This study was supported by grants from (1) National Key R&#38;D Program of China (2018YFC1704300 and 2020YFE0201600), (2) National Nature Science Foundation (81973877 and 82174408).

All animal experiments were approved by the animal welfare committee of Shanghai University of Traditional Chinese Medicine. Four-week-old male BALB/c athymic mice were acclimated for a week before the surgery for orthotopic injection of osteosarcoma cells. Mice were housed in individually ventilated&#160;mice cages with five mice per cage in a 12-hour light/dark cycle with ad libitum access to SPF feed and sterile water.
1. Preparation of cells
<ol>
	<li>On the day of osteo...

<ol>
	<li>Bielack, S. S., 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=Prognostic+factors+in+high-grade+osteosarcoma+of+the+extremities+or+trunk:+an+analysis+of+1,702+patients+treated+on+neoadjuvant+cooperative+osteosarcoma+study+group+protocols.">Prognostic factors in high-grade osteosarcoma of the extremities or trunk: an analysis of 1,702 patients treated on neoadjuvant cooperative osteosarcoma study group protocols.</a> Journal of Clinical Oncology. 20 (3), 776-790 (2002).</li><li>Yang, 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=Bone+microenvironment+and+osteosarcoma+metastasis.">Bone microenvironment and osteosarcoma metastasis.</a> International Journal of Molecular Sciences. 21 (19), (2020).</li><li>Mirabello, L., Troisi, R. J., Savage, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteosarcoma+incidence+and+survival+rates+from+1973+to+2004:+data+from+the+Surveillance,+Epidemiology,+and+End+Results+Program.">Osteosarcoma incidence and survival rates from 1973 to 2004: data from the Surveillance, Epidemiology, and End Results Program.</a> Cancer. 115 (7), 1531-1543 (2009).</li><li>Zhang, B., 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+efficacy+and+safety+comparison+of+first-line+chemotherapeutic+agents+(high-dose+methotrexate,+doxorubicin,+cisplatin,+and+ifosfamide)+for+osteosarcoma:+a+network+meta-analysis.">The efficacy and safety comparison of first-line chemotherapeutic agents (high-dose methotrexate, doxorubicin, cisplatin, and ifosfamide) for osteosarcoma: a network meta-analysis.</a> Journal of Orthopaedic Surgery and Research. 15 (1), 51 (2020).</li><li>Tsukamoto, S., Errani, C., Angelini, A., Mavrogenis, A. 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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Orthotopic+and+heterotopic+murine+models+of+pancreatic+cancer+and+their+different+responses+to+FOLFIRINOX+chemotherapy.">Orthotopic and heterotopic murine models of pancreatic cancer and their different responses to FOLFIRINOX chemotherapy.</a> Disease Models &amp; Mechanisms. 11 (7), (2018).</li><li>Chang, 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=MicroRNAs+for+osteosarcoma+in+the+mouse:+a+meta-analysis.">MicroRNAs for osteosarcoma in the mouse: a meta-analysis.</a> Oncotarget. 7 (51), 85650-85674 (2016).</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 Orthopaedics and Related Research. 476 (7), 1514-1522 (2018).</li><li>Yu, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+reproducible+osteosarcoma+rat+model+using+orthotopic+implantation+technique.">Establishment of reproducible osteosarcoma rat model using orthotopic implantation technique.</a> Oncology Reports. 21 (5), 1175-1180 (2009).</li><li>Fidler, I. J., Naito, S., Pathak, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Orthotopic+implantation+is+essential+for+the+selection,+growth+and+metastasis+of+human+renal+cell+cancer+in+nude+mice+[corrected].">Orthotopic implantation is essential for the selection, growth and metastasis of human renal cell cancer in nude mice [corrected].</a> Cancer Metastasis Reviews. 9 (2), 149-165 (1990).</li><li>Leacock, S. W., 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+zebrafish+transgenic+model+of+Ewing's+sarcoma+reveals+conserved+mediators+of+EWS-FLI1+tumorigenesis.">A zebrafish transgenic model of Ewing's sarcoma reveals conserved mediators of EWS-FLI1 tumorigenesis.</a> Disease Models &amp; Mechanisms. 5 (1), 95-106 (2012).