This work was supported by Grants-in-Aid for Scientific Research (KAKENHI) (26461185 and 25460137).

NOTE: This study was approved by the appropriate Ethics Committees.
1. Primary Culture of Human Lung Fibroblasts
<ol>
	<li>Collection of lung tissue:
	<ol>
		<li>Obtain human lung tissue samples from the surgical operating room directly. Collect approximately 1 cm3 blocks from cancerous and non-cancerous lung tissue, with the non-cancerous sample collected as far away from the tumor as possible.</li>
		<li>Suspend the samples in Dulbecco&#8217;s modified Eagle&#8217;s medium (DMEM) supplemented with 100 units/ml penicillin, 100 &#956;g/ml streptomycin and 0.25 &#956;g/ml amphotericin B (serum-free medium). Maintain the suspended samples in sterile 50 ml tubes and transfer to the laboratory. 
		NOTE: Fibroblasts are highly migratory and proliferative compared with other cell types, such as epithelial, endothelial and smooth muscle cells. The outgrowth method takes advantage of these features of fibroblasts, and outgrowing cells from tissue sections are abundant in fibroblasts. After several cell passages, other cell types fail to survive and propagate in DMEM with 10% fetal bovine serum (FBS), resulting in purified fibroblast cell cultures. The cells could be used 3-7 passages following primary culture.</li>
	</ol>
	</li>
	<li>Explant culture and conditioning for cell outgrowth:
	<ol>
		<li>Perform primary culture of fibroblasts using a previously reported protocol with modifications5.</li>
		<li>In the laboratory, place the tissue sample on a 10 cm tissue culture dish without culture medium and cut into small sections ~2-3 mm in size using sterile forceps and a scalpel. During this process, avoid making the section dry, otherwise the efficiency of cell outgrowth is impaired.</li>
	</ol>
	</li>
	<li>Separation of the epithelial cell layer and connective tissue:
	<ol>
		<li>Soak the cut tissue sections in culture medium containing 2,000 PU/ml dispase I and culture for 16 hr at 4 &#176;C.</li>
		<li>Transfer the tissue sections to a dish, and separate the epithelial cell layer from the adjacent connective tissue. Process the sections in a clean bench to avoid contamination of microorganisms. 
		NOTE: If primary culture of epithelial cells is needed, perform step 1.3. If only fibroblasts are to be isolated, omit step 1.3 because the subsequent explant culture and cell passages are unfavorable for epithelial cells, which yield purified fibroblast populations.</li>
	</ol>
	</li>
	<li>Attachment of tissue sections:
	<ol>
		<li>Mince the tissues into 1 mm pieces using two scalpels. If the pieces are not small enough, they detach more easily from the dish, and the cells will fail to outgrow on the dish surface.</li>
		<li>Place small lung tissue sections apart from each other to maintain an empty area surrounding each piece. Make scratches on the surface of the tissue culture dish using a scalpel blade to facilitate attachment of tissue sections. 
		NOTE: Scratching also appears to facilitate cell outgrowth, providing tracks along which cells can migrate.
		<ol>
			<li>Alternatively, place minced tissue pieces individually into each well of a 6-well plate, and cover them with a cover slip. Attach the cover slip to the surface of the plate using silicone grease.</li>
			<li>Place silicone grease at two points 1.5 cm apart in each well using a sterile pin. Coverage of tissue pieces enhances the efficacy of cell outgrowth and cell propagation following several passages.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Subsequent explant culture:
	<ol>
		<li>Gently add culture medium to the dish before the tissue sections dry out, as efficient cell outgrowth is lost for the most part if the samples dry out. Do not pour the medium too rapidly as the tissue sections would detach.</li>
		<li>Culture cells in DMEM with 10% FBS. Use enough medium to just cover the tissue, but not too much that it allows floating, as additional buoyancy promotes detachment from the dish.</li>
	</ol>
	</li>
	<li>Cell passage:
	<ol>
		<li>Handle the culture medium with care at all times as repeated movements of the culture dish can lead to detachment of the tissue sections.</li>
		<li>Place the culture dishes in an incubator at 37 &#176;C for 5-7 days. Refresh the medium every other day, and handle the culture dishes minimally during the medium changes. Fibroblasts outgrow from the edge of the tissue sections over the next few weeks. 
		NOTE: After ~2-3 weeks, outgrowing fibroblasts almost reach confluence, depending on the amount of surface area.</li>
		<li>Wash cells with 1x PBS, and add 1 ml of trypsin I to the plate.</li>
		<li>After trypsinization, detach the cells using 9 ml of DMEM supplemented with 10% FBS. Collect cells suspended in the medium in a 10 ml tube, together with the tissue sections. Following centrifugation to form cell pellets, resuspend the resulting pellets in the new medium.</li>
