Name: a syngeneic pancreatic cancer mouse model to study the effects of irreversible electroporation
Uploaded: 2018-06-08T12:30:00
Description: Watch this Scientific Journal Video about A Syngeneic Pancreatic Cancer Mouse Model to Study the Effects of Irreversible Electroporation at JoVE.com

RRW has received support for this work from a Collaborative Translational Research Grant funded by the San Diego C3 Padres Pedal the Cause (#PTC2017).

All animal experiments performed following this protocol must be approved by the respective Institutional Animal Care and Use Committee (IACUC). All procedures described here have been approved by IACUC UCSD.
1. Procure Recipient Animals
NOTE: The KPC-Luc 4580 cell line was established from a tumor arising in a LSL-KrasG12D/+; LSL-Trp53R172H/+; PDX1Cre/+; LSL-ROSA26 Luc/+ mouse (KPC), which is a genetically engineered model ...

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E., 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=Dynamics+of+the+immune+reaction+to+pancreatic+cancer+from+inception+to+invasion.">Dynamics of the immune reaction to pancreatic cancer from inception to invasion.</a> Cancer Res. 67 (19), 9518-9527 (2007).</li><li>Lee, E. W., Loh, C. T., Kee, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+guided+percutaneous+irreversible+electroporation:+ultrasound+and+immunohistological+correlation.">Imaging guided percutaneous irreversible electroporation: ultrasound and immunohistological correlation.</a> Technol Cancer Res Treat. 6 (4), 287-294 (2007).</li><li>Charpentier, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Irreversible+electroporation+for+the+ablation+of+liver+tumors:+are+we+there+yet?.">Irreversible electroporation for the ablation of liver tumors: are we there yet?.</a> Arch Surg. 147 (11), 1053-1061 (2012).</li><li>Narayanan, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Irreversible+Electroporation.">Irreversible Electroporation.</a> Seminars in Interventional Radiology. 32 (4), 349-355 (2015).</li><li>Martin, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Treatment+of+200+locally+advanced+(stage+III)+pancreatic+adenocarcinoma+patients+with+irreversible+electroporation:+safety+and+efficacy.">Treatment of 200 locally advanced (stage III) pancreatic adenocarcinoma patients with irreversible electroporation: safety and efficacy.</a> Ann Surg. 262 (3), 486-494 (2015).</li><li>Belfiore, M. P., 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=Percutaneous+CT-guided+irreversible+electroporation+followed+by+chemotherapy+as+a+novel+neoadjuvant+protocol+in+locally+advanced+pancreatic+cancer:+Our+preliminary+experience.">Percutaneous CT-guided irreversible electroporation followed by chemotherapy as a novel neoadjuvant protocol in locally advanced pancreatic cancer: Our preliminary experience.</a> Int J Surg. 21 Suppl 1, S34-S39 (2015).</li><li>Belfiore, G., 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=Concurrent+chemotherapy+alone+versus+irreversible+electroporation+followed+by+chemotherapy+on+survival+in+patients+with+locally+advanced+pancreatic+cancer.">Concurrent chemotherapy alone versus irreversible electroporation followed by chemotherapy on survival in patients with locally advanced pancreatic cancer.</a> Med Oncol. 34 (3), 38 (2017).</li><li>Chu, K. F., Dupuy, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+ablation+of+tumours:+biological+mechanisms+and+advances+in+therapy.">Thermal ablation of tumours: biological mechanisms and advances in therapy.</a> Nat Rev Cancer. 14 (3), 199-208 (2014).</li><li>Wissniowski, T. 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=Activation+of+tumor-specific+T+lymphocytes+by+radio-frequency+ablation+of+the+VX2+hepatoma+in+rabbits.">Activation of tumor-specific T lymphocytes by radio-frequency ablation of the VX2 hepatoma in rabbits.</a> Cancer Res. 63 (19), 6496-6500 (2003).</li><li>Eros de Bethlenfalva-Hora, C., 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=Radiofrequency+ablation+suppresses+distant+tumour+growth+in+a+novel+rat+model+of+multifocal+hepatocellular+carcinoma.">Radiofrequency ablation suppresses distant tumour growth in a novel rat model of multifocal hepatocellular carcinoma.</a> Clin Sci (Lond). 126 (3), 243-252 (2014).</li><li>Zerbini, A., 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=Radiofrequency+thermal+ablation+for+hepatocellular+carcinoma+stimulates+autologous+NK-cell+response.">Radiofrequency thermal ablation for hepatocellular carcinoma stimulates autologous NK-cell response.</a> Gastroenterology. 138 (5), 1931-1942 (2010).</li><li>Ali, M. Y., 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=Activation+of+dendritic+cells+by+local+ablation+of+hepatocellular+carcinoma.">Activation of dendritic cells by local ablation of hepatocellular carcinoma.</a> J Hepatol. 43 (5), 817-822 (2005).</li><li>Fietta, A. M., 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=Systemic+inflammatory+response+and+downmodulation+of+peripheral+CD25+Foxp3++T-regulatory+cells+in+patients+undergoing+radiofrequency+thermal+ablation+for+lung+cancer.">Systemic inflammatory response and downmodulation of peripheral CD25+Foxp3+ T-regulatory cells in patients undergoing radiofrequency thermal ablation for lung cancer.</a> Hum Immunol. 70 (7), 477-486 (2009).</li><li>Jiang, C., Davalos, R. V., Bischof, J. 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R., 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=Trp53R172H+and+KrasG12D+cooperate+to+promote+chromosomal+instability+and+widely+metastatic+pancreatic+ductal+adenocarcinoma+in+mice.">Trp53R172H and KrasG12D cooperate to promote chromosomal instability and widely metastatic pancreatic ductal adenocarcinoma in mice.</a> Cancer Cell. 7 (5), 469-483 (2005).</li><li>Safran, M., 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=Mouse+reporter+strain+for+noninvasive+bioluminescent+imaging+of+cells+that+have+undergone+Cre-mediated+recombination.">Mouse reporter strain for noninvasive bioluminescent imaging of cells that have undergone Cre-mediated recombination.</a> Mol Imaging. 2 (4), 297-302 (2003).</li><li>Martin, R. 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V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Characterization+and+Numerical+Modeling+of+Tissue+Electrical+Conductivity+during+Pulsed+Electric+Fields+for+Irreversible+Electroporation+Treatment+Planning.">Experimental Characterization and Numerical Modeling of Tissue Electrical Conductivity during Pulsed Electric Fields for Irreversible Electroporation Treatment Planning.</a> IEEE Transactions on Biomedical Engineering. 59 (4), 1076-1085 (2012).</li></ol>

