We would like to thank the Stanford Wu Tsai Neuroscience Microscopy Service, the Stanford Center for Innovations in In Vivo Imaging (SCi3) - small animal imaging center, NIH S10 Shared Instrumentation Grant (S10RR026917-01, PI Michael Moseley, Ph.D.), and Stanford Preclinical Imaging Facility at Porter Drive for providing the equipment and infrastructure for this project. This work was supported by a grant from the National Institute for Child Health and Human Development, grant number R01HD103638. We would like to thank the Schnitzer Group, Stanford University; the Zuo lab, University of Santa Cruz; and the Neurovascular Imaging Laboratory, Boston Photonic Center, University of Boston, for educational discussions on two-photon imaging and cranial window models.

Real-Time Tracking of Nanoparticles in Brain Tumors Using 2P-IVM in Mice

<ol>
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Z., 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=Intubation-free+in+vivo+imaging+of+the+tracheal+mucosa+using+two-photon+microscopy.">Intubation-free in vivo imaging of the tracheal mucosa using two-photon microscopy.</a> Sci Rep. 7 (1), 694 (2017).</li><li>Zong, W., 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=Large-scale+two-photon+calcium+imaging+in+freely+moving+mice.">Large-scale two-photon calcium imaging in freely moving mice.</a> Cell. 185 (7), 1240-1256.e30 (2022).</li><li>Takasaki, K., Abbasi-Asl, R., Waters, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superficial+bound+of+the+depth+limit+of+two-photon+imaging+in+mouse+brain.">Superficial bound of the depth limit of two-photon imaging in mouse brain.</a> eNeuro. 17 (1), (2019).</li><li>Birkner, A., Konnerth, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deep+two-photon+imaging+in+vivo+with+a+red-shifted+calcium+indicator.">Deep two-photon imaging in vivo with a red-shifted calcium indicator.</a> Methods Mol Biol. 1929, 15-26 (1929).</li><li>Busche, M. 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The authors declare that they have no conflict of interest.

We present a method for real-time in vivo NP tracking using 2P-IVM through a cranial window to evaluate the tumor delivery of fluorescent-labeled iron oxide NPs. The surgical technique for this procedure requires a steady hand and advanced experimental surgical skills. It is advisable to practice using carcasses or phantoms before moving forward to live animal experience. As an alternative, Hoeferlin et al. implemented a robotic drill to reduce thermal damage, minimize surgical technique variability, and standar...

