Edith Suss-Toby is thanked for her assistance in the time-lapse microscopy and image analysis. Nofar Rada is thanked for the artistic work.

Four- to six-week-old female C57BL/CJ mice (Harlan, Jerusalem, Israel) were used in the experiment according to the Association for Assessment and Accreditation of Laboratory Animal Care specifications. All experimental procedures were done in accordance with Institutional Animal Care and Use Committee and the Department of Agriculture regulations.
1. Harvesting the Spinal Cord
<ol>
	<li>Euthanize the mouse using a CO2 chamber. Avoid cervical dislocation as it might cause damage to the ganglion roots due to shear forces. From here on, perform all steps under sterile conditions.</li>
	<li>Soak animal down with 70% ethanol. This step is important for sterilization and for preventing the hair from dragging through the inner organs.</li>
	<li>Leave the mouse to dry from ethanol. Prevent any contact of ethanol with the inner organs due to neurotoxicity.</li>
	<li>After drying the mouse, position it using pins in prone position (face down). Place the pins on each hindlimb and forelimb.</li>
	<li>Using forceps, make a midline incision extending craniocaudally from the posterior neck to the lumbar spine. Next, raise dermal flaps bilaterally using forceps and expose subcutaneous tissue.</li>
	<li>Palpate mouse skull until reaching the craniocervical junction. Using scissors perpendicular to the animal, cut through the cervical muscles and spine at the craniocervical junction (the 7th cervical vertebrae), using heavy forceps. Dissect the spine caudally and excise the spine with heavy forceps until reaching the lumbar level (hind limbs level).</li>
	<li>Perform a complete caudal transection at the lumbar spine level (the 5th lumbar vertebrae) using heavy forceps.</li>
	<li>Roll the mouse over (face up). There is no need to cover the incision since the DRG is extracted from lower vertebral levels and not the cervical.</li>
	<li>Cut down at the midline from the neck to the abdomen, retract the skin laterally and then cut to open the peritoneum.</li>
	<li>Remove the inner organs inside the peritoneum (liver, spleen, pancreas, stomach, and intestine) en bloc. Next, remove the retroperitoneal organs (i.e., kidneys and pancreas). Cranially, open the chest wall.</li>
	<li>Using forceps and a surgical blade, cut the ribs, leaving 5 mm of ribs bilaterally away from the vertebral column. At this point, the vertebral column is separated from the rest of the body.</li>
	<li>Wash the vertebral column from blood with cold (4 &#176;C) fresh phosphate buffered saline (PBS) twice.</li>
</ol>
2. Isolating the Dorsal Root Ganglia (DRG)
<ol>
	<li>Use a stereomicroscope with 4X magnification.</li>
	<li>Position the spine on a non-adherent non absorbing platform (Telfa/nylon). Position the spine face up&#160;at the same cranio-caudal orientation.</li>
	<li>Remove any spinal muscles and connective tissue. Use the ribs as a landmark for nerves as they leave the spine. Ribs also protect the nerves from the surgical tools. The DRG are located at the cervical, thoracic, and lumbar sites of the vertebrae.</li>
	<li>Next, using scissors cut the vertebral body in the midline and expose the spinal cord and DRG roots by gentle lateral retraction of the vertebral body.</li>
	<li>In the intercostal space, follow the peripheral nerve medially along the rib lateral to the DRG.</li>
	<li>Identify the DRG. It looks like the yolk of &#39;fried egg&#39; lying on the nerve.</li>
	<li>Cut the intercostal nerve distal to the DRG leaving 2-3 mm of nerve distal to the ganglia, to be used for retraction. This &#34;tail&#34; will be removed after harvesting.</li>
	<li>Grasp the nerve using forceps. Pinching the DRG body itself will cause neural cell damage and should be avoided.</li>
	<li>Approach the DRG proximally along its attachment to the spinal cord, via its anterior and posterior roots.</li>
	<li>Apply gentle retraction to the DRG by pulling the efferent nerve (intercostal nerve stump) laterally, and cut the anterior and posterior roots close to the DRG.</li>
	<li>Keep the DRG in a 35 mm Petri dish filled with fresh, ice cold DMEM supplemented with 10% fetal calf serum (FCS), 1% penicillin-streptomycin, 1% non-essential amino acids, and 1% Sodium pyruvate.</li>
</ol>
3. Implantation in the Petri Dish
<ol>
	<li>Perform the next steps on ice using pre-cooled pipette tips to prevent ECM solidification.</li>
	<li>Under a stereomicroscope at 2-4X magnification, place a 35 mm glass bottom petri dish on a paper grid. 
	IMPORTANT: Work on ice in order to keep the ECM in liquid state. Create a 1 mm diameter spot (approximately 20 &#181;l) of growth factor-depleted ECM at the center of the grid.</li>
	<li>Under direct visualization, place the DRG at the center of the ECM spot close to the bottom of the dish. 
	Note: The cancer cells used in this protocol are murine pancreatic cancer cells (KPC) established from freshly isolated tumor specimens from KPC mice as described elsewhere19.</li>
	<li>Harvest 40,000 cancer cells from confluent cultures, wash them once with PBS, and resuspend them in 40 &#181;l ECM on ice.</li>
	<li>Under direct visualization of the grid using a stereomicroscope measure 500 &#181;m at each direction from the DRG. At this point slowly seed 10,000 cells/10 &#181;l ECM. Use a 2-10 &#181;l precooled tip to inject the cells close to the dish bottom, avoiding their spread in the matrix or detachment of the matrix. (Figure 1).</li>
	<li>Leave the dish within a laminar flow hood for 10-15 min&#160;to solidify. Avoid ECM drying.</li>
	<li>Slowly add DMEM, prepared as previously mentioned, against the side wall of the plate. Add enough medium to cover the ECM (about 2 ml).</li>
	<li>Put the dish back to the incubator at 37 &#176;C.</li>
	<li>Replace the medium with fresh medium on the following day.</li>
	<li>Replace the medium every 2 days.</li>
</ol>
4. Data Acquisition, Time-lapse Videomicroscopy
<ol>
	<li>On day 7 after the implantation, take the dish for time lapse microscopy. Note that certain cells might require acquisition earlier due to faster migration.</li>
	<li>During the live imaging, place the dish in a closed environment at a mean temperature of 37 &#177;0.1 &#176;C and 5% CO2.</li>
	<li>Record the cells by using a charge coupled device camera placed on the microscope.</li>
	<li>Take digitized images every 10 min&#160;for up to 72 hr&#160;to follow cell locomotion from three to six different cells.</li>
	<li>Replace medium after 24 hr.</li>
	<li>Perform data acquisition and simple analysis using the microscope software.</li>
</ol>
5. Data Analysis
<ol>
	<li>For more advanced applications (i.e., cell tracking in 2D or 3D) use specialized software (such as Imaris 4D). Note: This software determines the xy coordinates of a cell at any given time, along with the distance from origin, and speed of motion.</li>
	<li>Calculate the mean velocity by measuring the travel distance between subsequent positions in 10 min&#160;intervals. Calculate the Forward Migration Index (FMI) which is the distance of the cell front from the neurite and describes the unidirectional movement of the cells toward the DRG.</li>
</ol>

