This research was supported by NIH-CA100324, Einstein National Cancer Institute's cancer center support grant P30CA013330, R01CA172451 to JWP and the Integrated Imaging Program. This technology was developed in the Gruss-Lipper Biophotonics Center and the Integrated Imaging Program at the Albert Einstein College of Medicine. We acknowledge the support of these Centers in this work. The authors thank Mike Rottenkolber, Ricardo Ibagon and Anthony Leggiadro of the Einstein machine shop for their skilled and timely craftsmanship, the laboratory of Matthew Krummel for generously sharing their window design drawings, Kevin Elicieri and Jeremy Bredfeldt for their expertise in microscopy and their amplifier recommendations and Allison Harney and Bojana Gligorijevic for informative discussions.

The authors have nothing to disclose.

High resolution in vivo optical imaging combined with fluorescently labelled functional tags such as proteins and antibodies has dramatically increased our understanding of the metastatic cascade. It has enabled direct visualization and quantification of single-cell and sub-cellular parameters in tumor cells, host cells and their microenvironment. This imaging within the primary tumor has led, for example, to the discovery of discrete microenvironments that are supportive of either growth invasion or disseminati...

High resolution intravital optical imaging has proven to be crucial to understanding many biological processes, allowing single-cell and sub-cellular parameters to be measured and quantified. In cancer research, intravital imaging of tumor and stromal cells has led to the discovery of many microenvironmental interactions 6-11 that are only present in the intact animal.
Discoveries about microenvironments associated with intravasation and dissemination of tumor cells in breast cancer using single cell resolution optical imaging in vivo has even led to novel markers for prognosis and response to treatment in breast cancer patients 12-16. The best imaging technologies available for viewing deep within intact internal vital organs are the clinical modalities (MRI, PET, CT) which offer excellent views of the entire organ and can reveal pathologies even before they produce clinical symptoms. They are unable, however, to reveal the earliest stages of metastasis and the cellular mechanisms driving tumor progression due to their lack of single cell resolution. By the time lung metastases are visible in these modalities, they are well established and proliferating. Given the estimate that 90% of disseminated tumor cells that arrive to the lung either do not survive 17 or initially remain dormant 18, and the observation that they arrive much earlier than previously expected 19, imaging the earliest steps of arrival and survival becomes crucial to understanding the process of metastatic seeding and recurrence of tumor growth at distant sites.
Performing these observations in the lung has proven extremely difficult however; the vast majority of imaging studies have utilized ex vivo or explant preparations 20-23, which only give a view into the lung at single time points. While these preparations do provide useful information, they do not give a complete understanding of the interactions, cause and effect relationships, and dynamics that occur between the various components of the microenvironment. The lack of a proper circulatory system (and concomitant imbalance of homeostasis) and the disconnection from the rest of the body&#39;s immune system makes it desirous to validate the conclusions that these preparations generate in intact tissue in vivo.
Many groups have performed intravital imaging of the intact lung 2,4,5,24-33 with Wearn and German being the first to surgically expose the pleural layer 24 and Terry the first to utilize an implantable imaging window 25.
High resolution imaging in the lung is greatly hindered by the lung&#39;s constant motion and several techniques have been developed to overcome this limitation. Wagner and Filley 27 studied the natural motion of the canine lung and designed their surgical protocol to locate their implanted window over a relatively stationary region while Wagner utilized vacuum in his window surgical preparation to immobilize the tissue 28. Since that time, a variety of techniques have been utilized to image the lung including: bronchus clamping, sequential apnea and gated imaging, oversampled acquisition, gluing of the lung lobe and vacuum 34. Each of these has its advantages and disadvantages and no one technique has emerged as superior to another 34. For example, bronchus clamping and sequential apnea alter the normal exchange of gases in the lung and may cause atelectasis. Gated imaging and oversampled acquisition do not suffer from these disadvantages but require high-speed or specialized imaging equipment not widely accessible. Finally both gluing of the lung and the vacuum technique avoid both of the above mentioned drawbacks, but may exhibit shear force induced injury if care is not taken. In recent years, the vacuum window has been miniaturized and adapted for use in mice using confocal and multiphoton microscopy 4,5,33 and excellent high-resolution imaging has been attained 2. Table 1 summarizes this rich history and highlights those papers which describe novel advancements in the use of intravital lung imaging windows.
This protocol describes the use of extended time-lapse multiphoton intravital microscopy to image metastasis in the live, intact lung with the highest subcellular resolution possible. Images are acquired for up to 12 hr using a multiphoton microscope equipped with a high numerical aperture objective lens and multiple photomultiplier tube (PMT) detectors. Transgenic mouse models are utilized to fluorescently label native macrophages along with fluorescent high molecular weight dextran and fluorescent protein transfected tumor cells (to label the vasculature and tumor cells respectively). While this choice of fluorescently labeled cells enables visualization of tumor cell-endothelial cell-macrophage interactions and dynamics, this protocol will work for any strain of fluorescent or non-fluorescent mouse. After acquisition, residual drift motion (if any) is eliminated using a Fiji plugin 35,36 and custom macros time average the vascular channel to eliminate flashing caused by unlabeled circulating blood cells.
While this protocol focuses on imaging metastasis, the techniques are applicable to many other biological processes observable with high-resolution single-cell imaging in the lung.

