The authors acknowledge the critical contribution of Dr. Beth Chaffee, DVM, PhD, DACVP to the development of this technique.&#160;&#160;

All described animal experiments were approved by the institutional animal care and use committee of University of Cambridge, Cambridge, UK.
1. Preparation of cell lines
<ol>
	<li>Grow cell lines in accordance with the laboratory&#8217;s standard cell culture protocols for traditional cell culture or injection into mice. Standard protocols used here are growth in Dulbecco&#8217;s modified Eagle&#8217;s medium containing 10% fetal bovine serum (FBS), L-glutamine, and penicillin/streptomycin (...

<ol>
	<li>Bryda, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Mighty+Mouse:+the+impact+of+rodents+on+advances+in+biomedical+research.">The Mighty Mouse: the impact of rodents on advances in biomedical research.</a> Missouri Medicine. 110 (3), 207-211 (2013).</li><li>Vandamme, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+rodents+as+models+of+human+diseases.">Use of rodents as models of human diseases.</a> Journal of Pharmacy and Bioallied Sciences. 6 (1), 2-9 (2014).</li><li>Simmons, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+Models+of+Bone+Metastasis.">Animal Models of Bone Metastasis.</a> Veterinary Pathology. 52 (5), 827-841 (2015).</li><li>Wolfe, 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=Effect+of+zoledronic+acid+and+amputation+on+bone+invasion+and+lung+metastasis+of+canine+osteosarcoma+in+nude+mice.">Effect of zoledronic acid and amputation on bone invasion and lung metastasis of canine osteosarcoma in nude mice.</a> Clinical and Experimental Metastasis. 28 (4), 377-389 (2011).</li><li>Wang, 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=The+Clinicopathological+features+and+survival+outcomes+of+patients+with+different+metastatic+sites+in+stage+IV+breast+cancer.">The Clinicopathological features and survival outcomes of patients with different metastatic sites in stage IV breast cancer.</a> BMC Cancer. 19 (1), 1091 (2019).</li><li>James, J. 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=metastases+from+breast+carcinoma:+histopathological+-+radiological+correlations+and+prognostic+features.">metastases from breast carcinoma: histopathological - radiological correlations and prognostic features.</a> British Journal of Cancer. 89 (4), 660-665 (2003).</li><li>Pantel, K., Brakenhoff, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissecting+the+metastatic+cascade.">Dissecting the metastatic cascade.</a> Nature Reviews Cancer. 4 (6), 448-456 (2004).</li><li>Chaffee, B. K., Allen, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+clinically+relevant+mouse+model+of+canine+osteosarcoma+with+spontaneous+metastasis.">A clinically relevant mouse model of canine osteosarcoma with spontaneous metastasis.</a> In Vivo. 27 (5), 599-603 (2013).</li><li>Munajat, I., Zulmi, W., Norazman, M. Z., Wan Faisham, W. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumour+volume+and+lung+metastasis+in+patients+with+osteosarcoma.">Tumour volume and lung metastasis in patients with osteosarcoma.</a> Journal of Orthopaedic Surgery (Hong Kong). 16 (2), 182-185 (2008).</li><li>Huang, 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=Risk+and+clinicopathological+features+of+osteosarcoma+metastasis+to+the+lung:+A+population-based+study.">Risk and clinicopathological features of osteosarcoma metastasis to the lung: A population-based study.</a> Journal of Bone Oncology. 16, 100230 (2019).</li><li>Li, W., Zhang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Survival+of+patients+with+primary+osteosarcoma+and+lung+metastases.">Survival of patients with primary osteosarcoma and lung metastases.</a> Journal of BUON. 23 (5), 1500-1504 (2018).</li><li>Campbell, J. P., Merkel, A. R., Masood-Campbell, S. K., Elefteriou, F., Sterling, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+of+bone+metastasis.">Models of bone metastasis.</a> Journal of Visualized Experiments. (67), e4260 (2012).