The authors wish to thank members of the Cancer Neural-Immune Laboratory and Dr. Cameron Nowell at Monash Institute of Pharmaceutical Sciences, Monash University, Parkville. This work was supported by grants from National Health and Medical Research Council 1147498, the National Breast Cancer Foundation IIRS-20-025, the Australian and New Zealand College of Anaesthetists (ANZCA), Perpetual and CTC for Cancer Therapeutics.

All animal studies were undertaken under the approval of the Institutional Animal Care and Use Committee at Monash University. In this study, female Balb/c mice aged 6-8 weeks were used.
1. Prepare cancer cells
<ol>
	<li>Culture tumor cells in medium. Culture 66cl4 murine mammary cancer cells in alpha-MEM containing 10% FBS and 200 mM glutamine. Cells should text negative for mycoplasma. OPTIONAL:&#160;Use cells that are stably transduced to express firefly luciferase for bioluminescence imaging to enable cancer recurrence monitoring after resection surgery11 (see step 4). 
	NOTE: The cell line and the medium mentioned above were used in this study.</li>
	<li>Grow cells at 37 &#176;C with 5% CO2. Passage cells aseptically in a hood&#160;at &#60;80% confluency. Use low-passage cells in the logarithmic growth phase for optimal in vivo results.</li>
	<li>Lift the adherent cells with 0.5 mg/mL of trypsin in PBS with 10 mM EDTA; 2 mL for a T75 flask. When lifted, add medium to inactivate trypsin, and wash the cells in PBS.</li>
	<li>Count the cells using a hemocytometer. Dilute the cells in PBS for injection. For 66cl4 mammary cancer cells, inject 1 x 105 cells in 20 &#956;L of PBS per mouse.</li>
	<li>Place the cells on ice prior to the injection.</li>
</ol>
2. Generate a mouse model of breast cancer
<ol>
	<li>Use 4% isoflurane to anesthetize the mouse in an induction chamber. Then, maintain anesthesia with 2%-3% isoflurane using a nose cone. Confirm proper anesthetization by lack of response to toe pinch.</li>
	<li>Prepare the injection site by wiping the fourth left mammary fatpad area using a single-use alcohol swab.</li>
	<li>Draw up tumor cells (see step 1.4) into a 25 &#956;L Hamilton syringe attached to a sterile 27 G hypodermic needle.</li>
	<li>Inject the cells into the fourth left mammary fatpad. Use forceps to secure and lift the skin. Inject approximately 1 mm from the nipple.</li>
	<li>OPTIONAL: If cells are tagged with luciferase, confirm successful injection of tumor cells by bioluminescence imaging. Inject 100 &#956;L of 150 mg/kg D-luciferin into the lateral tail vein of the anesthetized mice using a 0.5 mL insulin syringe with a 30 G hypodermic needle.</li>
	<li>OPTIONAL: Place the mouse in a bioluminescence imaging system with the mammary fatpad facing up. Wait for 2 min from the luciferin injection for optimal tissue uptake of luciferin, then image for 10 s.</li>
	<li>Place the mouse in a clean cage and allow it to recover from anesthesia.</li>
	<li>Continue to monitor animal welfare as per the institutional animal ethics guidelines.</li>
</ol>
3. Induce stable anesthesia with intravenous delivery of propofol
<ol>
	<li>Monitor growth of the primary tumor using caliper measurement and calculate the tumor volume using the equation: Volume (mm3) = (length x (width)2 &#247; 2).</li>
	<li>Perform tumor resection surgery on mice when the primary tumor reaches the required volume (here, 80-90 mm3).</li>
	<li>Set up an automated syringe pump with a 30 G 1 mL insulin syringe containing propofol formulation (2% Lipuro propofol) (Figure 1A).</li>
	<li>Induce anesthesia of the mouse in an induction chamber with 3% sevoflurane or isoflurane. 
	NOTE: Here, sevoflurane was used as this is the predominant volatile used clinically.</li>