		<li>Seed the cells and tissue sections onto a new culture dish, at which point the tissues fail to attach to the dish while the cells adhere and grow. The following day, remove the floating tissue pieces by aspiration, and change the medium. Attached fibroblasts propagate with subsequent cultures.</li>
	</ol>
	</li>
</ol>
2. Three-dimensional Co-culture of Human Lung Fibroblasts and Cancer Cells
<ol>
	<li>Preparation of cells and reagents:
	<ol>
		<li>Approximately use 2 x 105 epithelial cells and 2.5 x 105 fibroblasts per well. Prepare collagen type IA (3 mg/ml, pH 3), FBS (100%), reconstitution buffer (50 mM NaOH, 260 mM NaHCO3, 200 mM HEPES), 5x DMEM, DMEM supplemented with 10% FBS for fibroblast culture, and a 3D co-culture medium (a 1:1 mixture of fibroblast culture medium and culture medium for cancer cells).</li>
		<li>Culture A549 lung adenocarcinoma cells, the fibroblasts and the A549 3D co-culture in DMEM supplemented with 10% FBS.</li>
	</ol>
	</li>
	<li>Collagen gel formation:
	<ol>
		<li>Wash fibroblasts cultured on 10 cm dish with 1x PBS, and add 1 ml of trypsin I to the plate. After trypsinization for ~5 min at 37 &#176;C, detach the cells using 9 ml DMEM supplemented with 10% FBS. Collect cells suspended in the medium in a 10 ml tube, and centrifuge them at 200-300 x g to form cell pellets.</li>
		<li>Resuspend the resulting pellets in 100% FBS at a density of 5 x 105/ml.</li>
		<li>Prepare the collagen gel on ice. Cool the reagents, pipettes and tubes in a refrigerator prior to the following procedure. Even on ice, the mixture solidifies to some extent, and the total volume is less than the sum of all constituents.</li>
		<li>In each well, prepare the collagen gel by mixing 0.5 ml of fibroblast suspension (2.5 x 105 cells) in FBS, 2.3 ml type IA collagen, 670 &#956;l 5x DMEM, and 330 &#956;l reconstitution buffer. Allow the gels to set readily at room temperature.
		<ol>
			<li>Vigorously pipette to ensure a homogenous mixture. Avoid creating bubbles during the pipetting process.</li>
		</ol>
		</li>
		<li>Add the mixture (3 ml) to each well of a 6-well plate and allow to gelatinize in the incubator at 37 &#176;C without disturbance for 30-60 min.</li>
	</ol>
	</li>
	<li>Cancer cell culture on the collagen gel:
	<ol>
		<li>Perform three-dimensional co-culture using a previously reported protocol with modifications6.</li>
		<li>Resuspend cancer cells in the 3D co-culture medium (or in DMEM with 10% FBS in the case of A549 cells) at a density of 1 x 105/ml.</li>
		<li>Pour 2 ml of the resuspended cell solution (2 x 105 cells) onto the surface of each gel. Modify cell number of cancer cells or fibroblasts in co-culture depending on experimental conditions.</li>
	</ol>
	</li>
	<li>Gel contraction:
	<ol>
		<li>Incubate gels overnight at 37 &#176;C so the cancer cells can adhere to the collagen gel. Detach each gel, and generate a &#8216;floating culture&#8217; in each well of the 6-well plate. 
		NOTE: By using a floating culture, various changes in gel size are induced by mechanical tension and collagen degradation, which are mediated by cellular interaction between co-cultured cancer cells and fibroblasts.</li>
		<li>Use an angled 21 G needle or small spatula to separate each gel from the edge of the well. Every 2-3 days, refresh the wells with 2 ml of 3D co-culture medium. Measure the size of each gel every day for 5 days.</li>
	</ol>
	</li>
	<li>Analysis of collagen gels:
	<ol>
		<li>Measure the collagen content of each gel using collagen quantitation methods, such as the Sircol assay. Perform transcriptomic analysis or quantitative RT-PCR after collecting RNA from the gels5.</li>
	</ol>
	</li>
</ol>
3. Air-liquid Interface Culture and Invasion Assay
<ol>
	<li>After culturing the collagen gels at 37 &#176;C for 5 days, expose the contracted gels to air by placing them on a mesh (70 &#956;m pore size) in new 6-well plates. Make the mesh from commercially available cell strainers used for flow cytometry.</li>
	<li>Gently fill each well with 11 ml of 3D co-culture medium.</li>
	<li>Position the gels onto the mesh using a sterile spoon, and remove any remaining medium from the gels. On this condition, submerge gels in the medium while expose the upper surface of the gel to air. Define this culture condition as air-liquid interface. 
	NOTE: After 5-7 days of maintaining the air-liquid interface culture at 37 &#176;C in the incubator, invasive cancer cells migrate into the gel. Depending on the cell type and as a result of cellular interactions, variable degrees of cell morphological change in the cancer cells are induced by the air-liquid interface culture.</li>
	<li>For histological evaluation, fix the gel in formalin solution overnight at room temperature and embed in paraffin. Stain vertical sections (4 &#956;m) with hematoxylin and eosin (H&#38;E). Perform immunohistochemical analysis on the sections4.</li>
</ol>

