We thank all the patients who have donated blood samples to support this work. We thank Drs. Guiseppe Giaconne, Ritesh Parajuli, and Marc E. Lippman for their assistance in clinical sample acquirement, and Drs. Carmen Gomez, Ralf Landgraf, Stephan Z&#252;chner, Toumy Guettouche, Diana Lopez for their insightful discussions. Zheng Ao thanks partial support and assistance from the Sheila and David Fuente Graduate Program in Cancer Biology, Sylvester Comprehensive Cancer Center.

Ethics Statement: To protect the rights of human subjects, blood samples were obtained following an informed consent under protocols approved by the University of Miami institutional review boards under IRB 20150020. 
NOTE: Blood to be filtered for CTC capture should be collected in an EDTA tube to prevent coagulation.
1. Coating the Microfilter with Poly (N-iso-propylacrylamide) (PIPAAm)
<ol>
	<li>Weigh out PIPAAm to prepare a 10% w/v solution in butanol. Mix using a vortex until the solution is clear.</li>
	<li>Cut plastic microscope slides into roughly 12 mm x 12 mm squares either with a pair of scissors or sharp blade. Alternatively use a guillotine. 
	NOTE: These squares will serve as a holder for the filters during the spin coating process.</li>
	<li>Using a sharp pair of straight edge scissors, cut the slot pore microfilter wafer into 8 mm x 8 mm squares.</li>
	<li>Using a polyimide film tape secure the cut filters onto the plastic squares previously cut in step 1.3. Apply the film only to the edge and the corner of the filter so that at least 7 mm X 7 mm of filter area is un-covered by the tape.</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/54435/54435fig2.jpg" /> 
Figure 2: Representative Illustration of the Microfilter Set-up for PIPAAm Coating. 8 mm x 8 mm microfilter is positioned onto the 12 mm x 12 mm plastic square cut from a plastic microscope slide. Polyimide tape is used to secure the microfilter in place to spin coat the PIPAAm.Reproduced with permission from reference15. <a href="http://cloudfront.jove.com/files/ftp_upload/54435/54435fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="5">
	<li>Place the microfilter that is secured on the plastic square, onto the vacuum chuck of the spin-coater.</li>
	<li>Program the spin-coater to the following recipe: Start, 500 rpm for 10 sec, 6,000 rpm for 60 sec, 500 rpm for 10 sec, Stop.</li>
	<li>Dispense enough 10% w/v PIPAAm solution (prepared in 1.1) to completely cover the microfilter surface using a standard plastic transfer pipette and start the spin coater.</li>
	<li>Remove the PIPAAm coated microfilter from the spin-coater after the coating process is completed. Leave the filter attached to the plastic square during storage. 
	NOTE: The coated-filter can be stored at room temperature for up to 3 months.</li>
</ol>
2. Assembly of Filtration Cassette with PIPAAm Coated Microfilter
<ol>
	<li>Rehydrate PIPAAm coated microfilter at room temperature by placing the microfilter still secured on the plastic square into a petri dish. Add 1x PBS until the microfilter is fully submerged and let stand for 5 min.</li>
	<li>After the hydration step, release the filter from the plastic square by cutting the polyimide film tape using a pair of scissor. 
	NOTE: Take note of which side of the filter has the PIPAAm coating.</li>
	<li>Assemble the microfilter into the filtration cassette, by sandwiching the microfilter between the top and bottom acrylic piece along with the 2 Polydimethylsiloxane (PDMS) pieces acting as a gasket/seal. Clamp the acrylic cassette with clips to secure the filter and provide a tight seal. 
	NOTE: The PIPAAm coating should be facing upwards, so as the sample is filtered through, the cells will be captured on PIPAAm coated surface of the filter (Figure 1).</li>
</ol>
3. Filtration of Blood Sample with Capture and Release of CTC from the Microfilter
<ol>
	<li>As each syringe pump brand has its own user interface, refer to the user manual of the pump and program the syringe pump to flow at a rate of 75ml/hr and set the volume to 20 ml.</li>