Two-photon intravital microscopy (2P-IVM) is a fluorescence imaging technique that allows the visualization of living tissue1.
First developed in the 1990s, 2P-IVM has been used for in vivo analysis of the retina2, kidney3, small intestine4, cochlea5, heart6, trachea7, and the brain in various preclinical models8,9. In the field of neuroscience, 2P-IVM has gained importance as a technique for real-time imaging of the healthy brain in awake animals10, as well as studying diseases of the nervous system such as Alzheimer&#39;s11, Parkinson&#39;s12 and glioblastoma (GBM)13,14,15,16.
2P-IVM offers an elegant solution for studying the tumor microenvironment during the development of GBM. While some previous studies focused on in vitro17 and ex vivo models18, others implemented orthotopic19 and xenotropic20&#160;in vivo models for examining GBM. Madden et al. performed native imaging of CNS-1 rat glioma cell line in a mouse model13. Using an orthotopic GL261-DsRed murine model, Ricard et al. performed an intravenous administration of a fluorophore to enhance the blood vessels in the tumor region in 2P-IVM14.
Here, we apply 2P-IVM for tracking the tumor delivery of fluorescent-labeled iron oxide nanoparticles (NP) in an orthotopic mouse model of GBM. Using a cranial window, this method allows us to study the real-time spatiotemporal distribution of NPs in the brain in detail.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.9% sodium chloride infusion solution</td>
			<td>Baxter Corp</td>
			<td>533-JB1301P</td>
			<td></td>
		</tr>
		<tr>
			<td> 
			Dulbecco&#39;s Modified Eagle Medium</td>
			<td>Invitrogen</td>
			<td>11965-092</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL syringes</td>
			<td>BD</td>
			<td>Luer-Lok syringe, REF309628</td>
			<td></td>
		</tr>
		<tr>
			<td>10%&#160;FBS</td>
			<td>Thermo fisher</td>
			<td>Cytiva SH30910.03HI</td>
			<td></td>
		</tr>
		<tr>
			<td>10% DMSO</td>
			<td>Sigma-Aldrich</td>
			<td>D8418-50ML</td>
			<td></td>
		</tr>
		<tr>
			<td>2-photon microscope</td>
			<td>Prairie Technologies, Bruker</td>
			<td>Prairie Ultima IV</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol applicators, 70%</td>
			<td>Medline Industries, LP</td>
			<td>MDS093810</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol, spray bottle</td>
			<td>Decon Labs Inc</td>
			<td>Decon SaniHol, 04-355-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Aluminum foil</td>
			<td>Reynold Brands</td>
			<td>Reynold Wrap non-stick aluminum foil</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia machine</td>
			<td>Patterson Scientific</td>
			<td>SAS3</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia monitoring&#160;</td>
			<td>Kent Scientific&#160;</td>
			<td>MouseSTAT Jr. Rodent Pulsoxymeter</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic (100x), liquid</td>
			<td>Invitrogen</td>
			<td>15240-096</td>
			<td></td>
		</tr>
		<tr>
			<td>Betadine applicators</td>
			<td>Professional Disposables International, Inc</td>
			<td>S41125</td>
			<td></td>
		</tr>
		<tr>
			<td>Biopsy punch, 5 mm&#160;</td>
			<td>Miltex</td>
			<td>Size 5</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine sustained release</td>
			<td>Zoo Pharm</td>
			<td>Bup SR Lab, 1.0 mg/mL</td>
			<td>A generic drug can be used instead.&#160;</td>
		</tr>
		<tr>
			<td>C6 rat glioma cell line</td>
			<td>ATCC (American Tissue Culture Collection)</td>
			<td>CCL-107</td>
			<td></td>
		</tr>
		<tr>
			<td>Cannulas</td>
			<td>BD</td>
			<td>16 G, 1.1/2&#8221;, 30 G, 1&#8221;</td>
			<td></td>
		</tr>
		<tr>
			<td>Carprofen</td>
			<td>Pfizer&#160;</td>
			<td>Rimadyl, 50 mg/ml</td>
			<td>A generic drug can be used instead.&#160;</td>
		</tr>
		<tr>
			<td>Cefazoline</td>
			<td>Sagent Pharmaceuticals</td>
			<td>25021-101-10, 1 g/vial</td>
			<td>A generic drug can be used instead.&#160;</td>
		</tr>
		<tr>
			<td>Cell strainer, 40 &#181;m</td>
			<td>Fisher Scientific</td>
			<td>87711</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton tip applicators, 6&#8221;&#160;</td>
			<td>Dyad Medical Sourcing, LLC</td>
			<td>HCS1005</td>
			<td></td>
		</tr>
		<tr>
			<td>Dental cement</td>
			<td>Stoelting Co</td>
			<td>51459</td>
			<td>Dental cement kit, clear, 2 components</td>
		</tr>
		<tr>
			<td>Dexamethasone</td>
			<td>Bimeda</td>
			<td>138RX, 2 mg/mL</td>
			<td>A generic drug can be used instead.&#160;</td>
		</tr>
		<tr>
			<td>DietGel</td>
			<td>ClearH2O</td>
			<td>Recovery, 72-06-502</td>
			<td></td>
		</tr>
		<tr>
			<td>Drape&#160;</td>
			<td>Cardinal Health</td>
			<td>Bio Shield Wrap</td>
			<td></td>
		</tr>
		<tr>
			<td>Drill</td>
			<td>Saeyang Microtech</td>
			<td>Escort Pro, B08350</td>
			<td></td>
		</tr>
		<tr>
			<td>Drill tips&#160;</td>
			<td>Hager &#38; Meissinger GmbH</td>
			<td>REF310104001001005</td>
