We thank all residents and attending physicians, notably Dr. A.F. Haney (the University of Chicago, Department of Obstetrics and Gynecology) for collecting omental biopsies. Also, we thank Stacey Tobin and Gail Isenberg for carefully editing this manuscript. This work was supported by Bears Care, the charitable beneficiary of the Chicago Bears Football Club, the National Institute of Neurological Disorders and Stroke (NINDS) R21 NS075702, and the National Cancer Institute grant R01 CA111882 to E.L.

All research protocols described have been reviewed by the University of Chicago Institutional Review Board (IRB). Informed consent was obtained from each patient before surgery and the study was approved by the University of Chicago IRB. A biological safety cabinet type 2 and gloves should be used when handling human tissue for protection and to reduce risk of contaminating cells.
1. Isolation and Culture of Primary Untransformed Stromal Cells
<ol>
	<li>Human tissue collection and preparation.
	<ol>
		<li>Obtain specimens of human omentum, 2 cm3, removed during an abdominal surgery, and immediately immerse tissue in RT phosphate-buffered saline (PBS) (Figure 2A). A piece of omentum 3 cm x 2 cm typically yields 1 million primary human mesothelial cells (HPMC) and 200,000 primary human fibroblasts or normal omental fibroblasts (NOF).</li>
		<li>Spin down the PBS the tissue was immersed in at 0.5 x g for 3 min&#160;as soon as possible after collection (&#60; 2 hr in PBS) and transfer the tissue to fresh 20 ml PBS in a 50 ml conical tube. Cut up tissue into 5mm3 pieces by mincing with scalpels in a 15 cm diameter, sterile culture dish (Figure 2B).</li>
	</ol>
	</li>
	<li>Primary human mesothelial cell isolation8
	<ol>
		<li>To isolate HPMC, transfer the minced tissue into 50 ml conical tubes and wait 1 min&#160;for the solid pieces to float to the top (Figure 2C &#38; D). HPMC and red blood cells (RBC) will be present in the liquid on the bottom. Use a pipet to remove the liquid from the bottom of the tube and into a new conical tube. Spin the liquid down at 0.5 x g for 3 min&#160;and aspirate the supernatant from the HPMC/RBC pellet.
		<ol>
			<li>Repeat the process three times: add 20 ml PBS to the minced tissue, allow tissue to rise, remove liquid from the bottom with a pipette and into the HPMC/RBC tube, spin down, and remove the supernatant. After all spins are completed and the supernatant is aspirated, the pellet will contain HPMC and RBC.</li>
		</ol>
		</li>
		<li>Plate all cells from the pellet into a 75 cm2 flask in 15 ml of full growth media (DMEM with 10% fetal bovine serum [FBS],1% MEM vitamins [93 mg/L], 1% MEM nonessential amino acids [81.4 mg/L], 1% penicillin streptomycin [Pen-Strep, 100 U/ml penicillin and 100 &#181;g/ml streptomycin]).</li>
		<li>Perform a secondary PBS wash to isolate additional HPMCs.
		<ol>
			<li>For the secondary PBS wash, shake the remaining solid tissue at 200 rpm, 37 &#176;C for 10 min&#160;in 20 ml of PBS, then wait 1 min&#160;for the tissue to float to the top. Remove the liquid from the bottom of the tube into a new tube, centrifuge at 0.5 x g for 3 min, and aspirate the supernatant.</li>
			<li>Plate all the HPMC/RBC from the secondary PBS wash in a separate 75 cm2 flask in 15 ml of full growth media.</li>
		</ol>
		</li>
		<li>To isolate any remaining HPMC, shake the minced tissue at 200 rpm, 37 &#176;C degrees for 10 min&#160;in 20 ml of a 1:1 0.25% trypsin 25 mM EDTA:PBS solution by volume. Allow the tissue to rise, collect the liquid at the bottom of the tube into a new 50 ml tube, and spin down at 0.5 g x 3 min.
		<ol>
			<li>Aspirate the supernatant and plate all the HPMC/RBC in a separate 75 cm2 flask in 15 ml of full growth media.</li>
		</ol>
		</li>
		<li>Culture the plated cells at 37&#176;C and 5% CO2 in a humidified environment. Feed plated cells by adding 15 ml of full growth media on days 3 and 5 without removing the spent media. HPMC can be cultured for 5-7 days before splitting.
		<ol>
			<li>Use low-passage HPMC (up to passage 2) in all experiments to minimize dedifferentiation and modification of original phenotype. Use a wide-field microscope preferably with a 20x objective with plastic differential interference contrast capabilities or 4-20x objective with phase contrast capabilities (phase contrast filters on microscope) for taking all images of cells, and a 10x objective ()in bright field to analyze immunohistochemical 3,3&#39;-Diaminobenzidine (DAB) staining.</li>