	<li>Transfer the mouse to a 37 &#176;C heating pad for the duration of the surgery. Briefly maintain anesthesia with 2%-3% sevoflurane using a nose cone.</li>
	<li>Apply aqueous lubricant to the eyes to prevent drying.&#160;</li>
	<li>Inject 0.05 mg/kg of buprenorphine subcutaneously for analgesia.</li>
	<li>To prepare for surgery, shave the abdomen and prepare the skin for surgery with an iodine-povidone solution. Wipe the skin using an alcohol or sterile wipe.</li>
	<li>To deliver propofol-based TIVA, cannulate the lateral tail vein using a sterile 30 G hypodermic needle attached to a sterile polyurethane catheter. Confirm correct placement by blood flashback into the catheter (Figure 1B). Adjust the delivery of sevoflurane as required during intravenous cannulation to maintain a stable depth of anesthesia demonstrated by loss of corneal and pedal reflex, and respiratory rate &#60; 100 breaths per min.</li>
	<li>Commence propofol-TIVA by administering 2% propofol as an initial bolus of 27 mg/kg for over 1 min. Cease sevoflurane administration.</li>
	<li>Continue the infusion of propofol at a maintenance rate of 2.2-4.0 mg/kg/min to maintain a stable depth of anesthesia for the duration of the surgery (Figure 1C).</li>
</ol>
4. Resect the primary tumor
<ol>
	<li>Make a straight&#160;1 cm incision inferior to the tumor in the region of the left fourth mammary fatpad. Carefully resect the tumor and the left inguinal lymph node using dissection with blunt forceps.</li>
	<li>OPTIONAL: If using luciferase-tagged tumor cells, use bioluminescence imaging to confirm clear surgical margins. Inject 150 mg/kg D-luciferin into the lateral tail vein, wait for 2 min, and then image for 60 s using a bioluminescence imaging system. If a residual tumor is identified, resect additional tissue from the mammary fatpad and re-image to achieve clear margins.</li>
	<li>Ensure hemostasis at the surgical site and close the skin using 5-0 nylon sutures. Ensure that the fur does not enter the surgical site.</li>
	<li>At the conclusion of resection surgery, cease anesthesia. Place the mouse in a clean cage on a 37 &#176;C heating pad and allow it to recover from anesthesia.</li>
	<li>Monitor every 15 min after anesthesia until the mouse has returned to normal alertness. Then, monitor the mouse every 12 h for 48 h after surgery.</li>
	<li>Administer 0.05 mg/kg of buprenorphine subcutaneously every 12 h for 48 h after surgery.</li>
	<li>After 7-10 days, remove sutures using sterile curved stitch cutters under brief sevoflurane or isoflurane anesthesia.</li>
</ol>
5. Track cancer recurrence with in vivo imaging
<ol>
	<li>Use bioluminescence imaging to track cancer recurrence after resection surgery non-invasively. Use a bioluminescence imaging system to monitor the mice once per week for evidence of primary tumor recurrence or distant recurrence, commencing the week following surgery.</li>
	<li>Induce anesthesia of the mouse in an induction chamber with 4% isoflurane. Then, transfer the mouse to a 37 &#176;C heating pad for the duration of anesthesia and maintain anesthesia with 2%-4% isoflurane using a nose cone.</li>
	<li>Apply aqueous lubricant to the eyes to prevent drying.</li>
	<li>Inject D-luciferin 150 mg/kg into the lateral tail vein. Wait for 2 min, then measure bioluminescence over a 60 s exposure to detect recurrence of the primary tumor or distant metastasis.</li>
	<li>If the primary tumor recurs and becomes palpable, commence monitoring of tumor growth using caliper measurements.</li>
	<li>At the end of the experiment, humanely kill the mice according to the approved protocol. Here, CO2 was used, followed by cervical dislocation.</li>
</ol>

