Name: a patient-derived xenograft model for venous malformation
Uploaded: 2020-06-15T15:00:00
Description: Watch this Scientific Journal Video about A Patient-Derived Xenograft Model for Venous Malformation at JoVE.com

The authors would like to thank Nora Lakes for proofreading. Research reported in this manuscript was supported by the National Heart, Lung, and Blood Institute, under Award Number R01 HL117952 (E.B.), part of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Patient tissue samples were obtained from participants after informed consent from the Collection and Repository of Tissue Samples and Data from Patients with Tumors and Vascular Anomalies under an approved Institutional Review Board (IRB) per institutional policies at Cincinnati Children&#8217;s Hospital Medical Center (CCHMC), Cancer and Blood Disease Institute and with approval of the Committee on Clinical Investigation. All animal procedures described below have been reviewed and approved by the CCHMC Institutional A...

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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=Interrogating+open+issues+in+cancer+precision+medicine+with+patient-derived+xenografts.">Interrogating open issues in cancer precision medicine with patient-derived xenografts.</a> Nature Reviews Cancer. 17 (4), 254-268 (2017).</li><li>Allen, P., Melero-Martin, J., Bischoff, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Type+I+collagen,+fibrin+and+PuraMatrix+matrices+provide+permissive+environments+for+human+endothelial+and+mesenchymal+progenitor+cells+to+form+neovascular+networks.">Type I collagen, fibrin and PuraMatrix matrices provide permissive environments for human endothelial and mesenchymal progenitor cells to form neovascular networks.</a> Journal of Tissue Engineering and Regenerative Medicine. 5 (4), 74 (2011).</li><li>Allen, P., Kang, K. 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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+management+of+hemangiomas+and+vascular+malformations.">Current management of hemangiomas and vascular malformations.</a> Clinics in Plastic Surgery. 32 (1), 99-116 (2005).</li><li>Goines, 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=A+xenograft+model+for+venous+malformation.">A xenograft model for venous malformation.</a> Angiogenesis. 21 (4), 725-735 (2018).</li><li>Li, X., 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=Ponatinib+Combined+With+Rapamycin+Causes+Regression+of+Murine+Venous+Malformation.">Ponatinib Combined With Rapamycin Causes Regression of Murine Venous Malformation.</a> Arteriosclerosis, thrombosis, and vascular biology. 39 (3), 496-512 (2019).</li><li>Le Cras, T. 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Here, we describe a method to generate a patient-derived xenograft model of VM. This murine model presents an excellent system that allows researchers to gain a deeper understanding of pathological lumen enlargement and will be instrumental in developing more effective and targeted therapies for the treatment of VM. This can be easily adapted to investigate other types of vascular anomalies such as capillary lymphatic venous malformation16. There are several steps that are crucial for the successf...

Defects in the development of the vasculature are the underlying cause of many diseases including venous malformation (VM). VM is a congenital disease characterized by abnormal morphogenesis and expansion of veins1. Important studies on VM tissue and endothelial cells (EC) have identified gain-of-function mutations in two genes: TEK, which encodes the tyrosine kinase receptor TIE2, and PIK3CA, which encodes the p110&#945; (catalytic subunit) isoform of PI3-kinase (PI3K)2,3,4,5. These somatic mutations result in ligand-independent hyper-activation of key angiogenic/growth signaling pathways, including PI3K/AKT, thereby resulting in dilated ectatic veins3. Despite these important genetic discoveries, the subsequent cellular and molecular mechanisms triggering abnormal angiogenesis and the formation of enlarged vascular channels are still not fully understood.
During normal and pathological angiogenesis, new vessels sprout from a pre-existing vascular network and EC undergo a sequence of important cellular processes including proliferation, migration, extracellular matrix (ECM) remodeling and lumen formation6. Two- and three- dimensional (2D/3D) in vitro cultures of EC are important tools to investigate each of these cellular properties individually. Nevertheless, there is a clear demand for a mouse model recapitulating pathological vessel enlargement within the host microenvironment while providing an efficient platform for preclinical evaluation of targeted drugs for translational research.
Up to date, a transgenic murine model of VM associated with TIE2 gain-of-function mutations has not been reported. Current transgenic VM mouse models rely on the ubiquitous or tissue-restricted expression of the activating mutation PIK3CA p.H1047R3,5. These transgenic animals provide significant insight into whole-body or tissue-specific effects of this hotspot PIK3CA mutation. The limitation of these models is the formation of a highly pathological vascular network resulting in early lethality. Thus, these mouse models do not fully reflect the sporadic occurrence of mutational events and localized nature of VM pathology.
On the contrary, patient-derived xenograft models are based on the transplantation or injection of pathological tissue or cells derived from patients into immunodeficient mice7. Xenograft models are a powerful tool to broaden knowledge about disease development and discovery of novel therapeutic agents8. In addition, using patient-derived cells allows scientists to recapitulate mutation heterogeneity to study the spectrum of patient phenotypes.
Here, we describe a protocol where patient-derived VM EC which express a mutant constitutively-active form of TIE2 and/or PIK3CA are injected subcutaneously in the back of athymic nude mice. Injected vascular cells are suspended in an ECM framework in order to promote angiogenesis as described in previous vascular xenograft models9,10,11. These VM EC undergo significant morphogenesis and generate enlarged, perfused pathological vessels in the absence of supporting cells. The described xenograft model of VM provides an efficient platform for preclinical evaluation of targeted drugs for their ability to inhibit uncontrolled lumen expansion.