<table border="0" cellpadding="0" cellspacing="0" width="1579">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Nickel-Plated Brass Vacuum Regulator 1/8 NPT Female, w/ Gauge, 0 - 20&#34; Hg Vacuum</td>
			<td style="width:291px;">McMaster Carr</td>
			<td style="width:141px;">4172K12&#160;</td>
			<td style="width:223px;">Vacuum Regulator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Brass Barbed Hose Fitting Adapter for 1/4&#34; Hose ID X 1/8&#34; NPTF Male Pipe</td>
			<td style="width:291px;">McMaster Carr</td>
			<td style="width:141px;">5346K13</td>
			<td>Vacuum Regulator Hose Adapter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Pyrex Brand Filtering Flasks with Tubulation; Neck tooled for rubber stopper No. 4; Capacity: 50mL</td>
			<td style="width:291px;">Corning Life Sciences Glass</td>
			<td style="width:141px;">5360-50</td>
			<td>Vacuum Flask</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Round Glass Coverslips Thickness #1.5, 0.16-0.19mm 10mm dia.&#160;</td>
			<td style="width:291px;">Ted Pella, Inc.</td>
			<td>260368</td>
			<td>Cover slips</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Exel International Disposable Safelet I.V. Catheters; 22gx1 in.&#160;</td>
			<td style="width:291px;">Exel International</td>
			<td style="width:141px;">26746</td>
			<td>Tracheal Catheter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">PERMA-HAND Black Braided Silk Sutures, ETHICON LIGAPAK Dispensing Reel Size 2-0</td>
			<td style="width:291px;">VWR</td>
			<td style="width:141px;">95056-992</td>
			<td>String</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Liquid Super Glue, Clear, 0.14oz</td>
			<td style="width:291px;">Hendel Corp.</td>
			<td style="width:141px;">LOC1647358</td>
			<td>Cyano-acrylate Glue</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Tetramethylrhodamine isothiocyanate&#8211;Dextran</td>
			<td style="width:291px;">Sigma-Aldrich</td>
			<td style="width:141px;">T1287-500MG</td>
			<td>155kD Dextran</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Laboratory Clear Tygon PVC Tubing, 1/16&#34; ID, 1/8&#34; OD, 1/32&#34; Wall Thickness, 25 ft. Length</td>
			<td style="width:291px;">McMaster Carr</td>
			<td style="width:141px;">5155T12</td>
			<td>Thin Tubing &#38; Tubing for Luer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Crack-Resistant Polyethylene Tubing, 1/8&#34; ID, 1/4&#34; OD, 1/16&#34; Wall Thickness, White, 50 ft. Length&#160;</td>
			<td style="width:291px;">McMaster Carr</td>
			<td style="width:141px;">5181K24&#160;</td>
			<td>Thick Tubing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Depillatory Lotion</td>
			<td style="width:291px;">Nair</td>
			<td style="width:141px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Micro Medical Tubing 95 Durometer LDPE</td>
			<td style="width:291px;">Scientific Commodities Inc.</td>
			<td style="width:141px;">BB31695-PE/1</td>
			<td>Tubing for tail vein catheter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">30 G x 1 in. BD PrecisionGlide Needle</td>
			<td style="width:291px;">BD</td>
			<td style="width:141px;">305128</td>
			<td>Needles for tail vein catheter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Puritan Nonsterile Cotton-Tipped Swabs&#160;</td>
			<td style="width:291px;">Fisher Scientific</td>
			<td>867WCNOGLUE</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Clear Polycarbonate Barbed Tube Fitting, Reducing Straight for 3/32&#34; x 1/16&#34; Tube ID</td>
			<td style="width:291px;">McMaster Carr</td>
			<td style="width:141px;">5117k51</td>
			<td>Connectors between tubes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">One-Hole Rubber Stoppers</td>
			<td style="width:291px;">Fisher Scientific</td>
			<td>14-135F</td>
			<td>Stopper for Vacuum Flask</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">SHARP Precision Barrier Tips, For P-100, 100&#181;l</td>
			<td style="width:291px;">Denville Scientific Inc.</td>
			<td style="width:141px;">P1125</td>
			<td>Pipette Tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Laboratory tape</td>
			<td style="width:291px;">Fisher Scientific</td>
			<td style="width:141px;">159015R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Puralube</td>
			<td style="width:291px;">Henry Schein Animal Health</td>
			<td style="width:141px;">008897</td>
			<td>Opthalmic Ointment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Gemini Cautery Kit</td>
			<td style="width:291px;">Harvard Apparatus</td>
			<td style="width:141px;">726067</td>
			<td>Cautery Pen</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Graefe Micro Dissecting Forceps; Serrated; Slight Curve; 0.8mm Tip Width; 4&#34; Length</td>
			<td style="width:291px;">Roboz Surgical</td>
			<td style="width:141px;">RS-5135&#160;</td>
			<td>Forceps</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Extra Fine Micro Dissecting Scissors 4&#34; Straight Sharp/Sharp 24mm</td>
			<td style="width:291px;">Roboz Surgical</td>
			<td style="width:141px;">RS-5912</td>
			<td>Sharp Scissors</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Micro Dissecting Scissors 4&#34; Straight Blunt/Blunt</td>
			<td style="width:291px;">Roboz Surgical</td>
			<td style="width:141px;">RS-5980</td>
			<td>Blunt Scissors</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Wipes</td>
			<td style="width:291px;">Fisher Scientific</td>
			<td style="width:141px;">06-666-A&#160;</td>
			<td>Harness</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">PhysioSuite System</td>
