We would like to thank Dr. Silvia Soddu and Dr. Giulia Federici (Unit of Cellular Networks and Molecular Therapeutic Targets, IRCCS-Regina Elena National Cancer Institute, Rome, Italy) for access to the IncuCyte S3 Live Cell Imaging System in the preliminary set up of the imaging protocol. Moreover, we thank Bernadett Kolozsvari for the technical advice. The study was supported by the Children with Cancer UK grant (16-234) and The Italian Ministry of Health Ricerca Corrente. M Vinci is a Children with Cancer UK Fellow. R Ferretti is a recipient of Fondazione Veronesi Fellowship (2018 and 2019). The authors acknowledge Fondazione Heal for their support and the Children&#39;s Hospital Foundation for funding the Queensland Children&#39;s Tumor Bank.

This protocol follows the guidelines of the institutions&#39; human research ethics committees.
NOTE: This study was performed using Incucyte S3 and/or SX5 Live-Cell Analysis Instrument (referenced as live cell analysis instrument).
1. Generation of reproducibly sized tumor spheroids
NOTE: The protocol (section 1) described by Vinci et al. 20157,12, was used as reported below, with some modifications:
<ol>
	<li>Collect the DMG H3K27M-mutant neurospheres (NS) and centrifuge at 170 x g for 10 minutes (min) at room temperature (RT).</li>
	<li>Incubate the NS with 500 &#181;L of the accutase solution for 3 min at 37 &#176;C to break them up.</li>
	<li>Neutralize the accutase solution with tumor stem cell (TSM) medium7 and centrifuge the cell suspension at 355 x g for 5 min at RT.</li>
	<li>Resuspend the cell pellet in 1 mL of TSM medium and then count the cells using a cell counting chamber.</li>
	<li>Dilute the cell suspension to obtain 2.5-5 x 103cells/mL and seed 100 &#181;L/well into ultra-low attachment (ULA) 96-well round-bottom plates (see Table of Materials). Use a proper cell density to obtain individual NS of ~300 &#181;m diameter, 4 days after cell seeding (250-500 cells/well for highly aggressive glioma cells).</li>
	<li>Visually confirm the NS formation by using an inverted microscope 4 days after cell seeding.</li>
</ol>
2. Preparation of the ALR/antibody complex and setup for the invasion assay
NOTE: For the antibody labeling procedure, the antibody labeling dyes protocol10 for live-cell Immunocytochemistry is used with some modifications, as reported below. For the invasion assay, the protocol previously described by Vinci et al. 201512 is followed.
<ol>
	<li>Consider the number of wells (e.g., 60 wells) to analyze and calculate the volume needed for each reagent. Also include the wells for the negative control (samples with ALR but without antibody).</li>
	<li>Add 100 &#181;L of sterile water to the ALR to rehydrate the reagent (final concentration = 0.5 mg/mL). Pipette to mix the solution. 
	NOTE: The reagent is light-sensitive; therefore, keep in the dark. Aliquot the leftover reagent and store at -80 &#176;C (avoid freezing and thawing).</li>
	<li>Mix the antibody with the ALR in the TSM medium (or appropriate cell growth media for the cell line of choice) in a round bottom multi-well plate or in an amber tube and protect from light.</li>
	<li>Prepare enough quantity of the medium to dispense 25 &#181;L/well at 3x final assay concentration. Incubate at RT for 15 min. 
	NOTE: A 1:3 molar ratio of antibody to ALR is recommended, with a final (1x) concentration of the test antibody &#60;1.5 &#181;g/mL. For the experiments in this protocol an anti-human CD44 mouse antibody is used (starting concentration 86 &#181;g/mL) at a final concentration of 0.1 &#181;g/mL (3x concentration = 0.3 &#181;g/mL).Add the reagents in the following order: i) antibody; ii) ALR; iii) TSM medium. Mix by pipetting.</li>