</li><li>Maloney, 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=Intratibial+Injection+Causes+Direct+Pulmonary+Seeding+of+Osteosarcoma+Cells+and+Is+Not+a+Spontaneous+Model+of+Metastasis:+A+Mouse+Osteosarcoma+Model.">Intratibial Injection Causes Direct Pulmonary Seeding of Osteosarcoma Cells and Is Not a Spontaneous Model of Metastasis: A Mouse Osteosarcoma Model.</a> Clinical Orthopedics and Related Research. 476 (7), 1514-1522 (2018).</li><li>Dai, J., Hensel, J., Wang, N., Kruithof-de Julio, M., Shiozawa, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+for+studying+prostate+cancer+bone+metastasis.">Mouse models for studying prostate cancer bone metastasis.</a> BoneKey Reports. 5, 777 (2016).</li><li>Marques da Costa, M. 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=Establishment+and+characterization+of+in+vivo+orthotopic+bioluminescent+xenograft+models+from+human+osteosarcoma+cell+lines+in+Swiss+nude+and+NSG+mice.">Establishment and characterization of in vivo orthotopic bioluminescent xenograft models from human osteosarcoma cell lines in Swiss nude and NSG mice.</a> Cancer Medicine. 7 (3), 665-676 (2018).</li><li>Raheem, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+patient-derived+intra-femoral+xenograft+model+of+bone+metastatic+prostate+cancer+that+recapitulates+mixed+osteolytic+and+osteoblastic+lesions.">A novel patient-derived intra-femoral xenograft model of bone metastatic prostate cancer that recapitulates mixed osteolytic and osteoblastic lesions.</a> Journal of Translational Medicine. 9, 185 (2011).</li><li>Sasaki, H., Iyer, S. V., Sasaki, K., Tawfik, O. W., Iwakuma, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+intrafemoral+injection+with+minimized+leakage+as+an+orthotopic+mouse+model+of+osteosarcoma.">An improved intrafemoral injection with minimized leakage as an orthotopic mouse model of osteosarcoma.</a> Analytical Biochemistry. 486, 70-74 (2015).</li><li>Valastyan, S., Weinberg, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+metastasis:+molecular+insights+and+evolving+paradigms.">Tumor metastasis: molecular insights and evolving paradigms.</a> Cell. 147 (2), 275-292 (2011).</li><li>Yu, 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=Intra-iliac+Artery+Injection+for+Efficient+and+Selective+Modeling+of+Microscopic+Bone+Metastasis.">Intra-iliac Artery Injection for Efficient and Selective Modeling of Microscopic Bone Metastasis.</a> Journal of Visualized Experiments. (115), e53982 (2016).</li><li>Kuchimaru, 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=A+reliable+murine+model+of+bone+metastasis+by+injecting+cancer+cells+through+caudal+arteries.">A reliable murine model of bone metastasis by injecting cancer cells through caudal arteries.</a> Nature Communications. 9 (1), 2981 (2018).</li><li>Haley, H. 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=Enhanced+Bone+Metastases+in+Skeletally+Immature+Mice.">Enhanced Bone Metastases in Skeletally Immature Mice.</a> Tomography. 4 (2), 84-93 (2018).</li><li>Lei, Z. G., Ren, X. H., Wang, S. S., Liang, X. H., Tang, Y. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunocompromised+and+immunocompetent+mouse+models+for+head+and+neck+squamous+cell+carcinoma.">Immunocompromised and immunocompetent mouse models for head and neck squamous cell carcinoma.</a> Onco Targets and Therapy. 9, 545-555 (2016).</li><li>Lefley, 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=Development+of+clinically+relevant+in+vivo+metastasis+models+using+human+bone+discs+and+breast+cancer+patient-derived+xenografts.">Development of clinically relevant in vivo metastasis models using human bone discs and breast cancer patient-derived xenografts.</a> Breast Cancer Research. 21 (1), 130 (2019).</li><li>Tuveson, D., Clevers, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+modeling+meets+human+organoid+technology.">Cancer modeling meets human organoid technology.</a> Science. 364 (6444), 952-955 (2019).</li></ol>

Dr. Hildreth was funded by the&#160;NIH under Award Number&#160;K01OD026527.&#160; Content is solely&#160;the responsibility of the authors&#160;and does not necessarily&#160;represent the official views of the&#160;NIH.