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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perineural+invasion+is+associated+with+increased+relapse+after+external+beam+radiotherapy+for+men+with+low-risk+prostate+cancer+and+may+be+a+marker+for+occult,+high-grade+cancer.">Perineural invasion is associated with increased relapse after external beam radiotherapy for men with low-risk prostate cancer and may be a marker for occult, high-grade cancer.</a> Int J Radiat Oncol Biol Phys. 58, 19-24 (2004).</li><li>Maru, N., Ohori, M., Kattan, M. W., Scardino, P. T., Wheeler, T. 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O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neurotrophic+factor+artemin+promotes+pancreatic+cancer+invasion.">The neurotrophic factor artemin promotes pancreatic cancer invasion.</a> Ann Surg. 244, 274-281 (2006).</li><li>Takahashi, T., 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=Perineural+invasion+by+ductal+adenocarcinoma+of+the+pancreas.">Perineural invasion by ductal adenocarcinoma of the pancreas.</a> J Surg Oncol. 65, 164-170 (1997).</li><li>Zhu, 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=Nerve+growth+factor+expression+correlates+with+perineural+invasion+and+pain+in+human+pancreatic+cancer.">Nerve growth factor expression correlates with perineural invasion and pain in human pancreatic cancer.</a> J Clin Oncol. 17, 2419-2428 (1999).</li><li>Hirai, I., 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=Perineural+invasion+in+pancreatic+cancer.">Perineural invasion in pancreatic cancer.</a> Pancreas. 24, 15-25 (2005).</li><li>Mitchem, J. 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O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+invasion+in+pancreatic+cancer,+a+mutual+tropism+between+neurons+and+cancer+cells.">Neural invasion in pancreatic cancer, a mutual tropism between neurons and cancer cells.</a> Biochem Biophys Res Commun. 374, 442-447 (2008).</li><li>Bapat, A. A., Hostetter, G., Von Hoff, D. D., Han, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perineural+invasion+and+associated+pain+in+pancreatic+cancer.">Perineural invasion and associated pain in pancreatic cancer.</a> Nat Rev Cancer. 11, 695-707 (2011).</li><li>Ketterer, K., 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=Reverse+transcription-PCR+analysis+of+laser-captured+cells+points+to+potential+paracrine+and+autocrine+actions+of+neurotrophins+in+pancreatic+cancer.">Reverse transcription-PCR analysis of laser-captured cells points to potential paracrine and autocrine actions of neurotrophins in pancreatic cancer.</a> Clin Cancer Res. 9, 5127-5136 (2003).</li><li>Gil, 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=Nerve-sparing+therapy+with+oncolytic+herpes+virus+for+cancers+with+neural+invasion.">Nerve-sparing therapy with oncolytic herpes virus for cancers with neural invasion.</a> Clin Cancer Res. 13, 6479-6485 (2007).</li><li>Gil, 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=Paracrine+regulation+of+pancreatic+cancer+cell+invasion+by+peripheral+nerves.">Paracrine regulation of pancreatic cancer cell invasion by peripheral nerves.</a> J Natl Cancer Inst. 102, 107-118 (2010).</li><li>Weizman, N., 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=Macrophages+mediate+gemcitabine+resistance+of+pancreatic+adenocarcinoma+by+upregulating+cytidinedeaminase.">Macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by upregulating cytidinedeaminase.</a> Oncogene. 33, 3812-3819 (2014).</li></ol>