	<li>Dilute the background suppressor reagent (BSR) in TSM medium (or appropriate cell growth media for cell line of choice) at 1.5 mM (3x) to obtain at the end of the assay a final concentration of 0.5 mM.</li>
	<li>Perform the invasion assay directly in the ULA 96-well round-bottom plate where cells were initially seeded. Check the NS visually using an inverted microscope before starting.</li>
	<li>Gently and slowly remove 75 &#181;L/well of the medium, avoiding touching the bottom of the well where the NS sits. Check the presence of the NS visually.</li>
	<li>Gently add 25 &#181;L of the BSR to each well.</li>
	<li>Gently add 25 &#181;L of the ALR/antibody complex to each well. Wait 2 or 3 min to let the ALR/antibody complex mix with the medium.</li>
	<li>Check visually using an inverted microscope to ensure that each NS is centrally located at the bottom of the well. Avoid the formation of bubbles. If any bubble is present, remove it by using a needle.</li>
	<li>Place the plate on ice and wait 5 min to let the bottom of the plate become cold.</li>
	<li>With a pre-cooled p200 tip, dispense 75 &#181;L/well of basal membrane matrix (BMM), placing the pipette tip on the internal wall of the well and avoiding touching the bottom of the well. Avoid the formation of bubbles and remove with a sterile needle the existing ones. 
	NOTE: Make sure to have thawed the BMM at 4 &#176;C from the night before.</li>
	<li>Leave the plate on ice for 5 min to let the BMM mix with the medium. Check visually using an inverted microscope the presence of the NS and that they are centrally located in the well. If not, centrifuge the plate at 4 &#176;C at 180 x g for 5 min.</li>
	<li>Transfer the plate in the live-cell analysis instrument (Table of Materials) placed within the incubator at 37 &#176;C, 5% CO2, 95% humidity.</li>
</ol>
3. Preparation of the ALR/antibody complex and setup for the migration assay
NOTE: For the antibody labeling procedure, the Labeling Dyes protocol10 for Live-Cell Immunocytochemistry is used.
<ol>
	<li>Consider the number of wells to analyze and calculate the volume needed for each reagent. Include also the wells needed for the negative controls. Check the NS visually using an inverted microscope before starting.</li>
	<li>Use flat-bottom 96-well plates. Perform the coating procedure as described by Vinci et al., 201314. For this study, the BMM is used as a thin coating.</li>
	<li>Once the coating is ready, remove the excess of BMM coating with a p200 tip placing the tip in the edge of the well and avoiding touching the bottom. If working with multiple wells, use a multichannel pipette.</li>
	<li>Cut a p200 tip, take 50 &#181;L of the cell medium + NS from each selected well, and transfer it to a coated flat bottom well. Check the presence and the position of the NS in each well visually. 
	NOTE: Each NS must be centrally located in the well. Avoid leaning on the tip on the edge of the well during the transfer but drop the medium centrally in the well without touching the bottom. For highly migratory cells, consider a higher number of replicates than the standard three replicates. This is because when NS sits too close to the edge of the well, the migrating cells may cover a smaller area of the well.</li>
	<li>Rehydrate the ALR as described above (steps 2.2-2.3). 
	NOTE: Reagent is light sensitive. See above for good handling procedures.</li>
	<li>Mix the antibody with ALR in the appropriate complete cell growth media in a round bottom multi-well plate or in an amber tube and protect from light. Prepare enough quantity to dispense 50 &#181;L/well at 3x final assay concentration. Incubate at RT for 15 min. 
	NOTE: Add the reagents in the order as indicated above (step 2.4).</li>
	<li>Follow the same procedure as reported in step 2.5.</li>