This report documents our model to create primary bone tumors or bone metastasis following the intratibial implantation of a tumor allograft. We believe that there are several critical steps in this process. A safe anesthetic plane should be established for both subcutaneous injection of the tumor cell suspension and intratibial placement of the resultant tumor fragments. There should be sterile preparation of the surgical site for both removal of the subcutaneous allograft and intratibial placement of the allograft. Tum...

Mouse models of human and animal disease are becoming increasingly popular in biomedical research. The utility of using mice in this context is that their anatomy and physiology are very similar to humans. They have a relatively short gestation period and time in post-natal life to achieve maturity, and are largely associated with a relatively low cost and ease of housing, albeit increasing costs of development or purchase are associated with greater degrees of genetic modification, immunodeficiency, and/or humanization1. Use of inbred strains results in a largely uniform animal population prior to study inclusion. A complete knowledge of their genome suggests a high degree of similarity to humans. Orthologous molecular targets for many disease processes have been identified in the mouse genome and there is now an extensive library of mouse-specific reagents that are easily obtainable. Therefore, they provide the opportunity for relatively high-throughput analysis in a more rapid and less expensive manner when compared to larger animal models1. In addition, with the advent of genetic editing strategies that allows for the overexpression or deletion of certain genes either globally or in a cell type specific manner and/or constitutively or in an inducible manner, they represent a very biologically useful model system for the investigation of human and animal diseases2.
Cancer is one field in which mouse models have great utility. Genetic mouse models of cancer rely on modulation of the expression of either oncogenes or tumor suppressor genes, alone or in combination, for cells to undergo oncogenic transformation. The injection of primary or established tumor cell lines into mice is also performed. The introduction of either cell lines or tissues from humans or other animal species, including mice, remains the most widely used model of cancer in vivo. The use of cells and tissues from dissimilar species (xenografts) in immunocompromised mice is most commonly performed2. However, the use of allograft tumor cells or tissues where both the host and recipient are of the same species allows for the interaction with an intact immune system when combined with the same host mouse strain in syngeneic systems3.
Primary bone tumors or bone metastasis from solid tumors result in painful osteolytic, osteoblastic, or mixed osteolytic/osteoblastic lesions3,4. These tumors compromise bone structure, increasing the risk of pathologic fracture, and leave patients with limited treatment options. Primary bone tumors metastasize to distant organs, with some types capable of spreading to other skeletal sites. In breast cancer patients, bone is the most common site of first metastasis and the most frequent first site of presentation of metastatic disease5,6. In addition, disseminated tumor cells (DTCs) are present in the bone marrow prior to the diagnosis of, and predict the development of, metastasis in other organs7. Therefore, it is believed that cancer cells present in bone are the source of cells that ultimately metastasize to other organ systems. Many mouse models of solid tumor metastasis exist that develop metastasis predominantly in the lung and lymph nodes, and depending on the tumor type and injection technique, potentially other organ systems3. However, mouse models of bone metastasis are lacking that dependably, reproducibly produce site specific skeletal metastasis and develop bone metastasis before mice reach early removal criteria from primary tumor burden or metastasis to other organs. We have reported a model of the primary bone tumor osteosarcoma that relies on the surgical implantation of a solid tumor allograft into the proximal tibia of mice8. Bone tumors formed in 100% of mice and 88% developed pulmonary metastasis. This incidence of metastasis exceeds what is commonly reported clinically in people (~20-50%), but is of great interest since the lung is the most common site of metastasis for osteosarcoma9,10,11. While this model is advantageous in modeling primary bone tumors, it also has great utility in modeling bone metastasis from other osteotropic solid tumors such as breast, lung, prostate, thyroid, hepatic, renal, and gastrointestinal tumors.
The rationale for the development of this model was to develop an alternative to the traditional intra-osseous injection typically into the proximal tibia or distal femur to model primary bone tumors or bone metastasis12. Our primary goal was to alleviate a known limitation of this technique i.e., tumor embolization of the lung. This results in the engraftment of these embolic tumor cells and &#8220;artifactual metastasis&#8221; that do not recapitulate the complete metastatic cascade from an established primary bone tumor that metastasizes to the lungs8,13. This would also be the situation when an established bone metastasis spreads to a distant site. In addition, this technique was, also, developed to produce a model of bone metastasis that would ensure a greater incidence of engraftment and growth of tumors in bone and at a uniform site when compared with orthotopic or intravascular injection techniques. This model has distinct advantages over these described techniques. This model involves controlled, consistent delivery of tumor cells into the bone. It, also, avoids artifactual lung metastasis following pulmonary embolization and establishes a baseline uniform study population. There is the benefit of site-specific tumors with this model without the risk of early removal criteria resulting from primary tumors or metastasis to other organs. Lastly, this model has great utility for modification, including the use of patient-derived xenografts.
The model presented has similarities to direct cell suspension injection into bone following a surgical approach followed by either injection through the cortex or delivery into the marrow cavity after making a small defect in the cortex (with or without reaming out the medullary cavity)8,14,15,16,17. However, the implantation of a tumor allograft makes this technique distinctly different. Therefore, the purpose of this report was to demonstrate this model of primary bone tumors and bone metastasis from solid tumors, which overcomes many limitations of previously described models. Research groups with experience in cell culture, mouse models, mouse anesthesia and surgery, and mouse anatomy are well equipped to reproduce our technique to model primary bone tumors or bone metastasis in mice.