This research was supported by the ICRF Barbara S. Goodman endowed research career development award (2011-601-BGPC) and a grant from the US-Israel Binational Science Foundation. No other financial disclosures from the authors are to be made.

This article presents an in vitro model that recapitulates the cancerous microenvironment in the neural niche, the DRG model. The video demonstrates all the steps starting from recognizing anatomical landmarks such as the DRG in the mouse, its extraction, and finally, its culturing in ECM. Co-culturing the DRG alongside with cancer cells is also presented. There are no other models for in vitro perineural invasion research described in the literature making this model essential for studying the perineur...

Solid tumors disseminate in three main ways: direct invasion, lymphatic spread, and hematogenic spread. However, there is a fourth means of cancer spread that is frequently disregarded, dissemination along nerves. Cancerous neural invasion (CNI) is a well-known route of cancer spread, especially in cancers of the head and neck,1 prostate2, 3 and pancreas.4-8 CNI occurs in more than 80% of individuals with pancreatic adenocarcinoma, leading to retroperitoneal tumor spread through celiac ganglion nerves. These neurotropic cancer cells have a unique ability to migrate unidirectionally along nerves towards the central nervous system (CNS).9 This finding suggests that the perineural microenvironment can be exploited by cancer cells, providing factors that support malignant growth.
One of the few in vitro models for CNI research is the dorsal root ganglia (DRG)/cancer cell model. This model is frequently used for studying the paracrine interaction between neural stroma and cancer cells.10-18 In this model, mouse or human cancer cell lines are grown in extracellular matrix (ECM) adjacent to preparations of freshly dissociated cultured DRG.
This video article shows the application of in vitro CNI in pancreatic ductal adenocarcinoma.