			<td style="width:291px;">Kent Scientific</td>
			<td style="width:141px;">PhysioSuite</td>
			<td>Vitals Monitor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">1 mL Syringe, Tuberculin Slip Tip</td>
			<td style="width:291px;">BD</td>
			<td style="width:141px;">309659</td>
			<td>Syringe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Cyano acrylate</td>
			<td style="width:291px;">Staples</td>
			<td>LOC1647358</td>
			<td>Cover Slip Adhesive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Petroleum Jelly</td>
			<td style="width:291px;">Fisher Scientific</td>
			<td style="width:141px;">19-086291</td>
			<td>Water Barrier</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Adapter Luer Cannulla 1.5-2.2mm</td>
			<td style="width:291px;">Harvard Apparatus</td>
			<td style="width:141px;">734118</td>
			<td>Catheter Connector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">MouseOx oximeter, software and sensors</td>
			<td style="width:291px;">STARR Life Sciences</td>
			<td style="width:141px;">MouseOx</td>
			<td>Pulse Oximeter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Isoethesia (isoflurane)</td>
			<td style="width:291px;">Henry Schein Animal Health</td>
			<td style="width:141px;">50033</td>
			<td>250 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Oxygen</td>
			<td style="width:291px;">TechAir</td>
			<td style="width:141px;">OX TM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">1 x PBS</td>
			<td style="width:291px;">Life Technologies</td>
			<td>10010-023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">PVC Ball Valve, Push to Connect, 1/4 In</td>
			<td style="width:291px;">Grainger</td>
			<td>3CGJ7</td>
			<td>Vacuum Valve</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Small Animal Ventilator</td>
			<td style="width:291px;">Harvard Apparatus</td>
			<td style="width:141px;">683</td>
			<td>Alternative is available from Kent Scientific: MouseVent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">OptiMEM Reduced Serum Medium</td>
			<td style="width:291px;">ThermoFisher Scientific</td>
			<td style="width:141px;">31985062&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Lipofectamine 2000 Transfection Reagent</td>
			<td style="width:291px;">ThermoFisher Scientific</td>
			<td style="width:141px;">11668019</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">MacBlue Tg(Csf1r*-GAL4/VP16,UAS-ECFP)1Hume/J Mice</td>
			<td style="width:291px;">Jackson Laboratory</td>
			<td style="width:141px;">026051&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Multiphoton Microscope</td>
			<td style="width:291px;">Olympus</td>
			<td style="width:141px;">Fluoview FV1000</td>
			<td>Alternative to custom built scope</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Environmental Enclosure</td>
			<td style="width:291px;">Precision Plastics</td>
			<td style="width:141px;">Chamber for FV1000</td>
			<td>Alternative to custom built enclosure</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Phosphate Buffered Saline</td>
			<td style="width:291px;">ThermoFisher Scientific</td>
			<td>14190136</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Laser Power Meter</td>
			<td style="width:291px;">Coherent</td>
			<td style="width:141px;">FieldMaxIITOP</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Laser Power Meter Head</td>
			<td style="width:291px;">Coherent</td>
			<td style="width:141px;">PM10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">pcDNA3-Clover Fluorescent Protein Vector</td>
			<td style="width:291px;">Addgene</td>
			<td style="width:141px;">40259</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">G418 Sulfate Selective Antibiotic</td>
			<td style="width:291px;">ThermoFisher Scientific</td>
			<td style="width:141px;">10131027</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">MoFlo Fluorescent-Activate Cell Sorter&#160;</td>
			<td style="width:291px;">Beckman Coulter</td>
			<td style="width:141px;">XDP</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Trypsin EDTA 1X</td>
			<td style="width:291px;">Corning</td>
			<td style="width:141px;">25-052-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">40 &#181;m Mesh</td>
			<td style="width:291px;">Falcon</td>
			<td style="width:141px;">352235</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">96 Well Plate</td>
			<td style="width:291px;">Costar</td>
			<td style="width:141px;">3599</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">60 mm Culture Dish</td>
			<td style="width:291px;">Corning</td>
			<td style="width:141px;">430196</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">10 cm Culture Dish</td>
			<td style="width:291px;">Corning</td>
			<td style="width:141px;">353003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Bovine Serum Albumin</td>
			<td style="width:291px;">Sigma-Aldrich</td>
			<td style="width:141px;">A4503</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Dulbecco&#39;s Phosphate Buffered Saline 1X</td>
			<td style="width:291px;">Corning</td>
			<td style="width:141px;">21-031-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">C57BL/6J Mouse</td>
			<td style="width:291px;">Jackson Laboratory</td>
			<td style="width:141px;">000664&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:924px;">Kim Wipes</td>
			<td style="width:291px;">Fisher Scientific</td>
			<td style="width:141px;">06-666-A&#160;</td>
			<td></td>
		</tr>
	</tbody>
</table>