	<li>Gently add 50 &#181;L of the BSR to each well.</li>
	<li>Gently add 50 &#181;L of the ALR/antibody to each well. Wait 2 or 3 min to let the reagents mix and check visually using an inverted microscope to ensure that most of the replicate NS are centrally located in the well.</li>
	<li>Avoid the formation of bubbles and remove any existing ones by using a needle. Gently transfer the plate in the live-cell analysis instrument placed within the incubator at 37 &#176;C, 5% CO2, 95% humidity.</li>
</ol>
4. Live-cell analysis instrument setting for image acquisition
<ol>
	<li>Scan the plates using the live-cell analysis instrument (for specifications, see Table of Materials) with scanning intervals starting from time point zero (t0) of the invasion and migration assays set up, respectively, after step 2.14. and 3.10. up to 96 h. 
	NOTE: Ensure to be able to dispose of the live-cell analysis instrument immediately after the starting of the invasion and migration assay. Depending on the tumor type, cells can start to invade or migrate from the NS already within 1 h from the assay setup.</li>
	<li>On the live-cell analysis instrument software, select the option Schedule to Acquire. Click on the + tab and select the option Scan on Schedule.</li>
	<li>On the software window Create or Restore Vessel, click on the option New.</li>
	<li>Select the specific application in the live-cell analysis instrument for the invasion and migration acquisition. Select Spheroid scan type, 4x objective, Phase+Brightfield and Green image channels for the invasion assay. Select Dilution Cloning scan type, 4x objective and Phase and Green for the migration assay.</li>
	<li>Select the plate type and define the wells to be scanned by highlighting them on the plate map.</li>
	<li>Set up the scanning frequency (for the experiments in this protocol scanning frequency was 15 min for invasion and 30 min for migration).</li>
	<li>Click on Add to Schedule and start the scan.</li>
</ol>
5. Live-cell analysis instrument setting for image analysis
<ol>
	<li>Select the tab Create New Analysis Definition.</li>
	<li>Select Spheroid Invasion or Basic Analyzer application for invasion and migration, respectively, on the tab.</li>
	<li>Select the invasion and migration appropriate channels (for Invasion: Phase+Brightfield-Green; for Migration: Phase-Green) in the image channel.</li>
	<li>Select few representative images from 3-4 wells for previewing and refining the analysis setting.</li>
	<li>For the invasion assay, in the Analysis Definition tab, adjust the application settings in the Brightfield and Green channels with the following setting to generate a precise segmentation between the Whole Spheroid and Invading Cells (see Figure 5; blue mask): 
	Brightfield Segmentation: Whole Spheroid sensitivity = 50; Invading Cell sensitivity = 100; Clean Up = default. 
	Whole Spheroid Filters: set all parameters as default. 
	Invading Cells Filters: set all parameters as default. 
	Green Segmentation: Radius = 900.</li>
	<li>For migration assay, adjust the application settings in the Phase and Green channels to generate a precise segmentation between the Confluence and Green Cells (see Figure 5, yellow and pink masks) with the following setting: 
	Phase: set all parameters as default. 
	Green Segmentation: Radius = 300; Threshold = 1000 
	Cleanup: Hole Fill = 400; Filters = default. 
	Whole Well: set all parameters as default.</li>
	<li>Check that the analysis settings are correct for the NS by clicking randomly on several wells. The segmentation must outline the spheroid. If not, adjust the setting accordingly.</li>
	<li>Select the wells and time points to analyze.</li>
	<li>Save the Analysis Definition and click on Finish.</li>
</ol>