In this study, we have demonstrated an immunocompetent mouse model for PC that can be used to study the effects of IRE on the tumor growth. Currently, IRE is being used as a non-thermal ablation technique only in highly selected locally advanced PC patients who do not have distant disease progression after months of preoperative therapy. Its use has therefore been limited because most patients with locally advanced PC develop distant metastatic disease20. This model will serve as a basis for studi...

Pancreatic ductal adenocarcinoma (PC) is projected to become the second leading cause of cancer deaths in the US around 20201. The vast majority of patients diagnosed with PC will eventually die from distant metastatic disease2. The PC microenvironment is notoriously immunosuppressive and chemoresistant. Its desmoplastic stroma contains a scarcity of effector (anti-tumor) T cells and a prominence of immunosuppressive leukocytes, including tumor-associated macrophages (TAMs), myeloid derived suppressor cells (MDSCs), and regulatory T cells (Tregs)3. These underlie the need to develop multimodal strategies that counteract these effects of the microenvironment.
IRE has been developed as a non-thermal method of tumor ablation. Unlike thermal ablation techniques, IRE does not cause rapid coagulative necrosis but instead results in gradual apoptotic cell death4. Importantly for pancreatic tumors, IRE is not vulnerable to "heat sink" effects and can be performed right next to blood vessels5. This technology has 510(k) clearance from the FDA6 and is currently being used clinically, for selected patients with locally advanced or borderline resectable pancreatic cancer. In the largest published series of IRE for PC7, the median survival of patients undergoing IRE was approximately double the survival of patients treated with modern chemotherapy alone without resection8,9. 
Several studies have demonstrated that thermal ablation induces a systemic immune response in other tumor types (reviewed in Chu et al.10). Radiofrequency ablation (RFA) in animal tumor models leads to increased T cell infiltrates11,12, including an increase in activated natural killer (NK) cells in hepatocellular cancer patients13,14, and a decrease in immunosuppressive Tregs in lung cancer patients15. A much smaller number of studies have examined immune, microenvironmental, and injury responses to IRE16. IRE has been shown to stimulate a systemic immune response in immunocompetent mouse models in which the growth of secondary (contralateral) renal cell allografts was reduced or prevented by IRE of a primary tumor two weeks earlier17. They also observed that immunocompetent mice required less voltage for complete regression than did immunocompromised mice. It has been hypothesized that IRE may result in improved antigen presentation compared to the coagulative necrosis of thermal ablation, but this has not been specifically studied.
We have developed a syngeneic mouse model of PC from the KPC-Luc 4580 cell line (gift from J.J. Yeh at University of North Carolina), which was derived from a tumor that developed in a male LSL-KrasG12D/+; LSL-Trp53R172H/+; PDX1Cre/+; LSL-ROSA26 Luc/+ mouse, to study the local and systemic effects of IRE18,19. This luciferase-expressing cell line is immunogenic and also tumorigenic in immunocompetent C57BL/6 mice when injected SQ or orthotopically and reliably produces liver metastases when injected into the spleen. We have utilized a programmable square wave pulse generator to deliver 100-&#181;s pulses of electricity at a voltage/distance ratio of 1,500 V/cm using a two-needle array probe (separated by 5 mm) or platinum tweezer-trodes to SQ or orthotopic tumors, respectively, in mice to model the effects of IRE in a small animal.

