Name: a patient-derived xenograft model for venous malformation
Uploaded: 2020-06-15T15:00:00.000+00:00
Duration: 6 min 51 s
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.

<ol>
	<li>Dompmartin, A., Vikkula, M., Boon, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Venous+malformation:+update+on+aetiopathogenesis,+diagnosis+and+management.">Venous malformation: update on aetiopathogenesis, diagnosis and management.</a> Phlebology: The Journal of Venous Disease. 25 (5), 224-235 (2010).</li><li>Limaye, 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=Somatic+mutations+in+angiopoietin+receptor+gene+TEK+cause+solitary+and+multiple+sporadic+venous+malformations.">Somatic mutations in angiopoietin receptor gene TEK cause solitary and multiple sporadic venous malformations.</a> Nature Genetics. 41 (1), 118-124 (2009).</li><li>Castel, 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=Somatic+PIK3CA+mutations+as+a+driver+of+sporadic+venous+malformations.">Somatic PIK3CA mutations as a driver of sporadic venous malformations.</a> Science Translational Medicine. 8 (332), 42 (2016).</li><li>Limaye, 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=Somatic+Activating+PIK3CA+Mutations+Cause+Venous+Malformation.">Somatic Activating PIK3CA Mutations Cause Venous Malformation.</a> The American Journal of Human Genetics. 97 (6), 914-921 (2015).</li><li>Castillo, S. D., 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=Somatic+activating+mutations+in+Pik3ca+cause+sporadic+venous+malformations+in+mice+and+humans.">Somatic activating mutations in Pik3ca cause sporadic venous malformations in mice and humans.</a> Science Translational Medicine. 8 (332), 43 (2016).</li><li>Stratman, A. 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=Endothelial+cell+lumen+and+vascular+guidance+tunnel+formation+requires+MT1-MMP-dependent+proteolysis+in+3-dimensional+collagen+matrices.">Endothelial cell lumen and vascular guidance tunnel formation requires MT1-MMP-dependent proteolysis in 3-dimensional collagen matrices.</a> Blood. 114 (2), 237-247 (2009).</li><li>Okada, S., Vaeteewoottacharn, K., Kariya, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+Highly+Immunocompromised+Mice+for+the+Establishment+of+Patient-Derived+Xenograft+(PDX)+Models.">Application of Highly Immunocompromised Mice for the Establishment of Patient-Derived Xenograft (PDX) Models.</a> Cells. 8 (8), 889 (2019).</li><li>Byrne, A. 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. T., 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=Rapid+onset+of+perfused+blood+vessels+after+implantation+of+ECFCs+and+MPCs+in+collagen,+PuraMatrix+and+fibrin+provisional+matrices.">Rapid onset of perfused blood vessels after implantation of ECFCs and MPCs in collagen, PuraMatrix and fibrin provisional matrices.</a> Journal of Tissue Engineering and Regenerative. 9 (5), 632-636 (2015).</li><li>Nowak-Sliwinska, 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=Consensus+guidelines+for+the+use+and+interpretation+of+angiogenesis+assays.">Consensus guidelines for the use and interpretation of angiogenesis assays.</a> Angiogenesis. 21 (3), 425 (2018).</li><li>Roh, Y. 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=The+results+of+surgical+treatment+for+patients+with+venous+malformations.">The results of surgical treatment for patients with venous malformations.</a> Annals of Vascular Surgery. 26 (5), 665-673 (2012).</li><li>Marler, J. J., Mulliken, J. 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. D., 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=Constitutively+active+PIK3CA+mutations+are+expressed+by+lymphatic+and+vascular+endothelial+cells+in+capillary+lymphatic+venous+malformation.">Constitutively active PIK3CA mutations are expressed by lymphatic and vascular endothelial cells in capillary lymphatic venous malformation.</a> Angiogenesis. , 1-18 (2020).</li><li>Boscolo, 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=Rapamycin+improves+TIE2-mutated+venous+malformation+in+murine+model+and+human+subjects.">Rapamycin improves TIE2-mutated venous malformation in murine model and human subjects.</a> Journal of Clinical Investigation. 125 (9), 3491-3504 (2015).</li></ol>

The authors have no conflicts-of-interests to disclose.