			<td>Size 005, US 1/4</td>
		</tr>
		<tr>
			<td>FIJI imaging analysis software</td>
			<td>National Institute of Health</td>
			<td>https://imagej.net/software/fiji/</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Fisher Scientific</td>
			<td>13-812-41</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze</td>
			<td>Fisher HealthCare</td>
			<td>Sterile Cotton Gauze Pad, 4 x 4&#8221;, 22-415-469</td>
			<td></td>
		</tr>
		<tr>
			<td>Gelfoam&#160;</td>
			<td>Ethicon Inc.&#160;</td>
			<td>Surgifoam absorbable gelatin sponge, Ref. 1972</td>
			<td></td>
		</tr>
		<tr>
			<td>Germinator&#160;</td>
			<td>Cellpoint Scientific&#160;</td>
			<td>Germinator 500, No. 11688</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass coverslips, 5 mm diameter</td>
			<td>Fisher Scientific</td>
			<td>Menzel Cover glass&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves, non-sterile</td>
			<td>Fisher Scientific</td>
			<td>Nitrile powder-free medical examination gloves</td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves, sterile</td>
			<td>Medline Industries, LP</td>
			<td>MDS104070</td>
			<td></td>
		</tr>
		<tr>
			<td>Hair removal cream</td>
			<td>Church &#38; Dwight</td>
			<td>Nair Hair remover lotion&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Hamilton syringe</td>
			<td>Hamilton Company Inc</td>
			<td>Gastight #1701, 10 &#181;L</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS without Ca, Mg</td>
			<td>Fisher Scientific</td>
			<td>PI88284</td>
			<td></td>
		</tr>
		<tr>
			<td>Head bar</td>
			<td>Hongway</td>
			<td>5 mm inner diameter O-rings</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating pad</td>
			<td>Stoelting Co.&#160;</td>
			<td>Rodent warmer X2</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin syringes</td>
			<td>Exel International Medical Products&#160;</td>
			<td>29G x 1/2&#8243;</td>
			<td></td>
		</tr>
		<tr>
			<td>Iron oxide nanoparticles</td>
			<td>Covis Pharma GmbH</td>
			<td>Feraheme ferumoxytol injection, 510 mg/17 mL, 59338077501</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Dechra</td>
			<td>26675-46-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Mice</td>
			<td>Jackson Laboratories</td>
			<td>NSG, Strain 005557</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope (surgery)</td>
			<td>Seiler Medical</td>
			<td>Seiler IQ Q-100-220</td>
			<td></td>
		</tr>
		<tr>
			<td>Nanoparticles</td>
			<td>Custom</td>
			<td></td>
			<td>Iron oxide nanoparticles (Ferumoxytol) labeled with fluorescein isothiocyanate</td>
		</tr>
		<tr>
			<td>Ophtalmic ointment</td>
			<td>Major pharmaceuticals</td>
			<td>Lubrifresh P.M. nighttime ointment, 203964</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen</td>
			<td>Linde Gas &#38; Equipment Inc.&#160;</td>
			<td>High Pressure Steel K Style Cylinder, 249CF, 2000PSIG, CGA 540</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic cups</td>
			<td>Georgia-Pacirif Consumer Products</td>
			<td>Dixie Portion Cup, 2 oz., Plastic, Clear, PK2400</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene tubing</td>
			<td>Braintree Scientific</td>
			<td>50-195-5494</td>
			<td></td>
		</tr>
		<tr>
			<td>Scale</td>
			<td>Ohaus Corp</td>
			<td>CR2200</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel</td>
			<td>Integra Life Sciences Production Corp</td>
			<td>Integra Miltex Stainless steel disposable scalpel</td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>Fisher Scientific</td>
			<td>13-804-18</td>
			<td></td>
		</tr>
		<tr>
			<td>Sealant</td>
			<td>Henkel Corp</td>
			<td>Loctite 4014</td>
			<td></td>
		</tr>
		<tr>
			<td>Single use lab gown</td>
			<td>High Tech Conversions</td>
			<td>17-444-081</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotactic frame</td>
			<td>Stoelting Co.&#160;</td>
			<td>Stoelting New Standard TM</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Vacuum Bottle Top Filtration Systems</td>
			<td>Fisher Scientific</td>
			<td>S2GPU05RE, MilliporeSigma NO.:S2GPU05RE</td>
			<td></td>
		</tr>
		<tr>
			<td>Styrofoam box</td>
			<td>N/A</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical gloves</td>
			<td>Cardinal Health</td>
			<td>19-163-108</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical glue, 3M Vetbond tissues adhesive</td>
			<td>3M Animal Care Prodcuts</td>
			<td>1469SB</td>
			<td></td>
		</tr>
		<tr>
			<td>Tail vein cathether</td>
			<td>Custom</td>
			<td></td>
			<td>Consists of two 30 G cannulas connected with sillicone tubing&#160;</td>
		</tr>
		<tr>
			<td>TrypLE Express (1x), no phenol red</td>
			<td>Invitrogen</td>
			<td>12604-039</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultraviolett torch</td>
			<td>Spring sunshine technology</td>
			<td>Consciot</td>
			<td></td>
		</tr>
	</tbody>
</table>