	<li>Warm 3 ml of McCoy&#39;s (commercially available) cell culture media (prepared by adding in 10% Fetal Bovine Serum and 1% Penicillin and Streptomycin) to 37 &#176;C. 
	NOTE: The media choice will be based on the patient&#39;s cancer type or else if this is a model system experiment where cultured cells are to be spiked into healthy donor blood, use the media the cells are normally cultured in. If unsure, please refer to culturing guide/method provided by the company the cells were purchased from.</li>
	<li>Add 7.5 ml of commercially available Hank&#39;s Balanced Salt Solution (HBSS) to the 7.5 ml of blood sample and aspirate this diluted blood into a 25 ml syringe. 
	NOTE: Adjust the volume of HBSS so that the blood sample is diluted with equal volume of 1:1 with HBSS. E.g. if 10 ml of blood is used, then mix with equal volume of 10 ml HBSS to achieve the 1:1 dilution.</li>
	<li>Engage the filtration cassette with the syringe and place it onto the syringe pump. Place a 50 ml tube at bottom to collect the flow through and start the pump. 
	NOTE: The filtration should take roughly 10- 12 min. All filtration steps are to be carried out at Normal Room Temperature (20-25 &#176;C) including step 3.8</li>
	<li>After filtration is complete, disengage the filtration cassette taking note which side is the top that has the cells caught on the PIPAAm-coated surface. Aspirate 1 ml of the warm culture media into a new syringe.</li>
	<li>Re-engage the filtration cassette with the syringe containing the media, but at this time engage the bottom end of the cassette so that the PIPAAm coated-surface of the filter is facing away from the syringe. 
	NOTE: This will be to release any cells that may be embedded into the slot pores by applying gentle reverse flow.</li>
	<li>Place the syringe back onto the syringe pump and hold a small petri dish or 6-well plate right under the filtration cassette. Set the flow rate to 100 ml/hr and start the pump.</li>
	<li>Pass all the media through the filter and collect the flow-through in the petri dish. Wait for all the media to pass through and then stop the pump and remove the syringe and filtration cassette from the pump.</li>
	<li>Disengage the filtration cassette from the syringe and open it to retrieve the filter from the cassette. Place the filter with the PIPAAm surface facing down into the same petri dish used to collect the reverse flow when releasing the cells from the pores. Add the rest of the warm media and place the petri dish into a culture incubator set at 37 &#176;C.</li>
	<li>After 30 min all the cells will be released from the filter. However, leave filter in the petri dish for up to 24 hours to ensure all cells detach. 
	NOTE: Alternatively, the released cells can be collected into a microcentrifuge tube to perform further downstream analysis such as PCR, ELISA, Western Blot to name a few examples.</li>
	<li>After 24 hr in culture, carefully remove the microfilter using forceps. 
	NOTE: The filter can be discarded at this time as the cells have been released from it.</li>
	<li>Gently pipette the culture medium up and down using a 1,000 &#181;l pipette, to re-suspend the erythrocytes and peripheral blood mononuclear cell (PBMC) that are caught on the filter and released into the plate with the CTC. Perform this action carefully and gently to avoid detaching the loosely-attached cancer cells. Carefully remove the entire medium containing the re-suspended erythrocytes and PBMC while leaving behind the attached-cancer cells and substitute with fresh medium pre-warmed to 37 &#176;C. 
	NOTE: This step can be repeated once if excessive erythrocytes are present after one wash.</li>
</ol>
4. CTC Viability Evaluation
<ol>
	<li>Evaluate cultured CTC viability using a Live/Dead Assay8. 
	NOTE: Numerous Live/Dead assays are available commercially. Following the manufacturer&#39;s protocol is highly advised. Please refer to the materials/reagents list for the commercial assay kit used for this experiment.</li>
</ol>

