This work was supported by Transcan 2017, ARC 2017, Ligue Contre le Cancer (Comit&#233; de la Gironde et de la Charente-Maritime). Joris Guyon is a recipient of fellowship from the Toulouse University Hospital (CHU Toulouse).

Informed written consent was obtained from all patients (from the Haukeland Hospital, Bergen, Norway according to local ethics committee regulations). Our protocol follows the guidelines of our institution&#8217;s human research ethics committee.&#160;
1. Generation of uniform size tumor spheroids
NOTE: Stem-like cells are cultured in neurobasal medium complemented with B27 supplement, heparin, FGF-2, penicillin, and streptomycin, as described in previous articles12. These cells spontaneously form spheroids in culture.
<ol>
	<li>Wash the tumor cells with 5 mL phosphate-buffered saline (PBS) and incubate the cells with 0.5-1 mL dissociation enzyme (see Table of Materials) for 5 minutes at 37 &#176;C.</li>
	<li>Wash with 4-4.5 mL PBS and add 10 mL of the complete growth medium (complete neurobasal medium, cNBM).</li>
	<li>Count the cells using an automatic counting technique with trypan blue and a cell counting chamber slide.</li>
	<li>To generate 100 spheroids with 104 cells per spheroid (according to preferred size), mix 106 cells in 8 mL of NBM with 2 mL of 2% methylcellulose.</li>
	<li>Transfer the suspension to a sterile system container and dispense 100 &#181;L/well with a multichannel pipette into a 96 well round bottom plate.</li>
	<li>Incubate the plate at 37 &#176;C, 5% CO2 and 95% humidity. Equal sized spheroids will form and can be used after 3-4 days.</li>
</ol>
2. Three-dimensional experiments
<ol>
	<li>Proliferation
	<ol>
		<li>Preparation
		<ol>
			<li>Suspend inhibitors (e.g., rotenone as in Figure 4A) and chemicals in 100 &#181;L of medium and add to the 100 &#181;L of medium in each well (i.e., one spheroid per well).</li>
			<li>Incubate the plate at 37 &#176;C, 5% CO2, and 95% humidity.</li>
		</ol>
		</li>
		<li>Image acquisition and analysis
		<ol>
			<li>Take pictures with a video microscope in brightfield to create a series of conditions at T0 and the following times expected.</li>
			<li>Use Fiji to analyze pictures either manually or in a semiautomated manner. To do so manually, draw a circle around the spheroid core with the freehand selection tool and measure the area of each spheroid. To analyze the images in a semiautomated manner, use the macro shown in Supplementary Document 1 with //Core Area only.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Invasion
	<ol>
		<li>Preparation
		<ol>
			<li>Prepare the collagen matrix in a tube on ice with type I collagen at 1 mg/mL final concentration, 1x PBS, 0.023xVcollagen, 1 M sodium hydroxide, and sterile H2O. Incubate the solution on ice for 30 min.</li>
			<li>Collect spheroids from the round bottom well plate in 500 &#181;L tubes and wash 2x with 200 &#181;L 1x PBS.</li>
			<li>Pipette the spheroids carefully into 100 &#181;L of the collagen matrix and insert in the center of a well in normal 96 well plates.</li>
			<li>Incubate the collagen gel for 30 min at 37 &#176;C and then add cNBM on top of the gel. Inhibitors or activators (e.g., hydrogen chloride as shown in Figure 4B, 4C) can be added to the medium at this step.</li>
		</ol>
		</li>
		<li>Image acquisition and analysis
		<ol>
			<li>Take pictures sequentially with a video microscope in brightfield mode 24 h after collagen inclusion.</li>
			<li>Use Fiji to analyze pictures either manually or in a semiautomated manner. To do so manually, draw around the core and the total area of the spheroid with the freehand selection tool and measure the invasive area of each spheroid by subtract total area with core area. To analyze the images in a semiautomated manner, use the macro as indicated in Supplementary Document 1 to determine the invasive area.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Migration