two-photon intravital microscopy of glioblastoma in a murine model

The delivery of intravenously administered cancer therapeutics to brain tumors is limited by the blood-brain barrier. A method to directly image the accumulation and distribution of macromolecules in brain tumors in vivo would greatly enhance our ability to understand and optimize drug delivery in preclinical models. This protocol describes a method for real-time in vivo tracking of intravenously administered fluorescent-labeled nanoparticles with two-photon intravital microscopy (2P-IVM) in a mouse model of glioblastoma (GBM).
The protocol contains a multi-step description of the procedure, including anesthesia and analgesia of experimental animals, creating a cranial window, GBM cell implantation, placing a head bar, conducting 2P-IVM studies, and post-surgical care for long-term follow-up studies. We show representative 2P-IVM imaging sessions and image analysis, examine the advantages and disadvantages of this technology, and discuss potential applications.
This method can be easily modified and adapted for different research questions in the field of in vivo preclinical brain imaging.

Here, we performed cranial window surgery and engrafted C6 cells in an NSG mouse model of GBM (n = 5). A proper seal between all components involved in the creation of the window (Figure 1A) will ensure the windows&#39; durability for long-term imaging and, additionally, reduce morbidity. Using the stage adapted for in vivo 2P-IVM (Figure 2), we could image animals under anesthesia for up to 2 h without any major motion artifacts. Approximately 10 min a...

Watch this Scientific Journal Video about Two-Photon Intravital Microscopy of Glioblastoma in a Murine Model at JoVE.com

Author Spotlight: Multimodal Imaging Strategies for Optimizing Drug Delivery and Early Detection in Glioblastoma Treatment

We present a novel approach for two-photon microscopy of the tumor delivery of fluorescent-labeled iron oxide nanoparticles to glioblastoma in a mouse model.

Two-Photon Intravital Microscopy of Glioblastoma in a Murine Model

The delivery of intravenously administered cancer therapeutics to brain tumors is limited by the blood-brain barrier. A method to directly image the ...

two-photon-intravital-microscopy-of-glioblastoma-in-a-murine-model

Research

JoVE Journal

Cancer Research

1.3K Views.  Stanford University School of Medicine. We present a novel approach for two-photon microscopy of the tumor delivery of fluorescent-labeled iron oxide nanoparticles to glioblastoma in a mouse model.

Video: Author Spotlight: Multimodal Imaging Strategies for Optimizing Drug Delivery and Early Detection in Glioblastoma Treatment

Coculture Assays to Study Macrophage and Microglia Stimulation of Glioblastoma Invasion

Glioblastoma multiforme (grade IV glioma) is a very aggressive human cancer with a median survival of 1 year post diagnosis. Despite the increased understanding of the molecular events that give rise to glioblastomas, this cancer still remains highly refractory to conventional treatment. Surgical resection of high grade brain tumors is rarely complete due to the highly infiltrative nature of glioblastoma cells. Therapeutic approaches which attenuate glioblastoma cell invasion therefore is an attractive option. Our laboratory and others have shown that tumor associated macrophages and microglia (resident brain macrophages) strongly stimulate glioblastoma invasion. The protocol described in this paper is used to model glioblastoma-macrophage/microglia interaction using in vitro culture assays. This approach can greatly facilitate the development and/or discovery of drugs that disrupt the communication with the macrophages that enables this malignant behavior. We have established two robust coculture invasion assays where microglia/macrophages stimulate glioma cell invasion by 5 - 10 fold. Glioblastoma cells labelled with a fluorescent marker or constitutively expressing a fluorescent protein are plated without and with macrophages/microglia on matrix-coated polycarbonate chamber inserts or embedded in a three dimensional matrix. Cell invasion is assessed by using fluorescent microscopy to image and count only invasive cells on the underside of the filter. Using these assays, several pharmacological inhibitors (JNJ-28312141, PLX3397, Gefitinib, and Semapimod), have been identified which block macrophage/microglia stimulated glioblastoma invasion.

