AFB, MAV and NJG would like to thank Ryan Quinton for comments on the manuscript and Adrian Salic for the TDRFP-NLS construct. AFB and MAV are funded by the NIGMS Biomolecular Pharmacology Training Grant 5T32GM008541. NJG is a member of the Shamim and Ashraf Dahod Breast Cancer Research Laboratories and is supported by NIH grants GM117150 and CA-154531, the Karin Grunebaum Foundation, the Smith Family Awards Program, the Searle Scholars Program, and the Melanoma Research Alliance.

This protocol focuses on using the non-transformed and chromosomally stable retinal pigmented epithelial (RPE-1) cell line for live-cell imaging experiments. However, this protocol can be adapted to any adherent cell line so long as cell culture conditions are adjusted as necessary. All procedures must adhere to institutional biosafety and ethical guidelines and regulations.
1. Preparing Cells for Live-cell Imaging
<ol>
	<li>Use freshly thawed and early passage RPE-1 cells expressing either human histone H2B fused to a fluorescent protein (e.g. H2B-GFP), or the FUCCI system (a detailed protocol on how to generate FUCCI-expressing cells can be found in reference45) to assess mitotic cell fate.
	<ol>
		<li>To measure the frequency of nuclear rupture, use RPE-1 cells expressing both H2B-GFP and a tandem dimer of red fluorescent protein fused to a single nuclear localization signal (TDRFP-NLS). 
		NOTE: Constructs of three green fluorescent proteins fused in tandem to a single nuclear localization signal (GFP3-NLS) have also been used to demonstrate rupture (as in reference42).</li>
		<li>Maintain cells on 10 cm tissue culture plates in the appropriate growth medium. RPE-1 cells are maintained in phenol red-free, Dulbecco&#39;s Modified Eagle Medium/Nutrient Mixture F-12 (DMEM:F12) supplemented with 10% fetal bovine serum (FBS), 100 IU/mL penicillin, and 100 &#956;g/mL streptomycin.</li>
	</ol>
	</li>
	<li>Aspirate medium from the cells, wash the tissue culture dish with 10 mL of sterile, room temperature phosphate buffered saline (PBS) to remove remaining medium, and then aspirate the PBS.
	<ol>
		<li>Add 2 mL of 0.25% Trypsin with ethylenediaminetetraacetic acid (EDTA) to the cells and incubate at 37 &#176;C for 3 min or until the majority of cells have detached from the plate. 
		NOTE: Do not keep cells in trypsin longer than needed.</li>
	</ol>
	</li>
	<li>Add 10 mL of complete medium to collect the trypsinized cells with a 10 mL serological stripette and dispense in a 15 mL conical tube.
	<ol>
		<li>Pellet the cells by centrifugation at 180 x g for 3 min at room temperature.</li>
	</ol>
	</li>
	<li>Aspirate the supernatant, being careful not to disrupt the pellet, and then thoroughly resuspend the pellet in 10 mL of fresh medium by gently pipetting the medium up and down in the serological stripette.</li>
	<li>Use a hemocytometer or automated cell counting machine to count cells46.
	<ol>
		<li>Dilute cells in a new conical tube to 30,000 cells/mL of complete medium.</li>
		<li>Plate 30,000 RPE-1 cells (1 mL volume) per well of a 12-well glass bottomed (#1.5 thickness) imaging dish to achieve the required cellular density the next day (30&#8211;50% confluent). 
		NOTE: Always handle the plate with gloves and be careful not to touch the glass-bottom.</li>
	</ol>
	</li>
	<li>Allow cells to grow in a 37 &#176;C tissue culture incubator until they fully attach and flatten on the glass-bottomed imaging plate. While cells can attach in as little as 4 h, it is recommended that cells are not treated with drugs and imaged until the following day.</li>
	<li>Add paclitaxel (dissolved in dimethyl sulfoxide (DMSO)) to the desired final concentration in complete medium and mix thoroughly.
	<ol>
		<li>Prepare complete medium with an equal volume of DMSO alone to use as a control.</li>
		<li>Warm the medium containing drug or DMSO to 37 &#176;C before adding to cells. This will prevent focal drift due to a sudden temperature change.</li>
		<li>Add 1 mL of medium containing either paclitaxel or DMSO alone to individual wells of the 12-well imaging dish.</li>
	</ol>
	</li>
</ol>
2. Setting Up the Microscope for Live-cell Imaging
<ol>
	<li>Clean the glass-bottom of the imaging dish with optical cleaner to remove any fingerprints or dust that may interfere with imaging. Use sufficient optical cleaner to wet the entire glass surface.</li>
	<li>Place the glass-bottom dish on the microscope stage in the imaging dish adaptor, remove the plastic cover from the dish, and cover the dish with a glass-topped chamber. Ensure the chamber has a valve to allow a steady flow of air consisting of 5% CO2. 
	NOTE: To humidify the 5% CO2, the gas is flowed through tubing inserted into a sterile water bath housing. This allows for the gas to become equilibrated to 95% humidity.</li>