		</ol>
		</li>
		<li>Confirm that the HPMC are cuboidal and express cytokeratin 8 and vimentin by performing immunohistochemistry8 (Figure 3A, C, E).</li>
	</ol>
	</li>
	<li>NOF isolation8
	<ol>
		<li>Prepare 10 ml of a stock of collagenase type III solution (10x) by combining a 1:1:1 mixture of 100x Pen-Strep: 1,500 units activity/ml of collagenase type III: 714 units activity/ml of hyaluronidase in PBS.</li>
		<li>Shake the minced omentum tissue that remains after HPMC isolation at 200 rpm, 37 &#176;C for 6 hr in 10 ml of the 10x collagenase type III solution diluted in serum-free media (DMEM with 1% MEM vitamins [93 mg/L], 1% MEM nonessential amino acids [81.4 mg/L], 1% penicillin streptomycin [Pen-Strep, 100 U/ml penicillin and 100 &#181;g/ml streptomycin]). Digested tissue will look opaque and may have some fibrous debris (Figure 2E).</li>
		<li>Centrifuge the solution containing NOF cells in suspension at 0.5 x g for 3 min&#160;at RT, aspirate the supernatant and plate the pellet in a 75 cm2 flask in 13 ml of full growth media.</li>
		<li>Remove old media and replace with 15 ml of fresh full growth media after 24 hr. NOF can be cultured for 1-3 days before splitting. Note proliferation of the NOF will cease when the cells reach confluency.</li>
		<li>Confirm that the primary human fibroblasts are flat, elongated cells and express vimentin but not cytokeratin 8 by performing immunohistochemistry8 (Figure 3B, D, F). Use low-passage NOF for experiments (ideally before passage 3) to minimize dedifferentiation and modification of original phenotype. Use a wide-field microscope with a 20x objective with plastic DIC capabilities for taking all phase images of cells, and a 10x objective in bright field to analyze immunohistochemical DAB staining.</li>
	</ol>
	</li>
</ol>
2. Plating the Organotypic Culture8
<ol>
	<li>Release NOF from the 75 cm culture flask by rinsing with 10 ml of PBS followed by 3 ml of 0.25% trypsin/25 mM EDTA for no more than 5 min. Neutralize trypsin with at least 3 times the volume of full growth media.</li>
	<li>Transfer trypsinized cells into a 50 ml conical tube and spin down at 0.5 g x 3 min. Remove supernatant and bring cells back up in 5 ml of full growth media. Use a cell counter to count the cells recovered from the culture flask.</li>
	<li>Dilute cells in the appropriate volume of full growth media to plate 2,000-4,000 NOF per 100 &#181;l onto a black, clear-bottomed, 96-well plate. Add 0.5 &#181;g/100 &#181;l of rat-tail collagen I to the cell mixture before plating. Let cells sit at 37 &#176;C in 5% CO2 in a humidified environment for at least 4 hr, or until the cells to adhere to the plate surface.</li>
	<li>Release HPMC from the culture flask using the same methods described in steps 2.1 and 2.2. Dilute cells in the appropriate amount of full growth media to plate 10,000-20,000 HPMC per 50 &#181;l on top of the NOF already plated with collagen I in 96-well plates. Let the cells sit at 37 &#176;C in 5% CO2 in a humidified environment for at least 18 hr before beginning experiments.</li>
	<li>Culture green fluorescent protein (GFP)-expressing HeyA8 ovarian cancer cells in full growth media. HeyA8 ovarian cancer cells are fluorescently labeled by expression of a lentiviral vector expressing copepod cGFP (pCDH-CMV-MCS-EF1). HeyA8 ovarian cancer cells should be 80-90% confluent on the day of use (logarithmic growth phase). Release cells from the culture plate and count using the same methods described in steps 2.1-2.2 for primary cells.</li>
	<li>Allow ovarian cancer cells to recover in full growth media for 15-20 min&#160;at 37&#176;C in a conical tube with the lid loosely sealed.</li>
</ol>
3. Adhesion Assay8
<ol>
	<li>After recovery, pellet the ovarian cancer cells by spinning for 3 min&#160;at 0.5 x g and then remove the supernatant and dilute the cells in the appropriate volume of serum-free media to achieve a concentration of 50,000 cells/100 &#181;l.</li>
	<li>Invert the 96-well plates with the HPMC/NOF organotypic cultures to remove spent media, and add 100 &#181;l of the cancer cell suspension in serum-free media to each well. Incubate the plate at 37 &#176;C in 5% CO2 in a humidified environment for 30 min&#160;to 4 hr.</li>