<ol>
	<li>Strell, C., Rundqvist, H., Ostman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibroblasts-a+key+host+cell+type+in+tumor+initiation,+progression,+and+metastasis.">Fibroblasts-a key host cell type in tumor initiation, progression, and metastasis.</a> Ups. J. Med. Sci. 117 (2), 187-195 (2012).</li><li>Augsten, M., H&#228;ggl&#246;f, C., Pe&#241;a, C., Ostman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+digest+on+the+role+of+the+tumor+microenvironment+in+gastrointestinal+cancers.">A digest on the role of the tumor microenvironment in gastrointestinal cancers.</a> Cancer Microenviron. 3 (1), 167-176 (2010).</li><li>Augsten, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer-Associated+Fibroblasts+as+Another+Polarized+Cell+Type+of+the+Tumor+Microenvironment.">Cancer-Associated Fibroblasts as Another Polarized Cell Type of the Tumor Microenvironment.</a> Front. Oncol. 4, 62 (2014).</li><li>Horie, M., 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=Characterization+of+human+lung+cancer-associated+fibroblasts+in+three-dimensional+in+vitro+co-culture+model.">Characterization of human lung cancer-associated fibroblasts in three-dimensional in vitro co-culture model.</a> Biochem. Biophys. Res. Commun. 423 (1), 158-163 (2012).</li><li>Ohshima, M., 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=TGF-&#946;+signaling+in+gingival+fibroblast-epithelial+interaction.">TGF-&#946; signaling in gingival fibroblast-epithelial interaction.</a> J. Dent. Res. 89 (11), 1315-1321 (2010).</li><li>Ikebe, D., Wang, B., Suzuki, H., Kato, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suppression+of+keratinocyte+stratification+by+a+dominant+negative+JunB+mutant+without+blocking+cell+proliferation.">Suppression of keratinocyte stratification by a dominant negative JunB mutant without blocking cell proliferation.</a> Genes Cells. 12 (2), 197-207 (2007).</li><li>Orimo, A., Weinberg, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stromal+fibroblasts+in+cancer:+a+novel+tumor-promoting+cell+type.">Stromal fibroblasts in cancer: a novel tumor-promoting cell type.</a> Cell Cycle. 5 (15), 1597-1601 (2006).</li><li>Paulsson, J., Micke, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prognostic+relevance+of+cancer-associated+fibroblasts+in+human+cancer.">Prognostic relevance of cancer-associated fibroblasts in human cancer.</a> Semin. Cancer Biol. 25, 61-68 (2014).</li><li>Navab, R., 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=Prognostic+gene-expression+signature+of+carcinoma-associated+fibroblasts+in+non-small+cell+lung+cancer.">Prognostic gene-expression signature of carcinoma-associated fibroblasts in non-small cell lung cancer.</a> Proc. Natl. Acad. Sci. U S A. 108 (17), 7160-7165 (2011).</li><li>Herrera, M., 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=Functional+heterogeneity+of+cancer-associated+fibroblasts+from+human+colon+tumors+shows+specific+prognostic+gene+expression+signature.">Functional heterogeneity of cancer-associated fibroblasts from human colon tumors shows specific prognostic gene expression signature.</a> Clin. Cancer Res. 19 (21), 5914-5926 (2013).</li><li>H&#228;ggl&#246;f, C., 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=Stromal+PDGFRbeta+expression+in+prostate+tumors+and+non-malignant+prostate+tissue+predicts+prostate+cancer+survival.">Stromal PDGFRbeta expression in prostate tumors and non-malignant prostate tissue predicts prostate cancer survival.</a> PLoS One. 5 (5), e10747 (2010).</li><li>Saito, R. A., 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=Forkhead+box+F1+regulates+tumor-promoting+properties+of+cancer-associated+fibroblasts+in+lung+cancer.">Forkhead box F1 regulates tumor-promoting properties of cancer-associated fibroblasts in lung cancer.</a> Cancer Res. 70 (7), 2644-2654 (2010).</li><li>Kalluri, R., Zeisberg, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibroblasts+in+cancer.">Fibroblasts in cancer.</a> Nat. Rev. Cancer. 6 (5), 392-401 (2006).</li><li>Calvo, F., 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=Mechanotransduction+and+YAP-dependent+matrix+remodelling+is+required+for+the+generation+and+maintenance+of+cancer-associated+fibroblasts.">Mechanotransduction and YAP-dependent matrix remodelling is required for the generation and maintenance of cancer-associated fibroblasts.</a> Nat. Cell Biol. 15 (6), 637-646 (2013).</li><li>Horie, M., 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=Histamine+induces+human+lung+fibroblast-mediated+collagen+gel+contraction+via+histamine+H1+receptor.">Histamine induces human lung fibroblast-mediated collagen gel contraction via histamine H1 receptor.</a> Exp. Lung Res. 40 (5), 222-236 (2014).</li></ol>

