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>
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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><tbody><tr><td>Ringer&#039;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&amp;nbsp;</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&#039; 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 ...

chick-heart-invasion-assay-for-testing-invasiveness-cancer-cells

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Medicine

9.0K Views.  University of Ghent. 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.

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

Moving Upwards: A Simple and Flexible In Vitro Three-dimensional Invasion Assay Protocol

Although 3D invasion assays have been developed, the challenge remains to study cells without affecting the integrity of their microenvironment. Traditional 3D assays such as the Boyden Chamber require that cells are displaced from the original culture location and moved to a new environment. Not only does this disrupt the cellular processes that are intrinsic to the microenvironment, but it often results in a loss of cells. These problems are especially challenging when dealing with cells that are either rare, or extremely sensitive to their microenvironment. Here, we describe the development of a 3D invasion assay that avoids both concerns. In this assay, cells are plated within a small well and an ECM matrix containing a chemoattractant is laid atop the cells. This requires no cell displacement, and allows the cells to invade upwards into the matrix. In this assay, cell invasion as well as cell morphology can be assessed within the collagen gel. Using this assay, we characterize the invasive capacity of rare and sensitive cells; the hybrid cells resulting from fusion between breast cancer cells MCF7 and mesenchymal/multipotent stem/stroma cells (MSCs).

Moving Upwards: A Simple and Flexible In Vitro Three-dimensional Invasion Assay Protocol

This protocol describes an inverted vertical invasion assay that could be used to quantify the migration and invasion capabilities of cells in a three-dimensional setting while preserving the cell microenvironment. This assay is suitable for rare and/or sensitive cells.

Although 3D invasion assays have been developed, the challenge remains to study cells without affecting the integrity of their microenvironment. ...

Cancer Research

A Real-time Electrical Impedance Based Technique to Measure Invasion of Endothelial Cell Monolayer by Cancer Cells

Metastatic dissemination of malignant cells requires degradation of basement membrane, attachment of tumor cells to vascular endothelium, retraction of endothelial junctions and finally invasion and migration of tumor cells through the endothelial layer to enter the bloodstream as a means of transport to distant sites in the host1-3. Once in the circulatory system, cancer cells adhere to capillary walls and extravasate to the surrounding tissue to form metastatic tumors4,5. The various components of tumor cell-endothelial cell interaction can be replicated in vitro by challenging a monolayer of human umbilical vein endothelial cells (HUVEC) with cancer cells. Studies performed with electron and phase-contrast microscopy suggest that the in vitro sequence of events fairly represent the in vivo metastatic process6. Here, we describe an electrical-impedance based technique that monitors and quantifies in real-time the invasion of endothelial cells by malignant tumor cells.
Giaever and Keese first described a technique for measuring fluctuations in impedance when a population of cells grow on the surface of electrodes7,8. The xCELLigence instrument, manufactured by Roche, utilizes a similar technique to measure changes in electrical impedance as cells attach and spread in a culture dish covered with a gold microelectrode array that covers approximately 80% of the area on the bottom of a well. As cells attach and spread on the electrode surface, it leads to an increase in electrical impedance9-12. The impedance is displayed as a dimensionless parameter termed cell-index, which is directly proportional to the total area of tissue-culture well that is covered by cells. Hence, the cell-index can be used to monitor cell adhesion, spreading, morphology and cell density.
The invasion assay described in this article is based on changes in electrical impedance at the electrode/cell interphase, as a population of malignant cells invade through a HUVEC monolayer (Figure 1). The disruption of endothelial junctions, retraction of endothelial monolayer and replacement by tumor cells lead to large changes in impedance. These changes directly correlate with the invasive capacity of tumor cells, i.e., invasion by highly aggressive cells lead to large changes in cell impedance and vice versa. This technique provides a two-fold advantage over existing methods of measuring invasion, such as boyden chamber and matrigel assays: 1) the endothelial cell-tumor cell interaction more closely mimics the in vivo process, and 2) the data is obtained in real-time and is more easily quantifiable, as opposed to end-point analysis for other methods.