long-term high-resolution intravital microscopy in the lung with a vacuum stabilized imaging window

Metastasis to secondary sites such as the lung, liver and bone is a traumatic event with a mortality rate of approximately 90% 1. Of these sites, the lung is the most difficult to assess using intravital optical imaging due to its enclosed position within the body, delicate nature and vital role in sustaining proper physiology. While clinical modalities (positron emission tomography (PET), magnetic resonance imaging (MRI) and computed tomography (CT)) are capable of providing noninvasive images of this tissue, they lack the resolution necessary to visualize the earliest seeding events, with a single pixel consisting of nearly a thousand cells. Current models of metastatic lung seeding postulate that events just after a tumor cell&#39;s arrival are deterministic for survival and subsequent growth. This means that real-time intravital imaging tools with single cell resolution 2 are required in order to define the phenotypes of the seeding cells and test these models. While high resolution optical imaging of the lung has been performed using various ex vivo preparations, these experiments are typically single time-point assays and are susceptible to artifacts and possible erroneous conclusions due to the dramatically altered environment (temperature, profusion, cytokines, etc.) resulting from removal from the chest cavity and circulatory system 3. Recent work has shown that time-lapse intravital optical imaging of the intact lung is possible using a vacuum stabilized imaging window 2,4,5 however, typical imaging times have been limited to approximately 6 hr. Here we describe a protocol for performing long-term intravital time-lapse imaging of the lung utilizing such a window over a period of 12 hr. The time-lapse image sequences obtained using this method enable visualization and quantitation of cell-cell interactions, membrane dynamics and vascular perfusion in the lung. We further describe an image processing technique that gives an unprecedentedly clear view of the lung microvasculature.

To demonstrate the type of results that can be achieved with this method, we injected E0771-LG tumor cells labeled with the fluorescent protein Clover into the tail vein of MacBlue mice 44 at varying time points before surgery. After surgery, 155 kD rhodamine labeled dextran was injected IV to mark the vasculature and time-lapse imaging was performed.
When imaging mice 24 hr post injection, single cells are visible in...