	<li>Invert the 96-well plate to remove media and non-adherent cells. Use a multichannel pipet at low power to carefully and gently pipet 100 &#181;l of PBS into each well, and invert plate again. Repeat the PBS wash once more.</li>
	<li>Invert to remove PBS and add 100 &#181;l 4% paraformaldehyde to each well. Allow the plate to sit for 20 min&#160;to fix the cells. After 20 min, invert the plate and add 100 &#181;l PBS.</li>
	<li>Note that the total fluorescence of wells can be reported or the number of cells can be quantified. For quantification, first plate a standard curve in duplicate using HeyA8 cells at a concentration of 1 million cells/ml.
	<ol>
		<li>Make the standard curve by spinning down 1 million cells, removing media, and allowing them to sit in 1 ml 4% paraformaldehyde for 20 min.</li>
		<li>Spin cells again and bring up in 1 ml PBS (recount cells to confirm 1 million/ml concentration). Plate 50,000, 40,000, 30,000, 20,000, 10,000, 5000, 1,000, and 0 cells into each well in duplicate, and add PBS for a final total volume of 50 &#181;l in each well.</li>
	</ol>
	</li>
	<li>Bottom read the culture plate on a fluorescent plate reader (excitation = 488 nm, emission = 528 nm), scaling high wells (50,000 on standard curve). Use the standard curve to calculate how many ovarian cancer cells adhered to the organotypic culture in each well (Figure 4A-C).</li>
</ol>
4. Proliferation Assay10
<ol>
	<li>After the ovarian cancer cells recover (see steps 2.5 and 2.6 above), pellet the cells by spinning for 3 min&#160;at 0.5 x g and then dilute the cells in the appropriate volume of 1% FBS media (DMEM with 1% FBS, 1% MEM vitamins [93 mg/L], 1% MEM nonessential amino acids [81.4 mg/L], 1% penicillin streptomycin [Pen-Strep, 100 U/ml penicillin and 100 &#181;g/ml streptomycin]) to achieve a concentration of 4,000 cells/150 &#181;l.</li>
	<li>Invert the 96-well plate with the HPMC/NOF organotypic cultures to remove spent media, and add 150 &#181;l of the cancer cell suspension in 1% FBS media to each well. Incubate the plate at 37&#176;C in 5% CO2 in a humidified environment for 72 hr.</li>
	<li>Bottom read the culture plate on a fluorescent plate reader once a day (excitation = 488 nm, emission = 528 nm) to evaluate the relative proliferation of cells. Continue the assay for 96 hr, changing the media at 48 hr (Figure 5A-C). Be careful not to disturb the culture when changing media (inverting the plate is preferable).</li>
</ol>
5. Invasion Assay8
<ol>
	<li>Before plating the 3D culture, add 7.5 &#181;g rat-tail collagen I in 200 &#181;l PBS to a 24-well culture plate insert (8 &#181;m pore size). Let the plate incubate O/N, then carefully remove the PBS with a pipet immediately before plating the HPMC/NOF organotypic culture onto the collagen-coated inserts (step 2, above).</li>
	<li>Prepare the ovarian cancer cells as in step 3.1. To plate the ovarian cancer cells onto the organotypic cultures on the inserts, carefully use a pipet to remove excess media from the top of the inserts. Add 100 &#181;l of the ovarian cancer cell suspension in serum-free media to each well.</li>
	<li>Add 750 &#181;l of full growth media into the well below the insert to induce cancer cell invasion into the organotypic cultures. Incubate the plate at 37 &#176;C in 5% CO2 in a humidified environment for 24 hr. 
	Note: Ovarian cancer cells that invade the organotypic culture will cross the insert and remain on the bottom side of the insert.</li>
	<li>After 24 hr, grasp the insert with tongs and briefly rinse it in a beaker of PBS, then move the insert into an empty well. Scrub the top of each insert with both sides of a cotton swab for a total of 1 min. Quickly place the insert into a plate containing 750 &#181;l 4% paraformaldehyde in each well. Allow each insert to sit in paraformaldehyde for 10 min&#160;before transferring the inserts into wells filled with 750 &#181;l PBS.</li>
	<li>View the invaded cells (adhered and fixed to the bottom of inserts) with a microscope at 2.5x magnification. When the entire well is within the field of view, adjust the magnification to 10x and take 5 pictures, one near the center and 1 in each quadrant of the well, avoiding taking images that are too close to the edges. Follow the same pattern for each well.</li>
	<li>Use the manufacturer&#39;s program to count the number of cells in each image to get an average number of cells invaded per field in each well (Figure 6A-C) according to their protocol.</li>
</ol>