The authors declare that they have no competing financial interests.

CAFs form a major component of the ECM surrounding cancer cells and not only provide a scaffold for the tumor, but also actively participate in tumor development7. Accumulating evidence unravels the impact of CAFs or their related molecules on the eventual prognosis, highlighting the critical roles of CAF-mediated tumor progression8.
In the previous study, we employed outgrowth method to isolate lung CAFs4. In this experiment, the maintenance of tissue section ...

Cancer tissue can be perceived as a type of organ, which evolves through close interactions between the cancer and the tumor stromal microenvironment, composed of cancer-associated fibroblasts (CAFs), immune cells, tumor vessels and the extracellular matrix (ECM). CAFs are the major source of soluble factors (cytokines, growth factors and chemokines) that exert mitogenic, pro-migratory and pro-invasive effects on cancer cells. They also stimulate tumor vessel formation and recruit precursor cells, such as bone marrow-derived cells (BMDC). Activated CAFs are involved in the production and remodeling of the ECM, thereby promoting the growth and spread of cancer cells1. CAFs also provide a niche that facilitates tumor cell colonization and metastasis and are capable of conferring stem cell phenotypes onto neighboring cancer cells. Pathological observations suggest that stromal reactions or fibrotic changes in cancer tissues are indicative of a poor prognosis. Recent studies have also demonstrated that tumor stromal features, such as the gene signature, can predict patient prognosis. Furthermore, CAF-derived factors can modulate sensitivity to chemotherapy, highlighting the role of CAFs in determining drug sensitivity and resistance2.
As CAFs play a multifaceted role in the promotion of tumor progression through signaling pathways that mediate interactions between CAFs and different cell types within the tumor microenvironment, they have attracted increasing attention as novel targets for cancer therapies. The heterogeneity of the cell populations within the cancer microenvironment presents an obstacle for targeting CAFs. Several markers for CAFs have been proposed, such as &#945;-smooth muscle actin (&#945;-SMA), fibroblast activation protein (FAP), and fibroblast specific proten-1 (FSP-1: also called S100A4); however, these molecular markers are not specific for distinguishing CAFs from other cells present in non-cancerous tissues3. Therefore, further studies are needed to obtain more knowledge about the specific properties of CAFs. To this end, it is informative to characterize primary cultured CAFs compared with patient-matched normal fibroblasts.
Recently, analyses on patient-derived CAFs have been reported in several cancer types, revealing unique gene expression patterns and cell behaviors compared with fibroblasts derived from non-cancerous tissues. Using isolated CAFs from human lung cancer tissues, we developed a three-dimensional co-culture method, enabling us to evaluate the properties of lung CAFs. In this model, we investigated the effects of the CAFs on lung cancer cell invasion, proliferation and collagen gel contraction, which experimentally recapitulated the tumor-promoting roles of lung CAFs4.