<table>
	<tbody>
		<tr>
			<td>#15 scalpel blade</td>
			<td>Henry Schein Ltd.</td>
			<td>75614</td>
			<td>None</td>
		</tr>
		<tr>
			<td>6-well tissue culture plates</td>
			<td>Thermo Fisher Scientific</td>
			<td>10578911</td>
			<td>Used for mincing tumor pieces. Can also be used for cell culture</td>
		</tr>
		<tr>
			<td>Abrams osteosarcoma cell line</td>
			<td>Not applicable</td>
			<td>Not applicable</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Anesthesia machine with isoflurane vaporiser and oxygen tank(s)</td>
			<td>VetEquip</td>
			<td>901805</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Animal weighing scale</td>
			<td>Kent Scientific</td>
			<td>SCL- 1015</td>
			<td>None</td>
		</tr>
		<tr>
			<td>BALB/c nude mouse (nu/nu)</td>
			<td>Charles River Ltd.</td>
			<td>NA</td>
			<td>6-8 weeks of age. Male or female mice</td>
		</tr>
		<tr>
			<td>Bone cement</td>
			<td>Depuy Synthes</td>
			<td>160504</td>
			<td>Optional use instead of bone wax</td>
		</tr>
		<tr>
			<td>Bone wax</td>
			<td>Ethicon</td>
			<td>W31G</td>
			<td>Optional</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Animalcare Ltd.</td>
			<td>N/A</td>
			<td>Buprecare 0.3 mg/ml Solution for Injection for Dogs and Cats</td>
		</tr>
		<tr>
			<td>Carbon dioxide euthanasia station</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Should be provided within animal facility</td>
		</tr>
		<tr>
			<td>Cell culture incubator set at 37 &#176;C and 5% carbon dioxide</td>
			<td>Heraeus</td>
			<td>Various</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Chlorhexidine surgical scrub</td>
			<td>Vetoquinol</td>
			<td>411412</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Cryovials (2 ml)</td>
			<td>Thermo Scientific Nalgene</td>
			<td>5000-0020</td>
			<td>Optional if cryopreserving tumor fragments</td>
		</tr>
		<tr>
			<td>D-luciferin (Firefly), potassium salt</td>
			<td>Perkin Elmer</td>
			<td>122799</td>
			<td>Optional if cell line of interest has a bioluminescent reporter gene</td>
		</tr>
		<tr>
			<td>Digital caliper</td>
			<td>Mitutoyo</td>
			<td>500-181-30</td>
			<td>Can be manual</td>
		</tr>
		<tr>
			<td>Digital microradiography cabinet</td>
			<td>Faxitron Bioptics, LLC</td>
			<td>MX-20</td>
			<td>Optional to evaluate bone response to tumor growth</td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide (DMSO)</td>
			<td>Sigma Aldrich</td>
			<td>1371171000</td>
			<td>Optional if cryopreserving tumor fragments</td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s modified Eagle&#8217;s medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>11965092</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Ethanol (70%)</td>
			<td>Sigma Aldrich</td>
			<td>2483</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Thermo Fisher Scientific</td>
			<td>26140079</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Forceps, Dumont</td>
			<td>Fine Science Tools, Inc.</td>
			<td>11200-33</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Freezer (&#8211; 80 &#176;C)</td>
			<td>Sanyo</td>
			<td>MDF-794C</td>
			<td>Optional if cryopreserving or snap freezing tumor fragments</td>
		</tr>
		<tr>
			<td>Hemocytometer</td>
			<td>Thermo Fisher Scientific</td>
			<td>11704939</td>
			<td>Can also use automated cell counter, if available</td>
		</tr>
		<tr>
			<td>Hypodermic needles (27 gauge)</td>