Watch this Scientific Journal Video about Long-term High-Resolution Intravital Microscopy in the Lung with a Vacuum Stabilized Imaging Window at JoVE.com

Long-term High-Resolution Intravital Microscopy in the Lung with a Vacuum Stabilized Imaging Window

This protocol describes the use of multiphoton microscopy to perform long-term high-resolution, single cell imaging of the intact lung in real time using a vacuum stabilized imaging window.

Metastasis to secondary sites such as the lung, liver and bone is a traumatic event with a mortality rate of approximately 90% 1. Of these sites, the lung ...

long-term-high-resolution-intravital-microscopy-lung-with-vacuum

Research

JoVE Journal

Cancer Research

13.1K Views.  Albert Einstein College of Medicine. This protocol describes the use of multiphoton microscopy to perform long-term high-resolution, single cell imaging of the intact lung in real time using a vacuum stabilized imaging window. 

Video: Long-term High-Resolution Intravital Microscopy in the Lung with a Vacuum Stabilized Imaging Window

Ex Vivo Imaging of Resident CD8 T Lymphocytes in Human Lung Tumor Slices Using Confocal Microscopy

CD8 T cell are key players in the fight against cancer. In order for CD8 T cells to kill tumor cells they need to enter into the tumor, migrate within the tumor microenvironment and respond adequately to tumor antigens. The recent development of improved imaging approaches, such as 2-photon microscopy, and the use of powerful mouse tumor models have shed light on some of the mechanisms that regulate anti-tumor T cell activities. Whereas such systems have provided valuable insights, they do not always predict human responses. In human, our knowledge in the field mainly comes from a description of fixed tumor samples from human patients, as well as in vitro studies. However, in vitro models lack the complex three-dimensional tumor milieu and, therefore, are incomplete approximations of in vivo T cell activities. Fresh slices made from explanted tissue represent a complex multi-cellular tumor environment that can act as an important link between co-cultured studies and animal models. Originally set up in murine lymph nodes1 and previously described in a JoVE article2, this approach has now been transposed to human tumors to examine the dynamics of both plated3&#160;as well as resident&#160;T cells4.
Here, a protocol for the preparation of human lung tumor slices, immunostaining of resident CD8 T and tumor cells, and tracking of CD8 T lymphocytes within the tumor microenvironment using confocal microscopy is described. This system is uniquely placed to screen for novel immunotherapy agents favoring T cell migration in tumors.

Ex Vivo Imaging of Resident CD8 T Lymphocytes in Human Lung Tumor Slices Using Confocal Microscopy

This protocol describes a method to image resident tumor-infiltrating CD8 T cells labeled with fluorescently coupled antibodies within human lung tumor slices. This technique permits real-time analyses of CD8 T cell migration using confocal microscopy.

CD8 T cell are key players in the fight against cancer. In order for CD8 T cells to kill tumor cells they need to enter into the tumor, migrate within the ...

The Establishment of a Lung Colonization Assay for Circulating Tumor Cell Visualization in Lung Tissues

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by CTCs critically contributes to early lung metastatic processes, has been vigorously investigated. As such, animal models are the only approach that captures the full systemic process of metastasis. Given that problems occur in previous experimental designs for examining the contributions of CTCs to blood vessel extravasation, we established an in vivo lung colonization assay in which a long-term-fluorescence cell-tracer, carboxyfluorescein succinimidyl ester (CFSE), was used to label suspended tumor cells and lung perfusion was performed to clear non-specifically trapped CTCs prior to lung removal, confocal imaging, and quantification. Polymeric fibronectin (polyFN) assembled on CTC surfaces has been found to mediate lung colonization in the final establishment of metastatic tumor tissues. Here, to specifically test the requirement of polyFN assembly on CTCs for lung colonization and extravasation, we performed short term lung colonization assays in which suspended Lewis lung carcinoma cells (LLCs) stably expressing FN-shRNA (shFN) or scramble-shRNA (shScr) and pre-labeled with 20 &#956;M of CFSE were intravenously inoculated into C57BL/6 mice. We successfully demonstrated that the abilities of shFN LLC cells to colonize the mouse lungs were significantly diminished in comparison to shScr LLC cells. Therefore, this short-term methodology may be widely applied to specifically demonstrate the ability of CTCs within the circulation to colonize the lungs.

An animal model is needed to decipher the role of circulating tumor cells (CTCs) in promoting lung colonization during cancer metastasis. Here, we established and successfully performed an in vivo assay to specifically test the requirement of polymeric fibronectin (polyFN) assembly on CTCs for lung colonization.