	<ol>
		<li>Preparation
		<ol>
			<li>Coat a 6 well plate with Matrigel (0.2 mg/mL) in NBM for 30 min at 37 &#176;C, then remove the Matrigel and add 2 mL of cNBM.</li>
			<li>Transfer spheroids into 50 &#181;L of cNBM from the round bottom well plate to the 6 well plate.</li>
			<li>Incubate the plate at 37 &#176;C and wait 30 min for the spheroids to adhere.</li>
			<li>After 24 h of incubation, stain with 10 ng/mL of Hoechst and incubate 30 min at 37 &#176;C.</li>
		</ol>
		</li>
		<li>Image acquisition and analysis
		<ol>
			<li>Obtain images using a video microscope in brightfield. A 405 nm laser is used for visualization of Hoechst staining.</li>
			<li>Use Fiji software to analyze pictures and run the macro as indicated in Supplementary Document 1. 
			NOTE: Touching the bottom of the well or completely removing the supernatant damages the spheroids. For collagen type I gel handling, keep the gel on ice to avoid collagen polymerization, do not add an acidic component because the change in pH will affect the compactness of the gel, and pipette cells rapidly into the collagen to prevent cell death and the degradation of the gel.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. Fiji Macro
NOTE: Fiji is an image analysis program developed in the public domain that allows the development of macros to speed up image analysis. Manual analysis is also possible, but this is a slow process and may introduce biases. Images can be imported by drag-and-drop in the software and quantified with the ROI Manager Tools plugin. The procedure used in this study is described below:
<ol>
	<li>Open the macro window: Plugins | Macros | Interactive Interpreter.</li>
	<li>Copy and paste the following adapted purple loop. Keep the purple sentences and add the green sentences of interest (Supplementary Document 1).</li>
	<li>To analyze the entire series, adjust the parameters in red for a specific quantification and run the macro using Macros | Run Macro or pressing Ctrl+R.</li>
	<li>Check and, if necessary, manually adapt the region of interest (ROI).</li>
</ol>
4. Electron microscopy of spheroids
NOTE: Most of the following steps must be done in a chemical hood.
<ol>
	<li>Fixation step
	<ol>
		<li>Collect the spheroid with a cut pipette tip, put it in a 1.5 mL tube, and wash 1x with 0.1 M phosphate buffer (PB).</li>
		<li>Fix the spheroid overnight at 4 &#176;C in 2% glutaraldehyde/2% paraformaldehyde (PFA) in 0.1 M PB.</li>
		<li>Replace the fixation solution with a solution of 1% PFA in 0.1 M PB followed by sample preparation.</li>
	</ol>
	</li>
	<li>Sample preparation
	<ol>
		<li>Transfer the spheroids into a strainer and put them in a glass beaker in order to avoid spheroid damage.</li>
		<li>Carefully wash 3x with 0.1 M PB.</li>
		<li>Incubate with osmium for 2 h in the dark. Dilute osmium to 4% in 1% 0.1 M PB buffer.</li>
		<li>Carefully wash 3x with 0.1 M PB.
		<ol>
			<li>Dehydrate as follows: soak in 50% ethanol for 10 min, 70% ethanol for 10 min, 2x 90% ethanol for 15 min, 2x 100% ethanol for 20 min, and 2x acetone for 30 min.</li>
		</ol>
		</li>
		<li>Incubate the samples in a 50/50 mixture of acetone/resin for 2 h. During this step, prepare the EPON resin (Embed-812: 11.25 g; DDSA: 9 g; NMA: 4.5 g).</li>
		<li>Discard the acetone/resin mixture, replace with freshly prepared resin and incubate overnight.</li>
		<li>Replace the resin by a new one and incubate between 2-6 h.</li>
		<li>Add the spheroids in resin into a mold at 60 &#176;C for 48-72 h.</li>
	</ol>
	</li>
</ol>