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The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript.

The live-3D-cell immunocytochemistry we have adopted here for pediatric DMG invasion and migration could be easily adapted also for other highly invasive tumor cell types, including breast and colon cancer cell lines. 
Different from previously performed live-2D-cell immunocytochemistry assays10, when working in 3D, it is suggested to pay attention to some critical steps. In particular, for the invasion assay we describe, it is advised to add the ALR/antibody mix direct...

The ability of tumor cells to evade and disseminate through the surrounding tissue is a hallmark of cancer1. In particular, tumor cell motility is a characteristic feature of malignant tumors, whether it is a metastatic tumor type such as breast2 or colorectal cancer3 or a locally invasive type such as diffuse glioma4,5.
Imaging has a central role in the investigation of many aspects of tumor cell phenotypes; however, live-cell imaging is definitely to be preferred when studying dynamic cellular processes such as migration and invasion, when changes in morphology and cell-cell interaction6,7 occur and can be more easily examined over time. For live-cell imaging, different optical microscopy systems can be used, from phase contrast to confocal fluorescent microscopes, and image acquisition performed over a short or long period of time on an inverted microscope equipped with a chamber for temperature and CO2 control, or in high-content image analysis systems which have built-in chambers, or alternatively in image systems that can sit in the incubator without the need to disturb the cells during the whole duration of the experiment. The choice of the system used is often dictated by a number of factors such as resolution needed, length of the overall acquisition time and time intervals, vessel type used and throughput of the assay (single chamber or multi-well plate), the sensitivity of the cells used (precious and/or rare cells) and phototoxicity of the cells if fluorophores are present.
With regard to fluorescent imaging in live mode, this can be achieved by transducing cells for the expression of fluorescent proteins either for stable expression or as an inducible system8, by transient cell transfection, or by using cell dyes which are now available for live-cell labeling7, for live-cell tracking as well as for labeling subcellular organelles9.
A useful approach has been recently developed for live-cell immunocytochemistry, where an antibody recognizing a surface marker of choice can be bound to a labeling reagent, and upon addition to the culture media, cells expressing the specific marker can be readily imaged in real-time by live-cell imaging. The visualization and quantification of marker expression using such a system can be easily achieved when cells are grown in two-dimensional (2D) culture conditions10.
In this study, we optimized protocols for live-3D-cell immunocytochemistry invasion and migration of pediatric diffuse midline glioma (DMG) patient-derived cells11,12. DMG are highly aggressive brain tumors affecting children, for the vast majority associated with the driver mutation K27M in histone H3 variants. DMG arise in the brain stem and the midline regions of the central nervous system (CNS) and are characterized by a highly infiltrative nature. This invasive capacity has been shown to be at least in part mediated by the intratumor heterogeneity and the cancer-stem-like features of DMG cells7.
To exemplify our assays, an antibody labeling reagent (ALR) was used in combination with an antibody for CD44. CD44 is a transmembrane glycoprotein and adhesion molecule expressed on stem-cell and other cell types, associated with cancer stem cell phenotype and tumor cell migration and invasion13. The protocols include the sample preparation, the image acquisition in brightfield and fluorescent mode, and the analysis on a live-cell analysis instrument that allowed to quantitatively measure in real-time the overall CD44 expression on the DMG cell membrane during 3D invasion and migration. The assays also allowed the possibility to visualize the intermittent fluorescent signal of CD44 on individual cells while migrating and invading. Interestingly an effect of the anti-CD44 antibody was also observed, which potentially acting as a blocking antibody, also seemed to reduce cell migration and invasion as well as to induce a switch of the invasion pattern from a collective mesenchymal-like to a more single-cell amoeboid-like phenotype.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96 Well TC-Treated Microplates</td>
			<td>Corning</td>
			<td>3595</td>
			<td>size 96 wells, polystyrene plate, flat bottom</td>
		</tr>
		<tr>
			<td>Accutase</td>
			<td>Euroclone</td>
			<td>ECB3056D</td>
			<td>solution for neurosphere dissociation</td>
		</tr>
		<tr>
			<td>Burker chamber</td>
			<td>Mv medical</td>
			<td>FFL16034</td>
			<td>cell counting chamber</td>
		</tr>
		<tr>
			<td>CD-44 (156-3C11)</td>
			<td>Cell Signaling Technology</td>
			<td>3570</td>
			<td>Mouse mAb IgG2a</td>
		</tr>
		<tr>
			<td>Corning Matrigel Matrix</td>
			<td>Corning</td>
			<td>356237</td>
			<td>Basement Membrane Matrix (BMM), Phenol Red-free, LDEV-free</td>
		</tr>
		<tr>
			<td>Fabfluor-488 Antibody Labeling Dye</td>
			<td>Incucyte</td>
			<td>4743</td>
			<td>Antibody labelling reagent (ALR): Mouse IgG2a 488 antibody for Live-Cell Immunocytochemistry</td>
		</tr>
		<tr>
			<td>Incucyte S3 and/or SX5 Live-Cell Analysis Instrument</td>
			<td>Sartorius</td>
			<td>-</td>
			<td>The Incucyte S3 and/or SX5 Instrument is used for real-time cell monitoring and surveillance, cell health and viability, migration and invasion, plus a wide range of phenotypic cell-based assays.</td>
		</tr>
		<tr>
			<td>Inverted Microscope</td>
			<td></td>
			<td>-</td>
			<td>any inverted microscope</td>
		</tr>
		<tr>
			<td>Opti-Green Background Suppressor Reagent</td>
			<td>Incucyte</td>
			<td>6500-0045</td>
			<td>Backgroung suppressor reagent (BSR)</td>
		</tr>
		<tr>
			<td>Tumor stem cell (TSM) medium</td>
			<td>-</td>
			<td>-</td>
			<td>growth cell medium (see reference in the text for details)</td>
		</tr>
		<tr>
			<td>Ultra-Low Attachment Multiple Well Plate</td>
			<td>Corning Costar</td>
			<td>7007</td>
			<td>size 96 well, round bottom clear</td>
		</tr>
	</tbody>
</table>