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K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ligand-independent+activation+of+c-Met+by+fibronectin+and+&#945;(5)&#946;(1)-integrin+regulates+ovarian+cancer+invasion+and+metastasis.">Ligand-independent activation of c-Met by fibronectin and &#945;(5)&#946;(1)-integrin regulates ovarian cancer invasion and metastasis.</a> Oncogene. 30, 1566-1576 (2011).</li></ol>

The authors have nothing to disclose.

An organotypic model of the peritoneal microenvironment was established to assess the individual and collective function(s) of both the cellular and innate components of the microenvironment in ovarian cancer dissemination. The specific protocols for plating and customizing the 3D organotypic culture to investigate ovarian cancer cell adhesion, proliferation, and invasion are provided. Primary human omental mesothelial cells and fibroblasts were isolated from patients and used at an early passage to preserve normal morph...

Ovarian cancer is the deadliest gynecologic malignancy1. The majority of patients are diagnosed after the cancer has disseminated throughout the peritoneal cavity. Once the cancer has spread throughout the peritoneal cavity, cytoreductive surgery and chemotherapy are often not sufficient treatment to prevent cancer recurrence and chemoresistance, resulting in a less than 30% 5-year survival rate. Ovarian cancer metastasis is predominantly limited to the peritoneal cavity, and several other cancer types, including gastric, pancreatic, and colon cancers, metastasize to the same anatomic sites in the peritoneal cavity. In general, ovarian cancer cells detach from the in situ carcinoma in the fallopian tube or the primary ovarian tumor, travel in peritoneal fluid as single cells or spheroids, and attach to mesothelium-lined surfaces of the omentum, bowel, and abdominal wall2. 
The tumor microenvironment plays an important role in disease progression and chemoresistance in many cancers3-6. The peritoneal cavity is a unique microenvironment, with a mesothelial cell monolayer covering the majority of surfaces (Figure 1A)7. The mesothelial lining acts as a barrier that creates a low-friction surface, which tends to be protective against cancer cell adhesion8. Immediately underneath this mesothelial-lined surface is a layer made predominantly of fibroblasts and extracellular matrix (ECM), which promote cancer cell adhesion and invasion8. Ovarian cancer cells secrete factors that induce changes in the mesothelial cell lining that enhance ovarian cancer cell adhesion, invasion, and metastasis9,10. Ovarian cancer cells adhere to the mesothelial surface via integrin and CD44-mediated mechanisms (Figure 1B)11-16. 
Historically, several 3D models have been developed to investigate ovarian cancer interactions with the microenvironment. Some of the first models studied ovarian cancer-ECM interface17-21, ovarian cancer-mesothelial cell communication13,14,21-24, or both25 (reviewed by us 26). Niedbala et al. discovered that ovarian cancer cells display a quicker and firmer adhesion to ECM than to mesothelial cells or to plastic alone25. However, these models did not histologically resemble the peritoneal microenvironment. Therefore, we established a 3D organotypic model to more thoroughly replicate the ovarian cancer microenvironment. In order to better understand the role of the microenvironment and the interaction between cancer and peritoneal cells in the peritoneal dissemination of ovarian cancer, we have developed a 3D organotypic in vitro culture model of the peritoneal cavity lining (schematic in Figure 1C). The proposed model is composed of primary human fibroblasts and ECM, covered with a layer of primary human mesothelial cells-each cell type is isolated from human omentum. Histologically, this model resembles the normal peritoneal or omental lining, and provides a surface on which we can study the tumor microenvironment, the interaction between cancer cells and normal tissue, and the processes of cancer cell adhesion, invasion, and proliferation8.

<table>
	<tbody>
		<tr>
			<td>1. Isolation and culture of primary cells</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Fisher Scientific</td>
			<td>SH3001304</td>
			<td></td>
		</tr>
		<tr>
			<td>Single-edged razor blades</td>
			<td>Fisher Scientific</td>
			<td>12-640</td>
			<td></td>
		</tr>
		<tr>
			<td>15 cm culture dishes</td>
			<td>BD Biosciences</td>
			<td>353025</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass flask</td>
			<td>?</td>
			<td>?</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Life Technologies</td>
			<td>16000044_3616914956</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM with L-Glutamine</td>
			<td>Corning</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Vitamins</td>
			<td>Corning</td>
			<td>25-020-Cl</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Nonessential amino acids</td>
			<td>Corning</td>
			<td>25-025-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Corning</td>
			<td>30-002-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Shaker&#160;</td>
			<td>Thermo-Fisher</td>
			<td>MaxQ 4450</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5702</td>
			<td></td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Thermo-Fisher</td>
			<td>Forma Series II Water Jacketed CO2 Incubator Model 3100</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin EDTA, 1x (0.25%)</td>
			<td>Corning</td>
			<td>25-053-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Hyaluronidase</td>
			<td>Worthington Biochemical</td>
			<td>LS002592</td>
			<td></td>
		</tr>
		<tr>
			<td>T-75 Flasks</td>
			<td>BD Biosciences</td>
			<td>353136</td>
			<td></td>
		</tr>
		<tr>
			<td>T-175 Flasks</td>
			<td>BD Biosciences</td>
			<td>353112</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipet tips</td>
			<td>Rainin</td>
			<td>P2, P10, P20, P200 and P1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipet tips</td>
			<td>Corning</td>
			<td>Filtered tips P2, P10, P20, P200 and P1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Name of Reagent/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>2. Plating 3D culture</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Counter</td>
			<td>Invitrogen</td>
			<td>Countess</td>
			<td></td>
		</tr>
		<tr>
			<td>Countess Cell Counting Chamber Slides</td>
			<td>Invitrogen</td>
			<td>C10313</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue Stain (0.4%)</td>
			<td>Gibco</td>
			<td>15250-061</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagen Type I (Rat Tail)</td>
			<td>BD Biosciences</td>
			<td>354236</td>
			<td></td>
		</tr>
		<tr>
			<td>96 well plate, clear bottom, black</td>
			<td>BD Biosciences</td>
			<td>353219</td>
			<td></td>
		</tr>
		<tr>
			<td>Name of Reagent/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>3. Adhesion assay</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Multichannel pipet</td>
			<td>Eppendorf</td>
			<td>Xplorer 300</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde solution 4% in PBS</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-281692</td>
			<td></td>
		</tr>
		<tr>
			<td>Plate reader</td>
			<td>Molecular Devices</td>
			<td>Minimax</td>
			<td></td>
		</tr>
		<tr>
			<td>Name of Reagent/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>5. Invasion assay</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Culture Inserts (8um, 24-well)</td>
			<td>BD Biosciences</td>
			<td>353097</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton swabs</td>
			<td>Q-tips</td>
			<td>cotton swabs</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Zeiss</td>
			<td>Axiovert 200m</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Profiler</td>
			<td>public domain</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>24 well plate</td>
			<td>BD Biosciences</td>
			<td>353047</td>
			<td></td>
		</tr>
		<tr>
			<td>Name of Reagent/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>6. Antibodies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Integrin &#945;V&#946;3 Antibody, clone LM609</td>
			<td>EMD Millipore</td>
			<td>MAB1976</td>
			<td></td>
		</tr>
		<tr>
			<td>Beta 1&#160;</td>
			<td>Oncosynergy</td>
			<td>OS2966</td>
			<td></td>
		</tr>
		<tr>
			<td>Alpha 5 [CD49e]</td>
			<td>ID Pharmingen</td>
			<td>555615</td>
			<td></td>
		</tr>
		<tr>
			<td>Beta 4 [CD104]</td>
			<td>EMD Millipore</td>
			<td>MAB 2058</td>
			<td></td>
		</tr>
	</tbody>
</table>