<table><tbody><tr><td>DMEM</td><td>Sigma-Aldrich</td><td>D5796</td><td></td></tr><tr><td>FBS</td><td>GIBCO</td><td>10437</td><td></td></tr><tr><td>Collagen type IA</td><td>Nitta gelatin Inc.</td><td>CELL-1A</td><td></td></tr><tr><td>Reconstitution buffer</td><td>Nitta gelatin Inc.</td><td></td><td></td></tr><tr><td>Cover slip</td><td>NUNC</td><td>174934</td><td></td></tr><tr><td>Silicone grease</td><td>Dow Corning Toray</td><td>High vacuum grease</td><td></td></tr><tr><td>Dispase I</td><td>WAKO</td><td>386-02271</td><td></td></tr><tr><td>6-well plate</td><td>BD Falcon</td><td>353046</td><td></td></tr><tr><td>Cell strainer (70 &amp;mu;m)</td><td>BD Falcon</td><td>352350</td><td></td></tr></tbody></table>

three-dimensional co-culture model for tumor-stromal interaction

Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal cells. The tumor microenvironment is comprised of a variety of cell types, such as fibroblasts, immune cells, vascular endothelial cells, pericytes and bone-marrow-derived cells, embedded in the extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs) have a pro-tumorigenic role through the secretion of soluble factors, angiogenesis and ECM remodeling. The experimental models for cancer cell survival, proliferation, migration, and invasion have mostly relied on two-dimensional monocellular and monolayer tissue cultures or Boyden chamber assays. However, these experiments do not precisely reflect the physiological or pathological conditions in a diseased organ. To gain a better understanding of tumor stromal or tumor matrix interactions, multicellular and three-dimensional cultures provide more powerful tools for investigating intercellular communication and ECM-dependent modulation of cancer cell behavior. As a platform for this type of study, we present an experimental model in which cancer cells are cultured on collagen gels embedded with primary cultures of CAFs.

This co-culture method, mimicking the tumor microenvironment, is a useful tool to investigate the interactions between cancer cells and fibroblasts embedded in collagen gels. In the previous study, three parameters were evaluated in this experimental model: collagen gel contraction, cancer cell invasion and morphological change. Cancer cell proliferation was also estimated using Ki67 immunostaining4. Lung tissue samples were collected from cancerous and non-cancerous sections of a resected lung lobe (F...

Watch this Scientific Journal Video about Three-dimensional Co-culture Model for Tumor-stromal Interaction at JoVE.com

Three-dimensional Co-culture Model for Tumor-stromal Interaction

Here we present a protocol to co-culture in three-dimensions, which is useful for investigating multicellular interactions and extracellular matrix-dependent modulation of cancer cell behavior. In this experimental model, cancer cells are cultured on collagen gels embedded with human cancer-associated fibroblasts.

Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal ...

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17.3K Views.  The University of Tokyo. Here we present a protocol to co-culture in three-dimensions, which is useful for investigating multicellular interactions and extracellular matrix-dependent modulation of cancer cell behavior. In this experimental model, cancer cells are cultured on collagen gels embedded with human cancer-associated fibroblasts.