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 &amp;micro;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 &amp;mu;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&#039;Diaminobenzidine Reagent (ImmPACT DAB)</td><td>Vector Laboratories</td><td>SK-4105</td><td>Histological anlaysis</td></tr><tr><td>Dulbecco&#039;s Modification of Eagle&#039;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 &amp;mu;L</td><td>MidSci</td><td>AV1250-H</td><td>Multiple steps</td></tr><tr><td>Filter tip 20 &amp;mu;L</td><td>VWR</td><td>10017-064</td><td>Multiple steps</td></tr><tr><td>Filter tip 200 &amp;mu;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 &amp;micro;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 ...

a-patient-derived-xenograft-model-for-venous-malformation

Research

JoVE Journal

Developmental Biology

5.2K Views.  Cincinnati Children's Hospital Medical Center. 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.

Video: A Patient-Derived Xenograft Model for Venous Malformation

Utilization of Ultrasound Guided Tissue-directed Cellular Implantation for the Establishment of Biologically Relevant Metastatic Tumor Xenografts

Preclinical testing of anticancer therapies relies on relevant xenograft models that mimic the innate tendencies of cancer. Advantages of standard subcutaneous flank models include procedural ease and the ability to monitor tumor progression and response without invasive imaging. Such models are often inconsistent in translational clinical trials and have limited biologically relevant characteristics with low proclivity to produce metastasis, as there is a lack of a native microenvironment. In comparison, orthotopic xenograft models at native tumor sites have been shown to mimic the tumor microenvironment and replicate important disease characteristics such as distant metastatic spread. These models often require tedious surgical procedures with prolonged anesthetic time and recovery periods. To address this, cancer researchers have recently utilized ultrasound-guided injection techniques to establish cancer xenograft models for preclinical experiments, which allows for rapid and reliable establishment of tissue-directed murine models. Ultrasound visualization also provides a noninvasive method for longitudinal assessment of tumor engraftment and growth. Here, we describe the method for ultrasound-guided injection of cancer cells, utilizing the adrenal gland for NB and renal sub capsule for ES. This minimally invasive approach overcomes tedious open surgery implantation of cancer cells in tissue-specific locations for growth and metastasis, and abates morbid recovery periods. We describe the utilization of both established cell lines and patient derived cell lines for orthotopic injection. Pre-made commercial kits are available for tumor dissociation and luciferase tagging of cells. Injection of cell suspension using image-guidance provides a minimally invasive and reproducible platform for the creation of preclinical models. This method is utilized to create reliable preclinical models for other cancers such as bladder, liver and pancreas exemplifying its untapped potential for numerous cancer models.

Here, we present a protocol to utilize ultrasound-guided injection of neuroblastoma (NB) and Ewing's sarcoma (ES) cells (established cell lines and patient-derived tumor cells) at biologically relevant sites to create reliable preclinical models for cancer research.

Preclinical testing of anticancer therapies relies on relevant xenograft models that mimic the innate tendencies of cancer. Advantages of standard ...

Cancer Research

Enhanced Viability for Ex vivo 3D Hydrogel Cultures of Patient-Derived Xenografts in a Perfused Microfluidic Platform