	<li>Initiate/calibrate the encoded stage using the software program controlling the microscope. This will ensure accurate X-Y coordinates and prevent focal drift.</li>
	<li>Focus on the cells using phase-contrast optics and perform Kohler illumination (described in detail in reference47) to focus the light and provide optimal contrast.</li>
	<li>Use acquisition software to determine the optimal exposure times for white light and all fluorescent channels being used (exposures that give 75% pixel saturation on the camera are ideal, provided this amount of light is not toxic to cells).
	<ol>
		<li>Use acquisition software to select several, non-overlapping fields of view from each well for imaging. Select imaging regions where cells have adhered well to the glass-bottom and are between 50% and 70% confluent. Avoid areas of clumped cells, as this will make subsequent analysis difficult. 
		NOTE: It is important to have non-overlapping fields of view from each well to avoid tracking the same cells twice. If cells are highly motile, it may be necessary to acquire several images radiating out from a central point and stitch them back together to make one large field of view.</li>
	</ol>
	</li>
	<li>Activate the microscope&#39;s autofocusing feature to ensure all points are maintained in focus for the duration of the experiment.</li>
	<li>To assess mitotic cell fate, set the imaging software to collect images from each selected field of view every 10 min for up to 96 h. Unperturbed mitosis lasts 20&#8211;40 min, and thus 10 min intervals will provide enough sampling to identify when cells divide. To identify nuclear rupture, which is a transient event, acquire images every 5 min. 
	NOTE: Make sure that the computer driving the image acquisition software has auto-updating, screensavers, and energy-savings modes disabled, as these can often interfere with image acquisition over long experiments.</li>
	<li>Initiate the imaging experiment. Periodically confirm that image acquisition is running smoothly over the course of the video.</li>
</ol>
3. Video Analysis to Identify Cell Fate in Response to Paclitaxel
<ol>
	<li>Confirm that imaged cells are healthy throughout the course of the imaging experiment. Control cells treated with DMSO should be viable and actively proliferating. 
	NOTE: If cells exhibit signs of stress, do not quantitate the video and instead focus on optimizing imaging conditions48. Signs of imaging stress include blebbing/dying cells, cells that fail to attach/spread on the plate, and cells that show a low mitotic index and/or prolonged mitosis. Possible sources of stress include fluctuations in temperature or CO2 levels inside the imaging chamber or phototoxicity48.</li>
	<li>When imaging an entire field of view with a 10X or 20X objective, hundreds of individual cells may be present. Therefore, to assist with quantitation, divide the field of view into smaller quadrants using available software tools. Score cells within each quadrant separately (as described in steps 3.3.1&#8211;3.6.2).</li>
	<li>When analyzing the video, track each cell in a merged view using phase-contrast and/or fluorescent images. Use software analysis tools to create the merged view.
	<ol>
		<li>Starting at the beginning of the video, identify a single interphase cell and track its progress through the cell cycle using phase optics. To track a single cell, observe the cell from frame to frame by eye. Identify interphase cells due to their flattened morphology (as assessed by phase-contrast) and their lack of DNA condensation (as assessed by H2B-GFP) (Figure 1A).</li>
	</ol>
	</li>
	<li>Identify cells that enter mitosis by observation of cell rounding (using phase-contrast optics) and/or chromosome condensation (using H2B-GFP) (Figure 1A-C). Both cell rounding and chromosome condensation are readily visualized by eye.
	<ol>
		<li>Annotate the time when the cell enters mitosis. Continue tracking the cell until it reaches its fate (anaphase as in step 3.5, cell death from mitosis as in step 3.6.1, or mitotic slippage as in step 3.6.2).</li>
	</ol>
	</li>
	<li>Control cells should efficiently align their chromosomes and enter anaphase within 1 h (Figure 1D). Visualize anaphase by phase-contrast optics as the cell begins to pinch into two or through visualization of poleward-moving chromosomes labeled with H2B-GFP (Figure 1A). Annotate the time when the cell undergoes anaphase.</li>
	<li>By contrast, cells treated with paclitaxel will remain rounded with condensed chromosomes for several hours (3-40 h) (Figure 1B-D).
	<ol>
		<li>Identify mitotically-arrested cells that undergo cell death. 