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			<td height="40" style="height:40px;width:216px;">ECM 830 square wave electroporator</td>
			<td style="width:147px;">Harvard Apparatus</td>
			<td style="width:344px;">BTX # 45-0002 ( 58018-004 )</td>
			<td style="width:167px;"></td>
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			<td height="40" style="height:40px;">2 needle array electrode</td>
			<td>Harvard Apparatus</td>
			<td>45-0167</td>
			<td></td>
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			<td height="40" style="height:40px;">Safety foot switch</td>
			<td>Harvard Apparatus</td>
			<td>45-0211</td>
			<td></td>
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			<td height="40" style="height:40px;">Platinum Tweezer-trode</td>
			<td>Harvard Apparatus</td>
			<td>&#160;45-0486</td>
			<td></td>
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			<td height="40" style="height:40px;">DMEM-F12 media</td>
			<td>ThermoFisher Scientific</td>
			<td>11320-033</td>
			<td></td>
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			<td height="40" style="height:40px;">Fetal Bovine Serum</td>
			<td>ThermoFisher Scientific</td>
			<td>10437028</td>
			<td></td>
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			<td height="40" style="height:40px;">Trypsin</td>
			<td>ThermoFisher Scientific</td>
			<td>25200056</td>
			<td></td>
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			<td height="40" style="height:40px;">Matrigel</td>
			<td>Corning&#160;</td>
			<td>354230</td>
			<td></td>
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			<td height="40" style="height:40px;">Isoflurane</td>
			<td>Sigma-Aldrich, Inc.</td>
			<td>792632</td>
			<td></td>
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			<td height="40" style="height:40px;">Lacrilube</td>
			<td>Fisher Scientific&#160;</td>
			<td>19090646</td>
			<td></td>
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			<td height="40" style="height:40px;">Buprenorphine</td>
			<td>Fisher Scientific&#160;</td>
			<td>NC1292810</td>
			<td></td>
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			<td height="40" style="height:40px;">D-luciferrin</td>
			<td>Perkin Elmer</td>
			<td>122799</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">IVIS&#160; Spectrum In Vivo Imaging System</td>
			<td>Perkin Elmer</td>
			<td>124262</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Mouse strain C57BL/6J</td>
			<td>The Jackson Laboratory&#160;</td>
			<td>000664/Black 6</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Cell line (KPC-Luc 4580)</td>
			<td colspan="2">J.J. Yeh Lab at University of North Carolina</td>
			<td></td>
		</tr>
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			<td height="40" style="height:40px;">BD Precisionglide syringe needles</td>
			<td>Sigma-Aldrich, Inc.</td>
			<td>Z192406</td>
			<td></td>
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			<td height="40" style="height:40px;">Alcohol Swab(70% isopropyl alcohol )</td>
			<td>BD</td>
			<td>326895</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Digital calipers</td>
			<td>ThermoFisher Scientific</td>
			<td>14-648-17</td>
			<td></td>
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		<tr height="40">
			<td height="40" style="height:40px;">Disposable Scalpels, Sterile</td>
			<td>VWR</td>
			<td>21909</td>
			<td></td>
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			<td height="40" style="height:40px;">Cotton Tipped Applicators</td>
			<td>VWR</td>
			<td>89198</td>
			<td></td>
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		<tr height="40">
			<td height="40" style="height:40px;">Suture Needle, 45 cm, Size 6-0</td>
			<td>Harvard Apparatus</td>
			<td>72-3308</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;">Suture Needle, 45 cm, Size 4-0</td>
			<td>Harvard Apparatus</td>
			<td>72-3314</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Povidone-iodine 10%</td>
			<td>BD</td>
			<td>29900-404</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disposable Warming Pad&#160;</td>
			<td>KENT SCIENTIFIC CORP.</td>
			<td>TP-3E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse Hair Clipper</td>
			<td>KENT SCIENTIFIC CORP.</td>
			<td>CL8787</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Surgical Drape</td>
			<td>Harvard Apparatus</td>
			<td>59-7421</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate-buffered Saline</td>
			<td>ThermoFisher Scientific</td>
			<td>10010023</td>
			<td></td>
		</tr>
	</tbody>
</table>

a syngeneic pancreatic cancer mouse model to study the effects of irreversible electroporation

Pancreatic cancer (PC), a disease which kills approximately 40,000 patients each year in the US, has successfully evaded several therapeutic approaches including the promising immunotherapeutic strategies. Irreversible electroporation (IRE) is a non-thermal ablation technique that induces tumor cell death without destruction of adjacent collagenous structures, thus enabling the procedure to be performed in tumors very close to blood vessels. Unlike thermal ablation techniques, IRE results in gradual apoptotic cell death, along with immediate ablation induced necrosis, and is currently in clinical use for selected patients with locally advanced PC. An ablative, non-target specific procedure like IRE can induce a myriad of responses in the tumor microenvironment. A few studies have addressed the effects of IRE on tumor growth in other tumor types, but none have focused on PC. We have developed a syngeneic mouse model of PC in which subcutaneous (SQ) and orthotopic tumors can be successfully treated with IRE in a highly controlled setting, facilitating various longitudinal studies post procedure. This animal model serves as a robust system to study the effects of IRE and ways to improve the clinical efficacy of IRE.

We followed the procedure described above and generated SQ tumors on 5 - 6 week old wild type C57BL/6 mice inoculated with 1 x 106 cells with 50% BMM. When the tumor size reached 5 - 6 mm in diameter, a few of the mice were euthanized, their tumors were excised, and implanted orthotopically in a recipient C57BL/6 mice. IRE was performed 10 days post implantation as shown in the timeline on Figure 1. IRE was performed on the remaining mice bearing S...