<table><tbody><tr><td>&lt;strong&gt;Equipment:&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Operating microscope</td><td>Leica</td><td>M205</td><td></td></tr><tr><td>Time Lapse System</td><td>Zeiss</td><td></td><td></td></tr><tr><td>Forceps</td><td>Sigma-Aldrich</td><td>F4142&amp;nbsp;</td><td></td></tr><tr><td>Surgical blade</td><td>Sigma-Aldrich</td><td>Z309036</td><td></td></tr><tr><td>Scissors</td><td>Sigma-Aldrich</td><td>S3271</td><td></td></tr><tr><td>35 mm Petri dishes, glass bottom</td><td>de groot</td><td>60-627860</td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&amp;nbsp;&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Materials:&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>70% ethanol</td><td>Sigma</td><td></td><td></td></tr><tr><td>Cold PBS</td><td>Biological industries</td><td>02-023-1A</td><td></td></tr><tr><td>DMEM</td><td>Biological industries</td><td>01-055-1A</td><td></td></tr><tr><td>FCS</td><td>Rhenium</td><td>10108165</td><td></td></tr><tr><td>Penicillin and streptomycin</td><td>Biological industries</td><td>01-031-1B</td><td></td></tr><tr><td>Sodium Pyruvate</td><td>Biological industries</td><td>03-042-1B</td><td></td></tr><tr><td>L-Glutamine</td><td>Biological industries</td><td>03-020-1B</td><td></td></tr><tr><td>Growth factor-depleted matrigel</td><td>Trevigen</td><td>3433-005-01</td><td></td></tr></tbody></table>

in vitro modeling of cancerous neural invasion: the dorsal root ganglion model

One way that solid tumors disseminate is through neural invasion. This route is well-known in cancers of the head and neck, prostate, and pancreas. These neurotropic cancer cells have a unique ability to migrate unidirectionally along nerves towards the central nervous system (CNS). The dorsal root ganglia (DRG)/cancer cell model is a three dimensional (3D) in vitro model frequently used for studying the interaction between neural stroma and cancer cells. In this model, mouse or human cancer cell lines are grown in ECM adjacent to preparations of freshly dissociated cultured DRG. In this article, the DRG isolation protocol from mice, and implantation in petri dishes for co-culturing with pancreatic cancer cells are demonstrated. Five days after implantation, the cancer cells made contact with the DRG neurites. Later, these cells formed bridgeheads to facilitate more extensive polarized, neurotropic migration of cancer cells.

Using video microscopy imaging, the DRG can be seen sprouting neurites 5-7 days after implantation while the cancer cells migrating away from their colonies toward the DRG. By the 7th day after the implantation, the cancer cells come in contact with the neurites (Figure 2).
The Forward migration index of the pancreatic cancer cells used in the protocol is 3-4 fold higher than that of other cell lines ...

Watch this Scientific Journal Video about In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model at JoVE.com

In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model

This video article shows the use of the dorsal root ganglia (DRG)/cancer cell model in pancreatic ductal adenocarcinoma.

In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model

One way that solid tumors disseminate is through neural invasion. This route is well-known in cancers of the head and neck, prostate, and pancreas. These ...

in-vitro-modeling-cancerous-neural-invasion-dorsal-root-ganglion

Research

JoVE Journal

Neuroscience

9.0K Views.  Rambam Medical Healthcare Campus. This video article shows the use of the dorsal root ganglia (DRG)/cancer cell model in pancreatic ductal adenocarcinoma.