<ol>
	<li>Sullivan, 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=Global+cancer+surgery:+delivering+safe,+affordable,+and+timely+cancer+surgery.">Global cancer surgery: delivering safe, affordable, and timely cancer surgery.</a> Lancet Oncology. 16 (11), 1193-1224 (2015).</li><li>Lim, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+propofol+and+sevoflurane+on+cancer+cell,+natural+killer+cell,+and+cytotoxic+T+lymphocyte+function+in+patients+undergoing+breast+cancer+surgery:+an+in+vitro+analysis.">The effect of propofol and sevoflurane on cancer cell, natural killer cell, and cytotoxic T lymphocyte function in patients undergoing breast cancer surgery: an in vitro analysis.</a> BMC Cancer. 18 (1), 159 (2018).</li><li>Pandit, 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=5th+National+Audit+Project+(NAP5)+on+accidental+awareness+during+general+anesthesia:+protocol,+methods,+and+analysis+of+data.">5th National Audit Project (NAP5) on accidental awareness during general anesthesia: protocol, methods, and analysis of data.</a> British Journal of Anaesthesia. 113 (4), 540-548 (2014).</li><li>Yap, A., Lopez-Olivo, M. 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T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retrospective+analysis+of+1-year+mortality+after+gastric+cancer+surgery:+Total+intravenous+anesthesia+versus+volatile+anesthesia.">Retrospective analysis of 1-year mortality after gastric cancer surgery: Total intravenous anesthesia versus volatile anesthesia.</a> Acta Anaesthesiologica Scandinavica. 63 (9), 1169-1177 (2019).</li><li>Lai, H. 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The authors declare no competing financial interests.

This study reports on a protocol for administering total intravenous anesthesia (TIVA) with propofol in a mouse model of breast cancer that replicates key aspects of clinical practice for TIVA in patients requiring cancer surgery. The protocol allows investigation of both short-term and long-term clinically relevant outcomes after cancer surgery in a mouse model of cancer progression, including measurement of cytokine levels and cancer recurrence (Figure 2, and Figure 3<...