Watch this Scientific Journal Video about A Syngeneic Pancreatic Cancer Mouse Model to Study the Effects of Irreversible Electroporation at JoVE.com

A Syngeneic Pancreatic Cancer Mouse Model to Study the Effects of Irreversible Electroporation

Irreversible electroporation (IRE) is a non-thermal ablation technique used for the treatment of locally advanced pancreatic cancer. Being a relatively new technique, the effects of IRE on the tumor growth are poorly understood. We have developed a syngeneic mouse model that facilitates studying the effects of IRE on pancreatic cancer.

Pancreatic cancer (PC), a disease which kills approximately 40,000 patients each year in the US, has successfully evaded several therapeutic approaches ...

The overall goal of this model is to study the effects of irreversible electroporation or IRE, on pancreatic cancer in immunocompetent mice. This model can help answer many key questions regarding the role of IRE in pancreatic cancer. Such as, how does IRE affect the local tumor microenvironment?The main advantage of this model is that it facilitate accurate tumor growth assessment in an immunocompetent system, without requiring knockout or mutant mouse models. This method can provide insight into the effects of IRE on the immune system, in an immunocompetent mouse model of pancreatic cancer. For subcutaneous tumor induction, first, shave the injection site on an anesthetized six-week old, male, C57 black six mouse, and use an alcohol swab to clean the site two times.Next, load a cold one-milliliter syringe with one to two times ten to the seven cells per milliliter and 250 microliters of basement membrane matrix. Attach a 25-gauge needle to the syringe, and load the needle with the tumor cell suspension. Press and retract the plunger a few times to remove any air bubbles.Carefully insert the needle under the skin of the injection site, at a 30 degree angle. With the needle parallel to the body, slowly inject 50 microliters of the tumor cells. After 10 seconds, slowly withdraw the needle, keeping it parallel without any sideways movement, and gently clean the injection site with an alcohol swab, before returning the mouse to its cage.When the tumor reaches five to seven millimeters, use sterile forceps and micro scissors to excise the subcutaneous tumor, under sterile conditions in a biosafety level two hood, taking care not to puncture the peritoneal cavity. Immediately wash the excised tumor, two times, in sterile PBS. And use sterile scalpels to mince the tumor into one to two cubed millimeter pieces.Then, transfer the tumor pieces into a Petri dish, containing cold, sterile DMEM basal medium on ice. To implant the tumor fragments, after confirming a lack of response to toe pinch, apply ointment to the anesthetized recipient animal's eyes, and place the mouse on its right side, so that the left side of the abdomen is exposed. Remove the abdominal hair with depilatory cream, and remove the cream with gauze.After disinfecting the exposed skin with three sequential 10%povidone plus iodine and alcohol wipes, use a sterile scalpel to make a 1.5 centimeter incision in the skin, one centimeter to the left of the midline, below the rib cage, and slightly medial to the spleen. Gently externalize the spleen with flat-tipped forceps and a sterile cotton applicator, and use the forceps to laterally retract the tail of the pancreas, at the bottom of the spleen. Using sterile forceps, grasp one finely-minced tumor piece, and pass a fine 6-O sterile suturing needle through the piece.Insert the needle containing tumor fragment into the tail of the pancreas, passing the suture slowly through the tissue. Take care to avoid contact between the tumor and the abdominal wall musculature and peritoneum, to prevent tumor seeding. When the tumor fragment has been secured, completely remove the needle from the tissue, and keep the organs completely externalized, for an additional 60 seconds, while inspecting for any signs of hemorrhage.If no bleeding is observed, use blunt forceps, or a cotton tip applicator, to gently return the spleen, pancreas, and tumor to the abdominal cavity. Before the tumor reaches six millimeters in diameter, place the anesthetized animal on its right side to allow access to the tumor, and use clippers and an alcohol swab to clean the tumor site. Using forceps, elevate the skin directly under the tumor, and insert two needle array electrodes through the skin, parallel to the body, to bracket the tumor, taking care that the electrodes do not penetrate the peritoneal cavity.Set the electroporator to deliver 100 microsecond pulses at a one hertz frequency, at 1500 volts per centimeter, for a total of 150 pulses, and use the foot pedal to deliver the pulses, separating each set of 10 pulses by 10 seconds, to allow heat dissipation between each set of pulses. As muscle twitching occurs during the IRE delivery, and is more pronounced during the initial set of pulses, ensure that the electrodes are still in the desired location, and that the animal is still sedated after each set of pulses. After no more than 200 seconds of dosing, remove the electrodes and record the actual voltage delivered, as displayed on the electroporator.Then, return the mouse to its cage. For IRE of an orthotopic tumor, eight to 10 days post tumor implantation, use blunt-nosed forceps to externalize the tumor with the forceps, and tightly capture the tumor with the platinum electrodes of the Tweezertrode, deliver the electroporation pulses, as just demonstrated, keeping the tumor externalized for the last set of pulses, for at least 60 seconds, to monitor for any signs of hemorrhage. Then, return the tumor to the abdominal cavity and close the incision, as demonstrated, monitoring the animal until it has fully recovered.In this representative experiment, subcutaneous tumors, in nearly 50%of the mice, regressed completely after 150 IRE pulses, with only minor regression after 75 pulses. Histological analysis of the tumor tissue, one week post IRE, revealed large regions of central tumor necrosis, that were not observed in control, untreated tumors, and that were flanked by live tumor tissue, in cases of incomplete tumor regression. Monitoring implanted orthotopic tumors growth rates revealed a consistent tumor growth over time in recipient animals, that could also be disrupted by IRE, demonstrating the ability of this model to simulate the effects of IRE, in an immunocompetent mouse model.Once mastered, this technique can be completed in 15 minutes per mouse, if it is performed properly. While attempting this procedure, it is important to remember to keep the tumor size within the working distance of the IRE electrodes available, as larger tumors will produce inconsistent responses due to incomplete ablation. Other treatment approaches, such as radiation or chemotherapies, can also be used to answer additional questions about whether combining treatments can improve tumor responses to IRE.After watching this video, you should have a good understanding of how to establish subcutaneous and orthotopic pancreatic cancers in mice, and how to perform IRE on these tumors.