Patient-derived xenografts (PDX), generated when resected patient tumor tissue is engrafted directly into immunocompromised mice, remain biologically stable, thereby preserving molecular, genetic, and histological features, as well as heterogeneity of the original tumor. However, using these models to perform a multitude of experiments, including drug screening, is prohibitive both in terms of cost and time. Three-dimensional (3D) culture systems are widely viewed as platforms in which cancer cells retain their biological integrity through biochemical interactions, morphology, and architecture. Our team has extensive experience culturing PDX cells in vitro using 3D matrices composed of hyaluronic acid (HA). In order to separate mouse fibroblast stromal cells associated with PDXs, we use rotation culture, where stromal cells adhere to the surface of tissue culture-treated plates while dissociated PDX tumor cells float and self-associate into multicellular clusters. Also floating in the supernatant are single, often dead cells, which present a challenge in collecting viable PDX clusters for downstream encapsulation into hydrogels for 3D cell culture. In order to separate these single cells from live cell clusters, we have employed density step gradient centrifugation. The protocol described here allows for the depletion of non-viable single cells from the healthy population of cell clusters that will be used for further in vitro experimentation. In our studies, we incorporate the 3D cultures in microfluidic plates which allow for media perfusion during culture. After assessing the resultant cultures using a fluorescent image-based viability assay of purified versus non-purified cells, our results show that this additional separation step substantially reduced the number of non-viable cells from our cultures.

This protocol demonstrates methods to enable extended in vitro culture of patient-derived xenografts (PDX). One step enhances overall viability of multicellular cluster cultures in 3D hydrogels, through straightforward removal of non-viable single cells. A secondary step demonstrates best practices for PDX culture in a perfused microfluidic platform.

Patient-derived xenografts (PDX), generated when resected patient tumor tissue is engrafted directly into immunocompromised mice, remain biologically ...

Adult Mouse Venous Hypertension Model: Common Carotid Artery to External Jugular Vein Anastomosis.

The understanding of the pathophysiology of brain arteriovenous malformations and arteriovenous fistulas has improved thanks to animal models. A rat model creating an artificial fistula between the common carotid artery (CCA) and the external jugular vein (EJV) has been widely described and proved technically feasible. This construct provokes a consistent cerebral venous hypertension (CVH), and therefore has helped studying the contribution of venous hypertension to formation, clinical symptoms, and prognosis of brain AVMs and dural AVFs. Equivalent mice models have been only scarcely described and have shown trouble with stenosis of the fistula. An established murine model would allow the study of not only pathophysiology but also potential genetic therapies for these cerebrovascular diseases.
We present a model of arteriovenous fistula that produces a durable intracranial venous hypertension in the mouse. Microsurgical anastomosis of the murine CCA and EJV can be difficult due to diminutive anatomy and frequently result in a non-patent fistula. In this step-by-step protocol we address all the important challenges encountered during this procedure. Avoiding excessive retraction of the vein during the exposure, using 11-0 sutures instead of 10-0, and making a carefully planned end-to-side anastomosis are some of the critical steps. Although this method requires advanced microsurgical skills and a longer learning curve that the equivalent in the rat, it can be consistently developed.
This novel model has been designed to integrate transgenic mouse techniques with a previously well-established experimental system that has proved useful to study brain AVMs and dural AVFs. By opening the possibility of using transgenic mice, a broader spectrum of valid models can be achieved and genetic treatments can also be tested. The experimental construct could also be further adapted to the study of other cerebrovascular diseases related with venous hypertension such as migraine, transient global amnesia, transient monocular blindness, etc.

We describe a method for creating a reliable model of cerebral venous hypertension in the adult mouse. This model has been widely described and tested in the rat. This new counterpart in the mice opens the possibility of using genetic modified animals and thereby broadens the applications of the model.

The understanding of the pathophysiology of brain arteriovenous malformations and arteriovenous fistulas has improved thanks to animal models. A rat model ...

Medicine

Implantation of Inferior Vena Cava Interposition Graft in Mouse Model

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. The long-term clinical results showed excellent patency rates, however, with significant incidence of stenosis. To investigate the cellular and molecular mechanisms of vascular neotissue formation and prevent stenosis development in tissue engineered vascular grafts (TEVGs), we developed a mouse model of the graft with approximately 1 mm internal diameter. First, the TEVGs were assembled from biodegradable tubular scaffolds fabricated from a polyglycolic acid nonwoven felt mesh coated with &#949;-caprolactone and L-lactide copolymer. The scaffolds were then placed in a lyophilizer, vacuumed for 24 hr, and stored in a desiccator until cell seeding. Second, bone marrow was collected from donor mice and mononuclear cells were isolated by density gradient centrifugation. Third, approximately one million cells were seeded on a scaffold and incubated O/N. Finally, the seeded scaffolds were then implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. The implanted grafts demonstrated excellent patency (&#62;90%) without evidence of thromboembolic complications or aneurysmal formation. This murine model will aid us in understanding and quantifying the cellular and molecular mechanisms of neotissue formation in the TEVG.