More than 60% of patients with cancer receive anesthesia for surgical resection1. Currently, there are no specific clinical guidelines that determine the choice of anesthesia used in cancer patients. Surveys of anesthesiologists indicate a preference for volatile-based anesthesia, including during cancer surgery2,3. However, there is a growing body of evidence that the use of propofol-based total intravenous anesthesia (TIVA) during cancer surgery may associate with improved postoperative outcomes (progression-free survival, overall survival) when compared to volatile anesthesia4. Subsequent clinical studies continue to report contradicting results5,6,7,8. These findings support the need for preclinical studies to better understand the mechanistic effects of different anesthetic agents on cancer-related outcomes.
However, in in vivo studies that model cancer surgery, anesthesia is frequently an incidental part of the procedure. The rationale for the choice of anesthesia is&#160;often not the focus of the experimental design, and its impact on cancer-related endpoints may not be evaluated. For example, in vivo studies that require maintenance of anesthesia for cancer surgery most commonly use inhaled volatile anesthesia9. Where propofol has been used in in vivo studies, it has been delivered by single bolus dosing with intraperitoneal delivery, which does not replicate clinical onco-anesthetic protocols10. That approach of propofol administration induces light anesthesia that is suitable for rapid procedures. However, it does not allow maintenance of anesthesia that is required for cancer resection surgery which may be protracted. Furthermore, the absorption kinetics of intraperitoneal delivery is distinct to clinical methods of administration.
A model of propofol-based TIVA for cancer resection surgery was developed to address this need. A protocol for sustained maintenance of anesthesia with titration of the anesthetic agent to allow response to the surgical stimulus was developed to replicate key aspects of anesthetic delivery to patients having cancer surgery. The resulting protocol is used with a mouse model of cancer to provide TIVA during cancer resection surgery. The effect on short-term and long-term cancer-related outcomes is evaluated.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.9% saline</td>
			<td>Fresnius Kabi</td>
			<td>AUST R 197198</td>
			<td></td>
		</tr>
		<tr>
			<td>Artery forceps</td>
			<td>Proscitech</td>
			<td>TS1322-140</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Temgesic</td>
			<td>TEMG I</td>
			<td></td>
		</tr>
		<tr>
			<td>Heated surgical mat</td>
			<td>Custom</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Hypodermic needle (30 G, 1 mL insulin syringe)</td>
			<td>Terumo</td>
			<td>NN3013R</td>
			<td></td>
		</tr>
		<tr>
			<td>IVIS Lumina</td>
			<td>PerkinElmer</td>
			<td>126274</td>
			<td></td>
		</tr>
		<tr>
			<td>Luciferin</td>
			<td>Promega</td>
			<td>P1041/2/3</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyurethane catheter</td>
			<td>Intramedic</td>
			<td>427401</td>
			<td></td>
		</tr>
		<tr>
			<td>Povidone Iodine</td>
			<td>Betadine</td>
			<td>AUST R 29562</td>
			<td></td>
		</tr>
		<tr>
			<td>Propofol Lipuro, 2%</td>
			<td>Braun</td>
			<td>3521490</td>
			<td></td>
		</tr>
		<tr>
			<td>Sevoflurane</td>
			<td>Baxter</td>
			<td>ANZ2L9117</td>
			<td></td>
		</tr>
		<tr>
			<td>Sevoflurane vaporiser</td>
			<td>Vetquip</td>
			<td>VQ1334</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile gauze</td>
			<td>Multigate Medical Products</td>
			<td>11-600A</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical scissors</td>
			<td>Proscitech</td>
			<td>TS1044</td>
			<td></td>
		</tr>
		<tr>
			<td>Sutures, 5-0 nylon</td>
			<td>Dynek</td>
			<td>V504</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>Harvard Apparatus</td>
			<td>70-4500</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringes (1 mL)</td>
			<td>Terumo</td>
			<td>SS+01T</td>
			<td></td>
		</tr>
	</tbody>
</table>

an in vivo mouse model of total intravenous anesthesia during cancer resection surgery

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been implicated in impacting long-term cancer outcomes, possibly through modulation of adrenergic-inflammatory responses that impact cancer cell behavior and immune cell function. Emerging evidence suggests that propofol-based total intravenous anesthesia (TIVA) may be beneficial for long-term cancer outcomes when compared to inhaled volatile anesthesia. However, the available clinical findings are inconsistent. Preclinical studies that identify the underlying mechanisms involved are critically needed to guide the design of clinical studies that will expedite insight. Most preclinical models of anesthesia have been extrapolated from the use of anesthesia in in vivo research and are not optimally designed to study the impact of anesthesia itself as the primary endpoint. This paper describes a method for delivering propofol-TIVA anesthesia in a mouse model of breast cancer resection that replicates key aspects of clinical delivery in cancer patients. The model can be used to study mechanisms of action of anesthesia on cancer outcomes in diverse cancer types and can be extrapolated to other non-cancer areas of preclinical anesthesia research.

This method describes a model of total intravenous anesthesia (TIVA) with propofol during cancer resection surgery in mice. Propofol is delivered in this mouse model through an intravenous catheter using a syringe pump (Figure 1A,B) to replicate delivery of TIVA in the clinical setting of anesthesia for cancer surgery. Use of the syringe pump minimizes exposure to volatile anesthesia by allowing rapid conversion from initial induction by inhalational anesthesia to intravenou...

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An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

This paper describes a method for modeling total intravenous anesthesia (TIVA) during cancer resection surgery in mice. The goal is to replicate key features of anesthesia delivery to patients with cancer. The method allows investigation of how anesthetic technique affects cancer recurrence after resection surgery.

An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been ...