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Part of this work has been protected under U.S. Provisional Patent Application No. 62/219,808. Siddarth Rawal is a shareholder of Circulogix Inc. that commercially produces the filters and filter cassettes/cartridges used in this Article.

The process of capturing viable CTC from whole blood and releasing them from the microfilter is relatively straightforward; however a few critical points are worth mentioning. It is imperative, as with all cell culture that a sterile condition is maintained through the whole process. The initial step of coating the filter with PIPAAm is critical, as the basis for the technique of releasing the cells from the filter is based on exploiting PIPAAm&#39;s temperature responsive interfacial properties. To ensure the filter has...

Metastatic disease is responsible for most cancer deaths. Developing prognostic and companion diagnostic biomarker for metastasis is crucial in cancer management and treatment. Circulating tumor cells (CTC) play a central role in tumor dissemination and metastasis. Furthermore, being easily accessible as a &#39;liquid biopsy&#39; biomarker, CTC in cancer patients&#39; peripheral blood has been rising as a &#39;hotbed&#39; for cancer biomarker research. CTC have been well validated as a prognostic biomarker in various cancer settings, including breast, prostate and colorectal cancer1-3. However, recent advances in CTC field has indicated that the mere enumeration of these rare cells has limited clinical utility, as shown in interventional clinical trials4. Thus, there is an emerging need for technologies that allow for molecular and functional characterization of CTC. Currently, only few technologies exist that allow for non-antigen biased, viable capture and release of CTC, enabling robust downstream molecular and functional analysis5,6. Majority of these microfabricated devices are coupled to microfluidic platforms and thus have a limiting factor in the amount of blood that that can be processed, which ranges from 2-4 ml7-10 . CTC are rare events in a single tube of blood draw (7.5 ml), therefore further reducing the amount of blood that can be processed, greatly hinders the chances of capturing and isolating these cells of interest.
We have developed two types of Parylene C membrane microfilter devices for the capture of CTC which exploit the size differences between larger tumor cells and the smaller normal blood cells11,12. We have previously reported on the round pore enumeration filter and compared it with a FDA-approved platform, where the microfilter was shown to be superior in CTC capture efficiency for cancer patient blood samples13,14. However, a limitation of the round filter is the necessity to use a formaldehyde-based fixative prior to filtration. This process preserves the cells morphology while allowing them to withstand the shear stress and pressure during the filtration process. While enumeration and molecular studies can be performed on-chip13, the fixative impairs the ability to perform functional characterization. To address this limitation, we developed a slot pore filter that negates the necessity to fix cells prior to filtration (Figure 1). The slot pore geometry (6 &#181;m width x 40 &#181;m length slot pores) allows the tumor cells to be captured while only partially occluding a pore and thus still permitting free passage for other blood cells and alleviating the rise in pressure that would lead to cell damage and eventual bursting15,16 The slot pore cartridge is composed of 2 acrylic pieces which sandwich the slot pore filter between the top and bottom piece with Polydimethylsiloxane (PDMS) acting as a gasket to provide a leak proof seal14,15 (Figure 1).
While the capture efficiency of the slot pore filter is high, (Table 1), the captured CTC are bound to the Parylene C membrane by strong non-specific electrostatic interactions instead of extracellular matrix (ECM) mediated adhesion15. Methods such as reverse flow or the use of cell scrapers fail to effectively release the cells from the filter, or result in cell damage and cell death. We explored an unconventional use of PIPAAm to formulate a release strategy15. PIPAAm is a polymer that undergoes a reversible lower critical solution temperature (LCST) phase transition at a solution temperature of 32 &#176;C17. Traditionally, this property of PIPAAm has been widely explored for tissue engineering applications. Typically, cells are cultured on PIPAAm coated surfaces at 37 &#176;C when PIPAAm is hydrophobic. The cells can then be detached as a sheet when the culture temperature is shifted to below 32 &#176;C, where the PIPAAm coated surface becomes hydrated17,18. We exploited this thermal property by performing the filtration process at room temperature (below 32 &#176;C) and then enabling cell release by placing the filter in culture media maintained at 37 &#176;C. At this temperature, the PIPAAm polymer layer becomes hydrophobic, thereby releasing the electrostatically bound cells15 (Figure 1).
Although the temperature responsive method as well as other methods have been successfully implemented to achieve viable CTC capture and release19-21, one key potential drawback shared by these technologies reported is that they all employ an antigen-dependent principle for CTC capture. Antigen based CTC capture, as shown previously, may lead to biased CTC analysis11,14. For example, many affinity-based technologies employ antibody that binds EpCAM for CTC capture. However, CTC has been shown to express various levels of EpCAM, leading to omission of EpCAM low and EpCAM negative CTC by these technologies. Also, limitations may occur when CTC from non-epithelial origin is of interest, such as CTC in melanoma and sarcoma settings. Thus, a technology that allows for viable CTC capture and release without potential bias introduced by antigen based capture is highly desirable.
Importantly, the microfilter capture device is purely sized based and the release strategy is agnostic to the presence of certain surface markers. We believe that the employment of the PIPAAm coated microfilter will help to expand our understanding of the metastatic process, through providing the ability to effectively and efficiently capture and release CTC for downstream analyses. This may potentially expose new molecules for which novel targeted systemic therapies might be directed as well as provide a biomarker that can be monitored easily and aid in cancer patient management.