modeling the early steps of ovarian cancer dissemination in an organotypic culture of the human peritoneal cavity

The pattern of ovarian cancer metastasis is markedly different from that of most other epithelial tumors, because it rarely spreads hematogenously. Instead, ovarian cancer cells exfoliated from the primary tumor are carried by peritoneal fluid to metastatic sites within the peritoneal cavity. These sites, most notably the abdominal peritoneum and omentum, are organs covered by a mesothelium-lined surface. To investigate the processes of ovarian cancer dissemination, we assembled a complex three-dimensional culture system that reconstructs the lining of the peritoneal cavity in vitro. Primary human fibroblasts and mesothelial cells were isolated from human omentum. The fibroblasts were then mixed with extracellular matrix and covered with a layer of the primary human mesothelial cells to mimic the peritoneal and omental surfaces encountered by metastasizing ovarian cancer cells. The resulting organotypic model is, as shown, used to examine the early steps of ovarian cancer dissemination, including cancer cell adhesion, invasion, and proliferation. This model has been used in a number of studies to investigate the role of the microenvironment (cellular and acellular) in early ovarian cancer dissemination. It has also been successfully adapted to high throughput screening and used to identify and test inhibitors of ovarian cancer metastasis.

The organotypic culture was assembled by first mixing primary human fibroblasts with collagen type I and then overlaying this culture with 5 times the number of mesothelial cells. The culture was incubated for at least 18 hr&#160;before ovarian cancer cells were added to study adhesion, invasion or proliferation. Each assay was repeated with multiple (n=3-5) 3D cultures obtained from different patients and numerous wells were tested in each condition for the adhesion (n=5), proliferation (n=5) and invasion assays (n=3). ...

Watch this Scientific Journal Video about Modeling the Early Steps of Ovarian Cancer Dissemination in an Organotypic Culture of the Human Peritoneal Cavity at JoVE.com

Modeling the Early Steps of Ovarian Cancer Dissemination in an Organotypic Culture of the Human Peritoneal Cavity

Here, we present a protocol to construct a three-dimensional in vitro model of the lining of the peritoneal cavity, composed of primary human mesothelial cells and fibroblasts layered with extracellular matrix, as a tool to investigate ovarian cancer cell adhesion, invasion, and proliferation.

The pattern of ovarian cancer metastasis is markedly different from that of most other epithelial tumors, because it rarely spreads hematogenously. ...

modeling-early-steps-ovarian-cancer-dissemination-an-organotypic

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JoVE Journal

Medicine

26.5K vistas.  University of Chicago. Here, we present a protocol to construct a three-dimensional in vitro model of the lining of the peritoneal cavity, composed of primary human mesothelial cells and fibroblasts layered with extracellular matrix, as a tool to investigate ovarian cancer cell adhesion, invasion, and proliferation. 

Video: Modeling the Early Steps of Ovarian Cancer Dissemination in an Organotypic Culture of the Human Peritoneal Cavity

Modeling and Imaging 3-Dimensional Collective Cell Invasion

A defining characteristic of cancer malignancy is invasion and metastasis 1. In some cancers (e.g. glioma 2), local invasion into surrounding healthy tissue is the root cause of disease and death. For other cancers (e.g. breast, lung, etc.), it is the process of metastasis, in which tumor cells move from a primary tumor mass, colonize distal sites and ultimately contribute to organ failure, that eventually leads to morbidity and mortality 3. It has been estimated that invasion and metastasis are responsible for 90&#37; of cancer deaths 4. As a result, there has been intense interest in identifying the molecular processes and critical protein mediators of invasion and metastasis for the purposes of improving diagnosis and treatment 5.
A challenge for cancer scientists is to develop invasion assays that sufficiently resemble the in vivo situation to enable accurate disease modeling 6. Two-dimensional cell motility assays are only informative about one aspect of invasion and do not take into account extracellular matrix (ECM) protein remodeling which is also a critical element. Recently, research has refined our understanding of tumor cell invasion and revealed that individual cells may move by elongated or rounded modes 7. In addition, there has been greater appreciation of the contribution of collective invasion, in which cells invade in strands, sheets and clusters, particularly in highly differentiated tumors that maintain epithelial characteristics, to the spread of cancer 8.
We present a refined method 9 for examining the contributions of candidate proteins to collective invasion 10. In particular, by engineering separate pools of cells to express different fluorescent proteins, it is possible to molecularly dissect the activities and proteins required in leading cells versus those required in following cells. The use of RNAi provides the molecular tool to experimentally disassemble the processes involved in individual cell invasion as well as in different positions of collective invasion. In this procedure, mixtures of fluorescently-labeled cells are plated on the bottom of a Transwell insert previously filled with Matrigel ECM protein, then allowed to invade "upwards" through the filter and into the Matrigel. Reconstruction of z-series image stacks, obtained by confocal imaging, into three-dimensional representations allows for visualization of collectively invading strands and analysis of the representation of fluorescently-labeled cells in leading versus following positions.