live-3d-cell immunocytochemistry assays of pediatric diffuse midline glioma

Cell migration and invasion are specific hallmarks of Diffuse Midline Glioma (DMG) H3K27M-mutant tumors. We have already modeled these features using three-dimensional (3D) cell-based invasion and migration assays. In this study, we have optimized these 3D assays for live-cell immunocytochemistry. An Antibody Labeling Reagent was used to detect in real-time the expression of the adhesion molecule CD44, on the plasma membrane of migrating and invading cells of a DMG H3K27M primary patient-derived cell line. CD44 is associated with cancer stem cell phenotype and tumor cell migration and invasion and is involved in the direct interactions with the central nervous system (CNS) extracellular matrix. Neurospheres (NS) from the DMG H3K27M cell line were embedded into the basal membrane matrix (BMM) or placed onto a thin coating layer of BMM, in the presence of an anti-CD44 antibody in conjunction with the antibody labeling reagent (ALR). The live-3D-cell immunocytochemistry image analysis was performed on a live-cell analysis instrument to quantitatively measure the overall CD44 expression, specifically on the migrating and invading cells. The method also allows visualizing in real-time the intermittent expression of CD44 on the plasma membrane of migrating and invading cells. Moreover, the assay also provided new insights into the potential role of CD44 in the mesenchymal to amoeboid transition in DMG H3K27M cells.

Live-3D-Cell Immunocytochemistry protocol for invasion and migration is summarized in a straightforward and reproducible workflow in Figure 1. By seeding the DMG cells in ULA 96-well round-bottom plates, reproducible sized NS are obtained and used in the steps displayed. When the NS have reached the ideal size of ~300 &#181;m (approximately 4 days post-seeding) the invasion12 and migration14 assays are initiated. The addition of the ALR/antibod...

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Live-3D-Cell Immunocytochemistry Assays of Pediatric Diffuse Midline Glioma

This study presents a protocol of live-3D-cell immunocytochemistry applied to a pediatric diffuse midline glioma cell line, useful to study in real-time the expression of proteins on the plasma membrane during dynamic processes like 3D cell invasion and migration.

Cell migration and invasion are specific hallmarks of Diffuse Midline Glioma (DMG) H3K27M-mutant tumors. We have already modeled these features using ...

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Cancer Research

2.4K Views.  IRCCS. This study presents a protocol of live-3D-cell immunocytochemistry applied to a pediatric diffuse midline glioma cell line, useful to study in real-time the expression of proteins on the plasma membrane during dynamic processes like 3D cell invasion and migration. 

Video: Live-3D-Cell Immunocytochemistry Assays of Pediatric Diffuse Midline Glioma

A Protocol for Rapid Post-mortem Cell Culture of Diffuse Intrinsic Pontine Glioma (DIPG)

Diffuse Intrinsic Pontine Glioma (DIPG) is a childhood brainstem tumor that carries a universally fatal prognosis. Because surgical resection is not a viable treatment strategy and biopsy is not routinely performed, the availability of patient samples for research is limited. Consequently, efforts to study this disease have been challenged by a paucity of faithful disease models. To address this need, we describe here a protocol for the rapid processing of post-mortem autopsy tissue samples in order to generate durable patient-derived cell culture models that can be used in in vitro assays or in vivo orthotopic xenograft experiments. These models can be used to screen for potential drug targets and to study fundamental pathobiological processes within DIPG. This protocol can further be extended to analyze and isolate tumor and microenvironmental cells using Fluorescence-activated Cell Sorting (FACS), which enables subsequent analysis of gene expression, protein expression, or epigenetic modifications of DNA at the bulk cell or single cell level. Finally, this protocol can also be adapted to generate patient-derived cultures for other central nervous system tumors.

A Protocol for Rapid Post-mortem Cell Culture of Diffuse Intrinsic Pontine Glioma DIPG

This protocol describes a method for the rapid processing of post-mortem diffuse intrinsic pontine glioma samples for the establishment of patient-derived cell culture models or direct characterization of tumor and microenvironmental cells.

Diffuse Intrinsic Pontine Glioma (DIPG) is a childhood brainstem tumor that carries a universally fatal prognosis. Because surgical resection is not a ...

Transplantation of Zebrafish Pediatric Brain Tumors into Immune-competent Hosts for Long-term Study of Tumor Cell Behavior and Drug Response