<table border="0" cellpadding="0" cellspacing="0" width="603">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="106">
			<td height="106" style="height:107px;width:216px;">Slot Filter</td>
			<td style="width:101px;">Circulogix Inc.</td>
			<td style="width:119px;">MSF-01</td>
			<td style="width:167px;">Different size filters available based for filtration for CTC from blood or urine (www.circulogixinc.com)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">poly(N-iso-propylacrylamide) (PIPAAm)&#160;</td>
			<td style="width:101px;">Ploysciences Inc.</td>
			<td style="width:119px;">21458</td>
			<td style="width:167px;">Non-Hazardous. Store at room temp.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">1-Butanol</td>
			<td style="width:101px;">Sigma Aldrich</td>
			<td style="width:119px;">B7906</td>
			<td style="width:167px;">Use in well ventilated area</td>
		</tr>
		<tr height="118">
			<td height="118" style="height:119px;width:216px;">Plastic Microscope Slides</td>
			<td style="width:101px;">Cole-Parmer</td>
			<td style="width:119px;">48510-30</td>
			<td style="width:167px;">Any plastic slides or alternatively any sort of square (Metal, Acrylic etc.) can be used if it will be bale to hold the 8mmx8mm filter square</td>
		</tr>
		<tr height="59">
			<td height="59" style="height:59px;width:216px;">Spin Coater</td>
			<td style="width:101px;">Specialty Coating Systems</td>
			<td style="width:119px;">SCS G3 Spin Coater</td>
			<td>Instrument</td>
		</tr>
		<tr height="62">
			<td height="62" style="height:63px;width:216px;">Polyimide Tape</td>
			<td style="width:101px;">Uline</td>
			<td style="width:119px;">S-7595</td>
			<td style="width:167px;">Polyimide is the generic name for Kapton Tape which can be purchased form multiple vendors (Amazon, Kaptontape.com)</td>
		</tr>
		<tr height="47">
			<td height="47" style="height:47px;width:216px;">HBSS- Hank&#39;s Balanced Salt Solution</td>
			<td style="width:101px;">Gibco</td>
			<td style="width:119px;">14025-092</td>
			<td></td>
		</tr>
		<tr height="50">
			<td height="50" style="height:50px;width:216px;">1XPBS</td>
			<td style="width:101px;">Gibco</td>
			<td style="width:119px;">10010-023</td>
			<td></td>
		</tr>
		<tr height="189">
			<td height="189" style="height:189px;width:216px;">McCoy&#39;s</td>
			<td style="width:101px;">Gibco</td>
			<td style="width:119px;">16600-082</td>
			<td style="width:167px;">Warm in 37 &#8304;C water bath before use. McCoys was used for SKBr3 cells, if you use different cell lines or patient blood, please use media that would be optimal for that particular case</td>
		</tr>
		<tr height="74">
			<td height="74" style="height:74px;width:216px;">Falcon Petri dishes 35x10 mm</td>
			<td style="width:101px;">VWR</td>
			<td style="width:119px;">25373-041</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="87">
			<td height="87" style="height:87px;width:216px;">Microfilter Cassette</td>
			<td style="width:101px;">Circulogix Inc.</td>
			<td style="width:119px;">FC-01</td>
			<td style="width:167px;">Custom catridges are avilable based on filtration for CTC from blood or urine&#160;</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Syringe 20mL</td>
			<td style="width:101px;">BD Scientific</td>
			<td style="width:119px;">302830</td>
			<td></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Syringe Pump</td>
			<td style="width:101px;">KD scientific&#160;</td>
			<td style="width:119px;">78-0100V</td>
			<td style="width:167px;">Any syringe pump capable of holding a 25mL syringe may be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cellstar 50mL Centrifuge tube</td>
			<td style="width:101px;">VWR</td>
			<td style="width:119px;">82050-322</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Greiner Bio One 6 well plate</td>
			<td style="width:101px;">VWR</td>
			<td style="width:119px;">89131-688</td>
			<td style="width:167px;">Any brand can be used, as long as the surface is compatiable for cell adesion and not repellant</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">SKBR3 Cells</td>
			<td style="width:101px;">ATCC</td>
			<td style="width:119px;">HTB-30</td>
			<td></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Live Dead Assay</td>
			<td style="width:101px;">Life Technologies</td>
			<td style="width:119px;">L3224</td>
			<td style="width:167px;">Any assay that can provide a reasonable analysis to evaluate live cells will work</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Cell Culture Incubator</td>
			<td style="width:101px;">VWR</td>
			<td style="width:119px;">98000-368</td>
			<td style="width:167px;">Any incubator that can be used for cell culture will suffice</td>
		</tr>
	</tbody>
</table>