Understanding the malignant behavior of cancer requires creating accurate models of how tumor cells interact with components of the tumor microenvironment, such as macrophages. Here we describe two methods to study glioblastoma cell interaction with tumor associated macrophages and microglia where the effect on glioblastoma invasion is assessed.

Glioblastoma multiforme (grade IV glioma) is a very aggressive human cancer with a median survival of 1 year post diagnosis. Despite the increased ...

Long-term High-Resolution Intravital Microscopy in the Lung with a Vacuum Stabilized Imaging Window

Metastasis to secondary sites such as the lung, liver and bone is a traumatic event with a mortality rate of approximately 90% 1. Of these sites, the lung is the most difficult to assess using intravital optical imaging due to its enclosed position within the body, delicate nature and vital role in sustaining proper physiology. While clinical modalities (positron emission tomography (PET), magnetic resonance imaging (MRI) and computed tomography (CT)) are capable of providing noninvasive images of this tissue, they lack the resolution necessary to visualize the earliest seeding events, with a single pixel consisting of nearly a thousand cells. Current models of metastatic lung seeding postulate that events just after a tumor cell&#39;s arrival are deterministic for survival and subsequent growth. This means that real-time intravital imaging tools with single cell resolution 2 are required in order to define the phenotypes of the seeding cells and test these models. While high resolution optical imaging of the lung has been performed using various ex vivo preparations, these experiments are typically single time-point assays and are susceptible to artifacts and possible erroneous conclusions due to the dramatically altered environment (temperature, profusion, cytokines, etc.) resulting from removal from the chest cavity and circulatory system 3. Recent work has shown that time-lapse intravital optical imaging of the intact lung is possible using a vacuum stabilized imaging window 2,4,5 however, typical imaging times have been limited to approximately 6 hr. Here we describe a protocol for performing long-term intravital time-lapse imaging of the lung utilizing such a window over a period of 12 hr. The time-lapse image sequences obtained using this method enable visualization and quantitation of cell-cell interactions, membrane dynamics and vascular perfusion in the lung. We further describe an image processing technique that gives an unprecedentedly clear view of the lung microvasculature.

This protocol describes the use of multiphoton microscopy to perform long-term high-resolution, single cell imaging of the intact lung in real time using a vacuum stabilized imaging window.

Metastasis to secondary sites such as the lung, liver and bone is a traumatic event with a mortality rate of approximately 90% 1. Of these sites, the lung ...

A Mouse Model of Fatigue Induced by Peripheral Irradiation

Cancer-related fatigue (CRF) is a distressing and costly condition that often affects patients receiving cancer treatments, including radiation therapy. Here we describe a method using targeted peripheral irradiation to induce fatigue-like behavior in mice. With appropriate shielding, the irradiation targets the lower abdominal/pelvic region of the mouse, sparing the brain, in an effort to model radiation treatment received by individuals with pelvic cancers. We deliver an irradiation dose that is sufficient to induce fatigue-like behavior in mice, measured by voluntary wheel-running activity (VWRA), without causing obvious morbidity. Since wheel running is a normal, voluntary behavior in mice, its use should have little confounding effect on other behavioral tests or biological measures. Hence, wheel running can be used as a feasible outcome measure in understanding the behavioral and biological correlates of fatigue. CRF is a complex condition with frequent comorbidities, and likely has causes related both to cancer and its various treatments. The methods described in this paper are useful for investigating radiation-induced changes that contribute to the development of CRF and, more generally, to explore the biological networks that can explain the development and persistence of a peripherally-triggered but centrally-driven behavior like fatigue.

We describe a method using targeted peripheral irradiation to induce fatigue-like behavior in mice. The selected non-lethal irradiation dose leads to a week-long reduction in voluntary wheel-running activity.

Cancer-related fatigue (CRF) is a distressing and costly condition that often affects patients receiving cancer treatments, including radiation therapy. ...