		NOTE: Cells that die during mitosis are visualized by phase-contrast microscopy, as cells will bleb, shrink, and/or rupture (Figure 1B). If imaging H2B-GFP, the chromosomes will also fragment during cell death.</li>
		<li>Identify mitotically-arrested cells that undergo cell slippage. 
		NOTE: Cells that undergo mitotic slippage are observed by phase-contrast microscopy, as they flatten back out into interphase and decondense chromosomes without undergoing anaphase (Figure 1C). Cells that undergo mitotic slippage give rise to large tetraploid cells that are often multinucleated (Figure 1C).</li>
	</ol>
	</li>
	<li>Continue tracking cells from the original field of view. Once a whole field of view is tracked, move to a separate field of view acquired from the same well and continue tracking cells.</li>
</ol>
4. Video Analysis to Identify Cell Fate Following Mitotic Slippage
<ol>
	<li>Assess cell fate following mitotic slippage (as described in step 3.6.2) using RPE-1 cells expressing the FUCCI system. In addition to phase-contrast imaging, it is necessary to acquire both red fluorescence (indicative of G1 phase) and green fluorescence (indicative of S/G2/M) images).
	<ol>
		<li>Track FUCCI RPE-1 cells as described in step 3.3 through 3.7.
		<ol>
			<li>To confirm that the FUCCI system is working properly, validate that control cells alternate expression of the red and green fluorescent proteins appropriately from analysis of the live-cell imaging data. Control cells should transition from exhibiting entirely nuclear red fluorescence to exhibiting entirely nuclear green fluorescence during interphase as cells progress from G1 to S phase. Cells should continue exhibiting green fluorescence throughout the completion of mitosis. Immediately following mitosis, cells should once again exhibit entirely red fluorescence during interphase. 
			NOTE: While methods exist to quantify both RFP and GFP fluorescence intensities from the FUCCI system in single cells using fluorescent traces49, this is often not necessary as the fluorescence color change is robust and visible by eye.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Identify cells arrested in mitosis using phase-contrast microscopy and track them until they undergo mitotic slippage, as described in 3.4 and 3.6.2. Cells that slip out of mitosis and back into interphase will change from exhibiting green fluorescence during mitosis to red fluorescence during G1 phase (Figure 2A-C).
	<ol>
		<li>Track these slipped cells using phase-contrast and epifluorescent imaging by eye to assess their cell fate (Figure 2D).
		<ol>
			<li>Identify cells that re-enter the cell cycle. These cells are identified by the red-to-green change in fluorescence expression using the FUCCI system that indicates G1/S transition (Figure 2A).</li>
			<li>Identify cells that undergo G1 cell cycle arrest. These cells are identified by expression of red fluorescence that persists for &#62;24 h (Figure 2B).</li>
			<li>Identify cells that die in interphase. These cells are identified by cell rupture/blebbing/shrinking using phase-contrast imaging (Figure 2C).</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
5. Video Analysis to Identify Frequency of Nuclear Envelope Rupture
<ol>
	<li>Use RPE-1 cells expressing H2B-GFP and TDRFP-NLS to assess nuclear envelope rupture. In addition to phase-contrast imaging, acquire both red fluorescence (TRITC) and green fluorescence (FITC) images. Acquire images every 5 min to visualize rupture. 
	NOTE: It is critical to generate cell lines in which the TDRFP-NLS is efficiently imported into the nucleus with minimal cytoplasmic fluorescence.</li>
	<li>Image cells as described in step 3.3 through 3.4. The TDRFP-NLS fluorescence signal and H2B-GFP should co-localize during interphase. Upon mitosis (as visualized by cell rounding using phase optics and/or chromosome condensation by H2B-GFP), the nuclear envelope will break down and the TDRFP-NLS signal will become cytoplasmic (Figure 3A). Following mitosis, the nuclear envelope will reform in the daughter cells and the TDRFP-NLS signal will become nuclear.</li>
	<li>Track daughter cells throughout the subsequent interphase by live-cell imaging. Identify nuclear rupture events by observing a transient burst of nuclear-localized TDRFP-NLS into the surrounding cytoplasm. Within minutes, the nuclear envelope will be repaired and the TDRFP-NLS will be relocalized to the nucleus (Figure 3A). 
	NOTE: Often, the nuclear DNA, as visualized by H2B-GFP, will be seen to protrude outside the rupture site as a small bleb.</li>
	<li>Score the fraction of nuclei that undergo a rupture event during interphase. To score this fraction, count the number of cells that undergo a rupture event over the total number of cells tracked.</li>
</ol>