<table>
	<tbody>
		<tr>
			<td>Athymic nude mice, (Foxn1-nu); 5-6 weeks, males</td>
			<td>Envigo</td>
			<td>069(nu)/070(nu/+)</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>Biotinylated Ulex europeaus Agglutinin-I (UEA-I)</td>
			<td>Vector Laboratories</td>
			<td>B-1065</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Bottle top filter (500 ml; 0.2 &#181;M)</td>
			<td>Thermo Fisher</td>
			<td>974106</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin (BSA)</td>
			<td>BSA</td>
			<td>A7906-50MG</td>
			<td>Cell culture; Histological analysis</td>
		</tr>
		<tr>
			<td>Calcium cloride dihydrate (CaCl2.2H2O)</td>
			<td>Sigma</td>
			<td>C7902-500G</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Caliper</td>
			<td>Electron Microscopy Sciences</td>
			<td>50996491</td>
			<td>Lesion plug measurment</td>
		</tr>
		<tr>
			<td>CD31-conjugated magnetic beads (Dynabeads)</td>
			<td>Life Technologies</td>
			<td>11155D</td>
			<td>EC separation</td>
		</tr>
		<tr>
			<td>Cell strainer (100 &#956;M)</td>
			<td>Greiner</td>
			<td>542000</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Collagenase A</td>
			<td>Roche</td>
			<td>10103578001</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Conical Tube; polypropylene (15 mL)</td>
			<td>Greiner</td>
			<td>07 000 241</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Conical Tube; polypropylene (50 mL)</td>
			<td>Greiner</td>
			<td>07 000 239</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Coplin staining jar</td>
			<td>Ted Pella</td>
			<td>21029</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Coverglass (50 X 22 mm)</td>
			<td>Fisher Scientific</td>
			<td>12545E</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>DAB: 3,3&#39;Diaminobenzidine Reagent (ImmPACT DAB)</td>
			<td>Vector Laboratories</td>
			<td>SK-4105</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modification of Eagle&#39;s Medium (DMEM)</td>
			<td>Corning</td>
			<td>10-027-CV</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>DynaMag-2</td>
			<td>Life Technologies</td>
			<td>12321D</td>
			<td>EC separation</td>
		</tr>
		<tr>
			<td>Ear punch</td>
			<td>VWR</td>
			<td>10806-286</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>EDTA (0.5M, pH 8.0)</td>
			<td>Life Technologies</td>
			<td>15575-020</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Endothelial Cell Growth Medium-2 (EGM2) Bulletkit (basal medium and supplements)</td>
			<td>Lonza</td>
			<td>CC-3162</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Eosin Y (alcohol-based)</td>
			<td>Thermo Scientific</td>
			<td>71211</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Decon Labs</td>
			<td>2716</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS) , HyClone</td>
			<td>GE Healthcare</td>
			<td>SH30910.03</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Filter tip 1,250 &#956;L</td>
			<td>MidSci</td>
			<td>AV1250-H</td>
			<td>Multiple steps</td>
		</tr>
		<tr>
			<td>Filter tip 20 &#956;L</td>
			<td>VWR</td>
			<td>10017-064</td>
			<td>Multiple steps</td>
		</tr>
		<tr>
			<td>Filter tip 200 &#956;L</td>
			<td>VWR</td>
			<td>10017-068</td>
			<td>Multiple steps</td>
		</tr>
		<tr>
			<td>Formalin buffered solution (10%)</td>
			<td>Sigma</td>
			<td>F04586</td>
			<td>Lesion plug dissection</td>
		</tr>
		<tr>
			<td>Hemacytometer (INCYTO; Disposable)</td>
			<td>SKC FILMS</td>
			<td>DHCN015</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Hematoxylin</td>
			<td>Vector Hematoxylin</td>
			<td>H-3401</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Human plasma fibronectin purified protein (1mg/mL)</td>
			<td>Sigma</td>
			<td>FC010-10MG</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Hydrogen Peroxide solution (30% w/w)</td>