Video: Three-dimensional Co-culture Model for Tumor-stromal Interaction

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

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

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

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

Multidimensional Coculture System to Model Lung Squamous Carcinoma Progression

Tumor-stroma interactions play a critical role in the development of lung squamous carcinoma (LUSC). However, understanding how these dynamic interactions contribute to tissue architectural changes observed during tumorigenesis remains challenging due to the lack of appropriate models. In this protocol, we describe the generation of a 3D coculture model using a LUSC primary cell culture known as TUM622. TUM622 cells were established from a LUSC patient-derived xenograft (PDX) and have the unique property to form acinar-like structures when seeded in a basement membrane matrix. We demonstrate that TUM622 acini in 3D coculture recapitulate key features of tissue architecture during LUSC progression as well as the dynamic interactions between LUSC cells and components of the tumor microenvironment (TME), including the extracellular matrix (ECM) and cancer-associated fibroblasts (CAFs). We further adapt our principal 3D culturing protocol to demonstrate how this system could be utilized for various downstream analyses. Overall, this organoid model creates a biologically rich and adaptable platform that enables one to gain insight into the cell-intrinsic and extrinsic mechanisms that promote the disruption of epithelial architectures during carcinoma progression and will aid the search for new therapeutic targets and diagnostic markers.

An in vitro model system was developed to capture tissue architectural changes during lung squamous carcinoma (LUSC) progression in a 3-dimensional (3D) co-culture with cancer-associated fibroblasts (CAFs). This organoid system provides a unique platform to investigate the roles of diverse tumor cell-intrinsic and extrinsic changes that modulate the tumor phenotype.

Tumor-stroma interactions play a critical role in the development of lung squamous carcinoma (LUSC). However, understanding how these dynamic interactions ...

Cancer Research

A Novel Stromal Fibroblast-Modulated 3D Tumor Spheroid Model for Studying Tumor-Stroma Interaction and Drug Discovery

Tumor-stroma interactions play an important role in cancer progression. Three-dimensional (3D) tumor spheroid models are the most widely used in vitro model in the study of cancer stem/initiating cells, preclinical cancer research, and drug screening. The 3D spheroid models are superior to conventional tumor cell culture and reproduce some important characters of real solid tumors. However, conventional 3D tumor spheroids are made up exclusively of tumor cells. They lack the participation of tumor stromal cells and have insufficient extracellular matrix (ECM) deposition, thus only partially mimicking the in vivo conditions of tumor tissues. We established a new multicellular 3D spheroid model composed of tumor cells and stromal fibroblasts that better mimics the in vivo heterogeneous tumor microenvironment and its native desmoplasia. The formation of spheroids is strictly regulated by the tumor stromal fibroblasts and is determined by the activity of certain crucial intracellular signaling pathways (e.g., Notch signaling) in stromal fibroblasts. In this article, we present the techniques for coculture of tumor cells-stromal fibroblasts, time-lapse imaging to visualize cell-cell interactions, and confocal microscopy to display the 3D architectural features of the spheroids. We also show two examples of the practical application of this 3D spheroid model. This novel multicellular 3D spheroid model offers a useful platform for studying tumor-stroma interaction, elucidating how stromal fibroblasts regulate cancer stem/initiating cells, which determine tumor progression and aggressiveness, and exploring involvement of stromal reaction in cancer drug sensitivity and resistance. This platform can also be a pertinent in vitro model for drug discovery.

A novel three-dimensional spheroid model based on the heterotypic interaction of tumor cells and stromal fibroblasts is established. Here, we present coculture of tumor cells and stromal fibroblasts, time-lapse imaging, and confocal microscopy to visualize the formation of spheroids. This three-dimensional model offers a pertinent platform to study tumor-stroma interactions and test cancer therapeutics.

Tumor-stroma interactions play an important role in cancer progression. Three-dimensional (3D) tumor spheroid models are the most widely used in vitro ...