The authors have nothing to disclose.

The most critical aspect of long-term live-cell imaging is ensuring the health of the cells being imaged. It is essential that cells be exposed to minimal extraneous environmental stressors, such as substandard conditions regarding temperature, humidity, and/or CO2 levels. It is also important to limit photodamage from fluorescent excitation illumination, as imaging stress is known to affect cell behavior50. Limiting photodamage can be achieved in multiple ways as detailed elsewhere<sup...

Anti-mitotic drugs have long been used in the chemotherapeutic regimens of various types of solid tumors and often show great efficacy1,2,3. Mechanistically, these drugs disrupt normal mitotic progression and promote mitotic arrest in rapidly proliferating cancer cells. However, cell fate in response to mitotic arrest is highly variable: while a fraction of cells undergoes cell death directly from mitosis, others exit out of mitosis and return to interphase as tetraploid cells (a process termed mitotic slippage)4,5,6,7,8. These interphase cells can execute apoptosis, undergo permanent cell cycle arrest, or even re-enter the cell cycle4,5,6,7,8,9,10,11. Cells that evade mitotic cell death by slipping into interphase, only to re-enter the cell cycle following drug removal, may therefore contribute to the re-emergence of cancer cell populations. Moreover, cells that slip from mitosis are tetraploid, and tetraploidy is known to promote chromosome instability that drives tumor relapse12,13,14,15. Defining the factors that control cell fate in response to anti-mitotic drug treatments is therefore critical to optimize current therapeutics.
In this protocol, we describe methods to directly observe and study the fate of cells that undergo prolonged mitotic arrest in response to the anti-mitotic drug paclitaxel. Paclitaxel is an established therapeutic in the clinic and has proven highly efficacious in many tumors types, including those of the breast, ovaries, and lungs16,17,18,19,20. Paclitaxel, which is a plant alkaloid derived from the bark of the Yew tree, stabilizes microtubules and thus prevents their dynamicity21,22. While dampening of microtubule dynamics by paclitaxel does not affect cell cycle progression from G1 through G2, the drug does lead to sustained activation of the spindle assembly checkpoint during mitosis by hindering kinetochore-microtubule attachment (reviewed in depth here23,24)25. As a consequence, anaphase onset is prevented in paclitaxel-treated cells and results in a prolonged mitotic arrest.
This protocol will first describe approaches to identify mitotic cells in live-cell imaging experiments. Mitosis can be visualized in adherent tissue culture cells due to two noticeable cell biological changes. First, chromosomes become highly condensed immediately prior to nuclear envelope breakdown. While often detectable by standard phase-contrast microscopy, chromosome condensation can be more clearly detected using fluorescent tags that label chromosomes (e.g. fluorescently-labeled histone proteins). Second, mitotic cells can also be identified by the dramatic morphological changes that result from cell rounding.
This protocol will then demonstrate how to use live-cell imaging approaches to track the fates of cells experiencing prolonged mitotic arrest. Cells arrested in mitosis undergo one of three distinct fates. First, cells can undergo cell death during mitosis. This phenomenon is readily visualized by light microscopy, as dying cells are observed to shrink, bleb, and/or rupture. Second, cells can exit from mitosis and return back to interphase without chromosome segregation or cytokinesis, a process termed mitotic slippage. The decondensation of chromosomes and/or the flattening of the mitotic cell readily identifies this process. Cells that slip from mitosis also often display irregular, multi-lobed nuclei and frequently harbor several micronuclei5. Third, cells arrested in mitosis can initiate anaphase and proceed through mitosis after a long delay. While uncommon at higher drug concentrations, this behavior suggests that the arrested cells may have satisfied the spindle assembly checkpoint, or that the spindle assembly checkpoint is partially weakened or defective. Anaphase onset can be visualized by chromosome segregation and subsequent cytokinesis using live-cell imaging.
Live-cell imaging methods to track the fate of cells that evade mitotic cell death by undergoing mitotic slippage will also be described. Cells that undergo mitotic slippage either die in the subsequent interphase, trigger a durable G1 cell cycle arrest, or re-enter the cell cycle to initiate a new round of cell division4. An approach using the FUCCI (fluorescent ubiquitination-based cell cycle indicator) system to determine the fraction of cells that re-enter the cell cycle following mitotic slippage will be described. FUCCI allows for the direct visualization of the G1/S transition and can be used in conjunction with long-term live-cell imaging both in vitro and in vivo26,27. The FUCCI system takes advantage of two fluorescently labeled proteins, truncated forms of hCdt1 (chromatin licensing and DNA replication factor 1) and hGeminin, whose levels oscillate based on cell cycle position. hCdt1 (fused to a red fluorescent protein) is present at high levels during G1 phase where it acts to license DNA for replication, but is ubiquitinated by the E3 ubiquitin ligase SCFSkp2 and degraded during S/G2/M phases to prevent re-replication of DNA26. By contrast, hGeminin (fused to a green fluorescent protein), is an inhibitor of hCdt1 whose levels peak during S/G2/M, but is ubiquitinated by the E3 ubiquitin ligase APCCdh1 and degraded at the end of mitosis and throughout G126. Consequently, FUCCI delivers a straightforward fluorescence readout of cell cycle phase, as cells exhibit red fluorescence during G1, and green fluorescence during S/G2/M. The FUCCI system is a significant advance over other approaches (such as bromodeoxyuridine staining) to identify proliferative cells, because it does not require cell fixation and allows for single cell imaging without the need for additional pharmacological treatments to synchronize cell populations. Though not discussed in this protocol, additional live-cell sensors have also been developed to visualize cell cycle progression, including a helicase B sensor for G128, DNA ligase-RFP29 and PCDNA-GFP30 sensors for S-phase, and the recent FUCCI-4 sensor, which detects all stages of the cell cycle31.
Finally, a live-cell imaging method to detect nuclear envelope rupture will be described. Recent studies have revealed that the nuclear envelopes of cancer cells are unstable and prone to bursting, thereby allowing the contents of the nucleoplasm and cytoplasm to intermix. This phenomenon, termed nuclear rupture, can promote DNA damage and stimulation of the innate immune response32,33,34,35,36,37,38,39,40,41,42,43,44. While the underlying causes of nuclear rupture remain incompletely characterized, it is known that deformations in nuclear structure correlate with an increased incidence of nuclear rupture42. One well-known effect of paclitaxel treatment is the generation of strikingly abnormal nuclear structures following mitosis; as such, a method using live-cell imaging to quantify nuclear rupture will be described, while also exploring if paclitaxel treatment increases the frequency of nuclear rupture events. Nuclear rupture can be detected by the observed leakage of a nuclear-targeted fluorescent protein into the cytoplasm (e.g. a tandem dimer repeat of RFP fused to a nuclear localization signal, TDRFP-NLS). This leakage is distinctly visible by eye, which enables simple quantitation of rupture events.
This protocol requires a widefield epifluorescence microscope that is equipped with an encoded stage and autofocusing software. The encoded stage allows for precise automated movement to defined X-Y coordinates, while autofocus software maintains cells in focus for the duration of the imaging period. In addition, this protocol requires equipment to maintain cells at 37 &#176;C with humidified 5% CO2 atmosphere. This can be achieved by enclosing the entire microscope within a temperature and atmosphere controlled enclosure, or by using stage-top devices that locally maintains temperature and environment. The phase-contrast objective used in this protocol is a plan fluor 10x with a numerical aperture of 0.30. However, 20X objectives are also sufficient to identify both rounded mitotic and flattened interphase cells in a single focal plane. If performing phase-contrast imaging (as described in this method), the cover can be either glass or plastic. If differential interference contrast (DIC) microscopy is used, it is imperative to use a glass cover to prevent depolarization of light.