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by ...

Long-term Live-cell Imaging to Assess Cell Fate in Response to Paclitaxel

Live-cell imaging is a powerful technique that can be used to directly visualize biological phenomena in single cells over extended periods of time. Over the past decade, new and innovative technologies have greatly enhanced the practicality of live-cell imaging. Cells can now be kept in focus and continuously imaged over several days while maintained under 37 &#176;C and 5% CO2 cell culture conditions. Moreover, multiple fields of view representing different experimental conditions can be acquired simultaneously, thus providing high-throughput experimental data. Live-cell imaging provides a significant advantage over fixed-cell imaging by allowing for the direct visualization and temporal quantitation of dynamic cellular events. Live-cell imaging can also identify variation in the behavior of single cells that would otherwise have been missed using population-based assays. Here, we describe live-cell imaging protocols to assess cell fate decisions following treatment with the anti-mitotic drug paclitaxel. We demonstrate methods to visualize whether mitotically arrested cells die directly from mitosis or slip back into interphase. We also describe how the fluorescent ubiquitination-based cell cycle indicator (FUCCI) system can be used to assess the fraction of interphase cells born from mitotic slippage that are capable of re-entering the cell cycle. Finally, we describe a live-cell imaging method to identify nuclear envelope rupture events.

Live-cell imaging provides a wealth of information on single cells or whole populations that is unattainable by fixed cell imaging alone. Here, live-cell imaging protocols to assess cell fate decisions following treatment with the anti-mitotic drug paclitaxel are described.

Live-cell imaging is a powerful technique that can be used to directly visualize biological phenomena in single cells over extended periods of time. Over ...

Phosphopeptide Enrichment Coupled with Label-free Quantitative Mass Spectrometry to Investigate the Phosphoproteome in Prostate Cancer

Phosphoproteomics involves the large-scale study of phosphorylated proteins. Protein phosphorylation is a critical step in many signal transduction pathways and is tightly regulated by kinases and phosphatases. Therefore, characterizing the phosphoproteome may provide insights into identifying novel targets and biomarkers for oncologic therapy. Mass spectrometry provides a way to globally detect and quantify thousands of unique phosphorylation events. However, phosphopeptides are much less abundant than non-phosphopeptides, making biochemical analysis more challenging. To overcome this limitation, methods to enrich phosphopeptides prior to the mass spectrometry analysis are required. We describe a procedure to extract and digest proteins from tissue to yield peptides, followed by an enrichment for phosphotyrosine (pY) and phosphoserine/threonine (pST) peptides using an antibody-based and/or titanium dioxide (TiO2)-based enrichment method. After the sample preparation and mass spectrometry, we subsequently identify and quantify phosphopeptides using liquid chromatography-mass spectrometry and analysis software.

This protocol describes a procedure to extract and enrich phosphopeptides from prostate cancer cell lines or tissues for an analysis of the phosphoproteome via mass spectrometry-based proteomics.

Phosphoproteomics involves the large-scale study of phosphorylated proteins. Protein phosphorylation is a critical step in many signal transduction ...

Characterization of the Effects of Migrastatic Inhibitors on 3D Tumor Spheroid Invasion by High-resolution Confocal Microscopy

Drug discovery and development in cancer research is increasingly being based on drug screens in a 3D format. Novel inhibitors targeting the migratory and invasive potential of cancer cells, and consequently the metastatic spread of disease, are being discovered and considered as complementary treatments in highly invasive cancers such as gliomas. Thus, generating data enabling the detailed analyses of cells in a 3D environment following the addition of a drug is required. The methodology described here, combining spheroid invasion assays with high-resolution image capture and data analysis by confocal laser scanning microscopy (CLSM), enabled detailed characterization of the effects of the potential anti-migratory inhibitor MI-192 on glioma cells. Spheroids were generated from cell lines for invasion assays in low adherent 96-well plates and then prepared for CLSM analysis. The described workflow was preferred over other commonly used spheroid-generating techniques due to both ease and reproducibility. This, combined with the enhanced image resolution attained by confocal microscopy compared to conventional wide-field approaches, allowed the identification and analysis of distinct morphological changes in migratory cells in a 3D environment following treatment with the migrastatic drug MI-192.

The effects of migrastatic inhibitors on glioma cancer cell migration in three-dimensional (3D) invasion assays using a histone deacetylase (HDAC) inhibitor are characterized by high-resolution confocal microscopy.