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Research

JoVE Journal

Cancer Research

Fluorescent Orthotopic Mouse Model of Pancreatic Cancer

Pancreatic cancer remains one of the cancers for which survival has not improved substantially in the last few decades. Only 7% of diagnosed patients will survive longer than five years. In order to understand and mimic the microenvironment of pancreatic tumors, we utilized a murine orthotopic model of pancreatic cancer that allows non-invasive imaging of tumor progression in real time. Pancreatic cancer cells expressing green fluorescent protein (PANC-1 GFP) were suspended in basement membrane matrix, high concentration, (e.g., Matrigel HC) with serum-free media and then injected into the tail of the pancreas via laparotomy. The cell suspension in the high concentration basement membrane matrix becomes a gel-like substance once it reaches room temperature; therefore, it gels when it comes in contact with the pancreas, creating a seal at the injection site and preventing any cell leakage. Tumor growth and metastasis to other organs are monitored in live animals by using fluorescence. It is critical to use the appropriate filters for excitation and emission of GFP. The steps for the orthotopic implantation are detailed in this article so researchers can easily replicate the procedure in nude mice. The main steps of this protocol are preparation of the cell suspension, surgical implantation, and whole body fluorescent in vivo imaging. This orthotopic model is designed to investigate the efficacy of novel therapeutics on primary and metastatic tumors.

A procedure to implant green fluorescent protein-expressing pancreatic cancer cells (PANC-1 GFP) orthotopically into the pancreas of Balb-c Ola Hsd-Fox1nu mice to assess tumor progression and metastasis is presented here.

Pancreatic cancer remains one of the cancers for which survival has not improved substantially in the last few decades. Only 7% of diagnosed patients will ...

The Colon-26 Carcinoma Tumor-bearing Mouse as a Model for the Study of Cancer Cachexia

Cancer cachexia is the progressive loss of skeletal muscle mass and adipose tissue, negative nitrogen balance, anorexia, fatigue, inflammation, and activation of lipolysis and proteolysis systems. Cancer patients with cachexia benefit less from anti-neoplastic therapies and show increased mortality1. Several animal models have been established in order to investigate the molecular causes responsible for body and muscle wasting as a result of tumor growth. Here, we describe methodologies pertaining to a well-characterized model of cancer cachexia: mice bearing the C26 carcinoma2-4. Although this model is heavily used in cachexia research, different approaches make reproducibility a potential issue. The growth of the C26 tumor causes a marked and progressive loss of body and skeletal muscle mass, accompanied by reduced muscle cross-sectional area and muscle strength3-5. Adipose tissue is also lost. Wasting is coincident with elevated circulating levels of pro-inflammatory cytokines, particularly Interleukin-6 (IL-6)3, which is directly, although not entirely, responsible for C26 cachexia. It is well-accepted that a primary mechanism by which the C26 tumor induces muscle tissue depletion is the activation of skeletal muscle proteolytic systems. Thus, expression of muscle-specific ubiquitin ligases, such as atrogin-1/MAFbx and MuRF-1, represent an accepted method for the evaluation of the ongoing muscle catabolism2. Here, we present how to execute this model in a reproducible manner and how to excise several tissues and organs (the liver, spleen, and heart), as well as fat and skeletal muscles (the gastrocnemius, tibialis anterior, and quadriceps). We also provide useful protocols that describe how to perform muscle freezing, sectioning, and fiber size quantification.

Mice bearing the Colon-26 (C26) carcinoma represent a classical model of cancer cachexia. Progressive muscle wasting occurs in association with tumor growth, over-expression of muscle-specific ubiquitin ligases, and reductions in muscle cross-sectional area. Fat loss is also observed. Cachexia is studied in a time-dependent manner with increasing severity of wasting.

Cancer cachexia is the progressive loss of skeletal muscle mass and adipose tissue, negative nitrogen balance, anorexia, fatigue, inflammation, and ...