Models of tumor cell invasion into three-dimensional extracellular matrix better reflect the in vivo situation than two-dimensional motility assays. Using matrix invasion assays combined with confocal imaging of fluorescently-labeled cells, detailed information on invasion modes and the distinct contributions of leading versus following cells can be obtained.

A defining characteristic of cancer malignancy is invasion and metastasis 1. In some cancers (e.g. glioma 2), local invasion into surrounding healthy ...

In vitro Mesothelial Clearance Assay that Models the Early Steps of Ovarian Cancer Metastasis

Ovarian cancer is the fifth leading cause of cancer related deaths in the United States1. Despite a positive initial response to therapies, 70 to 90 percent of women with ovarian cancer develop new metastases, and the recurrence is often fatal2. It is, therefore, necessary to understand how secondary metastases arise in order to develop better treatments for intermediate and late stage ovarian cancer. Ovarian cancer metastasis occurs when malignant cells detach from the primary tumor site and disseminate throughout the peritoneal cavity. The disseminated cells can form multicellular clusters, or spheroids, that will either remain unattached, or implant onto organs within the peritoneal cavity3 (Figure 1, Movie 1). 
All of the organs within the peritoneal cavity are lined with a single, continuous, layer of mesothelial cells4-6 (Figure 2). However, mesothelial cells are absent from underneath peritoneal tumor masses, as revealed by electron micrograph studies of excised human tumor tissue sections3,5-7 (Figure 2). This suggests that mesothelial cells are excluded from underneath the tumor mass by an unknown process. 
Previous in vitro experiments demonstrated that primary ovarian cancer cells attach more efficiently to extracellular matrix than to mesothelial cells8, and more recent studies showed that primary peritoneal mesothelial cells actually provide a barrier to ovarian cancer cell adhesion and invasion (as compared to adhesion and invasion on substrates that were not covered with mesothelial cells)9,10. This would suggest that mesothelial cells act as a barrier against ovarian cancer metastasis. The cellular and molecular mechanisms by which ovarian cancer cells breach this barrier, and exclude the mesothelium have, until recently, remained unknown. 
Here we describe the methodology for an in vitro assay that models the interaction between ovarian cancer cell spheroids and mesothelial cells in vivo (Figure 3, Movie 2). Our protocol was adapted from previously described methods for analyzing ovarian tumor cell interactions with mesothelial monolayers8-16, and was first described in a report showing that ovarian tumor cells utilize an integrin &#x2013;dependent activation of myosin and traction force to promote the exclusion of the mesothelial cells from under a tumor spheroid17. This model takes advantage of time-lapse fluorescence microscopy to monitor the two cell populations in real time, providing spatial and temporal information on the interaction. The ovarian cancer cells express red fluorescent protein (RFP) while the mesothelial cells express green fluorescent protein (GFP). RFP-expressing ovarian cancer cell spheroids attach to the GFP-expressing mesothelial monolayer. The spheroids spread, invade, and force the mesothelial cells aside creating a hole in the monolayer. This hole is visualized as the negative space (black) in the GFP image. The area of the hole can then be measured to quantitatively analyze differences in clearance activity between control and experimental populations of ovarian cancer and/ or mesothelial cells. This assay requires only a small number of ovarian cancer cells (100 cells per spheroid X 20-30 spheroids per condition), so it is feasible to perform this assay using precious primary tumor cell samples. Furthermore, this assay can be easily adapted for high throughput screening.

In vitro Mesothelial Clearance Assay that Models the Early Steps of Ovarian Cancer Metastasis

The mesothelial clearance assay described here takes advantage of fluorescently labeled cells and time-lapse video microscopy to visualize and quantitatively measure the interactions of ovarian cancer multicellular spheroids and mesothelial cell monolayers. This assay models the early steps of ovarian cancer metastasis.

Ovarian cancer is the fifth leading cause of cancer related deaths in the United States1. Despite a positive initial response to therapies, 70 to 90 ...

Heterotypic Three-dimensional In Vitro Modeling of Stromal-Epithelial Interactions During Ovarian Cancer Initiation and Progression