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M. <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+environment+interactions+in+tumor+microregions:+the+multicell+spheroid+model.">Cell and environment interactions in tumor microregions: the multicell spheroid model.</a> Science. 240, 177-184 (1988).</li><li>Desoize, B., Jardillier, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multicellular+resistance:+a+paradigm+for+clinical+resistance?.">Multicellular resistance: a paradigm for clinical resistance?.</a> Critical Reviews in Oncology/Hematology. 36, 193-207 (2000).</li><li>Corbet, C., Feron, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumour+acidosis:+from+the+passenger+to+the+driver's+seat.">Tumour acidosis: from the passenger to the driver's seat.</a> Nature Reviews Cancer. 17, 577-593 (2017).</li><li>Hirschhaeuser, F., 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=Multicellular+tumor+spheroids:+an+underestimated+tool+is+catching+up+again.">Multicellular tumor spheroids: an underestimated tool is catching up again.</a> Journal of Biotechnology. 148, 3-15 (2010).</li><li>Berens, E. 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The authors declare that they have no competing financial interests.

Tumor spheroid assays are well adapted to study tumor characteristics including proliferation, invasion, and migration, as well as cell death and drug response. Cancer cells invade the 3D matrix forming an invasive microtumor, as seen in Figure 4B,C. During the invasive process, matrix metalloproteinases (MMP) digest matrices surrounding tumor cells13, and MMP inhibitors (e.g., GM6001 or Rebimastat) may impair cell invasion but not migration<sup class...

In most studies using primary or commercially available cell lines, assays are performed on cells grown on plastic surfaces as monolayer cultures. Managing cell culture in 2D represents disadvantages, as it does not mimic an in vivo 3D cell environment. In 2D cultures, the entire cell surface is directly in contact with the medium, altering cell growth and modifying drug availability. Furthermore, the nonphysiological plastic surface triggers cell differentiation1. Three-dimensional culture models have been developed to overcome these difficulties. They have the advantage of mimicking the multicellular architecture and heterogeneity of tumors2, and thus could be considered to be a more relevant model for solid tumors3. The complex morphology of spheroids contributes to better evaluate drug penetrance and resistance4. The tumor heterogeneity in the spheroid impacts the diffusion of oxygen and nutrients, and the response to pharmacological agents (Figure 1A). Diffusion of oxygen is altered when the spheroid size reaches 300 &#181;m, inducing a hypoxic environment in the center of the spheroid (Figure 1A,C). Metabolites are also less penetrating through the cell layers and compensating metabolic reactions take place5. When the diameter of the spheroid increases, necrotic cores can be observed, further mimicking characteristics found in many solid cancers, including the aggressive brain cancer glioblastoma (GBM)6.
Several 2D or 3D invasion assays for glioblastoma have been reported in the literature7,8. Two-dimensional assays are mainly for studying invasion in a horizontal plane on a thin matrix layer or in a Boyden chamber assay9. Three-dimensional assays have been described with 3D spheroid cultures using classical glioblastoma cell lines10. More complex variants are represented by invasion of brain organoids by tumor spheroids in confrontation cultures11. However, it is still important to develop an easy-to-use and reproducible assay available to any laboratory. We have developed a protocol to generate glioblastoma stem-like cells from patient samples. The quantification of these assays is easily manageable and only requires open-access online software. Briefly, tumor pieces are cut into small pieces and enzymatically digested. Single cells derived from the digestion are cultivated in neurobasal medium. After 4-7 days, spheroid structures form spontaneously. Upon intracranial implantation in mice models, they form tumors exhibiting a necrotic core surrounded by pseudo-palisading cells12. This closely resembles the characteristics found in GBM patients.
In this article, we describe our protocol to produce spheroids from a determined number of cells to ensure reproducibility. Two complementary matrices can be used for this purpose: Matrigel and collagen type I. Matrigel is enriched in growth factors and mimics the mammalian basal membrane required for cell attachment and migration. On the other hand, collagen type I, a structural element of stroma, is the most common fibrillary extracellular matrix and is used in cell invasion assays. Herein, we illustrate our GBM spheroid model by performing migration and proliferation assays. Analysis was done not only at fixed time points but also by monitoring spheroid expansion and cell movement by live imaging. Furthermore, electron microscopy was done to visualize morphological details.