This article describes an in vitro technique for monitoring cancer cells invading through a monolayer of endothelial cells. The data is acquired in real-time as a function of changes in impedance on the surface of electrodes at the well bottom.

Metastatic dissemination of malignant cells requires degradation of basement membrane, attachment of tumor cells to vascular endothelium, retraction of ...

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 ...

Live-Cell Imaging Assays to Study Glioblastoma Brain Tumor Stem Cell Migration and Invasion

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include rapid proliferation and pervasive invasion into the normal brain. Recurrence is thought to result from the presence of radio- and chemo-resistant brain tumor stem cells (BTSCs) that invade away from the initial cancerous mass and, thus, evade surgical resection. Hence, therapies that target BTSCs and their invasive abilities may improve the otherwise poor prognosis of this disease. Our group and others have successfully established and characterized BTSC cultures from GBM patient samples. These BTSC cultures demonstrate fundamental cancer stem cell properties such as clonogenic self-renewal, multi-lineage differentiation, and tumor initiation in immune-deficient mice. In order to improve on the current therapeutic approaches for GBM, a better understanding of the mechanisms of BTSC migration and invasion is necessary. In GBM, the study of migration and invasion is restricted, in part, due to the limitations of existing techniques which do not fully account for the in vitro growth characteristics of BTSCs grown as neurospheres. Here, we describe rapid and quantitative live-cell imaging assays to study both the migration and invasion properties of BTSCs. The first method described is the BTSC migration assay which measures the migration toward a chemoattractant gradient. The second method described is the BTSC invasion assay which images and quantifies a cellular invasion from neurospheres into a matrix. The assays described here are used for the quantification of BTSC migration and invasion over time and under different treatment conditions.

Here, we describe live-cell imaging techniques to quantitatively measure the migration and invasion of glioblastoma brain tumor stem cells over time and under multiple treatment conditions.

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include ...

The Use of Mouse Mammary Tumor Cells in an In Vitro Invasion Assay as a Measure of Oncogenic Cell Behavior

The in vitro invasion assay uses a protein-rich matrix in a Boyden chamber to measure the ability of cultured cells to pass through the matrix and a porous membrane in a process analogous to the initial steps of cancer cell metastasis. The tested cells can be altered for the gene expression or treated with inhibitors to test for changes in the invasion potential. This experiment tests the aggressive phenotype of the mouse mammary tumor cells to discover and characterize the potential oncogenes that promote cell invasion. This technique, however, can be versatile and adapted to many different applications. The experiment itself can be done in one day and the results are acquired by light microscopy in less than a day. The results include counts of the number of invading cells for comparison and analysis. The in vitro invasion assay is a rapid, inexpensive, and clear-cut method for determining cell behavior in a culture that can be used as an initial assessment before more involved in vivo assays.

The in vitro cell invasion assay is used to measure the potential of cancer metastasis by quantifying the cellular potential for invasion and migration using cell culture inserts containing protein matrix. Cells are challenged to migrate through the protein matrix and a porous membrane, towards a chemoattractant, and then quantified by light microscopy.

The in vitro invasion assay uses a protein-rich matrix in a Boyden chamber to measure the ability of cultured cells to pass through the matrix and a ...

Genetics

Impedance-based Real-time Measurement of Cancer Cell Migration and Invasion

Cancer arises due to uncontrolled proliferation of cells initiated by genetic instability, mutations, and environmental and other stress factors. These acquired abnormalities in complex, multilayered molecular signaling networks induce aberrant cell proliferation and survival, extracellular matrix degradation, and metastasis to distant organs. Approximately 90% of cancer-related deaths are estimated to be caused by the direct or indirect effects of metastatic dissemination. Therefore, it is important to establish a highly reliable, comprehensive system to characterize cancer cell behaviors upon genetic and environmental manipulations. Such a system can give a clear understanding of the molecular regulation of cancer metastasis and the opportunity for successful development of stratified, precise therapeutic strategies. Hence, accurate determination of cancer cell behaviors such as migration and invasion with gain or loss of function of gene(s) allows assessment of the aggressive nature of cancer cells. The real-time measurement system based on cell impedance enables researchers to continually acquire data during a whole experiment and instantly compare and quantify the results under various experimental conditions. Unlike conventional methods, this method does not require fixation, staining, and sample processing to analyze cells that migrate or invade. This method paper emphasizes detailed procedures for real-time determination of migration and invasion of glioblastoma cancer cells.