capture and release of viable circulating tumor cells from blood

We demonstrate a method for size based capture of viable circulating tumor cell (CTC) from whole blood, along with the release of these cells from chip for downstream analysis and/or culture. The strategy employs the use of a novel Parylene C membrane slot pore microfilter to capture CTC and a coating of poly (N-iso-propylacrylamide) (PIPAAm) for thermoresponsive viable release of the captured CTC. The capture of live cells is enabled by leveraging the design of a slot pore geometry with specific dimensions to reduce the shear stress typically associated with the filtration process. While the microfilter exhibits a high capture efficiency, the release of these cells is non-trivial. Typically, only a small percentage of cells are released when techniques such as reverse flow or cell scraping are used. The strong adhesion of these epithelial cancer cells to the Parylene C membrane is attributable to non-specific electrostatic interaction. To counteract this effect, we employed the use of PIPAAm coating and exploited its thermal responsive interfacial properties to release the cells from the filter. Blood is first filtered at room temperature. Below 32 &#176;C, PIPAAm is hydrophilic. Thereafter, the filter is placed in either culture media or a buffer maintained at 37 &#176;C, which results in the PIPAAm turning hydrophobic, and subsequently releasing the electrostatically bound cells.

Using healthy donors&#39; blood (obtained under a protocol approved by the University of Miami IRB 20150020 following an informed consent) spiked with cultured cancer cells, the thermoresponsive technique for release of viable circulating tumor cells (CTC),achieved capture, release and retrieval efficiency of 94% &#177; 9%, 82% &#177; 5% and 77% &#177; 5% respectively (Table 1)15. By comparison, the release and retrieval efficiency of uncoated filters were sign...

Watch this Scientific Journal Video about Capture and Release of Viable Circulating Tumor Cells from Blood at JoVE.com

Capture and Release of Viable Circulating Tumor Cells from Blood

A protocol to utilize a poly(N-iso-propylacrylamide) (PIPAAm) coated microfilter for effective capture and thermoresponsive release of viable circulating tumor cells (CTC) is presented. This method allows capture of CTC from patients&#39; blood and subsequent release of viable CTC for downstream off-chip culture, analyses and characterization.

We demonstrate a method for size based capture of viable circulating tumor cell (CTC) from whole blood, along with the release of these cells from chip ...

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Cancer Research

8.4K Views.  University of Miami. A protocol to utilize a poly(N-iso-propylacrylamide) (PIPAAm) coated microfilter for effective capture and thermoresponsive release of viable circulating tumor cells (CTC) is presented. This method allows capture of CTC from patients' blood and subsequent release of viable CTC for downstream off-chip culture, analyses and characterization.

Video: Capture and Release of Viable Circulating Tumor Cells from Blood

Isolation of Circulating Tumor Cells in an Orthotopic Mouse Model of Colorectal Cancer

Despite the advantages of easy applicability and cost-effectiveness, subcutaneous mouse models have severe limitations and do not accurately simulate tumor biology and tumor cell dissemination. Orthotopic mouse models have been introduced to overcome these limitations; however, such models are technically demanding, especially in hollow organs such as the large bowel. In order to produce uniform tumors which reliably grow and metastasize, standardized techniques of tumor cell preparation and injection are critical. 
We have developed an orthotopic mouse model of colorectal cancer (CRC) which develops highly uniform tumors and can be used for tumor biology studies as well as therapeutic trials. Tumor cells from either primary tumors, 2-dimensional (2D) cell lines or 3-dimensional (3D) organoids are injected into the cecum and, depending on the metastatic potential of the injected tumor cells, form highly metastatic tumors. In addition, CTCs can be found regularly. We here describe the technique of tumor cell preparation from both 2D cell lines and 3D organoids as well as primary tumor tissue, the surgical and injection techniques as well as the isolation of CTCs from the tumor-bearing mice, and present tips for troubleshooting.

We describe the establishment of orthotopic colorectal tumors via injection of tumor cells or organoids into the cecum of mice and the subsequent isolation of circulating tumor cells (CTCs) from this model.