</li><li>Sharma, S., Boston, S. E., Riddle, D., Isakow, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteosarcoma+of+the+proximal+tibia+in+a+dog+6+years+after+tibial+tuberosity+advancement.">Osteosarcoma of the proximal tibia in a dog 6 years after tibial tuberosity advancement.</a> The Canadian Veterinary Journal. 61 (9), 946-950 (2020).</li><li>Mohseny, A. B., Hogendoorn, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish+as+a+model+for+human+osteosarcoma.">Zebrafish as a model for human osteosarcoma.</a> Advances in Experimental Medicine and Biology. 804, 221-236 (2014).</li><li>Hu, S., 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=Cantharidin+inhibits+osteosarcoma+proliferation+and+metastasis+by+directly+targeting+miR-214-3p/DKK3+axis+to+inactivate+&#946;-catenin+nuclear+translocation+and+LEF1+translation.">Cantharidin inhibits osteosarcoma proliferation and metastasis by directly targeting miR-214-3p/DKK3 axis to inactivate &#946;-catenin nuclear translocation and LEF1 translation.</a> International Journal of Biological Sciences. 17 (10), 2504-2522 (2021).</li><li>Chang, 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=Polyphyllin+I+suppresses+human+osteosarcoma+growth+by+inactivation+of+Wnt/&#946;-catenin+pathway+in+vitro+and+in+vivo.">Polyphyllin I suppresses human osteosarcoma growth by inactivation of Wnt/&#946;-catenin pathway in vitro and in vivo.</a> Scientific Reports. 7 (1), 7605 (2017).</li><li>Lamar, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SRC+tyrosine+kinase+activates+the+YAP/TAZ+axis+and+thereby+drives+tumor+growth+and+metastasis.">SRC tyrosine kinase activates the YAP/TAZ axis and thereby drives tumor growth and metastasis.</a> The Journal of Biological Chemistry. 294 (7), 2302-2317 (2019).</li><li>Benton, G., Arnaoutova, I., George, J., Kleinman, H. K., Koblinski, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrigel:+from+discovery+and+ECM+mimicry+to+assays+and+models+for+cancer+research.">Matrigel: from discovery and ECM mimicry to assays and models for cancer research.</a> Advanced Drug Delivery Reviews. , 3-18 (2014).</li><li>Chang, 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=Matrine+inhibits+prostate+cancer+via+activation+of+the+unfolded+protein+response/endoplasmic+reticulum+stress+signaling+and+reversal+of+epithelial+to+mesenchymal+transition.">Matrine inhibits prostate cancer via activation of the unfolded protein response/endoplasmic reticulum stress signaling and reversal of epithelial to mesenchymal transition.</a> Molecular Medicine Reports. 18 (1), 945-957 (2018).</li><li>Fridman, 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+tumor+growth+of+both+primary+and+established+human+and+murine+tumor+cells+in+athymic+mice+after+coinjection+with+Matrigel.">Enhanced tumor growth of both primary and established human and murine tumor cells in athymic mice after coinjection with Matrigel.</a> Journal of the National Cancer Institute. 83 (11), 769-774 (1991).</li><li>Kocat&#252;rk, B., Versteeg, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Orthotopic+injection+of+breast+cancer+cells+into+the+mammary+fat+pad+of+mice+to+study+tumor+growth.">Orthotopic injection of breast cancer cells into the mammary fat pad of mice to study tumor growth.</a> Journal of Visualized Experiments. (96), e51967 (2015).</li><li>Paschall, A. V., Liu, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+orthotopic+mouse+model+of+spontaneous+breast+cancer+metastasis.">An orthotopic mouse model of spontaneous breast cancer metastasis.</a> Journal of Visualized Experiments. (114), e54040 (2016).</li><li>Hildreth, B. E., Palmer, C., Allen, M. 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Orthotopic injection of osteosarcoma cells is an ideal model to study the function and mechanism of specific factors in osteosarcoma carcinogenesis and development to evaluate the therapeutic efficacy. To avoid differences in tumor growth, most active osteosarcoma cells at 80%-90% confluent with the same number are carefully injected into the tibia of each mouse, and the cell trypsinization time is strictly controlled without affecting the cell viability. As cell clumps affect cell counting leading to inaccurate cell num...