Epithelial ovarian cancers (EOCs) are the leading cause of death from gynecological malignancy in Western societies. Despite advances in surgical treatments and improved platinum-based chemotherapies, there has been little improvement in EOC survival rates for more than four decades 1,2. Whilst stage I tumors have 5-year survival rates &gt;85%, survival rates for stage III/IV disease are &lt;40%. Thus, the high rates of mortality for EOC could be significantly decreased if tumors were detected at earlier, more treatable, stages 3-5. At present, the molecular genetic and biological basis of early stage disease development is poorly understood. More specifically, little is known about the role of the microenvironment during tumor initiation; but known risk factors for EOCs (e.g. age and parity) suggest that the microenvironment plays a key role in the early genesis of EOCs. We therefore developed three-dimensional heterotypic models of both the normal ovary and of early stage ovarian cancers. For the normal ovary, we co-cultured normal ovarian surface epithelial (IOSE) and normal stromal fibroblast (INOF)&nbsp;cells, immortalized by retrovrial transduction of the catalytic subunit of human telomerase holoenzyme (hTERT) to extend the lifespan of these cells in culture. To model the earliest stages of ovarian epithelial cell transformation, overexpression of the CMYC oncogene in IOSE cells, again co-cultured with INOF cells. These heterotypic models were used to investigate the effects of aging and senescence on the transformation and invasion of epithelial cells. Here we describe the methodological steps in development of these three-dimensional model; these methodologies aren't specific to the development of normal ovary and ovarian cancer tissues, and could be used to study other tissue types where stromal and epithelial cell interactions are a fundamental aspect of the tissue maintenance and disease development.

Heterotypic Three-dimensional In Vitro Modeling of Stromal-Epithelial Interactions During Ovarian Cancer Initiation and Progression

We describe methodologies for establishing in vitro heterotypic three-dimensional models comprising ovarian fibroblasts and normal ovarian surface or ovarian cancer epithelial cells. We discuss the use of these models to study stromal-epithelial interactions that occur during ovarian cancer development.

Epithelial ovarian cancers (EOCs) are the leading cause of death from gynecological malignancy in Western societies. Despite advances in surgical ...

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As such, primary or &#39;neuronal-like&#39; cell culture systems are commonly utilized. While&#160;these systems are relatively easy to work with, and are useful model systems in which various functional outcomes (such as cell death) can be readily quantified, the examined outcomes and pathways in cultured immature neurons (such as excitotoxicity-mediated cell death pathways) are not necessarily the same as those observed in mature brain, or in intact tissue. Therefore, there is the need to develop models in which cellular mechanisms in mature neural tissue can be examined. We have developed an in vitro technique that can be used to investigate a variety of molecular pathways in intact nervous tissue. The technique described herein utilizes rat cortical tissue, but this technique can be adapted to use tissue from a variety of species (such as mouse, rabbit, guinea pig, and chicken) or brain regions (for example, hippocampus, striatum, etc.). Additionally, a variety of stimulations/treatments can be used (for example, excitotoxic, administration of inhibitors, etc.). In conclusion, the brain slice model described herein can be used to examine a variety of molecular mechanisms involved in excitotoxicity-mediated brain injury.

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

We have developed a brain slice model which can be used to examine molecular mechanisms involved in excitotoxicity-mediated brain injury.&#160;This technique generates viable mature brain tissue and reduces animal numbers required for experimentation, whilst keeping the neuronal circuitry, cellular interactions, and postsynaptic compartments partly intact.

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As ...

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

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

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

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

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

In Vivo and Ex Vivo Approaches to Study Ovarian Cancer Metastatic Colonization of Milky Spot Structures in Peritoneal Adipose

High-grade serous ovarian cancer (HGSC), the cause of widespread peritoneal metastases, continues to have an extremely poor prognosis; fewer than 30% of women are alive 5 years after diagnosis. The omentum is a preferred site of HGSC metastasis formation. Despite the clinical importance of this microenvironment, the contribution of omental adipose tissue to ovarian cancer progression remains understudied. Omental adipose is unusual in that it contains structures known as milky spots, which are comprised of B, T, and NK cells, macrophages, and progenitor cells surrounding dense nests of vasculature. Milky spots play a key role in the physiologic functions of the omentum, which are required for peritoneal homeostasis. We have shown that milky spots also promote ovarian cancer metastatic colonization of peritoneal adipose, a key step in the development of peritoneal metastases. Here we describe the approaches we developed to evaluate and quantify milky spots in peritoneal adipose and study their functional contribution to ovarian cancer cell metastatic colonization of omental tissues both in vivo and ex vivo. These approaches are generalizable to additional mouse models and cell lines, thus enabling the study of ovarian cancer metastasis formation from initial localization of cells to milky spot structures to the development of widespread peritoneal metastases.

In Vivo and Ex Vivo Approaches to Study Ovarian Cancer Metastatic Colonization of Milky Spot Structures in Peritoneal Adipose

We outline a protocol that implements both in vivo and ex vivo approaches to study ovarian cancer colonization of peritoneal adipose tissues, particularly the omentum. Furthermore, we present a protocol to quantitate and analyze immune cell-structures in the omentum known as milky spots, which promote metastases of peritoneal adipose.

High-grade serous ovarian cancer (HGSC), the cause of widespread peritoneal metastases, continues to have an extremely poor prognosis; fewer than 30% of ...