<table><tbody><tr><td>96 well round-bottom plate</td><td>Falcon</td><td>08-772-212</td><td></td></tr><tr><td>Accutase</td><td>Gibco</td><td>A11105-01</td><td>Stored at 4 &amp;deg;C, sphere dissociation enzyme</td></tr><tr><td>B27</td><td>Gibco</td><td>12587</td><td>Stored at -20 &amp;deg;C, defrost before use</td></tr><tr><td>Basic Fibroblast Growth Factor</td><td>Peprotech</td><td>100-18B</td><td>Stored at -20 &amp;deg;C, defrost before use</td></tr><tr><td>Countess Cell Counting Chamber Slides</td><td>Invitrogen</td><td>C10283</td><td></td></tr><tr><td>DPBS 10X</td><td>Pan Biotech</td><td>P04-53-500</td><td>Stored at 4 &amp;deg;C</td></tr><tr><td>Fiji software</td><td>ImageJ</td><td></td><td>Used to analyze pictures</td></tr><tr><td>Flask 75 cm&lt;sup&gt;2&lt;/sup&gt;</td><td>Falcon</td><td>10497302</td><td></td></tr><tr><td>Matrigel</td><td>Corning</td><td>354230</td><td>Stored at -20 &amp;deg;C, diluted to a final concentration of 0.2 mg/mL in cold NBM</td></tr><tr><td>Methylcellulose</td><td>Sigma</td><td>M0512</td><td>Diluted in NBM for a 2% final concentration</td></tr><tr><td>NBM</td><td>Gibco</td><td>21103-049</td><td>Stored at 4 &amp;deg;C</td></tr><tr><td>Neurobasal medium</td><td>Gibco</td><td>21103049</td><td>Stored at 4 &amp;deg;C</td></tr><tr><td>Penicillin - Streptomycin</td><td>Gibco</td><td>15140-122</td><td>Stored at 4 &amp;deg;C</td></tr><tr><td>Trypan blue 0.4%</td><td>ThermoFisher</td><td>T10282</td><td>Used to cell counting</td></tr><tr><td>Type I Collagen</td><td>Corning</td><td>354236</td><td>Stored at 4 &amp;deg;C</td></tr></tbody></table>

a 3d spheroid model for glioblastoma

Two-dimensional (2D) cell cultures do not mimic in vivo tumor growth satisfactorily. Therefore, three-dimensional (3D) culture spheroid models were developed. These models may be particularly important in the field of neuro-oncology. Indeed, brain tumors have the tendency to invade the healthy brain environment. We describe herein an ideal 3D glioblastoma spheroid-based assay that we developed to study tumor invasion. We provide all technical details and analytical tools to successfully perform this assay.

Spheroids were prepared as described in the protocols section and observations were made regarding migration, invasion, proliferation, and microscopy. To measure hypoxia in distinct areas of the spherical structure, carboxic anhydrase IX staining was used for determining hypoxic activity (Figure 1A-C). More CAIX-positive cells were observed in the spheroid center (Figure 1A-C). Hypoxic cells loca...

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A 3D Spheroid Model for Glioblastoma

Here, we describe an easy-to-use invasion assay for glioblastoma. This assay is suitable for glioblastoma stem-like cells. A Fiji macro for easy quantification of invasion, migration, and proliferation is also described.

Two-dimensional (2D) cell cultures do not mimic in vivo tumor growth satisfactorily. Therefore, three-dimensional (3D) culture spheroid models were ...

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JoVE Journal

Cancer Research

14.8K Views.  University Bordeaux, LAMC. Tweedimensionale celculturen bootsen de tumorgroei niet voldoende na. Om te verbeteren, zijn 3D-procedures ontwikkeld met behulp van sferoïden. Onze 3D glioblastoom sferoïde-gebaseerde test is bijzonder geschikt om hersentumor invasie te onderzoeken in de gezonde hersentumor omgeving.Driedimensionale cultuurmodellen kunnen worden gebruikt om een meercellige architectuur, heterogeniteit en metabole toestand van tumoren samen te vatten, waardoor een strengere evaluatie van de effecten ...