Osteosarcoma is the most common primary bone cancer in children and adolescents1,2, which mainly infiltrates the surrounding tissue, and even metastasizes to the lungs when the patients are diagnosed. Pulmonary metastasis is the main challenge for osteosarcoma therapy, and the five-year survival rate of osteosarcoma patients with pulmonary metastasis remains as low as 20%-30%3,4,5. However, the five-year survival rate of primary osteosarcoma has been increased to about 70% since the 1970s due to the introduction of chemotherapy6. Therefore, it&#39;s urgently needed to understand the fundamental mechanism of osteosarcoma carcinogenesis and pulmonary metastasis to develop novel therapies. The application of mouse models that best mimic the osteosarcoma progression in humans is of great significance7.
The osteosarcoma animal models are generated by spontaneous, induced genetic engineering, transplantation, and other techniques. The spontaneous osteosarcoma model is rarely used due to the long tumor formation time, inconsistent tumor occurrence rate, low morbidity, and poor stability8,9. Although the induced osteosarcoma model is more accessible to obtain than the spontaneous osteosarcoma, the application of the induced osteosarcoma model is limited because the inducing factor will affect the microenvironment, the pathogenesis, and pathological characteristics of osteosarcoma10. Transgenic models are helping to understand the pathogenesis of cancers since they can better simulate the human physiological and pathological environments; however, the transgenic animal models also have their limitations due to the difficulty, long-term, and high cost of transgenic modification. Moreover, even in the most widely accepted transgenic animal models generated by p53 and Rb gene modification, only 13.6% of sarcoma occurred in the four limb bones11,12.
Transplantation is one of the most commonly used primary and distant metastatic cancer model-producing methods in recent years due to its simple maneuver, stable tumor formation rate, and better homogeneity13. Transplantation includes heterotopic transplantation and orthotopic transplantation according to the transplantation sites. In osteosarcoma heterotopic transplantation, the osteosarcoma cells are injected outside the primary osteosarcoma sites (bone) of the animals, commonly under the skin, subcutaneously14. Although the heterotopic transplantation is straightforward without the necessity to perform surgery in animals, the sites where the osteosarcoma cells are injected do not represent the actual human osteosarcoma microenvironment. Osteosarcoma orthotopic transplantation is when the osteosarcoma cells are injected into animals&#39; bones, such as tibia15,16. Compared to the heterotopic grafts, orthotopic osteosarcoma grafts are characterized by a short incubation period, rapid growth, and strong erosive nature; therefore, they are ideal animal models for osteosarcoma-related studies17.
The most commonly used animals are mice, dogs, and zebrafish18,19. The spontaneous model of osteosarcoma is usually used in canines because osteosarcoma is one of the most common tumors in canines. However, the application of this model is limited because of the long tumor formation time, the low tumorigenesis rate, poor homogeneity, and stability. Zebrafishes are often used to construct transgenic or knockout tumor models because of their rapid reproduction20. But zebrafish genes are different from human genes, so their applications are limited.
This work describes the detailed procedures, precautions, and representative images for producing the primary osteosarcoma in the tibia with pulmonary metastasis via intratibia injection of osteosarcoma cells in athymic mice. This method was applied to create the primary osteosarcoma in mouse tibia for therapeutic efficacy evaluation, which showed a high reproducibility21,22.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Automatic cell counter</td>
			<td>Shanghai Simo Biological Technology Co., Ltd</td>
			<td>IC1000</td>
			<td>Counting cells</td>
		</tr>
		<tr>
			<td>Anesthesia machine</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>R500IP</td>
			<td>The Equipment of Anesthesia mice</td>
		</tr>
		<tr>
			<td>BALB/c athymic mice</td>
			<td>Shanghai SLAC Laboratory Animal Co, Ltd.</td>
			<td>/</td>
			<td>animal</td>
		</tr>
		<tr>
			<td>Basement Membrane Matrix</td>
			<td>Shanghai Uning Bioscience Technology Co., Ltd</td>
			<td>356234, BD, Matrigel</td>
			<td>re-suspende cells</td>
		</tr>
		<tr>
			<td>Bioluminescence imaging system</td>
			<td>Shanghai Baitai Technology Co., Ltd</td>
			<td>Vieworks</td>
			<td>tracking the tumor growth and pulmonary metastasis, if the injection cell is labeled by luciferase</td>
		</tr>
		<tr>
			<td>Centrifuge tube (15 mL)</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>&#160;430790, Corning</td>
			<td>Centrifuge the cells</td>
		</tr>
		<tr>
			<td>isoflurane</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>VETEASY</td>
			<td>Anesthesia mice</td>
		</tr>
		<tr>
			<td>MEM media</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>LM-E1141</td>
			<td>Cell culture medium</td>
		</tr>
		<tr>
			<td>Micro-volume syringe</td>
			<td>Shanghai high pigeon industry and trade Co., Ltd</td>
			<td>0-50 &#956;L</td>
			<td>Inject precise cells into the tibia</td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline</td>
			<td>Beyotime Biotechnology</td>
			<td>ST447</td>
			<td>wash the human osteosarcoma cells</td>
		</tr>
		<tr>
			<td>1ml syringes</td>
			<td>Shandong Weigao Group Medical Polymer Co., Ltd</td>
			<td>20200411</td>
			<td>drilling</td>
		</tr>
		<tr>
			<td>143B cell line</td>
			<td>ATCC</td>
			<td>CRL-8303</td>
			<td>osteosarcoma cell line</td>
		</tr>
		<tr>
			<td>Trypsin (0.25%)</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>25200056, Gibco</td>
			<td>trypsin treatment of cells</td>
		</tr>
		<tr>
			<td>Trypan blue</td>
			<td>Beyotime Biotechnology</td>
			<td>ST798</td>
			<td>Staining cells to assess activity</td>
		</tr>
		<tr>
			<td>vector (pLV-luciferase)</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>VL3613</td>
			<td>Plasmid</td>
		</tr>
		<tr>
			<td>Lipofectamine 2000</td>
			<td>Shanghai YueNian Biotechnology Co., Ltd</td>
			<td>11668027,Thermo fisher</td>
			<td>Plasmid transfection reagent</td>
		</tr>
		<tr>
			<td>X-ray imaging system</td>
			<td>Brook (Beijing) Technology Co., Ltd</td>
			<td>FX PRO</td>
			<td>X-ray images were obtained to detect tumor growth</td>
		</tr>
	</tbody>
</table>