Despite the advantages of easy applicability and cost-effectiveness, subcutaneous mouse models have severe limitations and do not accurately simulate ...

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 ...

Characterization of Tumor Cells Using a Medical Wire for Capturing Circulating Tumor Cells: A 3D Approach Based on Immunofluorescence and DNA FISH

Circulating tumor cells (CTCs) are associated with poor survival in metastatic cancer. Their identification, phenotyping, and genotyping could lead to a better understanding of tumor heterogeneity and thus facilitate the selection of patients for personalized treatment. However, this is hampered because of the rarity of CTCs. We present an innovative approach for sampling a high volume of the patient blood and obtaining information about presence, phenotype, and gene translocation of CTCs. The method combines immunofluorescence staining and DNA fluorescent-in-situ-hybridization (DNA FISH) and is based on a functionalized medical wire. This wire is an innovative device that permits the in vivo isolation of CTCs from a large volume of peripheral blood. The blood volume screened by a 30-min administration of the wire is approximately 1.5-3 L. To demonstrate the feasibility of this approach, epithelial cell adhesion molecule (EpCAM) expression and the chromosomal translocation of the ALK gene were determined in non-small-cell lung cancer (NSCLC) cell lines captured by the functionalized wire and stained with an immuno-DNA FISH approach. Our main challenge was to perform the assay on a 3D structure, the functionalized wire, and to determine immuno-phenotype and FISH signals on this support using a conventional fluorescence microscope. The results obtained indicate that catching CTCs and analyzing their phenotype and chromosomal rearrangement could potentially represent a new companion diagnostic approach and provide an innovative strategy for improving personalized cancer treatments.

We present a new approach to characterize tumor cells. We combined immunofluorescence with DNA fluorescent-in-situ-hybridization to evaluate cells captured by a functionalized medical wire capable of in vivo enriching CTCs directly from patient blood.

Circulating tumor cells (CTCs) are associated with poor survival in metastatic cancer. Their identification, phenotyping, and genotyping could lead to a ...

Isolation and Characterization of Tumor-initiating Cells from Sarcoma Patient-derived Xenografts

The existence and importance of tumor-initiating cells (TICs) have been supported by increasing evidence during the past decade. These TICs have been shown to be responsible for tumor initiation, metastasis, and drug resistance. Therefore, it is important to develop specific TIC-targeting therapy in addition to current chemotherapy strategies, which mostly focus on the bulk of non-TICs. In order to further understand the mechanism behind the malignancy of TICs, we describe a method to isolate and to characterize TICs in human sarcomas. Herein, we show a detailed protocol to generate patient-derived xenografts (PDXs) of human sarcomas and to isolate TICs by fluorescence-activated cell sorting (FACS) using human leukocyte antigen class I (HLA-1) as a negative marker. Also, we describe how to functionally characterize these TICs, including a sphere formation assay and a tumor formation assay, and to induce differentiation along mesenchymal pathways. The isolation and characterization of PDX TICs provide clues for the discovery of potential targeting therapy reagents. Moreover, increasing evidence suggests that this protocol may be further extended to isolate and characterize TICs from other types of human cancers.

We describe a detailed protocol for the isolation of tumor-initiating cells from human sarcoma patient-derived xenografts by fluorescence-activated cell sorting, using human leukocyte antigen-1 (HLA-1) as a negative marker, and for the further validation and characterization of these HLA-1-negative tumor-initiating cells.

The existence and importance of tumor-initiating cells (TICs) have been supported by increasing evidence during the past decade. These TICs have been ...

Investigation of Genetic Dependencies Using CRISPR-Cas9-based Competition Assays

Gene perturbation studies have been extensively used to investigate the role of individual genes in AML pathogenesis. For achieving complete gene disruption, many of these studies have made use of complex gene knockout models. While these studies with knockout mice offer an elegant and time-tested system for investigating genotype-to-phenotype relationships, a rapid and scalable method for assessing candidate genes that play a role in AML cell proliferation or survival in AML models will help accelerate the parallel interrogation of multiple candidate genes. Recent advances in genome-editing technologies have dramatically enhanced our ability to perform genetic perturbations at an unprecedented scale. One such system of genome editing is the CRISPR-Cas9-based method that can be used to make rapid and efficacious alterations in the target cell genome. The ease and scalability of CRISPR/Cas9-mediated gene-deletion makes it one of the most attractive techniques for the interrogation of a large number of genes in phenotypic assays. Here, we present a simple assay using CRISPR/Cas9 mediated gene-disruption combined with high-throughput flow-cytometry-based competition assays to investigate the role of genes that may play an important role in the proliferation or survival of human and murine AML cell lines.