PET and MRI Guided Irradiation of a Glioblastoma Rat Model Using a Micro-irradiator

For decades, small animal radiation research was mostly performed using fairly crude experimental setups applying simple single-beam techniques without the ability to target a specific or well-delineated tumor volume. The delivery of radiation was achieved using fixed radiation sources or linear accelerators producing megavoltage (MV) X-rays. These devices are unable to achieve sub-millimeter precision required for small animals. Furthermore, the high doses delivered to healthy surrounding tissue hamper response assessment. To increase the translation between small animal studies and humans, our goal was to mimic the treatment of human glioblastoma in a rat model. To enable a more accurate irradiation in a preclinical setting, recently, precision image-guided small animal radiation research platforms were developed. Similar to human planning systems, treatment planning on these micro-irradiators is based on computed tomography (CT). However, low soft-tissue contrast on CT makes it very challenging to localize targets in certain tissues, such as the brain. Therefore, incorporating magnetic resonance imaging (MRI), which has excellent soft-tissue contrast compared to CT, would enable a more precise delineation of the target for irradiation. In the last decade also biological imaging techniques, such as positron emission tomography (PET) gained interest for radiation therapy treatment guidance. PET enables the visualization of e.g., glucose consumption, amino-acid transport, or hypoxia, present in the tumor. Targeting those highly proliferative or radio-resistant parts of the tumor with a higher dose could give a survival benefit. This hypothesis led to the introduction of the biological tumor volume (BTV), besides the conventional gross target volume (GTV), clinical target volume (CTV), and planned target volume (PTV).
At the preclinical imaging lab of Ghent University, a micro-irradiator, a small animal PET, and a 7 T small animal MRI are available. The goal was to incorporate MRI-guided irradiation and PET-guided sub-volume boosting in a glioblastoma rat model.

In the past, small animal irradiation was usually performed without the ability to target a well-delineated tumor volume. The goal was to mimic the treatment of human glioblastoma in rats. Using a small animal irradiation platform, we performed MRI-guided 3D conformal irradiation with PET-based sub-volume boosting in a preclinical setting.

For decades, small animal radiation research was mostly performed using fairly crude experimental setups applying simple single-beam techniques without ...

Fluorescence Molecular Tomography for In Vivo Imaging of Glioblastoma Xenografts

Tumorigenicity is the capability of cancer cells to form a tumor mass. A widely used approach to determine if the cells are tumorigenic is by injecting immunodeficient mice subcutaneously with cancer cells and measuring the tumor mass after it becomes visible and palpable. Orthotopic injections of cancer cells aim to introduce the xenograft in the microenvironment that most closely resembles the tissue of origin of the tumor being studied. Brain cancer research requires intracranial injection of cancer cells to allow the tumor formation and analysis in the unique microenvironment of the brain. The in vivo imaging of intracranial xenografts monitors instantaneously the tumor mass of orthotopically engrafted mice. Here we report the use of fluorescence molecular tomography (FMT) of brain tumor xenografts. The cancer cells are first transduced with near infrared fluorescent proteins and then injected in the brain of immunocompromised mice. The animals are then scanned to obtain quantitative information about the tumor mass over an extended period of time. Cell pre-labeling allows for cost effective, reproducible, and reliable quantification of the tumor burden within each mouse. We eliminated the need for injecting imaging substrates, and thus reduced the stress on the animals. A limitation of this approach is represented by the inability to detect very small masses; however, it has better resolution for larger masses than other techniques. It can be applied to evaluate the efficacy of a drug treatment or genetic alterations of glioma cell lines and patient-derived samples.

Fluorescence Molecular Tomography for In Vivo Imaging of Glioblastoma Xenografts

Orthotopic intracranial injection of tumor cells has been used in cancer research to study brain tumor biology, progression, evolution, and therapeutic response. Here we present fluorescence molecular tomography of tumor xenografts, which provides real-time intravital imaging and quantification of a tumor mass in preclinical glioblastoma models.

Tumorigenicity is the capability of cancer cells to form a tumor mass. A widely used approach to determine if the cells are tumorigenic is by injecting ...

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.

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 ...

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 ...