<table>
	<tbody>
		<tr>
			<td>phenol red-free, DMEM:F12 media</td>
			<td>Hyclone</td>
			<td>SH3027202</td>
			<td></td>
		</tr>
		<tr>
			<td>10% fetal bovine serum (FBS)</td>
			<td>Gibco</td>
			<td>10438026</td>
			<td></td>
		</tr>
		<tr>
			<td>100 IU/ml penicillin, and 100 mg/ml streptomycin.</td>
			<td>Gibco</td>
			<td>15070063</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Gibco</td>
			<td>10010049</td>
			<td></td>
		</tr>
		<tr>
			<td>0.25% Trypsin/EDTA</td>
			<td>Gemini</td>
			<td>50-753-3104</td>
			<td></td>
		</tr>
		<tr>
			<td>12-well glass bottomed imaging dish</td>
			<td>Cellvis</td>
			<td>P12-1.5H-N</td>
			<td></td>
		</tr>
		<tr>
			<td>Paclitaxel</td>
			<td>TSZ Chem</td>
			<td>RS036</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide (DMSO)</td>
			<td>Sigma</td>
			<td>NC0215085</td>
			<td></td>
		</tr>
		<tr>
			<td>Environmental Chamber</td>
			<td>In Vivo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>5% CO2</td>
			<td>Airgas</td>
			<td>Z03NI7432000201</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Conical Tubes</td>
			<td>Fisherbrand</td>
			<td>05-539-12</td>
			<td></td>
		</tr>
		<tr>
			<td>10 cm polystyrene tissue culture plates</td>
			<td>Falcon</td>
			<td>08772E</td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL Disposable Serological Pipette</td>
			<td>Fisherbrand</td>
			<td>4488</td>
			<td></td>
		</tr>
		<tr>
			<td>5804R 15 amp Centrifuge</td>
			<td>Eppendorf</td>
			<td>97007-370</td>
			<td></td>
		</tr>
		<tr>
			<td>1000 microliters Pipette</td>
			<td>Gilson</td>
			<td>Pipetman Classic</td>
			<td></td>
		</tr>
		<tr>
			<td>20 microliters Pipette</td>
			<td>Gilson</td>
			<td>Pipetman Classic</td>
			<td></td>
		</tr>
		<tr>
			<td>p1000 Pipette Tips</td>
			<td>Sharp</td>
			<td>p1126</td>
			<td></td>
		</tr>
		<tr>
			<td>p20 Pipette Tips</td>
			<td>Sharp</td>
			<td>P1121</td>
			<td></td>
		</tr>
		<tr>
			<td>RPE-1 Cells</td>
			<td>ATCC</td>
			<td>CRL-4000</td>
			<td></td>
		</tr>
		<tr>
			<td>Incubator Galaxy 170S</td>
			<td>Eppendorf</td>
			<td>CO17011005</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette Boy</td>
			<td>Integra</td>
			<td>156401</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemacytometer</td>
			<td>Fisher Scientific</td>
			<td>0267110</td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon Ti-E-PFS Inverted Microscope for Live Cell Imaging</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MEA53100</td>
			<td></td>
		</tr>
		<tr>
			<td>Prior X-Y Stage System and White Light LED Illuminator</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>500-H117P1N4</td>
			<td></td>
		</tr>
		<tr>
			<td>Prior Proscan 3 Controller XYZ with Encoders</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>500-H31XYZE</td>
			<td></td>
		</tr>
		<tr>
			<td>Andor Digital Camera</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>D10NLC</td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon NIS Elements AR Software</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MQS31000</td>
			<td></td>
		</tr>
		<tr>
			<td>SOLA LED Illuminator for Fluorescence</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>SOLA-E</td>
			<td></td>
		</tr>
		<tr>
			<td>InVivo Environmental Chamber with CO2 Flow Control</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>Ti-IVS-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Ti-ND6-PFS Perfect Focus Motorized Nosepiece</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MEP59391</td>
			<td></td>
		</tr>
		<tr>
			<td>Ti-C System Condenser Turret</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MEL51000</td>
			<td></td>
		</tr>
		<tr>
			<td>Ti-C LWD LWD Lens Unit for System Condenser Turret</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MEL56200</td>
			<td></td>
		</tr>
		<tr>
			<td>Te-C LWD Ph1 Module</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MEH41100</td>
			<td></td>
		</tr>
		<tr>
			<td>CFI Plan Fluor DLL 10X Objectivena 0.3 wd 16mm</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MRH10101</td>
			<td></td>
		</tr>
		<tr>
			<td>CFI Super Plan Fluor ELWD 20xc ADM Objective</td>
			<td>Micro Video Instruments, Inc.</td>
			<td>MRH48230</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Using the protocol described above, RPE-1 cells expressing H2B-GFP were treated with an anti-mitotic or vehicle control (DMSO) and analyzed by live-cell imaging. Analysis revealed that 100% of control mitotic RPE-1 cells initiated anaphase an average of 22 min after entering mitosis (Figure 1A, 1D). By contrast, RPE-1 cells treated with paclitaxel exhibited a profound mitotic arrest lasting several hours (Figure 1D</stron...