Tumor cell transplantation is an important technique to define the mechanisms controlling cancer cell growth, migration, and host response, as well as to assess potential patient response to therapy. Current methods largely depend on using syngeneic or immune-compromised animals to avoid rejection of the tumor graft. Such methods require the use of specific genetic strains that often prevent the analysis of immune-tumor cell interactions and/or are limited to specific genetic backgrounds. An alternative method in zebrafish takes advantage of an incompletely developed immune system in the embryonic brain before 3 days, where tumor cells are transplanted for use in short-term assays (i.e., 3 to 10 days). However, these methods cause host lethality, which prevents the long-term study of tumor cell behavior and drug response. This protocol describes a simple and efficient method for the long-term orthotopic transplantation of zebrafish brain tumor tissue into the fourth ventricle of a 2-day-old immune-competent zebrafish. This method allows: 1) long-term study of tumor cell behaviors, such as invasion and dissemination; 2) durable tumor response to drugs; and 3) re-transplantation of tumors for the study of tumor evolution and/or the impact of different host genetic backgrounds. In summary, this technique allows cancer researchers to assess engraftment, invasion, and growth at distant sites, as well as to perform chemical screens and cell competition assays over many months. This protocol can be extended to studies of other tumor types and can be used to elucidate mechanisms of chemoresistance and metastasis.

The transplantation of cancer cells is an important tool for the identification of cancer mechanisms and therapeutic responses. Current techniques depend on immune-incompetent animals. Here, we describe a method to transplant zebrafish tumor cells into immune-competent embryos for the long-term analysis of tumor cell behavior and in vivo drug responses.

Tumor cell transplantation is an important technique to define the mechanisms controlling cancer cell growth, migration, and host response, as well as to ...

Whole-body PET/MRI of Pediatric Patients: The Details That Matter

Integrated PET/MRI is a hybrid imaging technique enabling clinicians to acquire diagnostic images for tumor assessment and treatment monitoring with both high soft tissue contrast and added metabolic information. Integrated PET/MRI has shown to be valuable in the clinical setting and has many promising future applications. The protocol presented here will provide step-by-step instructions for the acquisition of whole-body 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG) PET/MRI data in children with cancer. It also provides instructions on how to combine a whole-body staging scan with a local tumor scan for evaluation of the primary tumor. The focus of this protocol is to be both comprehensive and time-efficient, which are two ubiquitous needs for clinical applications. This protocol was originally developed for children above 6 years, or old enough to comply with breath-hold instructions, but can also be applied to patients under general anesthesia. Similarly, this protocol can be modified to fit institutional preferences in terms of choice of MRI pulse sequences for both the whole-body scan and local tumor assessment.

This article provides comprehensive step-by-step instructions for the acquisition of whole-body 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG) PET/MRI scans for cancer staging of pediatric patients. The protocol was developed for children above 6 years, or old enough to comply with breath-hold instructions, but can be used for general anesthesia patients as well.

Integrated PET/MRI is a hybrid imaging technique enabling clinicians to acquire diagnostic images for tumor assessment and treatment monitoring with both ...

Determination of Protein Expression Level in Cultured Cells by Immunocytochemistry on Paraffin-embedded Cell Blocks

Immunofluorescent staining is currently the method of choice for determination of protein expression levels in cell-culture systems when morphological information is also necessary. The protocol of immunocytochemical staining on paraffin-embedded cell blocks, presented herein, is an excellent alternative to immunofluorescent staining on non-paraffin-embedded fixed cells. In this protocol, a paraffin cell block from HeLa cells was prepared using the thromboplastin-plasma method, and immunocytochemistry was performed for the evaluation of two proliferation markers, CKAP2 and Ki-67. The nuclei and cytoplasmic morphology of the HeLa cells were well preserved in the cell-block slides. At the same time, the CKAP2 and Ki-67 staining patterns in the immunocytochemistry were quite similar to those in immunohistochemical staining in paraffin cancer tissues. With modified cell-culture conditions, including pre-incubation of HeLa cells under serum-free conditions, the effect could be evaluated while preserving architectural information. In conclusion, immunocytochemistry on paraffin-embedded cell blocks is an excellent alternative to immunofluorescent staining.

Currently, immunofluorescent staining on fixed cells is the method of choice for determination of protein expression levels when morphological information is also necessary. This protocol presented herein provides for an alternative method of immunocytochemistry on paraffin-embedded cell blocks.

Immunofluorescent staining is currently the method of choice for determination of protein expression levels in cell-culture systems when morphological ...

Evaluation of Biomarkers in Glioma by Immunohistochemistry on Paraffin-Embedded 3D Glioma Neurosphere Cultures

Analysis of protein expression in glioma is relevant for several aspects in the study of its pathology. Numerous proteins have been described as biomarkers with applications in diagnosis, prognosis, classification, state of tumor progression, and cell differentiation state. These analyses of biomarkers are also useful to characterize tumor neurospheres (NS) generated from glioma patients and glioma models. Tumor NS provide a valuable in vitro model to assess different features of the tumor from which they are derived and can more accurately mirror glioma biology. Here we describe a detailed method to analyze biomarkers in tumor NS using immunohistochemistry (IHC) on paraffin-embedded tumor NS.

