cell invasion. Specifically, we discuss the procedures required to set up such assays, quantification, and data analysis, as well as methods to examine the loss of membrane integrity that occurs when cells invade.

It is now well known that the cellular and tissue microenvironment are critical regulators influencing tumor initiation and progression. Moreover, the ...

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the actual molecules towards which the cells migrate remain elusive. This modified invasion assay has been developed to identify targets which drive cell migration and invasion. This technique compares the invasion index under three conditions to determine whether a specific hormone, growth factor, or cytokine plays a role in mediating the invasive potential of a cancer cell. These conditions include i) normal fetal bovine serum (FBS), ii) charcoal-stripped FBS (CS-FBS), which removes hormones, growth factors, and cytokines and iii) CS-FBS + molecule (denoted &#8220;X&#8221;). A significant change in cell invasion with CS-FBS as compared to FBS, indicates the involvement of hormones, cytokines or growth factors in mediating the change. Individual molecules can then be added back to CS-FBS to assay their ability to reverse or rescue the invasion phenotype. Furthermore, two or more factors can be combined to evaluate the additive or synergistic effects of multiple molecules in driving or inhibiting invasion. Overall, this method enables the investigator to determine whether hormones, cytokines, and/or growth factors play a role in cell invasion by serving as chemoattractants or inhibitors of invasion for a particular type of cancer cell or a specific mutant. By identifying specific chemoattractants and inhibitors, this modified invasion assay may help to elucidate signaling pathways that direct cancer cell invasion.

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

This video article describes a modified in vitro method to examine the role of hormones, cytokines and/or growth factors in driving cancer cell invasion.

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the ...

Assessment of Ovarian Cancer Spheroid Attachment and Invasion of Mesothelial Cells in Real Time

Ovarian cancers metastasize by shedding into the peritoneal fluid and dispersing to distal sites within the peritoneum. Monolayer cultures do not accurately model the behaviors of cancer cells within a nonadherent environment, as cancer cells inherently aggregate into multicellular structures which contribute to the metastatic process by attaching to and invading the peritoneal lining to form secondary tumors. To model this important stage of ovarian cancer metastasis, multicellular aggregates, or spheroids, can be generated from established ovarian cancer cell lines maintained under nonadherent conditions. To mimic the peritoneal microenvironment encountered by tumor cells in vivo, a spheroid-mesothelial co-culture model was established in which preformed spheroids are plated on top of a human mesothelial cell monolayer, formed over an extracellular matrix barrier. Methods were then developed using a real-time cell analyzer to conduct quantitative real time measurements of the invasive capacity of different ovarian cancer cell lines grown as spheroids. This approach allows for the continuous measurement of invasion over long periods of time, which has several advantages over traditional endpoint assays and more laborious real time microscopy image analyses. In short, this method enables a rapid, determination of factors which regulate the interactions between ovarian cancer spheroid cells invading through mesothelial and matrix barriers over time.

Ovarian cancer cell invasion into the mesothelial lining of the peritoneum is a dynamic process over time. Utilizing a real time analyzer, the invasive capacity of ovarian cancer cells in a spheroid-mesothelial cell co-culture model can be quantified over prolonged time periods, providing insights into factors regulating the metastatic process.

Ovarian cancers metastasize by shedding into the peritoneal fluid and dispersing to distal sites within the peritoneum. Monolayer cultures do not ...

Three-Dimensional (3D) Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in particular (e.g., brain tumors such as glioblastoma multiforme and squamous cell carcinoma of the head and neck &#8211; SCCHN) it is a cause of severe morbidity and can be life-threatening even in the absence of distant metastases. In addition, cancers which have relapsed following treatment unfortunately often present with a more aggressive phenotype. Therefore, there is an opportunity to target the process of invasion to provide novel therapies that could be complementary to standard anti-proliferative agents. Until now, this strategy has been hampered by the lack of robust, reproducible assays suitable for a detailed analysis of invasion and for drug screening. Here we provide a simple micro-plate method (based on uniform, self-assembling 3D tumor spheroids) which has great potential for such studies. We exemplify the assay platform using a human glioblastoma cell line and also an SCCHN model where the development of resistance against targeted epidermal growth factor receptor (EGFR) inhibitors is associated with enhanced matrix-invasive potential. We also provide two alternative methods of semi-automated quantification: one using an imaging cytometer and a second which simply requires standard microscopy and image capture with digital image analysis.

Three-Dimensional 3D Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is a defining characteristic of malignant tumors. We provide here a simple, semi-automated micro-plate assay of invasion into a natural 3D biomatrix that has been exemplified with a number of models of advanced human cancers.

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in ...