intratibial osteosarcoma cell injection to generate orthotopic osteosarcoma and lung metastasis mouse models

Osteosarcoma is the most common primary bone cancer in children and adolescents, with lungs as the most common metastatic site. The five-year survival rate of osteosarcoma patients with pulmonary metastasis is less than 30%.Therefore, the utilization of mouse models mimicking the osteosarcoma development in humans is of great significance for understanding the fundamental mechanism of osteosarcoma carcinogenesis and pulmonary metastasis to develop novel therapeutics. Here, detailed procedures are reported to generate the primary osteosarcoma and pulmonary metastasis mouse models via&#160;intratibia injection of osteosarcoma cells. Combined with the bioluminescence or X-ray live imaging system, these living mouse models are utilized to monitor and quantify osteosarcoma growth and metastasis. To establish this model, a basement membrane matrix containing osteosarcoma cells was loaded in a micro-volume syringe and injected into one tibia of each athymic mouse after being anesthetized. The mice were sacrificed when the primary osteosarcoma reached the size limitation in the IACUC-approved protocol. The legs bearing osteosarcoma and the lungs with metastasis lesions were separated. These models are characterized by a short incubation period, rapid growth, severe lesions, and sensitivity in monitoring the development of primary and pulmonary metastatic lesions. Therefore, these are ideal models for exploring the functions and mechanisms of specific factors in osteosarcoma carcinogenesis and pulmonary metastasis, the tumor microenvironment, and evaluating the therapeutic efficacy in vivo.

Successful orthotopic (primary) osteosarcoma and metastatic pulmonary models depend on the accurate orthotopic injection of osteosarcoma cells. Here, an orthotopic (primary) osteosarcoma model via intratibial osteosarcoma cell injection was successfully developed. Figure 3A shows a representative mouse bearing orthotopic (primary) osteosarcoma, and Figure 3B shows a representative isolated orthotopic (primary) osteosarcoma. The tumor volume was measured...