A Syngeneic Mouse Model of Metastatic Renal Cell Carcinoma for Quantitative and Longitudinal Assessment of Preclinical Therapies

Renal cell carcinoma (RCC) affects &#62; 60,000 people in the United States annually, and ~ 30% of RCC patients have multiple metastases at the time of diagnosis. Metastatic RCC (mRCC) is incurable, with a median survival time of only 18 months. Immune-based interventions (e.g., interferon (IFN) and interleukin (IL)-2) induce durable responses in a fraction of mRCC patients, and multikinase inhibitors (e.g., sunitinib or sorafenib) or anti-VEGF receptor monoclonal antibodies (mAb) are largely palliative, as complete remissions are rare. Such shortcomings in current therapies for mRCC patients provide the rationale for the development of novel treatment protocols. A key component in the preclinical testing of new therapies for mRCC is a suitable animal model. Beneficial features that recapitulate the human condition include a primary renal tumor, renal tumor metastases, and an intact immune system to investigate any therapy-driven immune effector responses and the formation of tumor-induced immunosuppressive factors. This report describes an orthotopic mRCC mouse model that has all of these features. We describe an intrarenal implantation technique using the mouse renal adenocarcinoma cell line Renca, followed by the assessment of tumor growth in the kidney (primary site) and lungs (metastatic site).

Implementation of an orthotopic model of renal cell carcinoma in immunocompetent mice affords the investigator a clinically-relevant system defined by the presence of a primary renal tumor and lung metastases in the same animal. This system can be used to preclinically test a variety of treatments in vivo.

Renal cell carcinoma (RCC) affects &#62; 60,000 people in the United States annually, and ~ 30% of RCC patients have multiple metastases at the time of ...

A Method to Define the Effects of Environmental Enrichment on Colon Microbiome Biodiversity in a Mouse Colon Tumor Model

Several recent studies have illustrated the beneficial effects of living in an enriched environment on improving human disease. In mice, environmental enrichment (EE) reduces tumorigenesis by activating the mouse immune system, or affects tumor bearing animal survival by stimulating the wound repair response, including improved microbiome diversity, in the tumor microenvironment. Provided here is a detailed procedure to assess the effects of environmental enrichment on the biodiversity of the microbiome in a mouse colon tumor model. Precautions regarding animal breeding and considerations for animal genotype and mouse colony integration are described, all of which ultimately affect microbial biodiversity. Heeding these precautions may allow more uniform microbiome transmission, and consequently will alleviate non-treatment dependent effects that can confound study findings. Further, in this procedure, microbiota changes are characterized using 16S rDNA sequencing of DNA isolated from stool collected from the distal colon following long-term environmental enrichment. Gut microbiota imbalance is associated with the pathogenesis of inflammatory bowel disease and colon cancer, but also of obesity and diabetes among others. Importantly, this protocol for EE and microbiome analysis can be utilized to study the role of microbiome pathogenesis across a variety of diseases where robust mouse models exist that can recapitulate human disease.

Environmental Enrichment (EE) is an animal housing environment that is used to reveal mechanisms that underlie the connections between lifestyle, stress, and disease. This protocol describes a procedure that uses a mouse model of colon tumorigenesis and EE to specifically define alterations in microbiota biodiversity that may impact animal mortality.

Several recent studies have illustrated the beneficial effects of living in an enriched environment on improving human disease. In mice, environmental ...

A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer

Orthotopic tumor modeling is a valuable tool for pre-clinical prostate cancer research, as it has multiple advantages over both subcutaneous and transgenic genetically engineered mouse models. Unlike subcutaneous tumors, orthotopic tumors contain more clinically accurate vasculature, tumor microenvironment, and responses to multiple therapies. In contrast to genetically engineered mouse models, orthotopic models can be performed with lower cost and in less time, involve the use of highly complex and heterogeneous mouse or human cancer cell lines, rather that single genetic alterations, and these cell lines can be genetically modified, such as to express imaging agents. Here, we present a protocol to surgically injecting a luciferase- and mCherry-expressing murine prostate cancer cell line into the anterior prostate lobe of mice. These mice developed orthotopic tumors that were non-invasively monitored in vivo and further analyzed for tumor volume, weight, mouse survival, and immune infiltration. Further, orthotopic tumor-bearing mice were surgically castrated, leading to immediate tumor regression and subsequent recurrence, representing castration-resistant prostate cancer. Although technical skill is required to carry out this procedure, this syngeneic orthotopic model of both androgen-dependent and castration-resistant prostate cancer is of great use to all investigators in the field.

The goal of this protocol is to demonstrate the intra-prostatic injection of prostate cancer cells, with subsequent castration. Orthotopic pre-clinical models of androgen-dependent and castration-resistant prostate cancer are critical to study the disease in the context of a clinically relevant tumor microenvironment and an immunocompetent host.

Orthotopic tumor modeling is a valuable tool for pre-clinical prostate cancer research, as it has multiple advantages over both subcutaneous and ...