Neurospheres grown as 3D cultures constitute a powerful tool to study glioma biology. Here we present a protocol to perform immunohistochemistry while maintaining the 3D structure of glioma neurospheres through paraffin embedding. This method enables the characterization of glioma neurosphere properties such as stemness and neural differentiation.

Analysis of protein expression in glioma is relevant for several aspects in the study of its pathology. Numerous proteins have been described as ...

Longitudinal Intravital Imaging of Brain Tumor Cell Behavior in Response to an Invasive Surgical Biopsy

Biopsies are standard of care for cancer treatment and are clinically beneficial as they allow solid tumor diagnosis, prognosis, and personalized treatment determination. However, perturbation of the tumor architecture by biopsy and other invasive procedures has been associated with undesired effects on tumor progression, which need to be studied in depth to further improve the clinical benefit of these procedures. Conventional static approaches, which only provide a snapshot of the tumor, are limited in their ability to reveal the impact of biopsy on tumor cell behavior such as migration, a process closely related to tumor malignancy. In particular, tumor cell migration is the key in highly aggressive brain tumors, where local tumor dissemination makes total tumor resection virtually impossible. The development of multiphoton imaging and chronic imaging windows allows scientists to study this dynamic process in living animals over time. Here, we describe a method for the high-resolution longitudinal imaging of brain tumor cells before and after a biopsy in the same living animal. This approach makes it possible to study the impact of this procedure on tumor cell behavior (migration, invasion, and proliferation). Furthermore, we discuss the advantages and limitations of this technique, as well as the ability of this methodology to study changes in the cancer cell behavior for other surgical interventions, including tumor resection or the implantation of chemotherapy wafers.

Here we describe a method for high-resolution time-lapse multiphoton imaging of brain tumor cells before and after invasive surgical intervention (e.g., biopsy) within the same living animal. This method allows studying the impact of these invasive surgical procedures on tumor cells&#39; migratory, invasive, and proliferative behavior at a single cell level.

Biopsies are standard of care for cancer treatment and are clinically beneficial as they allow solid tumor diagnosis, prognosis, and personalized ...

Real-Time Monitoring of Human Glioma Cell Migration on Dorsal Root Ganglion Axon-Oligodendrocyte Co-Cultures

Glioblastoma is one of the most aggressive human cancers due to extensive cellular heterogeneity and the migration properties of hGCs. In order to better understand the molecular mechanisms underlying glioma cell migration, an ability to study the interaction between hGCs and axons within the tumor microenvironment is essential. In order to model this cellular interaction, we developed a mixed culture system consisting of hGCs and dorsal root ganglia (DRG) axon-oligodendrocyte co-cultures. DRG cultures were selected because they can be isolated efficiently and can form the long, extensive projections which are ideal for migration studies of this nature. Purified rat oligodendrocytes were then added on purified rat DRG axons and induced to myelinate. After confirming the formation of compact myelin, hGCs were finally added to the co-culture and their interactions with DRG axons and oligodendrocytes was monitored in real-time using time-lapse microscopy. Under these conditions, hGCs form tumor-like aggregate structures that express GFAP and Ki67, migrate along both myelinated and non-myelinated axonal tracks and interact with these axons through the formation of pseudopodia. Our ex vivo co-culture system can be used to identify novel cellular and molecular mechanisms of hGC migration and could potentially be used for in vitro drug efficacy testing.

Here we present an ex-vivo mixed monolayer culture system for the study of human glioma cell (hGC) migration in real-time. This model provides the ability to observe interactions between hGCs and both myelinated and non-myelinated axons within a compartmentalized chamber.

Glioblastoma is one of the most aggressive human cancers due to extensive cellular heterogeneity and the migration properties of hGCs. In order to better ...