This manuscript describes a Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) CRISPR-Cas9-based method for simple and expeditious investigation of the role of multiple candidate genes in Acute Myeloid Leukemia (AML) cell proliferation in parallel. This technique is scalable and can be applied in other cancer cell lines as well.

Gene perturbation studies have been extensively used to investigate the role of individual genes in AML pathogenesis. For achieving complete gene ...

Mesenchymal Stem Cell Isolation from Pulp Tissue and Co-Culture with Cancer Cells to Study Their Interactions

Cancer as a multistep process and complicated disease is not only regulated by individual cell proliferation and growth but also controlled by tumor environment and cell-cell interactions. Identification of cancer and stem cell interactions, including changes in extracellular environment, physical interactions, and secreted factors, might enable the discovery of new therapy options. We combine known co-culture techniques to create a model system for mesenchymal stem cells (MSCs) and cancer cell interactions. In the current study, dental pulp stem cells (DPSCs) and PC-3 prostate cancer cell interactions were examined by direct and indirect co-culture techniques. Condition medium (CM) obtained from DPSCs and 0.4 &#181;m pore sized trans-well membranes were used to study paracrine activity. Co-culture of different cell types together was performed to study direct cell-cell interaction. The results revealed that CM increased cell proliferation and decreased apoptosis in prostate cancer cell cultures. Both CM and trans-well system increased cell migration capacity of PC-3 cells. Cells stained with different membrane dyes were seeded into the same culture vessels, and DPSCs participated in a self-organized structure with PC-3 cells under this direct co-culture condition. Overall, the results indicated that co-culture techniques could be useful for cancer and MSC interactions as a model system.

We provide protocols for evaluation of mesenchymal stem cells isolated from dental pulp and prostate cancer cell interactions based on direct and indirect co-culture methods. Condition medium and trans-well membranes are suitable to analyze indirect paracrine activity. Seeding differentially stained cells together is an appropriate model for direct cell-cell interaction.

Cancer as a multistep process and complicated disease is not only regulated by individual cell proliferation and growth but also controlled by tumor ...

Flow Cytometric Analysis of Mitochondrial Reactive Oxygen Species in Murine Hematopoietic Stem and Progenitor Cells and MLL-AF9 Driven Leukemia

We present a flow cytometric approach for analyzing mitochondrial ROS in various live bone marrow (BM)-derived stem and progenitor cell populations from healthy mice as well as mice with AML driven by MLL-AF9. Specifically, we describe a two-step cell staining process, whereby healthy or leukemia BM cells are first stained with a fluorogenic dye that detects mitochondrial superoxides, followed by staining with fluorochrome-linked monoclonal antibodies that are used to distinguish various healthy and malignant hematopoietic progenitor populations. We also provide a strategy for acquiring and analyzing the samples by flow cytometry. The entire protocol can be carried out in a timeframe as short as 3-4 h. We also highlight the key variables to consider as well as the advantages and limitations of monitoring ROS production in the mitochondrial compartment of live hematopoietic and leukemia stem and progenitor subpopulations using fluorogenic dyes by flow cytometry. Furthermore, we present data that mitochondrial ROS abundance varies among distinct healthy HSPC sub-populations and leukemia progenitors and discuss the possible applications of this technique in hematologic research.

We describe a method for using multiparameter flow cytometry to detect mitochondrial reactive oxygen species (ROS) in murine healthy hematopoietic stem and progenitor cells (HSPCs) and leukemia cells from a mouse model of acute myeloid leukemia (AML) driven by MLL-AF9.

We present a flow cytometric approach for analyzing mitochondrial ROS in various live bone marrow (BM)-derived stem and progenitor cell populations from ...