Immunophenotyping of Orthotopic Homograft (Syngeneic) of Murine Primary KPC Pancreatic Ductal Adenocarcinoma by Flow Cytometry

Homograft (syngeneic) tumors are the workhorse of today&#39;s immuno-oncology (I/O) preclinical research. The tumor microenvironment (TME), particularly its immune-components, is vital to the prognosis and prediction of treatment outcomes, especially those of immunotherapy. TME immune-components are composed of different subsets of tumor-infiltrating immune cells assessable by multi-color FACS. Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest malignances lacking good treatment options, thus an urgent and unmet medical need. One important reason for its non-responsiveness to various therapies (chemo-, targeted, I/O) has been its abundant TME, consisting of fibroblasts and leukocytes that protect tumor cells from these therapies. Orthotopically implanted PDAC is believed to more accurately recapture the TME of human pancreatic cancers than conventional subcutaneous (SC) models.
Homograft tumors (KPC) are transplants of mouse spontaneous PDAC originating from genetically engineered KPC-mice (KrasG12D/+/P53-/-/Pdx1-Cre) (KPC-GEMM). The primary tumor tissue is cut into small fragments (~2 mm3) and transplanted subcutaneously (SC) to the syngeneic recipients (C57BL/6, 7&#8211;9 weeks old). The homografts were then surgically orthotopically transplanted onto the pancreas of new C57BL/6 mice, along with SC-implantation, which reached tumor volumes of 300&#8211;1,000 mm3 by 17 days. Only tumors of 400&#8211;600 mm3 were harvested per approved autopsy procedure and cleaned to remove the adjacent non-tumor tissues. They were dissociated per protocol using a tissue dissociator into single-cell suspensions, followed by staining with designated panels of fluorescently-labeled antibodies for various markers of different immune cells (lymphoid, myeloid and NK, DCs). The stained samples were analyzed using multi-color FACS to determine numbers of immune cells of different lineages, as well as their relative percentage within tumors. The immune profiles of orthotopic tumors were then compared to those of SC tumors. The preliminary data demonstrated significantly elevated infiltrating TILs/TAMs in tumors over the pancreas, and higher B-cell infiltration into orthotopic rather than SC tumors.

Immunophenotyping of Orthotopic Homograft Syngeneic of Murine Primary KPC Pancreatic Ductal Adenocarcinoma by Flow Cytometry

The experimental procedure on the immunophenotyping of murine orthotopic PDAC homografts aims at profiling the tumor immuno-microenvironment. Tumors are orthotopically implanted via surgery. Tumors of 200&#8211;600 mm3 in size were harvested and dissociated to prepare single-cell suspensions, followed by multi-immune marker FACS analysis using different fluorescently-labeled antibodies.

Homograft (syngeneic) tumors are the workhorse of today&#39;s immuno-oncology (I/O) preclinical research. The tumor microenvironment (TME), particularly ...

Orthotopic Transplantation of Syngeneic Lung Adenocarcinoma Cells to Study PD-L1 Expression

The use of mouse models is indispensable for studying the pathophysiology of various diseases. With respect to lung cancer, several models are available, including genetically engineered models as well as transplantation models. However, genetically engineered mouse models are time-consuming and expensive, whereas some orthotopic transplantation models are difficult to reproduce. Here, a non-invasive intratracheal delivery method of lung tumor cells as an alternative orthotopic transplantation model is described. The use of mouse lung adenocarcinoma cells and syngeneic graft recipients allows studying tumorigenesis under the presence of a fully active immune system. Furthermore, genetic manipulations of tumor cells before transplantation makes this model an attractive time-saving approach to study the impact of genetic factors on tumor growth and tumor cell gene expression profiles under physiological conditions. Using this model, we show that lung adenocarcinoma cells express increased levels of the T-cell suppressor programmed death-ligand 1 (PD-L1) when grown in their natural environment as compared to cultivation in vitro.

Here we describe a minimally invasive syngeneic orthotopic transplantation model of mouse lung adenocarcinoma cells as a time- and cost-reducing model to study non-small cell lung cancer.

The use of mouse models is indispensable for studying the pathophysiology of various diseases. With respect to lung cancer, several models are available, ...

A Syngeneic Mouse B-Cell Lymphoma Model for Pre-Clinical Evaluation of CD19 CAR T Cells

The astonishing clinical success of CD19 chimeric antigen receptor (CAR) T-cell therapy has led to the approval of two second generation chimeric antigen receptors (CARs) for acute lymphoblastic leukemia (ALL) andnon-Hodgkin lymphoma (NHL). The focus of the field is now on emulating these successes in other hematological malignancies where less impressive complete response rates are observed. Further engineering of CAR T cells or co-administration of other treatment modalities may successfully overcome obstacles to successful therapy in other cancer settings.
We therefore present a model in which others can conduct pre-clinical testing of CD19 CAR T cells. Results in this well tested B-cell lymphoma model are likely to be informative CAR T-cell therapy in general.
This protocol allows the reproducible production of mouse CAR T cells through calcium phosphate transfection of Plat-E producer cells with MP71 retroviral constructs and pCL-Eco packaging plasmid followed by collection of secreted retroviral particles and transduction using recombinant human fibronectin fragment and centrifugation. Validation of retroviral transduction, and confirmation of the ability of CAR T cells to kill target lymphoma cells ex vivo, through the use of flow cytometry, luminometry and enzyme-linked immunosorbent assay (ELISA), is also described.
Protocols for testing CAR T cells in vivo in lymphoreplete and lymphodepleted syngeneic mice, bearing established, systemic lymphoma are described. Anti-cancer activity is monitored by in vivo bioluminescence and disease progression. We show typical results of eradication of established B-cell lymphoma when utilizing 1st or 2nd generation CARs in combination with lymphodepleting pre-conditioning and a minority of mice achieving long term remissions when utilizing CAR T cells expressing IL-12 in lymphoreplete mice.
These protocols can be used to evaluate CD19 CAR T cells with different additional modification, combinations of CAR T cells and other therapeutic agents or adapted for the use of CAR T cells against different target antigens.