To improve our knowledge of cellular and molecular neotissue formation, a murine model of the TEVG was recently developed. The grafts were implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. This model achieves similar results to those achieved in our clinical investigation, but over a far shortened time-course.

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. ...

The Arteriovenous (AV) Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in pathological situations such as cancer, vascularization plays a leading role in disease progression. Consequently, there is a strong need for a standardized and well-characterized in vivo model in order to elucidate the mechanisms of neovascularization and develop different vascularization approaches for tissue engineering and regenerative medicine.
We describe a microsurgical approach for a small animal model for induction of a vascular axis consisting of a vein and artery that are anastomosed to an arteriovenous (AV) loop. The AV loop is transferred to an enclosed implantation chamber to create an isolated microenvironment in vivo, which is connected to the living organism only by means of the vascular axis. Using 3D imaging (MRI, micro-CT) and immunohistology, the growing vasculature can be visualized over time. By implanting different cells, growth factors and matrices, their function in blood vessel network formation can be analyzed without any disturbing influences from the surroundings in a well controllable environment. 
In addition to angiogenesis and antiangiogenesis studies, the AV loop model is also perfectly suited for engineering vascularized tissues. After a certain prevascularization time, the generated tissues can be transplanted into the defect site and microsurgically connected to the local vessels, thereby ensuring immediate blood supply and integration of the engineered tissue. By varying the matrices, cells, growth factors and chamber architecture, it is possible to generate various tissues, which can then be tailored to the individual patient's needs.

The Arteriovenous AV Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

We describe a microsurgical approach for the generation of an arteriovenous (AV) loop as a model for analyzing vascularization in vivo in an isolated and well-characterized environment. This model is not only useful for the investigation of angiogenesis, but is also optimally suited for engineering axially vascularized and transplantable tissues.

A functional blood vessel network is a prerequisite for the survival and growth of almost all tissues and organs in the human body. Moreover, in ...

Bioengineering

Establishment of Orthotopic Patient-derived Xenograft Models for Brain Tumors using a Stereotaxic Device

The development of clinically relevant and reliable models for central nervous system (CNS) tumors has been pivotal in advancing the field of neuro-oncology. One of the most widely used techniques is the orthotopic intracranial injection, a method that allows investigating of tumor growth, invasion, and dissemination within a controlled setting. This technique involves transplanting tumor cells from a specific patient region into the corresponding anatomical site in an animal. By doing so, these orthotopic brain tumor models offer a unique advantage, as they more accurately replicate cancer's biological behavior and its interactions with the brain environment seen in human patients. This makes them especially valuable for preclinical therapeutic testing, where a close resemblance to the clinical scenario is essential for evaluating potential treatments. This protocol shares experiences in developing patient-derived xenograft (PDX) models for pediatric brain tumors, including diffuse midline glioma (DMG), glioblastoma (GBM), medulloblastoma, and ependymoma. This method delineates the procedure for conducting intracranial stereotaxic injections in mice, ensuring the correct targeting of the injection site within the brain. Additionally, we describe the post-procedural monitoring system employed to detect signs of successful tumor engraftment. Following tumor injection, a rigorous monitoring system is implemented to observe the animals for any signs of neurological impairment, behavioral changes, and/or weight loss, which are common indicators of tumor progression. This system allows for timely intervention and provides critical data regarding the tumor's growth dynamics. By refining these models and protocols, we aim to enhance the reliability and translational potential of preclinical studies, contributing to the development of more effective treatments for pediatric CNS tumors.