Monitoring Cancer Cell Invasion and T-Cell Cytotoxicity in 3D Culture

Significant progress has been made in treating cancer with immunotherapy, although a large number of cancers remain resistant to treatment. A limited number of assays allow for direct monitoring and mechanistic insights into the interactions between tumor and immune cells, amongst which, T-cells play a significant role in executing the cytotoxic response of the adaptive immune system to cancer cells. Most assays are based on two-dimensional (2D) co-culture of cells due to the relative ease of use but with limited representation of the invasive growth phenotype, one of the hallmarks of cancer cells. Current three-dimensional (3D) co-culture systems either require special equipment or separate monitoring for invasion of co-cultured cancer cells and interacting T-cells.
Here we describe an approach to simultaneously monitor the invasive behavior in 3D of cancer cell spheroids and T-cell cytotoxicity in co-culture. Spheroid formation is driven by enhanced cell-cell interactions in scaffold-free agarose microwell casts with U-shaped bottoms. Both T-cell co-culture and cancer cell invasion into type I collagen matrix are performed within the microwells of the agarose casts without the need to transfer the cells, thus maintaining an intact 3D co-culture system throughout the assay. The collagen matrix can be separated from the agarose cast, allowing for immunofluorescence (IF) staining and for confocal imaging of cells. Also, cells can be isolated for further growth or subjected to analyses such as for gene expression or fluorescence activated cell sorting (FACS). Finally, the 3D co-culture can be analyzed by immunohistochemistry (IHC) after embedding and sectioning. Possible modifications of the assay include altered compositions of the extracellular matrix (ECM) as well as the inclusion of different stromal or immune cells with the cancer cells.

The presented approach simultaneously evaluates cancer cell invasion in 3D spheroid assays and T-cell cytotoxicity. Spheroids are generated in a scaffold-free agarose multi-microwell cast. Co-culture and embedding in type I collagen matrix are performed within the same device which allows to monitor cancer cell invasion and T-cell mediated cytotoxicity.

Significant progress has been made in treating cancer with immunotherapy, although a large number of cancers remain resistant to treatment. A limited ...

A Three-Dimensional Spheroid Model to Investigate the Tumor-Stromal Interaction in Hepatocellular Carcinoma

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver cancer, rationalize its rank as the second most common cause of cancer-related death. Preclinical models need to be adapted to recapitulate the human conditions to select the best therapeutic candidates for clinical development and aid the delivery of personalized medicine. Three-dimensional (3D) cellular spheroid models show promise as an emerging in vitro alternative to two-dimensional (2D) monolayer cultures. Here, we describe a 3D tumor spheroid&#160;model which exploits the ability of individual cells to aggregate when maintained in hanging droplets, and is more representative of an in vivo environment than standard monolayers. Furthermore, 3D spheroids can be produced by combining homotypic or heterotypic cells, more reflective of the cellular heterogeneity in vivo, potentially enabling the study of environmental interactions that can influence progression and treatment responses. The current research optimized the cell density to form 3D homotypic and heterotypic tumor spheroids by immobilizing cell suspensions on the lids of standard 10 cm3 Petri dishes. Longitudinal analysis was performed to generate growth curves for homotypic versus heterotypic tumor/fibroblasts spheroids. Finally, the proliferative impact of fibroblasts (COS7 cells) and liver myofibroblasts (LX2) on homotypic tumor (Hep3B) spheroids was investigated. A seeding density of 3,000 cells (in 20 &#181;L media) successfully yielded Huh7/COS7 heterotypic spheroids, which displayed a steady increase in size up to culture day 8, followed by growth retardation. This finding was corroborated using Hep3B homotypic spheroids cultured in LX2 (human hepatic stellate cell line) conditioned medium (CM). LX2 CM triggered the proliferation of Hep3B spheroids compared to control tumor spheroids. In conclusion, this protocol has shown that 3D tumor spheroids can be used as a simple, economical, and prescreen in vitro tool to study tumor-stromal interactions more comprehensively.

Comprehensive in vitro models that faithfully recapitulate the relevant human disease are lacking. The current study presents three-dimensional (3D) tumor spheroid creation and culture, a reliable in vitro tool to study the tumor-stromal interaction in human hepatocellular carcinoma.

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver ...

Preparation and Analysis of In Vitro Three Dimensional Breast Carcinoma Surrogates