Watch this Scientific Journal Video about Intratibial Osteosarcoma Cell Injection to Generate Orthotopic Osteosarcoma and Lung Metastasis Mouse Models at JoVE.com

Intratibial Osteosarcoma Cell Injection to Generate Orthotopic Osteosarcoma and Lung Metastasis Mouse Models

The present protocol describes intratibia osteosarcoma cell injection to generate mouse models bearing orthotopic osteosarcoma and pulmonary metastasis lesions.

Osteosarcoma is the most common primary bone cancer in children and adolescents, with lungs as the most common metastatic site. The five-year survival ...

This protocol describes the technique to generate mouse models bearing primary osteosarcoma and the pulmonary metastasis lesions. By intratibial injection of osteosarcoma cells, this model best mimics the clinical development characteristics of tumor osteosarcoma. Accurate numbers of osteosarcoma cells are directly injected into the tibia using a microvolume syringe, allowing for identical tumor formation rates and tumor volumes.On the day of osteosarcoma cell injection, wash the cells twice with PBS. Trypsinize the cells with 1.5 milliliters of 0.25%trypsin for three minutes. Then add six milliliters of 10%serum-containing MEM media.Collect the cells in a 15-milliliter centrifuge tube. Aspirate 20 microliters of cell suspension into the chamber of the cell counting plate, and calculate cell concentration using an automatic cell counter. Centrifuge the cells at 800 times g for five minutes at room temperature.Aspirate the supernatant with a pipette, resuspend the cell pellet in an 8.5-milligram-per-milliliter basement membrane matrix, and place them on ice. Place the mouse in the supine position. Hold the ankle of the mouse using the thumb and index finger, and disinfect the injection site of the tibia with a 70%ethanol swab.Rotate the ankle joint of each mouse outward to move the tibia and fibula, and bend the knee joint to a suitable position until the proximal tibia plateau is visible through the skin. Attach the needle to a one-milliliter syringe, and point the needle tip toward the injection site, parallel to the axis of the tibia. Percutaneously insert the needle to drill a hole through the tibia platform toward the distal end of the tibia.Load the osteosarcoma cell suspension previously placed on ice into a microvolume syringe, and replace the one-milliliter syringe in the tibia with the osteosarcoma cell-loaded microvolume syringe. Slowly inject approximately 10 microliters of osteosarcoma cell suspension into each athymic mouse's tibia without applying much pressure. Then remove the microvolume syringe from the injection site, and press the site with the cotton swab for about 30 seconds.Place the mouse back into a clean cage, and observe its recovery for 10 minutes. This figure depicts the mouse model with orthotopic osteosarcoma developed from intratibial osteosarcoma cell injection and its isolated form. A gradual increase in the tumor volume is observed every week.The X-ray images obtained from the first through the sixth week after injection of luciferase-labeled osteosarcoma cells showed a gradual increase in volume. Furthermore, the image obtained after the injection into the mouse tibia showed orthotopic osteosarcoma growth in vivo. The pulmonary metastasis caused by intratibial injection of the osteosarcoma cells was successfully tracked in vivo using a bioluminescence live imaging system.Observation under a stereomicroscope revealed metastatic colonies in the isolated lung tissues. HE staining on paraffin-embedded lung tissues showed metastatic lesions. The needle should be percutaneously inserted into the joint capsule through the patellar ligament to drill a hole through the tibia platform toward the digital tibia by rotating the syringe.

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JoVE Journal

Cancer Research

7.8K vistas.  Shanghai University of Traditional Chinese Medicine. Este protocolo describe la técnica para generar modelos de ratón con osteosarcoma primario y las lesiones de metástasis pulmonar. Mediante la inyección intratibial de células de osteosarcoma, este modelo imita mejor las características de desarrollo clínico del osteosarcoma tumoral. Un número exacto de células de osteosarcoma se inyectan directamente en la tibia utilizando una jeringa de microvolumen, lo que permite tasas de formación de tumores y volúmenes tumorales idénticos.