			<td>Sigma</td>
			<td>H1009</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>ImageJ Software</td>
			<td></td>
			<td></td>
			<td>Analysis</td>
		</tr>
		<tr>
			<td>Isoflurane, USP</td>
			<td>Akorn Animal Health</td>
			<td>59399-106-01</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>magnesium sulfate heptahydrate (MgSO4.7H2O)</td>
			<td>Sigma</td>
			<td>M1880-500G</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Basement Membrane Matrix (Phenol Red-Free; LDEV-free)</td>
			<td>Corning</td>
			<td>356237</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>Microcentrifuge tube (1.5 mL)</td>
			<td>VWR</td>
			<td>87003-294</td>
			<td>EC separation</td>
		</tr>
		<tr>
			<td>Microscope Slide Superfrost (75mm X 25mm)</td>
			<td>Fisher Scientific</td>
			<td>1255015-CS</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Needles, 26G x 5/8 inch Sub-Q sterile needles</td>
			<td>Becton Dickinson (BD)</td>
			<td>BD305115</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>Normal horse serum</td>
			<td>Vector Laboratories</td>
			<td>S-2000</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin-L-Glutamine (100X)</td>
			<td>Corning</td>
			<td>30-009-CI</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Permanent mounting medium (VectaMount)</td>
			<td>Vector Laboratories</td>
			<td>H-5000</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Pestle Size C, Plain</td>
			<td>Thomas Scientific</td>
			<td>3431F55</td>
			<td>EC isolation</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Fisher Scientific</td>
			<td>BP3994</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Scale</td>
			<td>VWR</td>
			<td>65500-202</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>Serological pipettes (10 ml)</td>
			<td>VWR</td>
			<td>89130-898</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Serological pipettes (5ml)</td>
			<td>VWR</td>
			<td>89130-896</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Sodium carbonate (Na2CO3)</td>
			<td>Sigma</td>
			<td>223530</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Streptavidin, Horseradish Peroxidase, Concentrate, for IHC</td>
			<td>Vector Laboratories</td>
			<td>SA-5004</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Syringe (60ml)</td>
			<td>BD Biosciences</td>
			<td>309653</td>
			<td>Cel culture</td>
		</tr>
		<tr>
			<td>SYRINGE FILTER (0.2 &#181;M)</td>
			<td>Corning</td>
			<td>431219</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Syringes (1 mL with Luer Lock)</td>
			<td>Becton Dickinson (BD)</td>
			<td>BD-309628</td>
			<td>Subcutaneous injection</td>
		</tr>
		<tr>
			<td>Tissue culture-treated plate (100 X 20 mm)</td>
			<td>Greiner</td>
			<td>664160</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Tissue culture-treated plate (145X20 mm)</td>
			<td>Greiner</td>
			<td>639160</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Tissue culture-treated plates (60 X 15) mm</td>
			<td>Eppendorf</td>
			<td>30701119</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Tris-base (Trizma base)</td>
			<td>Sigma</td>
			<td>T6066</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Trypan Blue Solution (0.4 %)</td>
			<td>Life Technologies</td>
			<td>15250061</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Trypsin EDTA, 1X (0.05% Trypsin/0.53mM EDTA)</td>
			<td>Corning</td>
			<td>25-052-Cl</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Biorad</td>
			<td>170-6531</td>
			<td>Histological anlaysis</td>
		</tr>
		<tr>
			<td>Wheaton bottle</td>
			<td>VWR</td>
			<td>16159-798</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Xylenes</td>
			<td>Fisher Scientific</td>
			<td>X3P-1GAL</td>
			<td>Histological anlaysis</td>
		</tr>
	</tbody>
</table>