Here, we present a protocol for the production and pre-clinical testing of murine CD19 CAR T cells by retroviral transduction and utilization as a therapy against established syngeneic A20 B-cell lymphoma in BALB/c mice with or without lymphodepleting pre-conditioning.

The astonishing clinical success of CD19 chimeric antigen receptor (CAR) T-cell therapy has led to the approval of two second generation chimeric antigen ...

Ultrasound-Guided Orthotopic Implantation of Murine Pancreatic Ductal Adenocarcinoma

The recent success of immune checkpoint blockade in melanoma and lung adenocarcinoma has galvanized the field of immuno-oncology as well as revealed the limitations of current treatments, as the majority of patients do not respond to immunotherapy. Development of accurate preclinical models to quickly identify novel and effective therapeutic combinations are critical to address this unmet clinical need. Pancreatic ductal adenocarcinoma (PDA) is a canonical example of an immune checkpoint blockade resistant tumor with only 2% of patients responding to immunotherapy. The genetically engineered KrasG12D+/-;Trp53R172H+/-;Pdx-1 Cre (KPC) mouse model of PDA recapitulates human disease and is a valuable tool for assessing therapies for immunotherapy resistant in the preclinical setting, but time to tumor onset is highly variable. Surgical orthotopic tumor implantation models of PDA maintain the immunobiological hallmarks of the KPC tissue-specific tumor microenvironment (TME) but require a time-intensive procedure and introduce aberrant inflammation. Here, we use an ultrasound-guided orthotopic tumor implantation model (UG-OTIM) to non-invasively inject KPC-derived PDA cell lines directly into the mouse pancreas. UG-OTIM tumors grow in the endogenous tissue site, faithfully recapitulate histological features of the PDA TME, and reach enrollment-sized tumors for preclinical studies by four weeks after injection with minimal seeding on the peritoneal wall. The UG-OTIM system described here is a rapid and reproducible tumor model that may allow for high throughput analysis of novel therapeutic combinations in the murine PDA TME.

We describe a protocol for the ultrasound guided implantation of murine-derived pancreatic ductal adenocarcinoma cell lines directly into the native tumor site. This approach resulted in pancreatic tumors detectable by ultrasound scanning within 2-4 weeks of injection, and significantly reduced the proportion tumor cell seeding on the peritoneal wall as compared to surgical orthotopic implantation.

The recent success of immune checkpoint blockade in melanoma and lung adenocarcinoma has galvanized the field of immuno-oncology as well as revealed the ...

An Orthotopic Resectional Mouse Model of Pancreatic Cancer

There is a lack of satisfactory animal models to study adjuvant and/or neoadjuvant therapy in patients being considered for surgery of pancreatic cancer (PC). To address this deficiency, we describe a mouse model involving orthotopic implantation of PC followed by distal pancreatectomy and splenectomy. The model has been demonstrated to be safe and suitably flexible for the study of various therapeutic approaches in adjuvant and neo adjuvant settings.
In this model, a pancreatic tumor is first generated by implanting a mixture of human pancreatic cancer cells (luciferase-tagged AsPC-1) and human cancer associated pancreatic stellate cells into the distal pancreas of Balb/c athymic nude mice. After three weeks, the cancer is resected by re-laparotomy, distal pancreatectomy and splenectomy. In this model, bioluminescence imaging can be used to follow the progress of cancer development and effects of resection/treatments. Following resection, adjuvant therapy can be given. Alternatively, neoadjuvant treatment can be given prior to resection.
Representative data from 45 mice are presented. All mice underwent successful distal pancreatectomy/splenectomy with no issues of hemostasis. A macroscopic proximal pancreatic margin greater than 5 mm was achieved in 43 (96%) mice. The technical success rate of pancreatic resection was 100%, with 0% early mortality and morbidity. None of the animals died during the week after resection.
In summary, we describe a robust and reproducible technique for a surgical resection model of pancreatic cancer in mice which mimics the clinical scenario. The model may be useful for the testing of both adjuvant and neoadjuvant treatments.

In the clinical context, patients with localized pancreatic cancer will undergo pancreatectomy followed by adjuvant treatment. This protocol reported here aims to establish a safe and effective method of modelling this clinical scenario in nude mice, through orthotopic implantation of pancreatic cancer followed by distal pancreatectomy and splenectomy.

There is a lack of satisfactory animal models to study adjuvant and/or neoadjuvant therapy in patients being considered for surgery of pancreatic cancer ...