Video: In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model

A Model for Perineural Invasion in Head and Neck Squamous Cell Carcinoma

Perineural invasion (PNI) is found in approximately 40% of head and neck squamous cell carcinomas (HNSCC). Despite multimodal treatment with surgery, radiation, and chemotherapy, locoregional recurrences and distant metastases occur at higher rates, and overall survival is decreased by 40% compared to HNSCC without PNI. In vitro studies of the pathways involved in HNSCC PNI have historically been challenging given the lack of a consistent, reproducible assay. Described here is the adaptation of the dorsal root ganglion (DRG) assay for the examination of PNI in HNSCC. In this model, DRG are harvested from the spinal column of a sacrificed nude mouse and placed within a semisolid matrix. Over the subsequent days, neurites are generated and grow in a radial pattern from the cell bodies of the DRG. HNSCC cell lines are then placed peripherally around the matrix and invade preferentially along the neurites toward the DRG. This method allows for rapid evaluation of multiple treatment conditions, with very high assay success rates and reproducibility.

Perineural invasion (PNI) is a common feature of head and neck squamous cell carcinoma (HNSCC), conferring lower survival rates. Its mechanisms are poorly understood. Utilizing neurites generated from murine dorsal root ganglia confined to a semisolid matrix, the pathways involved in the PNI of HNSCC cell lines can be investigated.

Perineural invasion (PNI) is found in approximately 40% of head and neck squamous cell carcinomas (HNSCC). Despite multimodal treatment with surgery, ...

Cancer Research

An In Vivo Murine Sciatic Nerve Model of Perineural Invasion

Cancer cells invade nerves through a process termed perineural invasion (PNI), in which cancer cells proliferate and migrate in the nerve microenvironment. This type of invasion is exhibited by a variety of cancer types, and very frequently is found in pancreatic cancer. The microscopic size of nerve fibers within mouse pancreas renders the study of PNI difficult in orthotopic murine models. Here, we describe a heterotopic in vivo model of PNI, where we inject syngeneic pancreatic cancer cell line Panc02-H7 into the murine sciatic nerve. In this model, sciatic nerves of anesthetized mice are exposed and injected with cancer cells. The cancer cells invade in the nerves proximally toward the spinal cord from the point of injection. The invaded sciatic nerves are then extracted and processed with OCT for frozen sectioning. H&amp;E and immunofluorescence staining of these sections allow quantification of both the degree of invasion and changes in protein expression. This model can be applied to a variety of studies on PNI given its versatility. Using mice with different genetic modifications and/or different types of cancer cells allows for investigation of the cellular and molecular mechanisms of PNI and for different cancer types. Furthermore, the effects of therapeutic agents on nerve invasion can be studied by applying treatment to these mice.

An In Vivo Murine Sciatic Nerve Model of Perineural Invasion

We describe an in vivo murine model of perineural invasion by injecting syngeneic pancreatic cancer cells into the sciatic nerve. The model allows for quantification of the extent of nerve invasion, and supports investigation of the cellular and molecular mechanisms of perineural invasion.

Cancer cells invade nerves through a process termed perineural invasion (PNI), in which cancer cells proliferate and migrate in the nerve ...

Dorsal Root Ganglion Injection and Dorsal Root Crush Injury as a Model for Sensory Axon Regeneration

Achieving axon regeneration after nervous system injury is a challenging task. As different parts of the central nervous system (CNS) differ from each other anatomically, it is important to identify an appropriate model to use for the study of axon regeneration. By using a suitable model, we can formulate a specific treatment based on the severity of injury, the neuronal cell type of interest, and the desired spinal tract for assessing regeneration. Within the sensory pathway, DRG neurons are responsible for relaying sensory information from the periphery to the CNS. We present here a protocol that uses a DRG injection with a viral vector and a concurrent dorsal root crush injury in the lower cervical spinal cord of an adult rat as a model to study sensory axon regeneration. As demonstrated using a control virus, AAV5-GFP, we show the effectiveness of a direct DRG injection in transducing DRG neurons and tracing sensory axons into the spinal cord. We also show the effectiveness of the dorsal root crush injury in denervating the forepaw as an injury model for evaluating axon regeneration. Despite the requirement for specialized training to perform this invasive surgical procedure, the protocol is flexible, and potential users can modify many parts to accommodate their experimental requirements. Importantly, it can serve as a foundation for those in search of a suitable animal model for their studies. We believe that this article will help new users to learn the procedure in a very efficient and effective manner.