Drug discovery and development in cancer research is increasingly being based on drug screens in a 3D format. Novel inhibitors targeting the migratory and ...

Pathological Analysis of Lung Metastasis Following Lateral Tail-Vein Injection of Tumor Cells

Metastasis, the primary cause of morbidity and mortality for most cancer patients, can be challenging to model preclinically in mice. Few spontaneous metastasis models are available. Thus, the experimental metastasis model involving tail-vein injection of suitable cell lines is a mainstay of metastasis research. When cancer cells are injected into the lateral tail-vein, the lung is their preferred site of colonization. A potential limitation of this technique is the accurate quantification of the metastatic lung tumor burden. While some investigators count macrometastases of a pre-defined size and/or include micrometastases following sectioning of tissue, others determine the area of metastatic lesions relative to normal tissue area. Both of these quantification methods can be exceedingly difficult when the metastatic burden is high. Herein, we demonstrate an intravenous injection model of lung metastasis followed by an advanced method for quantifying metastatic tumor burden using image analysis software. This process allows for investigation of multiple end-point parameters, including average metastasis size, total number of metastases, and total metastasis area, to provide a comprehensive analysis. Furthermore, this method has been reviewed by a veterinary pathologist board-certified by the American College of Veterinary Pathologists (SEK) to ensure accuracy.

Intravenous injection of cancer cells is often used in metastasis research, but the metastatic tumor burden can be difficult to analyze. Herein, we demonstrate a tail-vein injection model of metastasis and include a novel approach to analyze the resulting metastatic lung tumor burden.

Metastasis, the primary cause of morbidity and mortality for most cancer patients, can be challenging to model preclinically in mice. Few spontaneous ...

Modeling Brain Metastases Through Intracranial Injection and Magnetic Resonance Imaging

Metastatic spread of cancer is an unfortunate consequence of disease progression, aggressive cancer subtypes, and/or late diagnosis. Brain metastases are particularly devastating, difficult to treat, and confer a poor prognosis. While the precise incidence of brain metastases in the United States remains hard to estimate, it is likely to increase as extracranial therapies continue to become more efficacious in treating cancer. Thus, it is necessary to identify and develop novel therapeutic approaches to treat metastasis at this site. To this end, intracranial injection of cancer cells has become a well-established method in which to model brain metastasis. Previously, the inability to directly measure tumor growth has been a technical hindrance to this model; however, increasing availability and quality of small animal imaging modalities, such as magnetic resonance imaging (MRI), are vastly improving the ability to monitor tumor growth over time and infer changes within the brain during the experimental period. Herein, intracranial injection of murine mammary tumor cells into immunocompetent mice followed by MRI is demonstrated. The presented injection approach utilizes isoflurane anesthesia and a stereotactic setup with a digitally controlled, automated drill and needle injection to enhance precision, and reduce technical error. MRI is measured over time using a 9.4 Tesla instrument in The Ohio State University James Comprehensive Cancer Center Small Animal Imaging Shared Resource. Tumor volume measurements are demonstrated at each time point through use of ImageJ. Overall, this intracranial injection approach allows for precise injection, day-to-day monitoring, and accurate tumor volume measurements, which combined greatly enhance the utility of this model system to test novel hypotheses on the drivers of brain metastases.

Intracranial brain metastasis modeling is complicated by an inability to monitor tumor size and response to treatment with precise and timely methods. The presented methodology couples intracranial tumor injection with magnetic resonance imaging analysis, which when combined, cultivates precise and consistent injections, enhanced animal monitoring, and accurate tumor volume measurements.

Metastatic spread of cancer is an unfortunate consequence of disease progression, aggressive cancer subtypes, and/or late diagnosis. Brain metastases are ...

Longitudinal Intravital Imaging Through Clear Silicone Windows

Intravital microscopy (IVM) enables visualization of cell movement, division, and death at single-cell resolution. IVM through surgically inserted imaging windows is particularly powerful because it allows longitudinal observation of the same tissue over days to weeks. Typical imaging windows comprise a glass coverslip in a biocompatible metal frame sutured to the mouse&#8217;s skin. These windows can interfere with the free movement of the mice, elicit a strong inflammatory response, and fail due to broken glass or torn sutures, any of which may necessitate euthanasia. To address these issues, windows for long-term abdominal organ and mammary gland imaging&#160;were developed from a thin film of polydimethylsiloxane (PDMS), an optically clear silicone polymer previously used for cranial imaging windows. These windows can be glued directly to the tissues, reducing the time needed for insertion. PDMS is flexible, contributing to its durability in mice over time&#8212;up to 35 days have been tested. Longitudinal imaging is imaging of the same tissue region during separate sessions. A stainless-steel grid was embedded within the windows to localize the same region, allowing the visualization of dynamic processes (like mammary gland involution) at the same locations, days apart. This silicone window also allowed monitoring of single disseminated cancer cells developing into micro-metastases over time. The silicone windows used in this study are simpler to insert than metal-framed glass windows and cause limited inflammation of the imaged tissues. Moreover, embedded grids allow for straightforward tracking of the same tissue region in repeated imaging sessions.