Assays for Validating Histone Acetyltransferase Inhibitors

Lysine acetyltransferases (KATs) catalyze acetylation of lysine residues on histones and other proteins to regulate chromatin dynamics and gene expression. KATs, such as CBP/p300, are under intense investigation as therapeutic targets due to their critical role in tumorigenesis of diverse cancers. The development of novel small molecule inhibitors targeting the histone acetyltransferase (HAT) function of KATs is challenging and requires robust assays that can validate the specificity and potency of potential inhibitors.
This article outlines a pipeline of three methods that provide rigorous in vitro validation for novel HAT inhibitors (HATi). These methods include a test tube HAT assay, Chromatin Hyperacetylation Inhibition (ChHAI) assay, and Chromatin Immunoprecipitation-quantitative PCR (ChIP-qPCR). In the HAT assay, recombinant HATs are incubated with histones in a test tube reaction, allowing for acetylation of specific lysine residues on the histone tails. This reaction can be blocked by a HATi and the relative levels of site-specific histone acetylation can be measured via immunoblotting. Inhibitors identified in the HAT assay need to be confirmed in the cellular environment.
The ChHAI assay uses immunoblotting to screen for novel HATi that attenuate the robust hyperacetylation of histones induced by a histone deacetylase inhibitor (HDACi). The addition of an HDACi is helpful because basal levels of histone acetylation can be difficult to detect via immunoblotting.
The HAT and ChHAI assays measure global changes in histone acetylation, but do not provide information regarding acetylation at specific genomic regions. Therefore, ChIP-qPCR is used to investigate the effects of HATi on histone acetylation levels at gene regulatory elements. This is accomplished through selective immunoprecipitation of histone-DNA complexes and analysis of the purified DNA through qPCR. Together, these three assays allow for the careful validation of the specificity, potency, and mechanism of action of novel HATi.

Inhibitors of histone acetyltransferases (HATs, also known as lysine acetyltransferases), such as CBP/p300, are potential therapeutics for treating cancer. However, rigorous methods for validating these inhibitors are needed. Three in vitro methods for validation include HAT assays with recombinant acetyltransferases, immunoblotting for histone acetylation in cell culture, and ChIP-qPCR.

Lysine acetyltransferases (KATs) catalyze acetylation of lysine residues on histones and other proteins to regulate chromatin dynamics and gene ...

A Rapid Screening Workflow to Identify Potential Combination Therapy for GBM using Patient-Derived Glioma Stem Cells

The glioma stem cells (GSCs) are a small fraction of cancer cells which play essential roles in tumor initiation, angiogenesis, and drug resistance in glioblastoma (GBM), the most prevalent and devastating primary brain tumor. The presence of GSCs makes the GBM very refractory to most of individual targeted agents, so high-throughput screening methods are required to identify potential effective combination therapeutics. The protocol describes a simple workflow to enable rapid screening for potential combination therapy with synergistic interaction. The general steps of this workflow consist of establishing luciferase-tagged GSCs, preparing matrigel coated plates, combination drug screening, analyzing, and validating the results.

The glioma stem cells (GSCs) are a small fraction of cancer cells which play essential roles in tumor initiation, angiogenesis, and drug resistance in ...

Co-culture of Glutamatergic Neurons and Pediatric High-Grade Glioma Cells Into Microfluidic Devices to Assess Electrical Interactions

Pediatric high-grade gliomas (pHGG) represent childhood and adolescent brain cancers that carry a rapid dismal prognosis. Since there is a need to overcome the resistance to current treatments and find a new way of cure, modeling the disease as close as possible in an in vitro setting to test new drugs and therapeutic procedures is highly demanding. Studying their fundamental pathobiological processes, including glutamatergic neuron hyperexcitability, will be a real advance in understanding interactions between the environmental brain and pHGG cells. Therefore, to recreate neurons/pHGG cell interactions, this work shows the development of a functional in vitro model co-culturing human-induced Pluripotent Stem (hiPS)-derived cortical glutamatergic neurons pHGG cells into compartmentalized microfluidic devices and a process to record their electrophysiological modifications. The first step was to differentiate and characterize human glutamatergic neurons. Secondly, the cells were cultured in microfluidic devices with pHGG derived cell lines. Brain microenvironment and neuronal activity were then included in this model to analyze the electrical impact of pHGG cells on these micro-environmental neurons. Electrophysiological recordings are coupled using multielectrode arrays (MEA) to these microfluidic devices to mimic physiological conditions and to record the electrical activity of the entire neural network. A significant increase in neuron excitability was underlined in the presence of tumor cells.

Recent works uncover the neuronal impact on high-grade pediatric glioma (pHGG) cells and their reciprocal interactions. The present work shows the development of an in vitro model co-culturing pHGG cells and glutamatergic neurons and recorded their electrophysiological interactions to mimic those interactivities.