This protocol presents the use of a dorsal root ganglion (DRG) injection with a viral vector and a concurrent dorsal root crush injury in an adult rat as a model to study sensory axon regeneration. This model is suitable for investigating the use of gene therapy to promote sensory axon regeneration.

Achieving axon regeneration after nervous system injury is a challenging task. As different parts of the central nervous system (CNS) differ from each ...

The Chick Chorioallantoic Membrane In Vivo Model to Assess Perineural Invasion in Head and Neck Cancer

Perineural invasion is a phenotype in which cancer surrounds or invades the nerves. It is associated with poor clinical outcome for head and neck squamous cell carcinoma and other cancers. Mechanistic studies have shown that the molecular crosstalk between nerves and tumor cells occurs prior to physical interaction. There are only a few in vivo models to study perineural invasion, especially to investigate early progression, before physical nerve-tumor interactions occur. The chick chorioallantoic membrane model has been used to study cancer invasion, because the basement membrane of the chorionic epithelium mimics that of human epithelial tissue. Here we repurposed the chick chorioallantoic membrane model to investigate perineural invasion, grafting rat dorsal root ganglia and human head and neck squamous cell carcinoma cells onto the chorionic epithelium. We have demonstrated how this model can be useful to evaluate the ability of cancer cells to invade neural tissue in vivo.&#160;

The Chick Chorioallantoic Membrane In Vivo Model to Assess Perineural Invasion in Head and Neck Cancer

Perineural invasion is an aggressive phenotype for head and neck squamous cell carcinomas and other tumors. The chick chorioallantoic membrane model has been used for studying angiogenesis, cancer invasion, and metastasis. Here we demonstrate how this model can be utilized to assess perineural invasion in vivo.

Perineural invasion is a phenotype in which cancer surrounds or invades the nerves. It is associated with poor clinical outcome for head and neck squamous ...

Medicine

Advanced In Vitro Model for Studying Neuronal Hypersensitivity in DRG Cultures

Harvesting, Embedding, and Culturing Dorsal Root Ganglia in Multi-compartment Devices to Study Peripheral Neuronal Features

The most common peripheral neuronal feature of pain is a lowered stimulation threshold or hypersensitivity of terminal nerves from the dorsal root ganglia (DRG). One proposed cause of this hypersensitivity is associated with the interaction between immune cells in the peripheral tissue and neurons. In vitro models have provided foundational knowledge in understanding how these mechanisms result in nociceptor hypersensitivity. However, in vitro models face the challenge of translating efficacy to humans. To address this challenge, a physiologically and anatomically relevant in vitro model has been developed for the culture of intact dorsal root ganglia (DRGs) in three isolated compartments in a 48-well plate. Primary DRGs are harvested from adult Sprague Dawley rats after humane euthanasia. Excess nerve roots are trimmed, and the DRG is cut into appropriate sizes for culture. DRGs are then grown in natural hydrogels, enabling robust growth in all compartments. This multi-compartment system offers anatomically relevant isolation of the DRG cell bodies from neurites, physiologically relevant cell types, and mechanical properties to study the interactions between neural and immune cells. Thus, this culture platform provides a valuable tool for investigating treatment isolation strategies, ultimately leading to an improved screening approach for predicting pain.

Author Spotlight: In Vitro and In Vivo Models to Enhance Chronic Pain Treatment Efficacy

This protocol provides a technique to harvest and culture explanted dorsal root ganglion (DRG) from adult Sprague Dawley rats in a multi-compartment (MC) device.

The most common peripheral neuronal feature of pain is a lowered stimulation threshold or hypersensitivity of terminal nerves from the dorsal root ganglia ...