Watch this Scientific Journal Video about Long-term Live-cell Imaging to Assess Cell Fate in Response to Paclitaxel at JoVE.com

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

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 ...

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Research

JoVE Journal

Cancer Research

9.8K Views.  Boston University School of Medicine. 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.

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

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.

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 ...

A Comprehensive Procedure to Evaluate the In Vivo Performance of Cancer Nanomedicines

Inspired by the success of previous cancer nanomedicines in the clinic, researchers have generated a large number of novel formulations in the past decade. However, only a small number of nanomedicines have been approved for clinical use, whereas the majority of nanomedicines under clinical development have produced disappointing results. One major obstacle to the successful clinical translation of new cancer nanomedicines is the lack of an accurate understanding of their in vivo performance. This article features a rigorous procedure to characterize the in vivo behavior of nanomedicines in tumor-bearing mice at systemic, tissue, single-cell, and subcellular levels via the integration of positron emission tomography-computed tomography (PET-CT), radioactivity quantification methods, flow cytometry, and fluorescence microscopy. Using this approach, researchers can accurately evaluate novel nanoscale formulations in relevant mouse models of cancer. These protocols may have the ability to identify the most promising cancer nanomedicines with high translational potential or to aid in the optimization of cancer nanomedicines for future translation.

A Comprehensive Procedure to Evaluate the In Vivo Performance of Cancer Nanomedicines

The poor understanding of the in vivo performance of nanomedicines stymies their clinical translation. Procedures to evaluate the in vivo behavior of cancer nanomedicines at systemic, tissue, single-cell, and subcellular levels in tumor-bearing immunocompetent mice are described here. This approach may help researchers to identify promising cancer nanomedicines for clinical translation.

Inspired by the success of previous cancer nanomedicines in the clinic, researchers have generated a large number of novel formulations in the past ...

Transplantation of Zebrafish Pediatric Brain Tumors into Immune-competent Hosts for Long-term Study of Tumor Cell Behavior and Drug Response

Tumor cell transplantation is an important technique to define the mechanisms controlling cancer cell growth, migration, and host response, as well as to assess potential patient response to therapy. Current methods largely depend on using syngeneic or immune-compromised animals to avoid rejection of the tumor graft. Such methods require the use of specific genetic strains that often prevent the analysis of immune-tumor cell interactions and/or are limited to specific genetic backgrounds. An alternative method in zebrafish takes advantage of an incompletely developed immune system in the embryonic brain before 3 days, where tumor cells are transplanted for use in short-term assays (i.e., 3 to 10 days). However, these methods cause host lethality, which prevents the long-term study of tumor cell behavior and drug response. This protocol describes a simple and efficient method for the long-term orthotopic transplantation of zebrafish brain tumor tissue into the fourth ventricle of a 2-day-old immune-competent zebrafish. This method allows: 1) long-term study of tumor cell behaviors, such as invasion and dissemination; 2) durable tumor response to drugs; and 3) re-transplantation of tumors for the study of tumor evolution and/or the impact of different host genetic backgrounds. In summary, this technique allows cancer researchers to assess engraftment, invasion, and growth at distant sites, as well as to perform chemical screens and cell competition assays over many months. This protocol can be extended to studies of other tumor types and can be used to elucidate mechanisms of chemoresistance and metastasis.

The transplantation of cancer cells is an important tool for the identification of cancer mechanisms and therapeutic responses. Current techniques depend on immune-incompetent animals. Here, we describe a method to transplant zebrafish tumor cells into immune-competent embryos for the long-term analysis of tumor cell behavior and in vivo drug responses.

Tumor cell transplantation is an important technique to define the mechanisms controlling cancer cell growth, migration, and host response, as well as to ...

Radionuclide-fluorescence Reporter Gene Imaging to Track Tumor Progression in Rodent Tumor Models

Metastasis is responsible for most cancer deaths. Despite extensive research, the mechanistic understanding of the complex processes governing metastasis remains incomplete. In vivo models are paramount for metastasis research, but require refinement. Tracking spontaneous metastasis by non-invasive in vivo imaging is now possible, but remains challenging as it requires long-time observation and high sensitivity. We describe a longitudinal combined radionuclide and fluorescence whole-body in vivo imaging approach for tracking tumor progression and spontaneous metastasis. This reporter gene methodology employs the sodium iodide symporter (NIS) fused to a fluorescent protein (FP). Cancer cells are engineered to stably express NIS-FP followed by selection based on fluorescence-activated cell sorting. Corresponding tumor models are established in mice. NIS-FP expressing cancer cells are tracked non-invasively in vivo at the whole-body level by positron emission tomography (PET) using the NIS radiotracer [18F]BF4-. PET is currently the most sensitive in vivo imaging technology available at this scale and enables reliable and absolute quantification. Current methods either rely on large cohorts of animals that are euthanized for metastasis assessment at varying time points, or rely on barely quantifiable 2D imaging. The advantages of the described method are: (i) highly sensitive non-invasive in vivo 3D PET imaging and quantification, (ii) automated PET tracer production, (iii) a significant reduction in required animal numbers due to repeat imaging options, (iv) the acquisition of paired data from subsequent imaging sessions providing better statistical data, and (v) the intrinsic option for ex vivo confirmation of cancer cells in tissues by fluorescence microscopy or cytometry. In this protocol, we describe all steps required for routine NIS-FP-afforded non-invasive in vivo cancer cell tracking using PET/CT and ex vivo confirmation of in vivo results. This protocol has applications beyond cancer research whenever in vivo localization, expansion and long-time monitoring of a cell population is of interest.