			<td>Henry Schein Ltd.</td>
			<td>DIS55510</td>
			<td>May also use 25G (DIS55509) and 30G (Catalog DIS599) needles</td>
		</tr>
		<tr>
			<td>Ice</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Ideally small pieces in a container for syringe and cell suspension storage</td>
		</tr>
		<tr>
			<td>Iris scissors</td>
			<td>Fine Science Tools, Inc.</td>
			<td>14084-08</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Henry Schein Ltd.</td>
			<td>1182098</td>
			<td>None</td>
		</tr>
		<tr>
			<td>IVIS Lumina III bioluminescence/fluorescence imaging system</td>
			<td>Perkin Elmer</td>
			<td>CLS136334</td>
			<td>Optional if cell line of interest has bioluminescent or fluorescent reporter genes</td>
		</tr>
		<tr>
			<td>L-glutamine</td>
			<td>Thermofisher scientifc</td>
			<td>25030081</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Liquid nitrogen</td>
			<td>British Oxygen Corporation</td>
			<td>NA</td>
			<td>Optional if cryopreserving or snap freezing tumor fragments</td>
		</tr>
		<tr>
			<td>Liquid nitrogen dewar, 5 litres</td>
			<td>Thermo Fisher Scientific</td>
			<td>TY509X1</td>
			<td>Optional if cryopreserving tumor fragments</td>
		</tr>
		<tr>
			<td>Matrigel&#174; Matrix GFR, LDEV-Free, 5 ml</td>
			<td>Corning Life Sciences</td>
			<td>356230</td>
			<td>Optional. Also available in 10 ml size (354230)</td>
		</tr>
		<tr>
			<td>Microcentrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>75002549</td>
			<td>Pellet cells at 1200 rpm for 5-6 minutes</td>
		</tr>
		<tr>
			<td>Mr. Frosty freezing containiner</td>
			<td>Fisher Scientific</td>
			<td>10110051</td>
			<td>Optional if cryopreserving tumor fragments</td>
		</tr>
		<tr>
			<td>NAIR Hair remover lotion/oil</td>
			<td>Thermo Fisher Scientific</td>
			<td>NC0132811</td>
			<td>Can alternatively use an electric clipper with fine blade</td>
		</tr>
		<tr>
			<td>Penicillin/streptomycin</td>
			<td>Sigma-Aldrich</td>
			<td>P4333</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Scalpel handle, #7 Short</td>
			<td>Fine Science Tools, Inc.</td>
			<td>10007-12</td>
			<td>User preference as long as it accepts #15 scalpel blade</td>
		</tr>
		<tr>
			<td>Small animal heated pad</td>
			<td>VetTech</td>
			<td>HE006</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>GT Vision Ltd.</td>
			<td>H600BV1</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Sterile phosphate-buffered saline (PBS)</td>
			<td>Thermo Fisher Scientific</td>
			<td>10010023</td>
			<td>Use for injections and also as part of the surgical scrub, alternating with chlorhexidine</td>
		</tr>
		<tr>
			<td>Tissue adhesive (sterile)</td>
			<td>3M Corporation</td>
			<td>84-1469SB</td>
			<td>Can alternatively use non-absorbable skin suture (6-0 size)</td>
		</tr>
		<tr>
			<td>Trypan blue</td>
			<td>Thermo Fisher Scientific</td>
			<td>5250061</td>
			<td>None</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA</td>
			<td>Thermo Fisher Scientific</td>
			<td>25300054</td>
			<td>Use 0.05%-0.25%</td>
		</tr>
		<tr>
			<td>Tuberculin syringe (1 ml with 0.1 ml gradations)</td>
			<td>Becton Dickinson</td>
			<td>309659</td>
			<td>Slip tip preferred over Luer</td>
		</tr>
		<tr>
			<td>Vented tissue culture flasks, T-75</td>
			<td>Corning Life Sciences</td>
			<td>CLS3290</td>
			<td>Can also use smaller or larger flasks, as needed</td>
		</tr>
	</tbody>
</table>