Video: A 3D Spheroid Model for Glioblastoma

A 3D Spheroid Model as a More Physiological System for Cancer-Associated Fibroblasts Differentiation and Invasion In Vitro Studies

Defining the ideal model for an in vitro study is essential, mainly if studying physiological processes such as differentiation of cells. In the tumor stroma, host fibroblasts are stimulated by cancer cells to differentiate. Thus, they acquire a phenotype that contributes to the tumor microenvironment and supports tumor progression. By using the spheroid model, we have set up such a 3D in vitro model system, in which we analyzed the role of laminin-332 and its receptor integrin &#945;3&#946;1 in this differentiation process. This spheroid model system not only reproduces the tumor microenvironment conditions in a more accurate way, but also is a very versatile model since it allows different downstream studies, such as immunofluorescent staining of both intra- and extracellular markers, as well as deposited extracellular matrix proteins. Moreover, transcriptional analyses by qPCR, flow cytometry and cellular invasion can be studied with this model. Here, we describe a protocol of a spheroid model to assess the role of CAFs&#39; integrin &#945;3&#946;1 and its ectopically deposited ligand, laminin-332, in differentiation and in supporting the invasion of pancreatic cancer cells.

The goal of this protocol is to establish a 3D in vitro model to study the differentiation of cancer-associated fibroblasts (CAFs) in a tumor bulk-like environment, which can be addressed in different analysis systems, such as immunofluorescence, transcriptional analysis and life cell imaging.

Defining the ideal model for an in vitro study is essential, mainly if studying physiological processes such as differentiation of cells. In the tumor ...

Optimization of High Grade Glioma Cell Culture from Surgical Specimens for Use in  Clinically Relevant Animal Models and 3D Immunochemistry

Glioblastomas, the most common and aggressive form of astrocytoma, are refractory to therapy, and molecularly heterogeneous. The ability to establish cell cultures that preserve the genomic profile of the parental tumors, for use in patient specific in vitro and in vivo models, has the potential to revolutionize the preclinical development of new treatments for glioblastoma tailored to the molecular characteristics of each tumor.
Starting with fresh high grade astrocytoma tumors dissociated into single cells, we use the neurosphere assay as an enrichment method for cells presenting cancer stem cell phenotype, including expression of neural stem cell markers, long term self-renewal in vitro, and the ability to form orthotopic xenograft tumors. This method has been previously proposed, and is now in use by several investigators. Based on our experience of dissociating and culturing 125 glioblastoma specimens, we arrived at the detailed protocol we present here, suitable for routine neurosphere culturing of high grade astrocytomas and large scale expansion of tumorigenic cells for preclinical studies. We report on the efficiency of successful long term cultures using this protocol&#160;and suggest affordable alternatives for culturing dissociated glioblastoma cells that fail to grow as neurospheres. We also describe in detail a protocol for preserving the neurospheres 3D architecture for immunohistochemistry. Cell cultures enriched in CSCs, capable of generating orthotopic xenograft models that preserve the molecular signatures and heterogeneity of GBMs, are becoming increasingly popular for the study of the biology of GBMs and for the improved design of preclinical testing of potential therapies.

Protocol for propagation of dissociated high grade glioma surgical specimens in serum-free neurosphere medium to select for cells with cancer stem cell phenotype. For specimens that fail to grow as neurospheres, an alternative protocol is suggested. A paraffin embedding technique for maintaining the 3D neurosphere architecture for immunocytochemistry is described.

Glioblastomas, the most common and aggressive form of astrocytoma, are refractory to therapy, and molecularly heterogeneous. The ability to establish cell ...