Longitudinal Intravital Imaging Through Clear Silicone Windows

Intravital microscopy (IVM) enables visualization of cell movement, division, and death at single-cell resolution. IVM through surgically inserted imaging windows is particularly powerful because it allows longitudinal observation of the same tissue over days to weeks. Typical imaging windows comprise a glass coverslip in a biocompatible metal frame sutured to the mouse&#8217;s skin. These windows can interfere with the free movement of the mice, elicit a strong inflammatory response, and fail due to broken glass or torn sutures, any of which may necessitate euthanasia. To address these issues, windows for long-term abdominal organ and mammary gland imaging&#160;were developed from a thin film of polydimethylsiloxane (PDMS), an optically clear silicone polymer previously used for cranial imaging windows. These windows can be glued directly to the tissues, reducing the time needed for insertion. PDMS is flexible, contributing to its durability in mice over time&#8212;up to 35 days have been tested. Longitudinal imaging is imaging of the same tissue region during separate sessions. A stainless-steel grid was embedded within the windows to localize the same region, allowing the visualization of dynamic processes (like mammary gland involution) at the same locations, days apart. This silicone window also allowed monitoring of single disseminated cancer cells developing into micro-metastases over time. The silicone windows used in this study are simpler to insert than metal-framed glass windows and cause limited inflammation of the imaged tissues. Moreover, embedded grids allow for straightforward tracking of the same tissue region in repeated imaging sessions.

An approach is here presented for long-term intravital imaging using optically clear, silicone windows that can be glued directly to the tissue/organ of interest and the skin.&#160;These windows are cheaper and more versatile than others currently used in the field, and the surgical insertion causes limited inflammation and distress to the animals.

Intravital microscopy (IVM) enables visualization of cell movement, division, and death at single-cell resolution. IVM through surgically inserted imaging ...

Surgical Technique for Superior Cervical Ganglionectomy in a Murine Model

Growing evidence suggests that the sympathetic nervous system plays an important role in cancer progression. Adrenergic innervation regulates salivary gland secretion, circadian rhythm, macular degeneration, immune function, and cardiac physiology. Murine surgical sympathectomy is a method for studying the effects of adrenergic innervation by allowing for complete, unilateral adrenergic ablation while avoiding the need for repeated pharmacologic intervention and the associated side effects. However, surgical sympathectomy in mice is technically challenging because of the small size of the superior cervical ganglion. This study describes a surgical technique for reliably identifying and resecting the superior cervical ganglion to ablate the sympathetic nervous system. The successful identification and removal of the ganglion are validated by imaging the fluorescent sympathetic ganglia using a transgenic mouse, identifying post-resection Horner's syndrome, staining for adrenergic markers in the resected ganglia, and observing diminished adrenergic immunofluorescence in the target organs following sympathectomy. This model enables future studies of cancer progression as well as other physiological processes regulated by the sympathetic nervous system.

The present protocol describes a mouse model of the ablation of adrenergic innervation by identifying and resecting the superior cervical ganglion.

Growing evidence suggests that the sympathetic nervous system plays an important role in cancer progression. Adrenergic innervation regulates salivary ...

Glioblastoma Relapse Post-Resection Model for Therapeutic Hydrogel Investigations

Tumor recurrence is an important factor indicative of a poor prognosis in glioblastoma (GBM). Many studies are attempting to identify effective therapeutic strategies to prevent the recurrence of GBM after surgery. Bioresponsive therapeutic hydrogels capable of sustaining locally released drugs are frequently used for the local treatment of GBM after surgery. However, research is limited due to the lack of a suitable GBM relapse post-resection model. Here, a GBM relapse post-resection model was developed and applied in therapeutic hydrogel investigations. This model was constructed based on the orthotopic intracranial GBM model, which is widely used in studies on GBM. Subtotal resection was performed on the orthotopic intracranial GBM model mouse to mimic the clinical treatment. The residual tumor was used to indicate the size of the tumor growth. This model is easy to build, can better mimic the situation of GBM surgical resection, and can be applied in various studies on the local treatment of GBM relapse post-resection. As a result, the GBM relapse post-resection model provides a unique GBM recurrence model for effective local treatment studies of relapse post-resection.

The present protocol establishes a glioblastoma (GBM) relapse post-resection model using microscopy to investigate the therapeutic effect of an injectable, bioresponsive hydrogel in vivo.