modeling primary bone tumors and bone metastasis with solid tumor graft implantation into bone

Primary bone tumors or bone metastasis from solid tumors result in painful osteolytic, osteoblastic, or mixed osteolytic/osteoblastic lesions. These lesions compromise bone structure, increase the risk of pathologic fracture, and leave patients with limited treatment options. Primary bone tumors metastasize to distant organs, with some types capable of spreading to other skeletal sites. However, recent evidence suggests that with many solid tumors, cancer cells that have spread to bone may be the primary source of cells that ultimately metastasize to other organ systems. Most syngeneic or xenograft mouse models of primary bone tumors involve intra-osseous (orthotopic) injection of tumor cell suspensions. Some animal models of skeletal metastasis from solid tumors also depend on direct bone injection, while others attempt to recapitulate additional steps of the bone metastatic cascade by injecting cells intravascularly or into the organ of the primary tumor. However, none of these models develop bone metastasis reliably or with an incidence of 100%. In addition, direct intra-osseous injection of tumor cells has been shown to be associated with potential tumor embolization of the lung. These embolic tumor cells engraft but do not recapitulate the metastatic cascade. We reported a mouse model of osteosarcoma in which fresh or cryopreserved tumor fragments (consisting of tumor cells plus stroma) are implanted directly into the proximal tibia using a minimally invasive surgical technique. These animals developed reproducible engraftment, growth, and, over time, osteolysis and lung metastasis. This technique has the versatility to be used to model solid tumor bone metastasis and can readily employ grafts consisting of one or multiple cell types, genetically-modified cells, patient-derived xenografts, and/or labeled cells that can be tracked by optical or advanced imaging. Here, we demonstrate this technique, modeling primary bone tumors and bone metastasis using solid tumor graft implantation into bone.

A positive result would be associated with tumor engraftment and progressive tumor growth over time. Depending on the tumor type, intraosseous tumor growth may be associated with progressive hind limb lameness, but many tumors do not cause lameness despite signs of attendant bone disease. Successful engraftment was documented with advanced imaging, whereby there would be progressive radiographic, &#181;CT, or &#181;MRI changes in the proximal tibia associated with the bone phenotype of the cell line of interest (osteolyt...

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Modeling Primary Bone Tumors and Bone Metastasis with Solid Tumor Graft Implantation into Bone

Bone metastasis models do not develop metastasis uniformly or with a 100% incidence. Direct intra-osseous tumor cell injection can result in embolization of the lung. We present our technique modeling primary bone tumors and bone metastasis using solid tumor graft implantation into bone, leading to reproducible engraftment and growth.

Primary bone tumors or bone metastasis from solid tumors result in painful osteolytic, osteoblastic, or mixed osteolytic/osteoblastic lesions. These ...