Medicine

An Orthotopic Glioblastoma Mouse Model Maintaining Brain Parenchymal Physical Constraints and Suitable for Intravital Two-photon Microscopy

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumors with no curative treatments available to date.
Murine models of this pathology rely on the injection of a suspension of glioma cells into the brain parenchyma following incision of the dura-mater. Whereas the cells have to be injected superficially to be accessible to intravital two-photon microscopy, superficial injections fail to recapitulate the physiopathological conditions. Indeed, escaping through the injection tract most tumor cells reach the extra-dural space where they expand abnormally fast in absence of mechanical constraints from the parenchyma.
Our improvements consist not only in focally implanting a glioma spheroid rather than injecting a suspension of glioma cells in the superficial layers of the cerebral cortex but also in clogging the injection site by a cross-linked dextran gel hemi-bead that is glued to the surrounding parenchyma and sealed to dura-mater with cyanoacrylate. Altogether these measures enforce the physiological expansion and infiltration of the tumor cells inside the brain parenchyma. Craniotomy was finally closed with a glass window cemented to the skull to allow chronic imaging over weeks in absence of scar tissue development.
Taking advantage of fluorescent transgenic animals grafted with fluorescent tumor cells we have shown that the dynamics of interactions occurring between glioma cells, neurons (e.g. Thy1-CFP mice) and vasculature (highlighted by an intravenous injection of a fluorescent dye) can be visualized by intravital two-photon microscopy during the progression of the disease.
The possibility to image a tumor at microscopic resolution in a minimally compromised cerebral environment represents an improvement of current GBM animal models which should benefit the field of neuro-oncology and drug testing.

We have established a cortical orthotopic glioblastoma model in mice for intravital two-photon microscopy that recapitulates the biophysical constraints normally at play during the growth of the tumor. A chronic glass window replacing the skull above the tumor enables the follow-up of the tumor progression over time by two-photon microscopy.

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumors with no curative treatments available to date.
Murine models of this pathology ...

Translational Orthotopic Models of Glioblastoma Multiforme

Genetically engineered mouse (GEM) models for human glioblastoma multiforme (GBM) are critical to understanding the development and progression of brain tumors. Unlike xenograft tumors, in GEMs, tumors arise in the native microenvironment in an immunocompetent mouse. However, the use of GBM GEMs in preclinical treatment studies is challenging due to long tumor latencies, heterogeneity in neoplasm frequency, and the timing of advanced grade tumor development. Mice induced via intracranial orthotopic injection are more tractable for preclinical studies, and retain features of the GEM tumors. We generated an orthotopic brain tumor model derived from a GEM model with Rb, Kras, and p53 aberrations (TRP), which develops GBM tumors&#160;displaying linear foci of necrosis by neoplastic cells, and dense vascularization analogous to human GBM. Cells derived from GEM GBM tumors are injected intracranially into wild-type, strain-matched recipient mice and reproduce grade IV tumors, therefore bypassing the long tumor latency period in GEM mice and allowing for the creation of large and reproducible cohorts for preclinical studies. The highly proliferative, invasive, and vascular features of the TRP GEM model for GBM are recapitulated in the orthotopic tumors, and histopathology markers reflect human GBM subgroups. Tumor growth is monitored by serial MRI scans. Due to the invasive nature of the intracranial tumors in immunocompetent models, carefully following the injection procedure outlined here is essential to prevent extracranial tumor growth.

Here, we describe a preclinical orthotopic mouse model for GBM, established by intracranial injection of cells derived from genetically engineered mouse model tumors. This model displays the disease hallmarks of human GBM. For translational studies, the mouse brain tumor is tracked by in vivo MRI and histopathology.

Genetically engineered mouse (GEM) models for human glioblastoma multiforme (GBM) are critical to understanding the development and progression of brain ...

Spheroid Drug Sensitivity Screening in Glioma Stem Cell Lines

In vitro drug sensitivity screens are important tools in the discovery of anti-cancer drug combination therapies. Typically, these in vitro drug screens are performed on cells grown in a monolayer. However, these two-dimensional (2D) models are considered less accurate compared to three-dimensional (3D) spheroid cell models; this is especially true for glioma stem cell lines. Cells grown in spheres activate different signaling pathways and are considered more representative of in vivo models than monolayer cell lines. This protocol describes a method for in vitro drug screening of spheroid lines; mouse and human glioma stem cell lines are used as an example. This protocol describes a 3D spheroid drug sensitivity and synergy assay that can be used to determine if a drug or drug combination induces cell death and if two drugs synergize. Glioma stem cell lines are&#160;modified to express RFP. Cells are plated in low attachment round well bottom 96 plates, and spheres are allowed to form overnight. Drugs are added, and the growth is monitored by measuring the RFP signal over time using the Incucyte live imaging system,&#160;a fluorescence microscope embedded in the tissue culture incubator. Half maximal inhibitory concentration (IC50), median lethal dose (LD50), and synergy score are subsequently calculated to evaluate sensitivities to drugs alone or in combination. The three-dimensional nature of this assay&#160;provides a more accurate reflection of tumor growth, behavior, and drug sensitivities in vivo, thus forming the basis for further preclinical investigation.