We describe a protocol for preclinical in vivo tracking of cancer metastasis. It is based on a radionuclide-fluorescence reporter combining the sodium iodide symporter, detected by non-invasive [18F]tetrafluoroborate-PET, and a fluorescent protein for streamlined ex vivo confirmation. The method is applicable for preclinical in vivo cell tracking beyond tumor biology.

Metastasis is responsible for most cancer deaths. Despite extensive research, the mechanistic understanding of the complex processes governing metastasis ...

Live Cell Imaging of the TGF-	&beta;/Smad3 Signaling Pathway In Vitro and In Vivo Using an Adenovirus Reporter System

Transforming Growth Factor &#946; (TGF-&#946;) signaling regulates many important functions required for cellular homeostasis and is commonly found overexpressed in many diseases, including cancer. TGF-&#946; is strongly implicated in metastasis during late stage cancer progression, activating a subset of migratory and invasive tumor cells. Current methods for signaling pathway analysis focus on endpoint models, which often attempt to measure signaling post-hoc of the biological event and do not reflect the progressive nature of the disease. Here, we demonstrate a novel adenovirus reporter system specific for the TGF-&#946;/Smad3 signaling pathway that can detect transcriptional activation in live cells. Utilizing an Ad-CAGA12-Td-Tom reporter, we can achieve a 100% infection rate of MDA-MB-231 cells within 24 h in vitro. The use of a fluorescent reporter allows for imaging of live single cells in real-time with direct identification of transcriptionally active cells. Stimulation of infected cells with TGF-&#946; displays only a subset of cells that are transcriptionally active and involved in specific biological functions. This approach allows for high specificity and sensitivity at a single cell level to enhance understanding of biological functions related to TGF-&#946; signaling in vitro. Smad3 transcriptional activity can also be reported in vivo in real-time through the application of an Ad-CAGA12-Luc reporter. Ad-CAGA12-Luc can be measured in the same manner as traditional stably transfected luciferase cell lines. Smad3 transcriptional activity of cells implanted in vivo can be analyzed through conventional IVIS imaging and monitored live during tumor progression, providing unique insight into the dynamics of the TGF-&#946; signaling pathway. Our protocol describes an advantageous reporter delivery system allowing for quick high-throughput imaging of live cell signaling pathways both in vitro and in vivo. This method can be expanded to a range of image based assays and presents as a sensitive and reproducible approach for both basic biology and therapeutic development.

Here, we present a protocol for live cell imaging of TGF-&#946;/Smad3 signaling activity using an adenovirus reporter system. This system tracks transcriptional activity in real-time and can be applied to both single cells in vitro and in live animalmodels.

Transforming Growth Factor &#946; (TGF-&#946;) signaling regulates many important functions required for cellular homeostasis and is commonly found ...

Live-Cell Imaging Assays to Study Glioblastoma Brain Tumor Stem Cell Migration and Invasion

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include rapid proliferation and pervasive invasion into the normal brain. Recurrence is thought to result from the presence of radio- and chemo-resistant brain tumor stem cells (BTSCs) that invade away from the initial cancerous mass and, thus, evade surgical resection. Hence, therapies that target BTSCs and their invasive abilities may improve the otherwise poor prognosis of this disease. Our group and others have successfully established and characterized BTSC cultures from GBM patient samples. These BTSC cultures demonstrate fundamental cancer stem cell properties such as clonogenic self-renewal, multi-lineage differentiation, and tumor initiation in immune-deficient mice. In order to improve on the current therapeutic approaches for GBM, a better understanding of the mechanisms of BTSC migration and invasion is necessary. In GBM, the study of migration and invasion is restricted, in part, due to the limitations of existing techniques which do not fully account for the in vitro growth characteristics of BTSCs grown as neurospheres. Here, we describe rapid and quantitative live-cell imaging assays to study both the migration and invasion properties of BTSCs. The first method described is the BTSC migration assay which measures the migration toward a chemoattractant gradient. The second method described is the BTSC invasion assay which images and quantifies a cellular invasion from neurospheres into a matrix. The assays described here are used for the quantification of BTSC migration and invasion over time and under different treatment conditions.

Here, we describe live-cell imaging techniques to quantitatively measure the migration and invasion of glioblastoma brain tumor stem cells over time and under multiple treatment conditions.

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include ...