An approach is here presented for long-term intravital imaging using optically clear, silicone windows that can be glued directly to the tissue/organ of interest and the skin.&#160;These windows are cheaper and more versatile than others currently used in the field, and the surgical insertion causes limited inflammation and distress to the animals.

Intravital microscopy (IVM) enables visualization of cell movement, division, and death at single-cell resolution. IVM through surgically inserted imaging ...

A Permanent Window for Investigating Cancer Metastasis to the Lung

Metastasis, accounting for ~90% of cancer-related mortality, involves the systemic spread of cancer cells from primary tumors to secondary sites such as the bone, brain, and lung. Although extensively studied, the mechanistic details of this process remain poorly understood. While common imaging modalities, including computed tomography (CT), positron emission tomography (PET), and magnetic resonance imaging (MRI), offer varying degrees of gross visualization, each lacks the temporal and spatial resolution necessary to detect the dynamics of individual tumor cells. To address this, numerous techniques have been described for intravital imaging of common metastatic sites. Of these sites, the lung has proven especially challenging to access for intravital imaging owing to its delicacy and critical role in sustaining life. Although several approaches have previously been described for single-cell intravital imaging of the intact lung, all involve highly invasive and terminal procedures, limiting the maximum possible imaging duration to 6-12 h. Described here is an improved technique for the permanent implantation of a minimally invasive thoracic optical Window for High-Resolution Imaging of the Lung (WHRIL). Combined with an adapted approach to microcartography, the innovative optical window facilitates serial intravital imaging of the intact lung at single-cell resolution across multiple imaging sessions and spanning multiple weeks. Given the unprecedented duration of time over which imaging data can be gathered, the WHRIL can facilitate the accelerated discovery of the dynamic mechanisms underlying metastatic progression and numerous additional biologic processes within the lung.

Here, we present a protocol for the surgical implantation of a permanently indwelling optical window for the murine thorax, which enables high-resolution, intravital imaging of the lung. The permanence of the window makes it well-suited to the study of dynamic cellular processes in the lung, especially those that are slowly evolving, such as metastatic progression of disseminated tumor cells.

Metastasis, accounting for ~90% of cancer-related mortality, involves the systemic spread of cancer cells from primary tumors to secondary sites such as ...

A Label-Free Segmentation Approach for Intravital Imaging of Mammary Tumor Microenvironment

The ability to visualize complex and dynamic physiological interactions between numerous cell types and the extracellular matrix (ECM) within a live tumor microenvironment is an important step toward understanding mechanisms that regulate tumor progression. While this can be accomplished through current intravital imaging techniques, it remains challenging due to the heterogeneous nature of tissues and the need for spatial context within the experimental observation. To this end, we have developed an intravital imaging workflow that pairs collagen second harmonic generation imaging, endogenous fluorescence from the metabolic co-factor NAD(P)H, and fluorescence lifetime imaging microscopy (FLIM) as a means to non-invasively compartmentalize the tumor microenvironment into basic domains of the tumor nest, the surrounding stroma or ECM, and the vasculature. This non-invasive protocol details the step-by-step process ranging from the acquisition of time-lapse images of mammary tumor models to post-processing analysis and image segmentation. The primary advantage of this workflow is that it exploits metabolic signatures to contextualize the dynamically changing live tumor microenvironment without the use of exogenous fluorescent labels, making it advantageous for human patient-derived xenograft (PDX) models and future clinical use where extrinsic fluorophores are not readily applicable.

The intravital imaging method described here utilizes collagen second harmonic generation and endogenous fluorescence from the metabolic co-factor NAD(P)H to non-invasively segment an unlabeled tumor microenvironment into tumor, stromal, and vascular compartments for in-depth analysis of 4D intravital images.

The ability to visualize complex and dynamic physiological interactions between numerous cell types and the extracellular matrix (ECM) within a live tumor ...