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2.3K Views.  Monash University. This paper describes a method for modeling total intravenous anesthesia (TIVA) during cancer resection surgery in mice. The goal is to replicate key features of anesthesia delivery to patients with cancer. The method allows investigation of how anesthetic technique affects cancer recurrence after resection surgery.

Video: An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

Quantitative Analysis of Cancer Metastasis using an Avian Embryo Model

During metastasis cancer cells disseminate from the primary tumor, invade into surrounding tissues, and spread to distant organs. Metastasis is a complex process that can involve many tissue types, span variable time periods, and often occur deep within organs, making it difficult to investigate and quantify. In addition, the efficacy of the metastatic process is influenced by multiple steps in the metastatic cascade making it difficult to evaluate the contribution of a single aspect of tumor cell behavior. As a consequence, metastasis assays are frequently performed in experimental animals to provide a necessarily realistic context in which to study metastasis. Unfortunately, these models are further complicated by their complex physiology. The chick embryo is a unique in vivo model that overcomes many limitations to studying metastasis, due to the accessibility of the chorioallantoic membrane (CAM), a well-vascularized extra-embryonic tissue located underneath the eggshell that is receptive to the xenografting of tumor cells (figure 1). Moreover, since the chick embryo is naturally immunodeficient, the CAM readily supports the engraftment of both normal and tumor tissues. Most importantly, the avian CAM successfully supports most cancer cell characteristics including growth, invasion, angiogenesis, and remodeling of the microenvironment. This makes the model exceptionally useful for the investigation of the pathways that lead to cancer metastasis and to predict the response of metastatic cancer to new potential therapeutics. The detection of disseminated cells by species-specific Alu PCR makes it possible to quantitatively assess metastasis in organs that are colonized by as few as 25 cells. Using the Human Epidermoid Carcinoma cell line (HEp3) we use this model to analyze spontaneous metastasis of cancer cells to distant organs, including the chick liver and lung. Furthermore, using the Alu-PCR protocol we demonstrate the sensitivity and reproducibility of the assay as a tool to analyze and quantitate intravasation, arrest, extravasation, and colonization as individual elements of metastasis.

Using quantitative PCR, we demonstrate how the well-established chick CAM model can be used to quantitatively analyze the metastasis of human tumor cells to distant organs.

During metastasis cancer cells disseminate from the primary tumor, invade into surrounding tissues, and spread to distant organs. Metastasis is a complex ...

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.

A comprehensive overview of the techniques involved in generating a mouse model of oral cancer and quantitative monitoring of tumor invasion within the tongue through multi-photon microscopy of labeled cells is presented. This system can serve as a useful platform for the molecular assessment and drug efficacy of anti-invasive compounds.

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient ...

Combination Radiotherapy in an Orthotopic Mouse Brain Tumor Model

Glioblastoma multiforme (GBM) are the most common and aggressive adult primary brain tumors1. In recent years there has been substantial progress in the understanding of the mechanics of tumor invasion, and direct intracerebral inoculation of tumor provides the opportunity of observing the invasive process in a physiologically appropriate environment2. As far as human brain tumors are concerned, the orthotopic models currently available are established either by stereotaxic injection of cell suspensions or implantation of a solid piece of tumor through a complicated craniotomy procedure3. In our technique we harvest cells from tissue culture to create a cell suspension used to implant directly into the brain. The duration of the surgery is approximately 30 minutes, and as the mouse needs to be in a constant surgical plane, an injectable anesthetic is used. The mouse is placed in a stereotaxic jig made by Stoetling (figure 1). After the surgical area is cleaned and prepared, an incision is made; and the bregma is located to determine the location of the craniotomy. The location of the craniotomy is 2 mm to the right and 1 mm rostral to the bregma. The depth is 3 mm from the surface of the skull, and cells are injected at a rate of 2 &mu;l every 2 minutes. The skin is sutured with 5-0 PDS, and the mouse is allowed to wake up on a heating pad. From our experience, depending on the cell line, treatment can take place from 7-10 days after surgery. Drug delivery is dependent on the drug composition. For radiation treatment the mice are anesthetized, and put into a custom made jig. Lead covers the mouse's body and exposes only the brain of the mouse. The study of tumorigenesis and the evaluation of new therapies for GBM require accurate and reproducible brain tumor animal models. Thus we use this orthotopic brain model to study the interaction of the microenvironment of the brain and the tumor, to test the effectiveness of different therapeutic agents with and without radiation.

The purpose of this article is to describe the use of an orthotopic glioblastoma model for chemoradiation studies. This article will go though cell processing, implanting, and radiotherapy of the mouse using an intracranial model.

Glioblastoma multiforme (GBM) are the most common and aggressive adult primary brain tumors1. In recent years there has been substantial progress in the ...

An Ex vivo Model to Study Hormone Action in the Human Breast

The study of hormone action in the human breast has been hampered by lack of adequate model systems. Upon in vitro culture, primary mammary epithelial cells tend to lose hormone receptor expression. Widely used hormone receptor positive breast cancer cell lines are of limited relevance to the in vivo situation. Here, we describe an ex vivo model to study hormone action in the human breast. Fresh human breast tissue specimens from surgical discard material such as reduction mammoplasties or mammectomies are mechanically and enzymatically digested to obtain tissue fragments containing ducts and lobules and multiple stromal cell types. These tissue microstructures kept in basal medium without growth factors preserve their intercellular contacts, the tissue architecture, and remain hormone responsive for several days. They are readily processed for RNA and protein extraction, histological analysis or stored in freezing medium. Fluorescence activated cell sorting (FACS) can be used to enrich for specific cell populations. This protocol provides a straightforward, standard approach for translational studies with highly complex, varied human specimens.

An Ex vivo Model to Study Hormone Action in the Human Breast

We have developed a novel ex vivo model to study hormone action in the human breast. It is based on tissue microstructures isolated from surgical breast tissue specimens which preserve tissue architecture, intercellular interactions, and paracrine signaling.

The study of hormone action in the human breast has been hampered by lack of adequate model systems. Upon in vitro culture, primary mammary epithelial ...

An Orthotopic Mouse Model of Spontaneous Breast Cancer Metastasis

Metastasis is the primary cause of mortality of breast cancer patients. The mechanism underlying cancer cell metastasis, including breast cancer metastasis, is largely unknown and is a focus in cancer research. Various breast cancer spontaneous metastasis mouse models have been established. Here, we report a simplified procedure to establish orthotopic transplanted breast cancer primary tumor and resultant spontaneous metastasis that mimic human breast cancer metastasis. Combined with the bioluminescence live tumor imaging, this mouse model allows tumor growth and progression kinetics to be monitored and quantified. In this model, a low dose (1 x 104 cells) of 4T1-Luc breast cancer cells was injected into BALB/c mouse mammary fat pad using a tuberculin syringe. Mice were injected with luciferin and imaged at various time points using a bioluminescent imaging system. When the primary tumors grew to the size limit as in the IACUC-approved protocol (approximately 30 days), mice were anesthetized under constant flow of 2% isoflurane and oxygen. The tumor area was sterilized with 70% ethanol. The mouse skin around the tumor was excised to expose the tumor which was removed with a pair of sterile scissors. Removal of the primary tumor extends the survival of the 4T-1 tumor-bearing mice for one month. The mice were then repeatedly imaged for metastatic tumor spreading to distant organs. Therapeutic agents can be administered to suppress tumor metastasis at this point. This model is simple and yet sensitive in quantifying breast cancer cell growth in the primary site and progression kinetics to distant organs, and thus is an excellent model for studying breast cancer growth and progression, and for testing anti-metastasis therapeutic and immunotherapeutic agents in vivo.

An orthotopic breast cancer primary tumor model and surgical removal of primary tumor to extend mouse life to generate spontaneous metastasis are described. The tumor growth and progression are monitored and quantified by luciferase fluorescence imaging.

Metastasis is the primary cause of mortality of breast cancer patients. The mechanism underlying cancer cell metastasis, including breast cancer ...

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic patient tumors in different assays1. Human tumor xenografts represent the gold standard with respect to tumor biology, drug discovery, and metastasis research 2-4. Tumor xenografts can be derived from different types of material like tumor cell lines, tumor tissue from primary patient tumors4 or serially transplanted tumors. When propagated in vivo, xenografted tissue is infiltrated and vascularized by cells of mouse origin. Multiple factors such as the tumor entity, the origin of xenografted material, growth rate and region of transplantation influence the composition and the amount of mouse cells present in tumor xenografts. However, even when these factors are kept constant, the degree of mouse cell contamination is highly variable.
Contaminating mouse cells significantly impair downstream analyses of human tumor xenografts. As mouse fibroblasts show high plating efficacies and proliferation rates, they tend to overgrow cultures of human tumor cells, especially slowly proliferating subpopulations. Mouse cell derived DNA, mRNA, and protein components can bias downstream gene expression analysis, next-generation sequencing, as well as proteome analysis 5. To overcome these limitations, we have developed a fast and easy method to isolate untouched human tumor cells from xenografted tumor tissue. This procedure is based on the comprehensive depletion of cells of mouse origin by combining automated tissue dissociation with the benchtop tissue dissociator and magnetic cell sorting. Here, we demonstrate that human target cells can be can be obtained with purities higher than 96% within less than 20 min independent of the tumor type.

Human tumor xenografts are vascularized and infiltrated by cells of mouse origin during the growth phase in vivo. To circumvent the bias caused by these contaminating cells during downstream analysis, we developed a method allowing for comprehensive depletion of all mouse cells by magnetic cell sorting.

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...

An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model

Pedicle screw fixation is the gold standard for the treatment of spinal diseases. However, many studies have reported the issue of loosening pedicle screws after spinal surgery, which is a serious concern. To address this problem, diverse types of pedicle screws have been examined to identify those with good fixation strength and osseointegration in spine bone. The porcine spine is a good alternative for the human spine in the evaluation of pedicle screws due to the anatomical size, mechanical characteristics, and cost. Although several studies have reported that pedicle screws are efficient in the porcine model, no study has described detailed protocols for the evaluation of a pedicle screw using the porcine model. Here, we describe a detailed method for evaluating transpedicular screws using an in vivo porcine lumbar spine model. The technical details for anesthesia, spine surgery, and harvest provided here will facilitate with the evaluation of the transpedicular screw fixation model.

An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model

Here, we introduce a method to evaluate transpedicular screws by using an in vivo porcine lumbar spine model.

Pedicle screw fixation is the gold standard for the treatment of spinal diseases. However, many studies have reported the issue of loosening pedicle ...

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The amount of the different tissues in the callus provides important information on the fracture healing progress. Available in vivo techniques to longitudinally monitor the callus tissue development in preclinical fracture-healing studies using small animals include digital radiography and &#181;CT imaging. However, both techniques are only able to distinguish between mineralized and non-mineralized tissue. Consequently, it is impossible to discriminate cartilage from fibrous tissue. In contrast, magnetic resonance imaging (MRI) visualizes anatomical structures based on their water content and might therefore be able to noninvasively identify soft tissue and cartilage in the fracture callus. Here, we report the use of an MRI-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice. The experiments demonstrated that the fixator and a custom-made mounting device allow repetitive MRI scans, thus enabling longitudinal analysis of fracture-callus tissue development.

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

The evaluation of tissue development in the fracture callus during endochondral bone healing is essential to monitor the healing process. Here, we report the use of a magnetic resonance imaging (MRI)-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice.

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The ...

Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular (LV) filling compared with a continuous linear jet. Vortex ring development is most often quantified with vortex formation time (VFT), a dimensionless parameter based on fluid ejection from a rigid tube. Our group is interested in factors that affect LV filling efficiency during cardiac surgery. In this report, we describe how to use standard two-dimensional (2D) and Doppler transesophageal echocardiography (TEE) to noninvasively derive the variables needed to calculate VFT. We calculate atrial filling fraction (&#946;) from velocity-time integrals of trans-mitral early LV filling and atrial systole blood flow velocity waveforms measured in the mid-esophageal four-chamber TEE view. Stroke volume (SV) is calculated as the product of the diameter of the LV outflow track measured in the mid-esophageal long axis TEE view and the velocity-time integral of blood flow through the outflow track determined in the deep transgastric view using pulse-wave Doppler. Finally, mitral valve diameter (D) is determined as the average of major and minor axis lengths measured in orthogonal mid-esophageal bicommissural and long axis imaging planes, respectively. VFT is then calculated as 4 &#215; (1-&#946;) &#215; SV/(&#960;D3). We have used this technique to analyze VFT in several groups of patients with differing cardiac abnormalities. We discuss our application of this technique and its potential limitations and also review our results to date. Noninvasive measurement of VFT using TEE is straightforward in anesthetized patients undergoing cardiac surgery. The technique may allow cardiac anesthesiologists and surgeons to assess the impact of pathological conditions and surgical interventions on LV filling efficiency in real time.

We describe a protocol to measure vortex formation time, an index of left ventricular filling efficiency, using standard transesophageal echocardiography techniques in patients undergoing cardiac surgery. We apply this technique to analyze vortex formation time in several groups of patients with differing cardiac pathologies.

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular ...

In Vivo Mouse Model of Spinal Implant Infection

Spine implant infections portend poor outcomes as diagnosis is challenging and surgical eradication is at odds with mechanical spinal stability. The purpose of this method is to describe a novel mouse model of spinal implant infection (SII) that was created to provide an inexpensive, rapid, and accurate in vivo tool to test potential therapeutics and treatment strategies for spinal implant infections.
In this method, we present a model of posterior-approach spinal surgery in which a stainless-steel k-wire is transfixed into the L4 spinous process of 12-week old C57BL/6J wild-type mice and inoculated with 1 x 103 CFU of a bioluminescent strain of Staphylococcus aureus Xen36 bacteria. Mice are then longitudinally imaged for bioluminescence in vivo on post-operative days 0, 1, 3, 5, 7, 10, 14, 18, 21, 25, 28, and 35. Bioluminescence imaging (BLI) signals from a standardized field of view are quantified to measure in vivo bacterial burden.
To quantify bacteria adhering to implants and peri-implant tissue, mice are euthanized and the implant and surrounding soft tissue are harvested. Bacteria are detached from the implant by sonication, cultured overnight and then colony forming units (CFUs) are counted. The results acquired from this method include longitudinal bacterial counts as measured by in vivo S. aureus bioluminescence (mean maximum flux) and CFU counts following euthanasia.
While prior animal models of instrumented spine infection have involved invasive, ex vivo tissue analysis, the mouse model of SII presented in this paper leverages noninvasive, real time in vivo optical imaging of bioluminescent bacteria to replace static tissue study. Applications of the model are broad and may include utilizing alternative bioluminescent bacterial strains, incorporating other types of genetically engineered mice to contemporaneously study host immune response, and evaluating current or investigating new diagnostic and therapeutic modalities such as antibiotics or implant coatings.

The protocol describes a novel in vivo mouse model of spinal implant infection where a stainless-steel k-wire implant is infected with bioluminescent Staphylococcus aureus Xen36. Bacterial burden is monitored longitudinally with bioluminescent imaging and confirmed with colony forming unit counts after euthanasia.

Spine implant infections portend poor outcomes as diagnosis is challenging and surgical eradication is at odds with mechanical spinal stability. The ...