Bioengineering

Establishing a Three-dimensional Co-culture Model of Murine Dorsal Root Ganglia and Cancer Cells: An In Vitro Model to Study Perineural Cancer Cell Invasion

Source: Huyett, P. et al. <a href="https://www.jove.com/video/55043" target="_blank">A Model for Perineural Invasion in Head and Neck Squamous Cell Carcinoma.</a> J. Vis. Exp. (2017)
In this video, we demonstrate the procedure for developing an in vitro perineural cancer cell invasion model by co-culturing mouse dorsal root ganglion and neurotropic cancer cells. The model can be utilized to conduct cancer assays, producing rapid and reproducible results.

Source: Huyett, P. et al. A Model for Perineural Invasion in Head and Neck Squamous Cell Carcinoma. J. Vis. Exp. (2017)
In this video, we demonstrate the ...

JoVE Encyclopedia of Experiments

Head and Neck Cancer

Assays & techniques

Murine Perineural Invasion Model: Generating an In Vivo Model to Simulate Perineural Invasion in Mouse Sciatic Nerve

Source: Deborde, S. et al. <a href="https://www.jove.com/video/56857" target="_blank">An In Vivo Murine Sciatic Nerve Model of Perineural Invasion.</a> J. Vis. Exp. (2018)
In this video, we develop an in vivo mouse model for perineural invasion by injecting pancreatic cancer cells into the sciatic nerve. This model helps quantify the extent of invasion and study the interactions between cancer cells and nerves.

Source: Deborde, S. et al. An In Vivo Murine Sciatic Nerve Model of Perineural Invasion. J. Vis. Exp. (2018)
In this video, we develop an in vivo mouse ...

Cancers of the Nervous System

In vivo studies

Modeling Cancerous Neural Invasion In Vitro: A Method to Co-culture Dorsal Root Ganglia and Cancer Cells

Source: Na&#39;ara, S. et al. <a href="https://www.jove.com/video/52990" target="_blank">In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model.</a> J. Vis. Exp. (2016)
In this video, we demonstrate an in vitro method for co-culturing DRG and cancer cells to study neurotropism and neural invasion.

Source: Na&#39;ara, S. et al. In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model. J. Vis. Exp. (2016)
In this video, we ...

Generating Dorsal Root Ganglion Explant and Dissociated Cell Culture

Source: Fornaro, M. et al., <a href="https://app.jove.com/v/56757">Adult Mouse DRG Explant and Dissociated Cell Models to Investigate Neuroplasticity and Responses to Environmental Insults Including Viral Infection.</a> J. Vis. Exp. (2018).
This video demonstrates a method to develop dorsal root ganglia or DRG explant culture and DRG-dissociated cell models using isolated mouse DRG tissues. These models help to study various mechanisms with neuron-glial interactions in a controlled environment.

1. Explant culture of DRG from Adult Mouse

	Place the collected DRG in a 35 mm Petri dish containing 3 mL of ice-cold serum-free media (SFM).
	Transfer ...

Neuronal Culture Techniques

Primary Neuronal Culture

Chick Chorioallantoic Membrane or CAM Tumor Model: An In Ovo Method to Simulate Perineural Invasion of Tumor Cells

For grafting of a dorsal root ganglion onto the chorioallantoic membrane, use fine, sterile forceps to carefully grasp one ganglion in the culture dish and gently wash the tissue in a container of fresh HBSS. Place the ganglion onto the chorioallantoic membrane of one egg, being careful not to puncture the membrane, and cover all of the egg openings with sterile transparent film dressings. When all of the eggs have been grafted, return them to the humidifying egg incubator for 2 days without rotation.
At the end of the incubation, transfer the eggs to the laminar flow cabinet, and use scissors and forceps to open the transparent film dressing. Next, add 0.5 to 1 million fluorescently labeled tumor cells in 5 microliters of HBSS onto the chorioallantoic membrane of each egg, about 2 millimeters from each dorsal root ganglion, keeping a uniform distance between the ganglia and the cells. Then, cover the eggs with a new film dressing and return the eggs to the egg incubator for 7 days without rotation.

In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model

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