In vitro drug sensitivity screens are important tools for discovering anti-cancer drug combinations. Cells grown in spheres activate different signaling pathways and are considered more representative of in vivo models than monolayer cell lines. This protocol describes a method for in vitro drug screening for spheroid lines.

In vitro drug sensitivity screens are important tools in the discovery of anti-cancer drug combination therapies. Typically, these in vitro drug screens ...

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 ...

Fabrication Followed by 3D Encapsulation of Tumor Spheroids in PEG Hydrogels

Tumor Spheroid Fabrication and Encapsulation in Polyethylene Glycol Hydrogels for Studying Spheroid-Matrix Interactions

Three-dimensional (3D) encapsulation of spheroids is crucial to adequately replicate the tumor microenvironment for optimal cell growth. Here, we designed an in vitro 3D glioblastoma model for spheroid encapsulation to mimic the tumor extracellular microenvironment. First, we formed square pyramidal microwell molds using polydimethylsiloxane. These microwell molds were then used to fabricate tumor spheroids with tightly controlled sizes from 50-500 &#956;m. Once spheroids were formed, they were harvested and encapsulated in polyethylene glycol (PEG)-based hydrogels. PEG hydrogels are a versatile platform for spheroid encapsulation, as hydrogel properties such as stiffness, degradability, and cell adhesiveness can be tuned independently. Here, we used a representative soft (~8 kPa) hydrogel to encapsulate glioblastoma spheroids. Finally, a method to stain and image spheroids was developed to obtain high-quality images via confocal microscopy. Due to the dense spheroid core and relatively sparse periphery, imaging can be difficult, but using a clearing solution and confocal optical sectioning helps alleviate these imaging difficulties. In summary, we show a method to fabricate uniform spheroids, encapsulate them in PEG hydrogels and perform confocal microscopy on the encapsulated spheroids to study spheroid growth and various cell-matrix interactions.

Author Spotlight: In Vitro Hydrogel Model for Glioblastoma Microenvironment Study

Here, we present a protocol that enables fast, robust, and cheap fabrication of tumor spheroids followed by hydrogel encapsulation. It is widely applicable as it does not require specialized equipment. It would be particularly useful for exploring spheroid-matrix interactions and building in vitro tissue physiology or pathology models.

Three-dimensional (3D) encapsulation of spheroids is crucial to adequately replicate the tumor microenvironment for optimal cell growth.  Here, we ...

Bioengineering

Replicating Glioblastoma Invasion with Hyaluronan-Collagen I Hydrogel System

A Photopolymerizable Hyaluronic Acid-Collagen Model of the Invasive Glioma Microenvironment with Interstitial Flow

Glioblastoma recurrence is a major hindrance to treatment success and is driven by the invasion of glioma stem cells (GSCs) into healthy tissue that are inaccessible to surgical resection and are resistant to existing chemotherapies. Tissue-level fluid movement, or interstitial fluid flow (IFF), regulates GSC invasion in a manner dependent on the tumor microenvironment (TME), highlighting the need for model systems that incorporate both IFF and the TME. We present an accessible method for replicating the invasive TME in glioblastoma: a hyaluronan-collagen I hydrogel composed of human GSCs, astrocytes, and microglia seeded in a tissue culture insert. Elevated IFF can be represented by applying a fluid pressure head to the hydrogel. Additionally, this model can be tuned to replicate inter- or intra-patient differences in cellular ratios, flow rates, or matrix stiffnesses. Invasion can be quantified, while gels can be harvested for a variety of outcomes, including GSC invasion, flow cytometry, protein or RNA extraction, or imaging.