The development of orthotopic pediatric brain tumor models requires meticulous precision, using a stereotaxic device to implant cancer cells precisely. The methodology presented here outlines the steps involved in preparing brain tumor cells, performing intracranial injections, and implementing a post-operative monitoring system to assess brain tumor engraftment.

The development of clinically relevant and reliable models for central nervous system (CNS) tumors has been pivotal in advancing the field of ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

Murine Model of Central Venous Stenosis using Aortocaval Fistula with an Outflow Stenosis

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ligation of the inferior vena cava (IVC) in the outflow of the fistula, mimicking central venous stenosis. Technical aspects of this model are introduced. The aorta and IVC are exposed, following an abdominal incision. The infra-renal aorta and IVC are dissected for proximal clamping, and the distal aorta is exposed for puncture. The IVC at the midpoint between the left renal vein and the aortic bifurcation is carefully dissected to place an 8-0 suture beneath the IVC. After clamping the aorta and IVC, an AVF is created by puncturing the infra-renal aorta through both walls into the IVC with a 25 G needle, followed by ligating a 22 G intra-venous (IV) catheter and IVC together. The catheter is then removed, creating a reproducible venous stenosis without occlusion. The aorta and IVC are unclamped after confirming primary hemostasis. This novel model of central vein stenosis is easy to perform, reproducible, and will facilitate studies on AVF failure.

An aortocaval fistula was created by puncturing the murine infra-renal aorta through both walls into the inferior vena cava and was followed by creation of a stenosis in its outflow via partial ligation of the inferior vena cava. This reproducible model can be used to study central venous stenosis.

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ...

A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor because of the acceleration of intimal hyperplasia due to the exposure to arterial blood pressure. The present protocol is designed for the establishment of experimental venous intimal hyperplasia by interposing rabbit jugular veins to the ipsilateral carotid arteries. The protocol does not require surgical procedures deep in the body trunk and the extent of the incision is limited, which is less invasive for the animals, allowing long-term observation after implantation. This simple procedure enables researchers to investigate strategies to attenuate the progression of intimal hyperplasia of the implanted vein grafts. Using this protocol, we reported the effects transduction of microRNA-145 (miR-145), which is known to control the phenotype of vascular smooth muscle cells (VSMCs) from the proliferative to the contractile state, into harvested vein grafts. We confirmed the attenuation of intimal hyperplasia of vein grafts by transducing miR-145 before implantation surgery through the phenotype change of the VSMCs. Here we report a less invasive experimental platform to investigate the strategies that can be used to attenuate intimal hyperplasia of vein grafts in revascularization surgeries.

The present protocol aims to experimentally create venous intimal hyperplasia by subjecting veins to arterial blood pressure for developing strategies to attenuate venous intimal hyperplasia following revascularization surgery using vein grafts.

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor ...

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the investigation of disease mechanisms and the development of therapeutic strategies. 
To perform the surgery, we enter the cardiac chamber through the third intercostal space and carefully dissect the internal mammary vein and immerse it in normal saline. The right main coronary artery is then treated for ischemia. The target vessel is incised, a shunt plug is placed, and the distal end of the graft vein is anastomosed. The ascending aorta is partially blocked, and the proximal end of the graft vein is anastomosed after perforation. The graft vein is checked for patency, and the proximal right coronary artery is ligated. 
CABG surgery is performed in minipigs to harvest the left internal mammary vein for its use as a vascular graft. Serum biochemical tests are used to evaluate the physiological status of the animals after surgery. Ultrasound examination shows that the proximal, middle, and distal end of the graft vessel are unobstructed. In the surgical model, turbulent blood flow in the graft is observed upon histological examination after the CABG surgery, and venous graft stenosis associated with intimal hyperplasia is observed in the graft. The study here provides detailed surgical procedures for the establishment of a repeatable CABG-induced VGD model.

In this protocol, novel pig vein bypass grafting was performed through a small incision in the left chest wall without cardiopulmonary bypass. A postoperative pathology study was done, which showed intimal thickening.