Micromanipulation of Circulating Tumor Cells for Downstream Molecular Analysis and Metastatic Potential Assessment

Blood-borne metastasis accounts for&#160;most cancer-related deaths and involves circulating tumor cells (CTCs) that are successful in establishing new tumors at distant sites. CTCs are found in the bloodstream of patients as single cells (single CTCs) or as multicellular aggregates (CTC clusters and CTC-white blood cell clusters), with the latter displaying a higher metastatic ability. Beyond enumeration, phenotypic and molecular analysis is extraordinarily important to dissect CTC biology and to identify actionable vulnerabilities. Here, we provide a detailed description of a workflow that includes CTC immunostaining and micromanipulation, ex vivo culture to assess&#160;proliferative and survival capabilities of individual cells, and in vivo metastasis-formation assays. Additionally, we provide a protocol to achieve the dissociation of CTC clusters into individual cells and the investigation of intra-cluster heterogeneity. With these approaches, for instance, we precisely quantify survival and proliferative potential of single CTCs and individual cells within CTC clusters, leading us to the observation that cells within clusters display better survival and proliferation in ex vivo cultures compared to single CTCs. Overall, our workflow offers a platform to dissect the characteristics of CTCs at the single cell level, aiming towards the identification of metastasis-relevant pathways and a better understanding of CTC biology.

Here, we present an integrated workflow to identify phenotypic and molecular features that characterize circulating tumor cells (CTCs). We combine live immunostaining and robotic micromanipulation of single and clustered CTCs with single cell-based techniques for downstream analysis and assessment of metastasis-seeding ability.

Blood-borne metastasis accounts for&#160;most cancer-related deaths and involves circulating tumor cells (CTCs) that are successful in establishing new ...

Detection and Monitoring of Tumor Associated Circulating DNA in Patient Biofluids

Complications associated with upfront and repeat surgical tissue sampling present the need for minimally invasive platforms capable of molecular sub-classification and temporal monitoring of tumor response to therapy. Here, we describe our dPCR-based method for the detection of tumor somatic mutations in cell free DNA (cfDNA), readily available in&#160;patient biofluids. Although limited in the number of mutations that can be tested for in each assay, this method provides a high level of sensitivity and specificity. Monitoring of mutation abundance, as calculated by MAF, allows for the evaluation of tumor response to therapy, thereby providing a much-needed supplement to radiographic imaging.

Here, we present a protocol to detect tumor somatic mutations in circulating DNA present in patient biological fluids (biofluids). Our droplet digital polymerase chain reaction (dPCR)-based method enables quantification of the tumor mutation allelic frequency (MAF), facilitating a minimally invasive complement to diagnosis and temporal monitoring of tumor response.

Complications associated with upfront and repeat surgical tissue sampling present the need for minimally invasive platforms capable of molecular ...

Semi-automatic PD-L1 Characterization and Enumeration of Circulating Tumor Cells from Non-small Cell Lung Cancer Patients by Immunofluorescence

Circulating tumor cells (CTCs) derived from the primary tumor are shed into the bloodstream or lymphatic system. These rare cells (1&#8722;10 cells per mL of blood) warrant a poor prognosis and are correlated with shorter overall survival in several cancers (e.g., breast, prostate and colorectal). Currently, the anti-EpCAM-coated magnetic bead-based CTC capturing system is the gold standard test approved by the U.S. Food and Drug Administration (FDA) for enumerating CTCs in the bloodstream. This test is based on the use of magnetic beads coated with anti-EpCAM markers, which specifically target epithelial cancer cells. Many studies have illustrated that EpCAM is not the optimal marker for CTC detection. Indeed, CTCs are a heterogeneous subpopulation of cancer cells and are able to undergo an epithelial-to-mesenchymal transition (EMT) associated with metastatic proliferation and invasion. These CTCs are able to reduce the expression of cell surface epithelial marker EpCAM, while increasing mesenchymal markers such as vimentin. To address this technical hurdle, other isolation methods based on physical properties of CTCs have been developed. Microfluidic technologies enable a label-free approach to CTC enrichment from whole blood samples. The spiral microfluidic technology uses the inertial and Dean drag forces with continuous flow in curved channels generated within a spiral microfluidic chip. The cells are separated based on the differences in size and plasticity between normal blood cells and tumoral cells. This protocol details the different steps to characterize the programmed death-ligand 1 (PD-L1) expression of CTCs, combining a spiral microfluidic device with customizable immunofluorescence (IF) marker set.

The characterization of circulating tumor cells (CTCs) is a popular topic in translational research. This protocol describes a semi-automatic immunofluorescence (IF) assay for PD-L1 characterization and enumeration of CTCs in non-small cell lung cancer (NSCLC) patient samples.

Circulating tumor cells (CTCs) derived from the primary tumor are shed into the bloodstream or lymphatic system. These rare cells (1&#8722;10 cells per mL ...