a patient-derived xenograft model for venous malformation

Venous malformation (VM) is a vascular anomaly that arises from impaired development of the venous network resulting in dilated and often dysfunctional veins. The purpose of this article is to carefully describe the establishment of a murine xenograft model that mimics human VM and is able to reflect patient heterogeneity. Hyper-activating non-inherited (somatic) TEK (TIE2) and PIK3CA mutations in endothelial cells (EC) have been identified as the main drivers of pathological vessel enlargement in VM. The following protocol describes the isolation, purification and expansion of patient-derived EC expressing mutant TIE2 and/or PIK3CA. These EC are injected subcutaneously into the back of immunodeficient athymic mice to generate ectatic vascular channels. Lesions generated with TIE2 or PIK3CA-mutant EC are visibly vascularized within 7&#8210;9 days of injection and recapitulate histopathological features of VM patient tissue. This VM xenograft model provides a reliable platform to investigate the cellular and molecular mechanisms driving VM formation and expansion. In addition, this model will be instrumental for translational studies testing the efficacy of novel drug candidates in preventing the abnormal vessel enlargement seen in human VM.

This protocol describes the process of generating a murine xenograft model of VM based on the subcutaneous injection of patient-derived EC into the back of immunodeficient nude mice. Endothelial cell colonies can be harvested within 4 weeks after initial cell isolation from VM tissue or lesional blood (Figure 1A,B). The day after injection, the xenograft lesion plug covers a surface area of approximately 80&#8210;100 mm2. In our hands, lesion plugs with TIE2/PIK3CA-mutant EC are visibly vascul...

Watch this Scientific Journal Video about A Patient-Derived Xenograft Model for Venous Malformation at JoVE.com

A Patient-Derived Xenograft Model for Venous Malformation

We present a detailed protocol to generate a murine xenograft model of venous malformation. This model is based on the subcutaneous injection of patient-derived endothelial cells containing hyper-activating TIE2 and/or PIK3CA gene mutations. Xenograft lesions closely recapitulate the histopathological features of VM patient tissue.

Venous malformation (VM) is a vascular anomaly that arises from impaired development of the venous network resulting in dilated and often dysfunctional ...

This protocol can be used to create patient-derived xenografts that recapitulate the histopathology of venous malformations. This was further allowed to carry our preclinical therapeutic testing. This technique provides a fast and reliable NVivo system that allows daily monitoring of the growth of patient direct endothelial cells and the response to experimental therapy.This method could be easily adapted to investigate other types of vascular or lymphatic anomalies. Begin by preparing the cell suspension for injection. Trypsinize the endothelial cells with five milliliters of pre-warmed 0.05%tripsin-EDTA at 37 degrees Celsius for two minutes.Neutralize the tripsin and by adding five milliliters of EGM and collect the cells into 150 milliliter conical tube. Centrifuge it to 400 times G for five minutes then aspirate the supernatant and resuspend the cells in three milliliters of EGM. Count the cells with a hemocytometer.Venture the volume with the desired cell number into a new 50 milliliter conical tube and pellet the cells again by centrifugation. Aspirate the supernatant leaving a small volume to loosen the cell pellet. Resuspend the cell pellet with 220 microliters of BMEM per injection.Mix the cell suspension thoroughly on ice making sure to avoid creating bubbles. Aspirate the BMEM cell culture mix into a one milliliter syringe opening by pulling the plunger. You'll lock a 26 gauge sterile needle to the syringe and keep the prepared syringes flat on ice prior to injection.After ensuring that the mouse has properly anesthetized place it on its stomach and disinfect the injection region with 70%ethanol. Gently roll the prepared syringe to resuspend any settled cells. Flake bubbles to the end of the syringe and expel a small volume of the cell suspension.Pinch the skin at the injection site to create a tent like structure. Then insert the needle right under the skin and sure that the needle is only skin deep by releasing pinch skin to prevent injection into muscle tissue. Holding the needle steadily carefully inject 200 microliters of the cell suspension to create a small spherical mass.Take care to avoid injecting the cell suspension into muscle. Measure the length and width of each plug with a caliper. Align the dissected xenograft plugs on a cutting board next to a ruler and take an image to record the gross vascularity of the lesions.Then fix the plugs by submerging them in 10%formalin overnight at room temperature. After dissection, the lesion plugs are processed for histological analysis and stained for UEA-1 to detect human derived endothelial cells within the plug. Take five HPF images per lesion section with a bright field microscope at at 20 X magnification in an X plane pattern within the lesion section to avoid overlap.Make sure to include a scale bar on the images taken. Open the HPF images in image J.To calibrate the pixels of the scale bar, use the straight line tool and go over the scale bar. Then convert the measured pixels into millimeters by clicking on Analyze and Set Scale.Next click on Analyze Set Measurements and select area and add to overlay. Measure the total field area of the HPF using analyze and measure saving this measurement for quantification. Using the free hand selections tool manually outline the UEA-1 positive vascular channel.Click on Analyze and Measure to quantify the outlined area. Measure all vascular channels within the HPF. Repeat the process for the five HPF taken within each section and transfer the values to Excel for further analysis.Then calculate the percentage of vascular area and vascular density according to manuscript directions. Using this protocol the lesion plugs with TIE2 or PIK3CA hyperactive mutant endothelial cells are visibly vascularized and perfused within seven to nine days after injection. The lesion plugs closely resemble the histopathological features of human VM tissue and large vascular channels aligned by a thin layer of endothelial cells are visible.These vascular structures typically contain erythrocytes confirming functional anastomosis with the host mouse vasculature. Immunohistochemical staining using the human specific lectin UEA-1 confirms that the cells lining vascular regions are derived from human implanted cells rather than mouse vasculature. Following this procedure, additional staining of lesion sections for markers of proliferation or apoptosis can be performed to analyze specific effects of experimental treatments.This scenographic model has been used for preclinical studies of new therapies for venous malformation, such as the mTOR inhibitor rapamycin, which has shown efficacy in several clinical trials for VM patients.

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