Establishing Cell Lines Overexpressing DR3 to Assess the Apoptotic Response to Anti-mitotic Therapeutics

Studying the function of a gene of interest can be achieved by manipulating its level of expression, such as decreasing its expression with knockdown cell lines or increasing its expression with overexpression cell lines. Transient and stable transfection are two methods that are often used for exogenous gene expression. Transient transfection is only useful for short-term expression, whereas stable transfection allows exogenous genes to be integrated into the host cell genome where it will be continuously expressed. As a result, stable transfection is usually employed for research into long-term genetic regulation. Here we describe a simple protocol to generate a stable cell line overexpressing tagged death receptor 3 (DR3) to explore DR3 function. We picked single clones after a retroviral infection in order to maintain the homogeneity and purity of the stable cell lines. The stable cell lines generated using this protocol render DR3-deficient HT29 cells sensitive to antimitotic drugs, thus reconstituting the apoptotic response in HT29 cells. Moreover, the FLAG tag on DR3 compensates for the unavailability of good DR3 antibody and facilitates the biochemical study of the molecular mechanism by which antimitotic agents induce apoptosis.

Establishing a stable cell line overexpressing a gene of interest to study gene function can be done by stable transfection-picking single clones after transfecting them via retroviral infection. Here we show that HT29-DR3 cell lines generated in this way elucidate the mechanisms by which death receptor 3 (DR3) contributes to antimitotics-induced apoptosis.

Studying the function of a gene of interest can be achieved by manipulating its level of expression, such as decreasing its expression with knockdown cell ...

Using Microarrays to Interrogate Microenvironmental Impact on Cellular Phenotypes in Cancer

Understanding the impact of the microenvironment on the phenotype of cells is a difficult problem due to the complex mixture of both soluble growth factors and matrix-associated proteins in the microenvironment in vivo. Furthermore, readily available reagents for the modeling of microenvironments in vitro typically utilize complex mixtures of proteins that are incompletely defined and suffer from batch to batch variability. The microenvironment microarray (MEMA) platform allows for the assessment of thousands of simple combinations of microenvironment proteins for their impact on cellular phenotypes in a single assay. The MEMAs are prepared in well plates, which allows the addition of individual ligands to separate wells containing arrayed extracellular matrix (ECM) proteins. The combination of the soluble ligand with each printed ECM forms a unique combination. A typical MEMA assay contains greater than 2,500 unique combinatorial microenvironments that cells are exposed to in a single assay. As a test case, the breast cancer cell line MCF7 was plated on the MEMA platform. Analysis of this assay identified factors that both enhance and inhibit the growth and proliferation of these cells. The MEMA platform is highly flexible and can be extended for use with other biological questions beyond cancer research.

The purpose of the method presented here is to show how microenvironment microarrays (MEMA) can be fabricated and used to interrogate the impact of thousands of simple combinatorial microenvironments on the phenotype of cultured cells.

Understanding the impact of the microenvironment on the phenotype of cells is a difficult problem due to the complex mixture of both soluble growth ...

A Simple Migration/Invasion Workflow Using an Automated Live-cell Imager

Cancer cell mobility is crucial for the initiation of metastasis. Therefore, investigation of the cell movement and invasive capacity is of great significance. Migration assays provide basic insight of cell movement at a 2D level, whereas invasion assays are more physiologically relevant, mimicking in vivo cancer cell dislodgment from the original site and invading through the extracellular matrix. The current protocol provides a single workflow for migration and invasion assays. Together with the integrated automated microscopic camera for real-time HD images and built-in analysis module, it gives researchers a time-efficient, simple and reproducible experimental option. This protocol also includes substitutions for the consumables and alternative analysis methods for users to choose from.

The current protocol describes an integrated method investigating cancer cell migration and invasion on a single platform in real-time, providing an easily reproducible and time-efficient option to study cell mobility and morphology.

Cancer cell mobility is crucial for the initiation of metastasis. Therefore, investigation of the cell movement and invasive capacity is of great ...

Longitudinal Intravital Imaging of Brain Tumor Cell Behavior in Response to an Invasive Surgical Biopsy

Biopsies are standard of care for cancer treatment and are clinically beneficial as they allow solid tumor diagnosis, prognosis, and personalized treatment determination. However, perturbation of the tumor architecture by biopsy and other invasive procedures has been associated with undesired effects on tumor progression, which need to be studied in depth to further improve the clinical benefit of these procedures. Conventional static approaches, which only provide a snapshot of the tumor, are limited in their ability to reveal the impact of biopsy on tumor cell behavior such as migration, a process closely related to tumor malignancy. In particular, tumor cell migration is the key in highly aggressive brain tumors, where local tumor dissemination makes total tumor resection virtually impossible. The development of multiphoton imaging and chronic imaging windows allows scientists to study this dynamic process in living animals over time. Here, we describe a method for the high-resolution longitudinal imaging of brain tumor cells before and after a biopsy in the same living animal. This approach makes it possible to study the impact of this procedure on tumor cell behavior (migration, invasion, and proliferation). Furthermore, we discuss the advantages and limitations of this technique, as well as the ability of this methodology to study changes in the cancer cell behavior for other surgical interventions, including tumor resection or the implantation of chemotherapy wafers.

Here we describe a method for high-resolution time-lapse multiphoton imaging of brain tumor cells before and after invasive surgical intervention (e.g., biopsy) within the same living animal. This method allows studying the impact of these invasive surgical procedures on tumor cells&#39; migratory, invasive, and proliferative behavior at a single cell level.