This study allows for flexibility in creating primary bone tumors or bone metastasis by placing solid tumor grafts into bone. This technique is a departure from injecting tumor cell suspensions in the bone. This method overcomes the limitation of tumor cell suspension injections lung emboli.Another advantage is creating a more uniform model when compared to spontaneous bone metastasis or after intravascular cell injection. Based on solid tumor graft implantation, possibilities exist beyond human or mouse models, but the use of patient-derived xenografts which can lead to therapies tailored to specific patients. The primary focus is for use at cancer research such as tumor microenvironment, metastasis, drug discovery, cancer genetics, and precision medicine.Visual demonstration is key to showing the key steps of creating the subcutaneous tumor, dissection and creation of the tumor graft, and surgical implantation into the tibia. For subcutaneous tumor induction, harvest the cell line of interest using an appropriate cell dissociation solution and resuspend the cells at a one to two times 10 to the fifth cells to 100 to 150 microliter sterile PBS concentration. Place the cells on ice.Clean the exposed skin with 70%ethanol, and load the cells into a Tuberculin syringe equipped with a 27 gauge needle. Then inject the cell subcutaneously into a region of disinfected skin that will not be impacted by the movement of the shoulder blades. Use a caliper to monitor the size of the subcutaneous tumor overlying the dorsal thorax or abdomen, and measure the animal's body weight weekly to ensure that the tumor does not ulcerate or that the mouse does not meet early removal criteria as established by the Institutional Animal Care and Use Committee.When the tumor reaches 15 millimeters in any dimension, use 70%ethanol to sterilize the skin and use a 15 scalpel to incise the skin overlying the tumor. Use sterile surgical scissors to dissect the tumor from the surrounding attached soft tissues sharply and place the tumor in one well of a six-well plate containing complete growth medium. Use the scalpel to mince the tumor into appropriately sized fragments and place the fragments into a new container of sterile complete growth medium at room temperature.For cryopreservation, pool multiple fragments in a single cryovial in complete growth medium supplemented with 20%fetal bovine serum and 10%dimethyl sulfoxide and use a commercial cryopreservation system at minus 80 degrees Celsius to gradually freeze the tissue before long-term storage in liquid nitrogen. To preserve tumor fragments for subsequent analysis but not future implantation, snap freeze the samples by liquid nitrogen immersion and store the frozen tumor fragments long term at minus 80 degrees Celsius. For subcutaneous tumor fragment implantation, first bring the tumor fragments suspension to room temperature.Next, confirm a lack of response to pedal reflex in an anesthetized recipient mouse and subcutaneously administer analgesia. To minimize the potential trauma to the skin, use depilating cream to remove the hair on the right knee joint and proximal tibia of the connected hindlimb. Scrub the exposed skin with 70%ethanol, followed by alternating chlorhexidine and saline scrubs.While flexing and extending the joint, visualize the proximal tibia as the region just distal to the knee joint and use a 15 scalpel blade to create a three to four millimeter incision at the level of the proximal tibia on the medial aspect of the limb through the skin and subcutaneous tissue to expose the medial cortex of the proximal tibia. To create a small hole in the medial cortex of the proximal tibia, use the tip of a 25 gauge needle to apply gentle pressure while rotating the tip approximately two millimeters distal to the knee joint and equidistant between the cranial and caudal tibial cortexes. When the hole has been created, use sterile forceps or a 27 to 30 gauge needle to insert a minimum of 0.5 cubed millimeter tumor fragments into the medullary cavity of the proximal tibia and use a 27 to 30 gauge needle to manipulate the tumor fragments into the medullary canal.After placing all the fragments, oppose the skin edges with the appropriate material and return the animal to its cage with monitoring until ambulatory. Then evaluate the tibial tumor growth noninvasively by weekly digital radiography, bioluminescence, or fluorescence imaging, and use calipers to measure the limb at the implantation site. Successful engraftment can be documented with advanced imaging.In this representative analysis, the cortical defect created for tumor graft implantation was visible in the proximal tibia one week after implantation. By week two, visible osteolysis and bone remodeling adjacent to the cortical defect could be observed. From weeks two to five, additional progressive bone destruction and the formation of new bone associated with tumor engraftment and growth occurred.Care should be taken while creating a small hole in the proximal tibia. Rely on rotating the tip with gentle to minimal pressure allowing the needle tip to do the work. Following this procedure, tumor graft placement in other bone sites, placement of organoids or tumor cells in the extracellular matrix into the bone defect or molecular and histologic analysis in addition to imaging can be performed.

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Research

JoVE Journal

Cancer Research

2.5K visualizações.  University of Alabama at Birmingham. This study allows for flexibility in creating primary bone tumors or bone metastasis by placing solid tumor grafts into bone. This technique is a departure from injecting tumor cell suspensions in the bone. This method overcomes the limitation of tumor cell suspension injections lung emboli.Another advantage is creating a more uniform model when compared to spontaneous bone metastasis or after intravascular cell injection. Based on solid tumor graft implantation, possibilities exist be...