Cancer is a lethal disease due to its ability to metastasize to different organs. Determining the ability of cancer cells to migrate and invade under various treatment conditions is crucial to assessing therapeutic strategies. This protocol presents a method to assess the real-time metastatic abilities of a glioblastoma cancer cell line.&#160;

Cancer arises due to uncontrolled proliferation of cells initiated by genetic instability, mutations, and environmental and other stress factors. These ...

Discovery of Metastatic Regulators using a Rapid and Quantitative Intravital Chick Chorioallantoic Membrane Model

Recent advances in cancer research has illustrated the highly complex nature of cancer metastasis. Multiple genes or genes networks have been found to be involved in differentially regulating cancer metastatic cascade genes and gene products dependent on the cancer type, tissue, and individual patient characteristics. These represent potentially important targets for genetic therapeutics and personalized medicine approaches. The development of rapid screening platforms is essential for the identification of these genetic targets.
The chick chorioallantoic membrane (CAM) is a highly vascularized, collagen rich membrane located under the eggshell that allows for gas exchange in the developing embryo. Due to the location and vascularization of the CAM, we developed it as an intravital human cancer metastasis model that allows for robust human cancer cell xenografting and real-time imaging of cancer cell interactions with the collagen rich matrix and vasculature. 
Using this model, a quantitative screening platform was designed for the identification of novel drivers or suppressors of cancer metastasis. We transduced a pool of head and neck HEp3 cancer cells with a complete human genome shRNA gene library, then injected the cells, at low density, into the CAM vasculature. The cells proliferated and formed single-tumor cell colonies. Individual colonies that were unable to invade into the CAM tissue were visible as a compact colony phenotype and excised for identification of the transduced shRNA present in the cells. Images of individual colonies were evaluated for their invasiveness. Multiple rounds of selections were performed to decreases the rate of false positives. Individual, isolated cancer cell clones or newly engineered clones that express genes of interest were subjected to primary tumor formation assay or cancer cell vasculature co-option analysis. In summary we present a rapid screening platform that allows for anti-metastatic target identification and intravital analysis of a dynamic and complex cascade of events.

This is an effective method to screen for suppressors or drivers of cancer metastasis. Cells, transduced with an expression library, are injected into the chicken chorioallantoic membrane vasculature to form metastatic colonies. Colonies having decreased or increased invasiveness are excised, expanded, reinjected to confirm their phenotype, and finally, analyzed using high throughput sequencing.

Recent advances in cancer research has illustrated the highly complex nature of cancer metastasis. Multiple genes or genes networks have been found to be ...

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 ...