Utilization of the Soft Agar Colony Formation Assay to Identify Inhibitors of Tumorigenicity in Breast Cancer Cells

Given the inherent difficulties in investigating the mechanisms of tumor progression in vivo, cell-based assays such as the soft agar colony formation assay (hereafter called soft agar assay), which measures the ability of cells to proliferate in semi-solid matrices, remain a hallmark of cancer research. A key advantage of this technique over conventional 2D monolayer or 3D spheroid cell culture assays is the close mimicry of the 3D cellular environment to that seen in vivo. Importantly, the soft agar assay also provides an ideal tool to rigorously test the effects of novel compounds or treatment conditions on cell proliferation and migration. Additionally, this assay enables the quantitative assessment of cell transformation potential within the context of genetic perturbations. We recently identified peptidylarginine deiminase 2 (PADI2) as a potential breast cancer biomarker and therapeutic target. Here we highlight the utility of the soft agar assay for preclinical anti-cancer studies by testing the effects of the PADI inhibitor, BB-Cl-amidine (BB-CLA), on the tumorigenicity of human ductal carcinoma in situ (MCF10DCIS) cells.

Here, we document the use of the soft agar colony formation assay to test the effects of a peptidylarginine deiminase (PADI) enzyme inhibitor, BB-Cl-amidine, on breast cancer tumorigenicity in vitro.

Given the inherent difficulties in investigating the mechanisms of tumor progression in vivo, cell-based assays such as the soft agar colony formation ...

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor initiation, metastasis and resistance to radio- and chemotherapy. Here we describe a specific methodology for culturing primary human pancreatic CSCs as tumor spheres in anchorage-independent conditions. Cells are grown in serum-free, non-adherent conditions in order to enrich for CSCs while their more differentiated progenies do not survive and proliferate during the initial phase following seeding of single cells. This assay can be used to estimate the percentage of CSCs present in a population of tumor cells. Both size (which can range from 35 to 250 micrometers) and number of tumor spheres formed represents CSC activity harbored in either bulk populations of cultured cancer cells or freshly harvested and digested tumors 1,2. Using this assay, we recently found that metformin selectively ablates pancreatic CSCs; a finding that was subsequently further corroborated by demonstrating diminished expression of pluripotency-associated genes/surface markers and reduced in vivo tumorigenicity of metformin-treated cells. As the final step for preclinical development we treated mice bearing established tumors with metformin and found significantly prolonged survival. Clinical studies testing the use of metformin in patients with PDAC are currently underway (e.g., NCT01210911, NCT01167738, and NCT01488552). Mechanistically, we found that metformin induces a fatal energy crisis in CSCs by enhancing reactive oxygen species (ROS) production and reducing mitochondrial transmembrane potential. In contrast, non-CSCs were not eliminated by metformin treatment, but rather underwent reversible cell cycle arrest. Therefore, our study serves as a successful example for the potential of in vitro sphere formation as a screening tool to identify compounds that potentially target CSCs, but this technique will require further in vitro and in vivo validation to eliminate false discoveries.

Pancreatic cancer stem cells (CSCs) can be expanded in vitro using the anchorage-independent sphere culture technique, which represents a powerful tool to study CSC biology and can serve as the first step to develop novel CSC-targeting therapies. Here the methodology for expanding, analyzing and targeting of pancreatic CSCs is provided.

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor ...

Isolation and Propagation of Circulating Tumor Cells from a Mouse Cancer Model

Cancer metastasis is the foremost cause of cancer-associated deaths. Recent studies have shown that circulating tumor cells (CTCs) are important in cancer metastasis. Indeed, the number of CTCs correlates with tumor size. Here, a detailed description is provided of a methodology for isolation and propagation of CTCs from a syngeneic mouse model of hepatocellular carcinoma (HCC) which allows for downstream analysis of potentially important molecular mechanisms of solid organ tumor metastasis. This method is efficient and reproducible. It is a non-invasive technique and, therefore, has potential to replace the invasive biopsy of tissues from humans which may be associated with complications. Therefore, the method discussed here allows for the isolation and propagation of CTCs from whole blood samples such that they can be examined and characterized. This has potential for future adaptation for clinical applications such as diagnosis, and personalized targeted therapy.

Circulating tumor cells (CTCs) have been shown to play an important role in tumor metastasis. Here, a method for the isolation and propagation of CTCs from the whole blood of a syngeneic mouse tumor model of hepatocellular carcinoma (HCC) metastasis is described.

Cancer metastasis is the foremost cause of cancer-associated deaths. Recent studies have shown that circulating tumor cells (CTCs) are important in cancer ...

Cutaneous Surgical Denervation:  A Method for Testing the Requirement for Nerves in Mouse Models of Skin Disease

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies have suggested that nerves may also modulate skin disorders including atopic dermatitis, psoriasis and cancer. Here, we describe protocols for testing the requirement for nerves in maintaining a cutaneous mechanosensory organ, the touch dome (TD). Specifically, we discuss methods for genetically labeling, harvesting and visualizing TDs by whole-mount staining, and for performing unilateral surgical denervation on mouse dorsal back skin. Together, these approaches can be used to directly compare TD morphology and gene expression in denervated as well as sham-operated skin from the same animal. These methods can also be readily adapted to examine the requirement for nerves in mouse models of skin pathology. Finally, the ability to repeatedly sample the skin provides an opportunity to monitor disease progression at different stages and times after initiation.

This article includes detailed protocols for genetic labeling of mouse skin, surgical denervation, skin biopsy and visualizing labeled epithelia by whole-mount &#946;-galactosidase staining. These methods can be used to test the requirement for nerves in mouse models of normal and pathological skin.

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies ...