This research was supported by National Key R&#38;D Program of China (2017YFA0103200), National Natural Science Foundation of China (81671734), and Key Projects of Tianjin Science and Technology Support Program (18YFZCSY00010), Fundamental Research Funds for the Central Universities (63191155). We acknowledge the Gloria Nance&#8217;s revisions, which were valuable in improving the quality of our manuscript.

Experiments must comply with national and institutional regulations concerning the use of animals for research purposes. Permissions to carry out experiments must be obtained. The treatment of animals and experimental procedures of the study adhere to the Nankai University Animal Care and Use Committee Guidelines that conform to the Guidelines for Animal Care approved by the National Institutes of Health (NIH).
1. LV-Rluc-RFP (RR) and LV-Rluc-RFP-HSV-ttk (RRT) lentiviral packaging and production
NOTE: The pLV-RR carries the gene sequences of Renilla luciferase (Rluc) and red fluorescent protein (RFP) under the promoter EF1&#945;, whereas the pLV-RRT carries the gene sequences coding Rluc, RFP, and herpes simplex virus truncated thymidine kinase (HSV-ttk) (Figure 2).
<ol>
	<li>Seed 1 x 106 of 293T cells per well into a 6 well plate and culture overnight in a humidified incubator with 5% CO2 at 37 &#176;C with Dulbecco&#8217;s modified eagle medium (DMEM) containing 10% fetal bovine serum (FBS).</li>
	<li>Prepare the liposome suspension: mix 7.5 &#181;L of liposome and 0.25 mL of minimal essential medium (MEM) into a 1.5 mL tube following incubation for 5 min at room temperature (RT) to disperse liposomes equally.</li>
	<li>Prepare the DNAs solution (DNAs-RR): separately, add the pLV-RR vector and helper plasmids to 0.25 mL of MEM in a 1.5 mL tube as described in Table 1.</li>
	<li>Obtain the liposome/DNAs-RR compound: gently add the DNAs-RR solution into prepared liposome suspension drop by drop and incubate for 20 min at RT so the DNA bonds to the lipid membrane.</li>
	<li>Replace the medium of the 293T cells with 1 mL of DMEM containing 10% FBS and add the liposome/DNAs-RR compound to the medium of the 293T cells gently.</li>
	<li>After incubating in a humidified incubator with 5% CO2 at 37 &#176;C for 12&#8211;16 h, replace the liposome/DNAs-RR compound containing medium of the 293T cells with 1 mL of DMEM containing 10% FBS and 100 U/mL penicillin&#8722;streptomycin.</li>
	<li>Continue culturing the 293T cells in the humidified incubator for 48 h after transfection. Then, collect the supernatant of the 293T cells and centrifuge the medium at 300 x g for 5 min to pellet the 293T cells. Transfer the lentivirus-RR (LV-RR)-containing supernatant into 1.5 mL sterile polypropylene storage tubes and store at -80 &#176;C. 
	NOTE: A Biosafety Level 2 (BSL-2) facility is required in order to work with recombinant lentivirus.</li>
	<li>Repeat steps 1.1&#8211;1.7 and use pLV-RRT vector instead of pLV-RR vector in step 1.3 to obtain the lentivirus-RRT (LV-RRT). Store the LV-RRT at -80 &#176;C. 
	NOTE: The non-purified lentiviral stock may inhibit cell growth in some cases. Lentiviral stock may need to be purified. The lentiviral stocks containing LV-RR or LV-RRT particles should be divided into 1.5 mL tubes (1 mL per tube) for storage to avoid multiple free-thaw cycles.</li>
</ol>
2. LV-RR and LV-RRT lentiviral transduction for gene expression in 4T1 cells
<ol>
	<li>Seed 4T1 cells into a 6-well plate (5 x 105 cells/well) and culture with Roswell Park Memorial Institute (RPMI) 1640 medium containing 10% FBS overnight in a humidified incubator with 5% CO2 at 37 &#176;C.</li>
	<li>Remove the medium from the culture plate and replace it with 1 mL fresh RPMI 1640 medium as well as 1 mL of lentiviral stock (LV-RR or LV-RRT) to each well. Add 8 &#181;g/mL polybrene and gently blend the medium containing lentiviral particles by pipetting up and down. 
	NOTE: Please be aware that the medium contains lentiviral particles, which could transduce human cells.</li>
	<li>Spin transduction solution in a centrifuge at 1,000 &#215; g for 60 min at RT to help increase transduction efficiency. After centrifugation, culture 4T1 cells for 4&#8211;12 h and maintain in a humidified incubator with 5% CO2 at 37 &#176;C. 
	NOTE: For some cell lines, polybrene may be toxic for long-term culture. Therefore, the incubation time for transducing different cells may be changeable. Check the cell status multiple times to find appropriate incubation time.</li>
	<li>Refresh the medium of transduced 4T1 cells with 2 mL of RPMI 1640 medium containing 10% FBS and 100 U/mL penicillin&#8722;streptomycin to remove lentiviral particles and polybrene.</li>
</ol>
3. Drug screening and identification of LV-RR and LV-RRT transduced 4T1 cells
<ol>
	<li>Select transduced cells with medium containing blasticidin (BSD) according to the BSD-resistance gene carried by LV-RR or LV-RRT as the following steps described. 
	NOTE: Alternatively, the transduced cells which are RFP-positive could be selected by flow cytometry according to the RFP gene carried by LV-RR or LV-RRT.</li>
	<li>48 h after transduction, passage 4T1 cells at the ratio of 1:3 to 1:4 with selection medium (RPMI 1640 medium containing 10% FBS, 100 U/mL penicillin&#8722;streptomycin, and 5 &#181;g/mL BSD). Change medium every 2 or 3 days. 
	NOTE: The optimal BSD concentration may vary from cell line to cell line. Therefore, a pilot experiment of kill curve should be performed to determine the optimal concentration of BSD before initial experiment.</li>
	<li>7 days post-drug screening, observe the LV-RR transduced 4T1 cells (4T1-RR) and LV-RRT transduced 4T1 cells (4T1-RRT) under the fluorescence inverted phase-contrast microscope. Count the number of RFP+ 4T1 cells and all 4T1 cells in three fields of vision to estimate the RFP-positive ratio, respectively (Figure 2). 
	NOTE: Alternatively, the RFP-positive ratio of transduced 4T1 cells could be identified by flow cytometry.</li>
	<li>Measure the renilla signals of 4T1-RR cells and 4T1-RRT cells by using a living imaging system to detect the linear relationship between cell numbers and renilla signals (Figure 3).</li>
	<li>Expand BSD-screened 4T1-RR and 4T1-RRT cells with selection medium at split ratios between 1:3 and 1:4 and store the cell line stocks in liquid nitrogen.</li>
</ol>
4. Vegfr2-Fluc-KI mice and tumor-bearing mouse model
NOTE: The transgenic Vegfr2-Fluc-KI mice, 6-8 weeks old and female, are used in this experiment to non-invasively monitor angiogenesis in vivo by BLI.
<ol>
	<li>Culture 4T1-RR cells and 4T1-RRT cells in 60 mm Petri dishes in a humidified incubator with 5% CO2 at 37 &#176;C, respectively. When the cells are at 80% confluence, remove the medium and rinse with phosphate buffered saline (PBS).</li>
	<li>Remove the PBS and add an additional 2 mL of 0.25% trypsin-0.53 mM EDTA solution respectively. Keep the dish at RT (or at 37 &#176;C) until the cells detach.</li>
	<li>Add 5&#8211;10 mL of fresh medium containing 10% FBS, then aspirate and dispense cells to resuspend 4T1-RR and 4T1-RRT cells into 15 mL centrifuge tubes, respectively. Count two types of 4T1 cells using a counting chamber and prepare the cell suspensions at a concentration of 1 x 106 per 100 &#181;L in RPMI 1640 medium.</li>
	<li>Anesthetize the Vegfr2-Fluc-KI mice with 1%&#8211;3% isoflurane in 100% oxygen at anesthesia induction chamber with a flow rate of 1 L/min. Monitor the toe pinch response of the mouse to confirm the status of anesthesia. Then, apply ophthalmic ointment to the eyes of mouse to prevent dehydration.</li>
	<li>Remove mouse from chamber and position in nosecone. Entirely remove the hair of the shoulder of mouse by using electric shaver and hair removal cream, which could provide a good view of surgical field and avoid blocking the BLI signals in following-up experiments.</li>
	<li>Subcutaneously inject 4T1-RR cells (1 x 106 cells at a 100 &#181;L total volume) and 4T1-RRT cells (1 x 106 cells at a 100 &#181;L total volume) in left and right shoulders of each mouse, respectively (record as Day 0). Place mice in recovery area with thermal support until fully recovered.</li>
	<li>After implantation of 4T1-RR and 4T1-RRT cells, touch the tumor masses to check that the mice are tumor-bearing every day (Figure S1). At day 7 post-implantation, intraperitoneally inject 50 mg/kg ganciclovir (GCV) to the tumor-bearing mice two times per day until the end of experiment. 
	NOTE: Before this experiment, the cytotoxic of GCV on 4T1-RRT cells should be detected. The killing efficiency of GCV could be evaluated by cell counting assay with different concentration of GCV (Figure S2).</li>
	<li>On the day 0, 3, 7, 14, and 21 after 4T1 implantation, monitor the tumor growth and angiogenesis of tumor-bearing mice and assess by both Rluc and Fluc imaging (Figure 4).</li>
</ol>
5. Dual bioluminescence imaging of tumor (Rluc) and angiogenesis (Fluc)
<ol>
	<li>Open the living imaging system, initialize the living imaging software, and then initialize the system. 
	NOTE: The system initialization will take few minutes to cool down the charge-coupled device (CCD) camera to -90 &#176;C before able to start imaging. The temperature will turn green when the CCD camera is cooled.</li>
	<li>Use the following camera settings: 
	Check the Luminescence and Photograph. 
	Check Overlay. 
	Luminescence settings: 
	Exposure Time sets AUTO in normal conditions. 
	Binning sets to 8. 
	F/Stop sets to 1. 
	Emission Filter sets Open. 
	Photograph settings: 
	Binning sets to medium. 
	F/Stop sets to 8. 
	IVIS system settings: 
	Field of view: C=1 mouse view, D=5 mice view. 
	Subject height sets 1.5 cm.</li>
	<li>Weigh and record the mice and calculate the volume of coelenterazine (CTZ; 2.5 mg/kg) and D-luciferin (150 mg/kg) needed.</li>
	<li>Anesthetize tumor-bearing mouse by 1%&#8211;3% isoflurane in 100% oxygen at anesthesia induction chamber with a flow rate of 1 L/min. Monitor the toe pinch response of the mouse to confirm the status of anesthesia. Then, dispense a drop of lubricating eye ointment onto both eyes to avoid corneal damage.</li>
	<li>Inject 2.5 mg CTZ (3.33 mg/mL) per kilogram body weight into the retrobulbar of the mouse (e.g., for a 20 g mouse, inject 15 &#956;L to deliver 50 &#956;g of CTZ) by using an insulin syringe needle.</li>
	<li>Move the tumor-bearing mouse into the camera chamber with its nose in the anesthesia cone gently and acquire several pictures of the mouse dorsal immediately to get the Rluc signals from 4T1 cells until the BLI signals fade away. 
	NOTE: The half-life of CTZ is very short and the signals of Rluc drop precipitously ~30 s. To ensure any residual Rluc signal has dissipated and the interval between Rluc and Fluc imaging should be more than 10 min.</li>
	<li>Intraperitoneally inject 150 mg/kg D-luciferin (30 mg/mL) using an insulin syringe needle (e.g., for a 20 g mouse, inject 100 &#956;L to deliver 3 mg of D-luciferin). Keep the mouse at RT for 10 min before Fluc imaging.</li>
	<li>Move this mouse into camera chamber with its nose in the anesthesia cone again and acquire several pictures of the mouse dorsal to get the Fluc signals from angiogenesis. 
	NOTE: The Fluc kinetic monitor should be performed for each mouse until the signals reach the maximum and then fade.</li>
	<li>Repeat the procedures steps 5.4&#8211;5.8 for each mouse.</li>
	<li>After imaging, maintain the mice in a warm environment until animals wake up.</li>
	<li>At the desired time point (day 3, 7, 14, and 21), repeat above procedures (step 5.3&#8211;5.10) to detect the tumor progression and tumor angiogenesis over time.</li>
	<li>Analyze the Rluc and Fluc signals data to investigate the relationship between the tumor growth and angiogenesis in tumor progression. 
	NOTE: The regions of interest (ROI) which cover the BLI signal site are used to analyze the data. Measure the total radiance (Photons) of ROI in the unit of Photons/seconds/cm2/steradian (p/s/cm2/sr) for every timepoint.</li>
	<li>Analyze the Rluc and Fluc signals of ROI by using graphics software (Figure 4).</li>
</ol>

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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=Tumor+cell-specific+bioluminescence+platform+to+identify+stroma-induced+changes+to+anticancer+drug+activity.">Tumor cell-specific bioluminescence platform to identify stroma-induced changes to anticancer drug activity.</a> Nature Medicine. 16, 483-489 (2010).</li><li>Madero-Visbal, R. A., Hernandez, I. C., Myers, J. N., Baker, C. H., Shellenberger, T. 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The authors have nothing to disclose.

In this protocol, a non-invasive dual BLI approach is described for monitoring tumor development and angiogenesis. The BLI reporter system is first developed, containing the HSV-ttk/GCV suicide gene for tracking tumor progression and regression in vivo by Rluc imaging. Meanwhile, tumor angiogenesis is assessed using Vegfr2-Fluc-KI mice via Fluc imaging. This tumor-bearing mouse model is able to provide a practical platform for continuous and non-invasive tracking tumor development and tumor angiogenesis by dual BLI in a ...

Angiogenesis is an essential process in the progression of cancer from small, localized neoplasms to larger, potentially metastatic tumors1,2. The correlation between tumor growth and angiogenesis becomes one of the points of emphasis in the field of oncology research. However, traditional methods of measuring morphologic changes fail to monitor tumor progression and angiogenesis simultaneously in living animals using a visualized approach.
Bioluminescence imaging (BLI) of tumor cells is a particularly appropriate experimental method to monitor tumor growth because of its non-invasiveness, sensitivity, and specificity3,4,5,6. BLI technology is based on the principle that the luciferase can catalyze oxidation of a specific substrate while emitting bioluminescence. The luciferase expressed in &#160;implanted tumor cells reacts with the injected substrate, which can be detected by a living imaging system, and signals indirectly reflect the changes in cell number or cell localization in vivo6,7.
Except for tumor growth, tumor angiogenesis (the critical step in cancer progression) can also be visualized through BLI technology using Vegfr2-Fluc-KI transgenic mice8,9,10. The vascular endothelial growth factor (Vegf) receptor 2 (Vegfr2), one type of Vegf receptor, is mostly expressed in the vascular endothelial cells of adult mice11. In Vegfr2-Fluc-KI transgenic mice, the DNA sequence of Firefly luciferase (Fluc) is knocked into the first exon of the endogenous Vegfr2 sequence. As a result, the Fluc is expressed (which appears as BLI signals) in a manner that is identical to the level of angiogenesis in mice. To grow beyond a few millimeters in size, the tumor recruits new vasculatures from existing blood vessels, which highly express the Vegfr2 triggered by growth factors from tumor cells1. This opens the possibility of using Vegfr2-Fluc-KI transgenic mice to non-invasively monitor tumor angiogenesis by BLI.
In this protocol, a tumor-bearing mouse model is established to monitor tumor progression and angiogenesis in a single mouse through Firefly luciferase (Fluc) and Renilla luciferase (Rluc) imaging, respectively (Figure 1). A 4T1 cell line (4T1-RR) is created that stably expresses Rluc and red fluorescent protein (RFP) to trace cell growth by Rluc imaging. To further investigate the dynamic changes of angiogenesis in the progression and regression of the tumor, another 4T1 cell line (4T1-RRT) is created that expresses suicide gene herpes simplex virus truncated thymidine kinase (HSV-ttk), Rluc, and RFP. By administration of ganciclovir (GCV), the HSV-ttk expressing cells are selectively ablated. Based on these cell lines, a tumor-bearing model in Vegfr2-Fluc-KI mice is built that serves as an experimental model bridging tumor progression and tumor angiogenesis in vivo.

<table>
	<tbody>
		<tr>
			<td>0.25% Trypsin-0.53 mM EDTA</td>
			<td>Gibco</td>
			<td>25200072</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL Tubes</td>
			<td>Axygen Scientific</td>
			<td>MCT-105-C-S</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Tubes</td>
			<td>Corning Glass Works</td>
			<td>601052-50</td>
			<td></td>
		</tr>
		<tr>
			<td>293T</td>
			<td>ATCC</td>
			<td>CRL-3216</td>
			<td></td>
		</tr>
		<tr>
			<td>4T1</td>
			<td>ATCC</td>
			<td>CRL-2539</td>
			<td></td>
		</tr>
		<tr>
			<td>60 mm Dish</td>
			<td>Corning Glass Works</td>
			<td>430166</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well Plate</td>
			<td>Corning Glass Works</td>
			<td>3516</td>
			<td></td>
		</tr>
		<tr>
			<td>Biosafety Cabinet</td>
			<td>Shanghai Lishen Scientific</td>
			<td>Hfsafe-900LC</td>
			<td></td>
		</tr>
		<tr>
			<td>Blasticidine S Hydrochloride (BSD)</td>
			<td>Sigma-Aldrich</td>
			<td>15205</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Counting Kit-8</td>
			<td>MedChem Express</td>
			<td>HY-K0301</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 Tegulated Incubator</td>
			<td>Thermo Fisher Scientific</td>
			<td>4111</td>
			<td></td>
		</tr>
		<tr>
			<td>Coelenterazine (CTZ)</td>
			<td>NanoLight Technology</td>
			<td>479474</td>
			<td></td>
		</tr>
		<tr>
			<td>D-luciferin Potassium Salt</td>
			<td>Caliper Life Sciences</td>
			<td>119222</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM Medium</td>
			<td>Gibco</td>
			<td>C11995500BT</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>BIOIND</td>
			<td>04-001-1A</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence Microscope</td>
			<td>Nikon</td>
			<td>Ti-E/U/S</td>
			<td></td>
		</tr>
		<tr>
			<td>Ganciclovir (GCV)</td>
			<td>Sigma-Aldrich</td>
			<td>Y0001129</td>
			<td></td>
		</tr>
		<tr>
			<td>Graphics Software</td>
			<td>GraphPad Software</td>
			<td>Graphpad Prism 6</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin Syringe Needles</td>
			<td>Becton Dickinson</td>
			<td>328421</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Baxter</td>
			<td>691477H</td>
			<td></td>
		</tr>
		<tr>
			<td>Lentiviral Packaging System</td>
			<td>Biosettia</td>
			<td>cDNA-pLV03</td>
			<td></td>
		</tr>
		<tr>
			<td>Liposome</td>
			<td>Invitrogen</td>
			<td>11668019</td>
			<td></td>
		</tr>
		<tr>
			<td>Living Imaging Software</td>
			<td>Caliper Life Sciences</td>
			<td>Living Imaging Software 4.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Living Imaging System</td>
			<td>Caliper Life Sciences</td>
			<td>IVIS Lumina II</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Medium</td>
			<td>Invitrogen</td>
			<td>31985-070</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Invitrogen</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Corning Glass Works</td>
			<td>R21031399</td>
			<td></td>
		</tr>
		<tr>
			<td>Polybrene</td>
			<td>Sigma-Aldrich</td>
			<td>H9268-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI1640 Medium</td>
			<td>Gibco</td>
			<td>C11875500BT</td>
			<td></td>
		</tr>
		<tr>
			<td>SORVALL ST 16R Centrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>Thermo Sorvall ST 16 ST16R</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra-low Temperature Refrigerator</td>
			<td>Haier</td>
			<td>DW-86L338</td>
			<td></td>
		</tr>
		<tr>
			<td>XGI-8 Gas Anesthesia System</td>
			<td>XENOGEN Corporation</td>
			<td>7293</td>
			<td></td>
		</tr>
	</tbody>
</table>

dual bioluminescence imaging of tumor progression and angiogenesis

Angiogenesis, as a crucial process of tumor progression, has become a research hotspot and target of anti-tumor therapy. However, there is no reliable model for tracing tumor progression and angiogenesis simultaneously in a visual and sensitive manner. Bioluminescence imaging displays its unique superiority in living imaging due to its advantages of high sensitivity, strong specificity, and accurate measurement. Presented here is a protocol to establish a tumor-bearing mouse model by injecting a Renilla luciferase-labeled murine breast cancer cell line 4T1 into the transgenic mouse with angiogenesis-induced Firefly luciferase expression. This mouse model provides a valuable tool to simultaneously monitor tumor progression and angiogenesis in real-time by dual bioluminescence imaging in a single mouse. This model may be widely applied in anti-tumor drug screening and oncology research.

In this experiment, a breast cancer mouse model was established using 4T1 cells to investigate the relationship between tumor growth and tumor angiogenesis (Figure 1). Firstly, two lentivirus were packaged, which carried gene sequences expressing Rluc/RFP (LV-RR) and Rluc/RFP/HSV-ttk (LV-RRT), respectively, as previously reported7. Then, two different 4T1 cell lines, named 4T1-RR and 4T1-RRT, were created by transducing LV-RR and LV-RR...

Watch this Scientific Journal Video about Dual Bioluminescence Imaging of Tumor Progression and Angiogenesis at JoVE.com

Dual Bioluminescence Imaging of Tumor Progression and Angiogenesis

This protocol describes the establishment of a tumor-bearing mouse model to monitor tumor progression and angiogenesis in real-time by dual bioluminescence imaging.

Angiogenesis, as a crucial process of tumor progression, has become a research hotspot and target of anti-tumor therapy. However, there is no reliable ...

dual-bioluminescence-imaging-of-tumor-progression-and-angiogenesis

Research

JoVE Journal

Medicine

8.0K Views.  Nankai University School of Medicine. This protocol describes the establishment of a tumor-bearing mouse model to monitor tumor progression and angiogenesis in real-time by dual bioluminescence imaging.

Video: Dual Bioluminescence Imaging of Tumor Progression and Angiogenesis

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function

Accurate assessment of cutaneous tissue oxygenation and vascular function is important for appropriate detection, staging, and treatment of many health disorders such as chronic wounds. We report the development of a dual-mode imaging system for non-invasive and non-contact imaging of cutaneous tissue oxygenation and vascular function. The imaging system integrated an infrared camera, a CCD camera, a liquid crystal tunable filter and a high intensity fiber light source. A Labview interface was programmed for equipment control, synchronization, image acquisition, processing, and visualization. Multispectral images captured by the CCD camera were used to reconstruct the tissue oxygenation map. Dynamic thermographic images captured by the infrared camera were used to reconstruct the vascular function map. Cutaneous tissue oxygenation and vascular function images were co-registered through fiduciary markers. The performance characteristics of the dual-mode image system were tested in humans.

A dual-mode imaging system was developed for non-contact assessment of cutaneous tissue oxygenation and vascular function.

Accurate assessment of cutaneous tissue oxygenation and vascular function is important for appropriate detection, staging, and treatment of many health ...

Monitoring Tumor Metastases and Osteolytic Lesions with Bioluminescence and Micro CT Imaging

Following intracardiac delivery of MDA-MB-231-luc-D3H2LN cells to Nu/Nu mice, systemic metastases developed in the injected animals. Bioluminescence imaging using IVIS Spectrum was employed to monitor the distribution and development of the tumor cells following the delivery procedure including DLIT reconstruction to measure the tumor signal and its location.
Development of metastatic lesions to the bone tissues triggers osteolytic activity and lesions to tibia and femur were evaluated longitudinally using micro CT. Imaging was performed using a Quantum FX micro CT system with fast imaging and low X-ray dose. The low radiation dose allows multiple imaging sessions to be performed with a cumulative X-ray dosage far below LD50. A mouse imaging shuttle device was used to sequentially image the mice with both IVIS Spectrum and Quantum FX achieving accurate animal positioning in both the bioluminescence and CT images. The optical and CT data sets were co-registered in 3-dimentions using the Living Image 4.1 software. This multi-mode approach allows close monitoring of tumor growth and development simultaneously with osteolytic activity.

An experimental mouse model of bone metastasis was established following intracardiac delivery of luciferase expressing mammary tumor cells. Tumor development and resulted osteolytic lesion were monitored longitudinally with bioluminescence and micro CT imaging.

Following intracardiac delivery of MDA-MB-231-luc-D3H2LN cells to Nu/Nu mice, systemic metastases developed in the injected animals. Bioluminescence ...

In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model

It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There is little knowledge about in situ, in vivo, tumor hypoxia during intracranial development of malignant brain tumors because of lack of efficient means to monitor it in these deep-seated orthotopic tumors. Bioluminescence imaging (BLI), based on the detection of light emitted by living cells expressing a luciferase gene, has been rapidly adopted for cancer research, in particular, to evaluate tumor growth or tumor size changes in response to treatment in preclinical animal studies. Moreover, by expressing a reporter gene under the control of a promoter sequence, the specific gene expression can be monitored non-invasively by BLI. Under hypoxic stress, signaling responses are mediated mainly via the hypoxia inducible factor-1&alpha; (HIF-1&alpha;) to drive transcription of various genes. Therefore, we have used a HIF-1&alpha; reporter construct, 5HRE-ODD-luc, stably transfected into human breast cancer MDA-MB231 cells (MDA-MB231/5HRE-ODD-luc). In vitro HIF-1&alpha; bioluminescence assay is performed by incubating the transfected cells in a hypoxic chamber (0.1% O2) for 24 hr before BLI, while the cells in normoxia (21% O2) serve as a control. Significantly higher photon flux observed for the cells under hypoxia suggests an increased HIF-1&alpha; binding to its promoter (HRE elements), as compared to those in normoxia. Cells are injected directly into the mouse brain to establish a breast cancer brain metastasis model. In vivo bioluminescence imaging of tumor hypoxia dynamics is initiated 2 wks after implantation and repeated once a week. BLI reveals increasing light signals from the brain as the tumor progresses, indicating increased intracranial tumor hypoxia. Histological and immunohistochemical studies are used to confirm the in vivo imaging results. Here, we will introduce approaches of in vitro HIF-1&alpha; bioluminescence assay, surgical establishment of a breast cancer brain metastasis in a nude mouse and application of in vivo bioluminescence imaging to monitor intracranial tumor hypoxia.

In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model

Bioluminescence imaging of hypoxia inducible factor-1&alpha; activity is applied to monitor intracranial tumor hypoxia development in a breast cancer brain metastasis mouse model.

It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There ...

In vivo Dual Substrate Bioluminescent Imaging

Our understanding of how and when breast cancer cells transit from established primary tumors to metastatic sites has increased at an exceptional rate since the advent of in vivo bioluminescent imaging technologies 1-3. Indeed, the ability to locate and quantify tumor growth longitudinally in a single cohort of animals to completion of the study as opposed to sacrificing individual groups of animals at specific assay times has revolutionized how researchers investigate breast cancer metastasis. Unfortunately, current methodologies preclude the real-time assessment of critical changes that transpire in cell signaling systems as breast cancer cells (i) evolve within primary tumors, (ii) disseminate throughout the body, and (iii) reinitiate proliferative programs at sites of a metastatic lesion. However, recent advancements in bioluminescent imaging now make it possible to simultaneously quantify specific spatiotemporal changes in gene expression as a function of tumor development and metastatic progression via the use of dual substrate luminescence reactions. To do so, researchers take advantage for two light-producing luciferase enzymes isolated from the firefly (Photinus pyralis) and sea pansy (Renilla reniformis), both of which react to mutually exclusive substrates that previously facilitated their wide-spread use in in vitro cell-based reporter gene assays 4. Here we demonstrate the in vivo utility of these two enzymes such that one luminescence reaction specifically marks the size and location of a developing tumor, while the second luminescent reaction serves as a means to visualize the activation status of specific signaling systems during distinct stages of tumor and metastasis development. Thus, the objectives of this study are two-fold. First, we will describe the steps necessary to construct dual bioluminescent reporter cell lines, as well as those needed to facilitate their use in visualizing the spatiotemporal regulation of gene expression during specific steps of the metastatic cascade. Using the 4T1 model of breast cancer metastasis, we show that the in vivo activity of a synthetic Smad Binding Element (SBE) promoter was decreased dramatically in pulmonary metastasis as compared to that measured in the primary tumor 4-6. Recently, breast cancer metastasis was shown to be regulated by changes within the primary tumor microenvironment and reactive stroma, including those occurring in fibroblasts and infiltrating immune cells 7-9. Thus, our second objective will be to demonstrate the utility of dual bioluminescent techniques in monitoring the growth and localization of two unique cell populations harbored within a single animal during breast cancer growth and metastasis.

In vivo Dual Substrate Bioluminescent Imaging

Herein we describe the methods to construct, visualize, and quantify the bioluminescent reactions of both firefly and renilla luciferase enzymes expressed in metastatic breast cancer cells during their growth and metastasis in vivo.

Our understanding of how and when breast cancer cells transit from established primary tumors to metastatic sites has increased at an exceptional rate ...

MAME Models for 4D Live-cell Imaging of Tumor: Microenvironment Interactions that Impact Malignant Progression

We have developed 3D coculture models, which we term MAME (mammary architecture and microenvironment engineering), and used them for live-cell imaging in real-time of cell:cell interactions. Our overall goal was to develop models that recapitulate the architecture of preinvasive breast lesions to study their progression to an invasive phenotype. Specifically, we developed models to analyze interactions among pre-malignant breast epithelial cell variants and other cell types of the tumor microenvironment that have been implicated in enhancing or reducing the progression of preinvasive breast epithelial cells to invasive ductal carcinomas. Other cell types studied to date are myoepithelial cells, fibroblasts, macrophages and blood and lymphatic microvascular endothelial cells. In addition to the MAME models, which are designed to recapitulate the cellular interactions within the breast during cancer progression, we have developed comparable models for the progression of prostate cancers. 
Here we illustrate the procedures for establishing the 3D cocultures along with the use of live-cell imaging and a functional proteolysis assay to follow the transition of cocultures of breast ductal carcinoma in situ (DCIS) cells and fibroblasts to an invasive phenotype over time, in this case over twenty-three days in culture. The MAME cocultures consist of multiple layers. Fibroblasts are embedded in the bottom layer of type I collagen. On that is placed a layer of reconstituted basement membrane (rBM) on which DCIS cells are seeded. A final top layer of 2% rBM is included and replenished with every change of media. To image proteolysis associated with the progression to an invasive phenotype, we use dye-quenched (DQ) fluorescent matrix proteins (DQ-collagen I mixed with the layer of collagen I and DQ-collagen IV mixed with the middle layer of rBM) and observe live cultures using confocal microscopy. Optical sections are captured, processed and reconstructed in 3D with Volocity visualization software. Over the course of 23 days in MAME cocultures, the DCIS cells proliferate and coalesce into large invasive structures. Fibroblasts migrate and become incorporated into these invasive structures. Fluorescent proteolytic fragments of the collagens are found in association with the surface of DCIS structures, intracellularly, and also dispersed throughout the surrounding matrix. Drugs that target proteolytic, chemokine/cytokine and kinase pathways or modifications in the cellular composition of the cocultures can reduce the invasiveness, suggesting that MAME models can be used as preclinical screens for novel therapeutic approaches.

We have developed 3D coculture models for live-cell imaging in real-time of interactions among breast tumor cells and other cells in their microenvironment that impact progression to an invasive phenotype. These models can serve as preclinical screens for drugs to target paracrine-induced proteolytic, chemokine/cytokine and kinase pathways implicated in invasiveness.

We have developed 3D coculture models, which we term MAME (mammary architecture and microenvironment engineering), and used them for live-cell imaging in ...

Multi-modal Imaging of Angiogenesis in a Nude Rat Model of Breast Cancer Bone Metastasis Using Magnetic Resonance Imaging, Volumetric Computed Tomography and Ultrasound

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell proliferation in the bone marrow cavity as well as for interaction of tumor and bone cells resulting in local bone destruction. Our aim was to develop a model of experimental bone metastasis that allows in vivo assessment of angiogenesis in skeletal lesions using non-invasive imaging techniques.
For this purpose, we injected 105 MDA-MB-231 human breast cancer cells into the superficial epigastric artery, which precludes the growth of metastases in body areas other than the respective hind leg1. Following 25-30 days after tumor cell inoculation, site-specific bone metastases develop, restricted to the distal femur, proximal tibia and proximal fibula1. Morphological and functional aspects of angiogenesis can be investigated longitudinally in bone metastases using magnetic resonance imaging (MRI), volumetric computed tomography (VCT) and ultrasound (US).
MRI displays morphologic information on the soft tissue part of bone metastases that is initially confined to the bone marrow cavity and subsequently exceeds cortical bone while progressing. Using dynamic contrast-enhanced MRI (DCE-MRI) functional data including regional blood volume, perfusion and vessel permeability can be obtained and quantified2-4. Bone destruction is captured in high resolution using morphological VCT imaging. Complementary to MRI findings, osteolytic lesions can be located adjacent to sites of intramedullary tumor growth. After contrast agent application, VCT angiography reveals the macrovessel architecture in bone metastases in high resolution, and DCE-VCT enables insight in the microcirculation of these lesions5,6. US is applicable to assess morphological and functional features from skeletal lesions due to local osteolysis of cortical bone. Using B-mode and Doppler techniques, structure and perfusion of the soft tissue metastases can be evaluated, respectively. DCE-US allows for real-time imaging of vascularization in bone metastases after injection of microbubbles7.
In conclusion, in a model of site-specific breast cancer bone metastases multi-modal imaging techniques including MRI, VCT and US offer complementary information on morphology and functional parameters of angiogenesis in these skeletal lesions.

In the pathogenesis of bone metastasis, angiogenesis is a crucial process and therefore represents a target for imaging and therapy. Here, we present a rat model of site-specific breast cancer bone metastasis and describe strategies to non-invasively image angiogenesis in vivo using magnetic resonance imaging, volumetric computed tomography and ultrasound.

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell ...

In vivo Imaging of Tumor Angiogenesis using Fluorescence Confocal Videomicroscopy

Fibered confocal fluorescence in vivo imaging with a fiber optic bundle uses the same principle as fluorescent confocal microscopy. It can excite fluorescent in situ elements through the optical fibers, and then record some of the emitted photons, via the same optical fibers. The light source is a laser that sends the exciting light through an element within the fiber bundle and as it scans over the sample, recreates an image pixel by pixel. As this scan is very fast, by combining it with dedicated image processing software, images in real time with a frequency of 12 frames/sec can be obtained.
We developed a technique to quantitatively characterize capillary morphology and function, using a confocal fluorescence videomicroscopy device. The first step in our experiment was to record 5 sec movies in the four quadrants of the tumor to visualize the capillary network. All movies were processed using software (ImageCell, Mauna Kea Technology, Paris France) that performs an automated segmentation of vessels around a chosen diameter (10 &mu;m in our case). Thus, we could quantify the 'functional capillary density', which is the ratio between the total vessel area and the total area of the image. This parameter was a surrogate marker for microvascular density, usually measured using pathology tools.
The second step was to record movies of the tumor over 20 min to quantify leakage of the macromolecular contrast agent through the capillary wall into the interstitium. By measuring the ratio of signal intensity in the interstitium over that in the vessels, an 'index leakage' was obtained, acting as a surrogate marker for capillary permeability.

In vivo Imaging of Tumor Angiogenesis using Fluorescence Confocal Videomicroscopy

In this paper, we present a method to analyze tumor microvessels in vivo using dynamic contrast-enhanced fluorescence videomicroscopy. Two quantitative parameters were acquired: functional capillary density reflecting the vascularity of the tumor, and index leakage reflecting the leakiness of the endothelial wall.

Fibered confocal fluorescence in vivo imaging with a fiber optic bundle uses the same principle as fluorescent confocal microscopy. It can excite ...

A Novel High-resolution In vivo Imaging Technique to Study the Dynamic Response of Intracranial Structures to Tumor Growth and Therapeutics

We have successfully integrated previously established Intracranial window (ICW) technology 1-4 with intravital 2-photon confocal microscopy to develop a novel platform that allows for direct long-term visualization of tissue structure changes intracranially. Imaging at a single cell resolution in a real-time fashion provides supplementary dynamic information beyond that provided by standard end-point histological analysis, which looks solely at 'snap-shot' cross sections of tissue.
Establishing this intravital imaging technique in fluorescent chimeric mice, we are able to image four fluorescent channels simultaneously. By incorporating fluorescently labeled cells, such as GFP+ bone marrow, it is possible to track the fate of these cells studying their long-term migration, integration and differentiation within tissue. Further integration of a secondary reporter cell, such as an mCherry glioma tumor line, allows for characterization of cell:cell interactions. Structural changes in the tissue microenvironment can be highlighted through the addition of intra-vital dyes and antibodies, for example CD31 tagged antibodies and Dextran molecules.
Moreover, we describe the combination of our ICW imaging model with a small animal micro-irradiator that provides stereotactic irradiation, creating a platform through which the dynamic tissue changes that occur following the administration of ionizing irradiation can be assessed.
Current limitations of our model include penetrance of the microscope, which is limited to a depth of up to 900 &mu;m from the sub cortical surface, limiting imaging to the dorsal axis of the brain. The presence of the skull bone makes the ICW a more challenging technical procedure, compared to the more established and utilized chamber models currently used to study mammary tissue and fat pads 5-7. In addition, the ICW provides many challenges when optimizing the imaging.

A Novel High-resolution In vivo Imaging Technique to Study the Dynamic Response of Intracranial Structures to Tumor Growth and Therapeutics

We describe a novel in vivo imaging technique that couples fluorescent chimeric mice with intracranial windows and high-resolution 2-photon microscopy. This imaging platform aids studies of dynamic changes in brain tissue and microvasculature, at a single-cell level, following pathological insults and is adaptable to assess intracranial drug delivery and distribution.

We have successfully integrated previously established Intracranial window (ICW) technology 1-4 with intravital 2-photon confocal microscopy to develop a ...

Retinal Detachment Model in Rodents by Subretinal Injection of Sodium Hyaluronate

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the occurrence of subretinal hemorrhage can affect photoreceptor cell death in the detached retina. Hence, it is advantageous to create reproducible RDs without subretinal hemorrhage for evaluating photoreceptor cell death. We modified a previously reported method to create bullous and persistent RDs in a reproducible location with rare occurrence of subretinal hemorrhage. The critical step of this modified method is the creation of a self-sealing scleral incision, which can prevent leakage of sodium hyaluronate after injection into the subretinal space. To make the self-sealing scleral incision, a scleral tunnel is created, followed by scleral penetration into the choroid with a 30 G needle. Although choroidal hemorrhage may occur during this step, astriction with a surgical spear reduces the rate of choroidal hemorrhage. This method allows a more reproducible and reliable model of photoreceptor death in diseases that involve RD such as rhegmatogenous RD, retinopathy of prematurity, diabetic retinopathy, central serous chorioretinopathy, and age-related macular degeneration (AMD).

Creating experimental retinal detachments with a reproducible and sustained height of detachment, and without subretinal hemorrhage, is important for studying the pathophysiology of photoreceptor cell loss in retinal disease and evaluating potential therapeutic interventions. Here, we report such a method in detail.

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the ...

Candida albicans Biofilm Development on Medically-relevant Foreign Bodies in a Mouse Subcutaneous Model Followed by Bioluminescence Imaging

Candida albicans biofilm development on biotic and/or abiotic surfaces represents a specific threat for hospitalized patients. So far, C. albicans biofilms have been studied predominantly in vitro but there is a crucial need for better understanding of this dynamic process under in vivo conditions. We developed an in vivo subcutaneous rat model to study C. albicans biofilm formation. In our model, multiple (up to 9) Candida-infected devices are implanted to the back part of the animal. This gives us a major advantage over the central venous catheter model system as it allows us to study several independent biofilms in one animal. Recently, we adapted this model to study C. albicans biofilm development in BALB/c mice. In this model, mature C. albicans biofilms develop within 48 hr and demonstrate the typical three-dimensional biofilm architecture. The quantification of fungal biofilm is traditionally analyzed post mortem and requires host sacrifice. Because this requires the use of many animals to perform kinetic studies, we applied non-invasive bioluminescence imaging (BLI) to longitudinally follow up in vivo mature C. albicans biofilms developing in our subcutaneous model. C. albicans cells were engineered to express the Gaussia princeps luciferase gene (gLuc) attached to the cell wall. The bioluminescence signal is produced by the luciferase that converts the added substrate coelenterazine into light that can be measured. The BLI signal resembled cell counts obtained from explanted catheters. Non-invasive imaging for quantifying in vivo biofilm formation provides immediate applications for the screening and validation of antifungal drugs under in vivo conditions, as well as for studies based on host-pathogen interactions, hereby contributing to a better understanding of the pathogenesis of catheter-associated infections.

Candida albicans Biofilm Development on Medically-relevant Foreign Bodies in a Mouse Subcutaneous Model Followed by Bioluminescence Imaging

We present an experimental procedure of Candida albicans biofilm development in a mouse subcutaneous model. Fungal biofilms were quantified by determining the number of colony forming units and by a non-invasive bioluminescence imaging, where the amount of light that is produced corresponds with the number of viable cells.