Chick ex ovo Culture and ex ovo CAM Assay: How it Really Works

Chicken eggs in the early phase of breeding are between in vitro and in vivo systems and provide a vascular test environment not only to study angiogenesis but also to study tumorigenesis. After the chick chorioallantoic membrane (CAM) has developed, its blood vessel network can be easily accessed, manipulated and observed and therefore provides an optimal setting for angiogenesis assays. Since the lymphoid system is not fully developed until late stages of incubation, the chick embryo serves as a naturally immunodeficient host capable of sustaining grafted tissues and cells without species-specific restrictions. In addition to nurturing developing allo- and xenografts, the CAM blood vessel network provides a uniquely supportive environment for tumor cell intravasation, dissemination, and vascular arrest and a repository where arrested cells extravasate to form micro metastatic foci.
For experimental purposes, in most of the recent studies the CAM was exposed by cutting a window through the egg shell and experiments were carried out in ovo, resulting in significant limitations in the accessibility of the CAM and possibilities for observation and photo documentation of effects. When shell-less cultures of the chick embryo were used1-4, no experimental details were provided and, if published at all, the survival rates of these cultures were low. We refined the method of ex ovo culture of chick embryos significantly by introducing a rationally controlled extrusion of the egg content. These ex ovo cultures enhance the accessibility of the CAM and chick embryo, enabling easy in vivo documentation of effects and facilitating experimental manipulation of the embryo. This allows the successful application to a large number of scientific questions: (1) As an improved angiogenesis assay5,6, (2) an experimental set up for facilitated injections in the vitreous of the chick embryo eye7-9, (3) as a test environment for dissemination and intravasation of dispersed tumor cells from established cell lines inoculated on the CAM10-12, (4) as an improved sustaining system for successful transplantation and culture of limb buds of chicken and mice13 as well as (5) for grafting, propagation, and re-grafting of solid primary tumor tissue obtained from biopsies on the surface of the CAM14.
In this video article we describe the establishment of a refined chick ex ovo culture and CAM assay with survival rates over 50%. Besides we provide a step by step demonstration of the successful application of the ex ovo culture for a large number of scientific applications. 
Daniel S. Dohle, Susanne D. Pasa, and Sebastian Gustmann contributed equally to this study.

Chick ex ovo Culture and ex ovo CAM Assay: How it Really Works

The chick chorioallantoic membrane (CAM) is a unique, naturally immunodeficient supportive culture environment to study angiogenesis and tumorigenesis. This video article demonstrates the different steps in chick ex ovo culture, application of potentially angiogenic substances and successful inoculation of tumor cells and tissues on the surface of the CAM.

Chicken eggs in the early phase of breeding are between in vitro and in vivo systems and provide a vascular test environment not only to study ...

Biology

A Cancer Cell Spheroid Assay to Assess Invasion in a 3D Setting

The invasive nature of cancer cell lines is thought to correlate with their metastatic potential. Most traditional assays, however, do not examine these invasive features in a three-dimensional environment and the resulting data suffer from reduced biological applicability. Here an approach is presented to visualize the invasive ability of cell lines in a physiologically relevant setting. The cancer cell spheroid invasion assay first utilizes gravity to generate spheroids within drops of media that hang from the lid of a cell culture dish. Next, these spheroids are embedded in a 3D matrix consisting of a mixture of basement membrane materials and type I collagen. Cancer cell egression from the spheroids into the surrounding matrix is then monitored over time. The method described here can be modified to examine invasion after coculture of different cell types, inclusion of drugs/inhibitors, or alterations in extracellular matrix (ECM) constituents.

This method evaluates cancer cell invasion from spheroids into a surrounding 3D matrix. Spheroids are generated via the hanging drop culture method and then embedded in a matrix comprised of basement membrane materials and type I collagen. Invasion out of the spheroids is subsequently monitored.

The invasive nature of cancer cell lines is thought to correlate with their metastatic potential.  Most traditional assays, however, do not examine these ...

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

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Moving Upwards: A Simple and Flexible In Vitro Three-dimensional Invasion Assay Protocol

A Real-time Electrical Impedance Based Technique to Measure Invasion of Endothelial Cell Monolayer by Cancer Cells

Modeling and Imaging 3-Dimensional Collective Cell Invasion

Live-Cell Imaging Assays to Study Glioblastoma Brain Tumor Stem Cell Migration and Invasion

The Use of Mouse Mammary Tumor Cells in an In Vitro Invasion Assay as a Measure of Oncogenic Cell Behavior

Impedance-based Real-time Measurement of Cancer Cell Migration and Invasion

Discovery of Metastatic Regulators using a Rapid and Quantitative Intravital Chick Chorioallantoic Membrane Model

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

Chick ex ovo Culture and ex ovo CAM Assay: How it Really Works

A Cancer Cell Spheroid Assay to Assess Invasion in a 3D Setting