Author Spotlight: Patient-Informed 3D Model for Studying Glioblastoma Invasion via Interstitial Fluid Flow

We present a method for replicating the glioma tumor microenvironment at the invasive front that incorporates interstitial fluid flow. This model is a hyaluronan-collagen I hydrogel in a tissue culture insert where a fluid pressure head can be applied. Invasion can be quantified, and cells can be isolated or lysed.

Glioblastoma recurrence is a major hindrance to treatment success and is driven by the invasion of glioma stem cells (GSCs) into healthy tissue that are ...

Using Chick Embryo Brain as a Model to Study Human Glioblastoma Cell Behavior

Using the Chick Embryo Brain as a Model for In Vivo and Ex Vivo Analyses of Human Glioblastoma Cell Behavior

The chick embryo has been an ideal model system for the study of vertebrate development, particularly for experimental manipulations. Use of the chick embryo has been extended for studying the formation of human glioblastoma (GBM) brain tumors in vivo and the invasiveness of tumor cells into surrounding brain tissue. GBM tumors can be formed by injection of a suspension of fluorescently labeled cells into the E5 midbrain (optic tectum) ventricle in ovo. 
Depending on the GBM cells, compact tumors randomly form in the ventricle and within the brain wall, and groups of cells invade the brain wall tissue. Thick tissue sections (350 &#181;m) of fixed E15 tecta with tumors can be immunostained to reveal that invading cells often migrate along blood vessels when analyzed by 3D reconstruction of confocal z-stack images. Live E15 midbrain and forebrain slices (250-350 &#181;m) can be cultured on membrane inserts, where fluorescently labeled GBM cells can be introduced into non-random locations to provide ex vivo co-cultures to analyze cell invasion, which also can occur along blood vessels, over a period of about 1 week. These ex vivo co-cultures can be monitored by widefield or confocal fluorescence time-lapse microscopy to observe live cell behavior. 
Co-cultured slices then can be fixed, immunostained, and analyzed by confocal microscopy to determine whether or not the invasion occurred along blood vessels or axons. Additionally, the co-culture system can be used for investigating potential cell-cell interactions by placing aggregates of different cell types and colors in different precise locations and observing cell movements. Drug treatments can be performed on ex vivo cultures, whereas these treatments are not compatible with the in ovo system. These two complementary approaches allow for detailed and precise analyses of human GBM cell behavior and tumor formation in a highly manipulatable vertebrate brain environment.

Author Spotlight: Using the Chick Embryo Brain as a Model for In Vivo and Ex Vivo Analyses of Human Glioblastoma Cell Behavior  

Chick embryos are used for studying human glioblastoma (GBM) brain tumors in ovo and in ex vivo brain slice co-cultures. GBM cell behavior can be recorded by time-lapse microscopy in ex vivo co-cultures, and both preparations can be analyzed at the experimental endpoint by detailed 3D confocal analysis.

The chick embryo has been an ideal model system for the study of vertebrate development, particularly for experimental manipulations. Use of the chick ...

Neuroscience

Generation of a Three-Dimensional Spheroid Model of Tumor Cell Invasion

<a href='https://app.jove.com/v/60998/a-3d-spheroid-model-for-glioblastoma'>Source: Guyon, J., et al. A 3D Spheroid Model for Glioblastoma.&#160;J. Vis. Exp.&#160;(2020)</a>The video demonstrates the generation of a three-dimensional spheroid model of tumor cell invasion. Spheroids are formed from human brain tumor cells and embedded in a collagen matrix. The tumor cells at the spheroid periphery adopt an invasive phenotype, secreting proteases to degrade the collagen and advancing to invade the surrounding matrix.

Source: Guyon, J., et al. A 3D Spheroid Model for Glioblastoma.&#160;J. Vis. Exp.&#160;(2020)The video demonstrates the generation of a three-dimensional ...

A 3D Spheroid Model for Glioblastoma

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