An Organotypic High Throughput System for Characterization of Drug Sensitivity of Primary Multiple Myeloma Cells

In this work we describe a novel approach that combines ex vivo drug sensitivity assays and digital image analysis to estimate chemosensitivity and heterogeneity of patient-derived multiple myeloma (MM) cells. This approach consists in seeding primary MM cells freshly extracted from bone marrow aspirates into microfluidic chambers implemented in multi-well plates, each consisting of a reconstruction of the bone marrow microenvironment, including extracellular matrix (collagen or basement membrane matrix) and stroma (patient-derived mesenchymal stem cells) or human-derived endothelial cells (HUVECs). The chambers are drugged with different agents and concentrations, and are imaged sequentially for 96 hr through bright field microscopy, in a motorized microscope equipped with a digital camera. Digital image analysis software detects live and dead cells from presence or absence of membrane motion, and generates curves of change in viability as a function of drug concentration and exposure time. We use a computational model to determine the parameters of chemosensitivity of the tumor population to each drug, as well as the number of sub-populations present as a measure of tumor heterogeneity. These patient-tailored models can then be used to simulate therapeutic regimens and estimate clinical response.

We describe a high-throughput drug sensitivity assay for primary multiple myeloma cells. It consists of a reconstruction of the bone marrow microenvironment (including extracellular matrix and stroma) in multi-well plates, and a non-invasive method for longitudinal quantification of cell viability.

In this work we describe a novel approach that combines ex vivo drug sensitivity assays and digital image analysis to estimate chemosensitivity and ...

Quantitation of Intra-peritoneal Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancy in the United States. Mortality is due to diagnosis of 75% of women with late stage disease, when metastasis is already present. EOC is characterized by diffuse and widely disseminated intra-peritoneal metastasis. Cells shed from the primary tumor anchor in the mesothelium that lines the peritoneal cavity as well as in the omentum, resulting in multi-focal metastasis, often in the presence of peritoneal ascites. Efforts in our laboratory are directed at a more detailed understanding of factors that regulate EOC metastatic success. However, quantifying metastatic tumor burden represents a significant technical challenge due to the large number, small size and broad distribution of lesions throughout the peritoneum. Herein we describe a method for analysis of EOC metastasis using cells labeled with red fluorescent protein (RFP) coupled with in vivo multispectral imaging. Following intra-peritoneal injection of RFP-labelled tumor cells, mice are imaged weekly until time of sacrifice. At this time, the peritoneal cavity is surgically exposed and organs are imaged in situ. Dissected organs are then placed on a labeled transparent template and imaged ex vivo. Removal of tissue auto-fluorescence during image processing using multispectral unmixing enables accurate quantitation of relative tumor burden. This method has utility in a variety of applications including therapeutic studies to evaluate compounds that may inhibit metastasis and thereby improve overall survival.

Ovarian cancer metastasis is characterized by numerous diffuse intra-peritoneal lesions, such that accurate visual quantitation of tumor burden is challenging. Herein we describe a method for in situ and ex vivo quantitation of metastatic tumor burden using red fluorescent protein (RFP)-labeled tumor cells and optical imaging.

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancy in the United States.  Mortality is due to diagnosis of 75% of ...

Tubal Cytology of the Fallopian Tube as a Promising Tool for Ovarian Cancer Early Detection

Currently, it is widely accepted that the vast majority of ovarian high-grade serous carcinoma (HGSC) originate from the fallopian tube. However, due to the lack of markers or tools for the ovarian cancer identification, the early detection of HGSC remains challenging. Direct sampling of the fallopian tube can enhance sensitivity for detection of neoplastic cells when the tumor is not grossly visible. We developed a procedure to collect fallopian tube cells directly from freshly received surgical specimens, which has shown excellent correlation with histological findings. This approach lays a foundation for the future utility of minimally invasive laparoscopic screening in high-risk patient populations.

We explored a tubal cytologic method by sampling the fallopian tube directly post-surgical excision as a tool of ovarian cancer early detection. Here, we present a protocol to collect fallopian tube cells from freshly received surgical specimens.

Currently, it is widely accepted that the vast majority of ovarian high-grade serous carcinoma (HGSC) originate from the fallopian tube. However, due to ...

Preparation Steps for Measurement of Reactivity in Mouse Retinal Arterioles Ex Vivo

Vascular insufficiency and alterations in normal retinal perfusion are among the major factors for the pathogenesis of various sight-threatening ocular diseases, such as diabetic retinopathy, hypertensive retinopathy, and possibly glaucoma. Therefore, retinal microvascular preparations are pivotal tools for physiological and pharmacological studies to delineate the underlying pathophysiological mechanisms and to design therapies for the diseases. Despite the wide use of mouse models in ophthalmic research, studies on retinal vascular reactivity are scarce in this species. A major reason for this discrepancy is the challenging isolation procedures owing to the small size of these retinal blood vessels, which is ~ &#8804; 30 &#181;m in luminal diameter. To circumvent the problem of direct isolation of these retinal microvessels for functional studies, we established an isolation and preparation technique that enables ex vivo studies of mouse retinal vasoactivity under near-physiological conditions. Although the present experimental preparations will specifically refer to the mouse retinal arterioles, this methodology can readily be employed to microvessels from rats.

Preparation Steps for Measurement of Reactivity in Mouse Retinal Arterioles Ex Vivo

Many vision-threatening ocular diseases are associated with dysfunctional retinal microvessels. Therefore, the measurement of retinal arteriole responses is important to investigate the underlying pathophysiological mechanisms. This article describes a detailed protocol for mouse retinal arteriole isolation and preparation to assess the effects of vasoactive substances on vascular diameter.

Vascular insufficiency and alterations in normal retinal perfusion are among the major factors for the pathogenesis of various sight-threatening ocular ...