Three dimensional (3D) culture is a more physiologically relevant method to model cell behavior in vitro than two dimensional culture. Carcinomas, including breast carcinomas, are complex 3D tissues composed of cancer epithelial cells and stromal components, including fibroblasts and extracellular matrix (ECM). Yet most in vitro models of breast carcinoma consist only of cancer epithelial cells, omitting the stroma and, therefore, the 3D architecture of a tumor in vivo. Appropriate 3D modeling of carcinoma is important for accurate understanding of tumor biology, behavior, and response to therapy. However, the duration of culture and volume of 3D models is limited by the availability of oxygen and nutrients within the culture. Herein, we demonstrate a method in which breast carcinoma epithelial cells and stromal fibroblasts are incorporated into ECM to generate a 3D breast cancer surrogate that includes stroma and can be cultured as a solid 3D structure or by using a perfusion bioreactor system to deliver oxygen and nutrients. Following setup and an initial growth period, surrogates can be used for preclinical drug testing. Alternatively, the cellular and matrix components of the surrogate can be modified to address a variety of biological questions. After culture, surrogates are fixed and processed to paraffin, in a manner similar to the handling of clinical breast carcinoma specimens, for evaluation of parameters of interest. The evaluation of one such parameter, the density of cells present, is explained, where ImageJ and CellProfiler image analysis software systems are applied to photomicrographs of histologic sections of surrogates to quantify the number of nucleated cells per area. This can be used as an indicator of the change in cell number over time or the change in cell number resulting from varying growth conditions and treatments.

Preparation and Analysis of In Vitro Three Dimensional Breast Carcinoma Surrogates

We demonstrate a method to generate 3D breast cancer surrogates, which can be cultured using a perfusion bioreactor system to deliver oxygen and nutrients. Following growth, surrogates are fixed and processed to paraffin for evaluation of parameters of interest. The evaluation of one such parameter, cell density, is explained.

Three dimensional (3D) culture is a more physiologically relevant method to model cell behavior in vitro than two dimensional culture. Carcinomas, ...

Bioengineering

Heteromulticellular Stromal Cells in Scaffold-free 3D Cultures of Epithelial Cancer Cells to Drive Invasion

Breast cancer is the second leading cause of cancer-related death among women in the U.S. Organoid models of solid tumors have been shown to faithfully recapitulate aspects of cancer progression such as proliferation and invasion. Although patient-derived organoids and patient-derived xenograft organoids are pathophysiologically relevant, they are costly to propagate, difficult to manipulate, and comprised primarily of the most proliferative cell types within the tumor microenvironment (TME). These limitations prevent their use for elucidating cellular mechanisms of disease progression that depend upon tumor-associated stromal cells which are found within the TME and known to contribute to metastasis and therapy resistance. 
Here, we report on methods for cultivating epithelial-stromal multicellular 3D cultures. The advantages of these methods include a cost-effective system for rapidly generating organoid-like 3D cultures within scaffold-free environments that can be used to track invasion at single-cell resolution within hydrogel scaffolds. Specifically, we demonstrate how to generate these heteromulticellular 3D cultures using BT-474 breast cancer cells in combination with fibroblasts (BJ-5ta), monocyte-like cells (THP-1), and/or endothelial cells (EA.hy926). Additionally, differential fluorescent labeling of cell populations enables time-lapse microscopy to define 3D culture assembly and invasion dynamics. 
Notably, the addition of any two stromal cell combinations to 3D cultures of BT-474 cells significantly reduces circularity of the 3D cultures, consistent with the presence of organoid-like or secondary spheroid structures. In tracker dye experiments, fibroblasts and endothelial cells co-localize in the peripheral organoid-like protrusions and are spatially segregated from the primary BT-474 spheroid. Finally, heteromulticellular 3D cultures of BT-474 cells have increased hydrogel invasion capacity. Since we observed these protrusive structures in heteromulticellular 3D cultures of both non-tumorigenic and tumorigenic breast epithelial cells, this work provides an efficient and reproducible method for generating organoid-like 3D cultures in a scaffold-free environment for subsequent analyses of phenotypes associated with solid tumor progression.

There is a critical need for 3D cancer models that capture heterocellular crosstalk to study cancer metastasis. Our study presents the generation of heteromulticellular stromal-epithelial in a scaffold and scaffold-free environment that can be used to study invasion and cellular spatial distributions.

Breast cancer is the second leading cause of cancer-related death among women in the U.S. Organoid models of solid tumors have been shown to faithfully ...

Three-Dimensional Culture Assay to Explore Cancer Cell Invasiveness and Satellite Tumor Formation

Mammalian cell culture in monolayers is widely used to study various physiological and molecular processes. However, this approach to study growing cells often generates unwanted artifacts. Therefore, cell culture in a three-dimensional (3D) environment, often using extracellular matrix components, emerged as an interesting alternative due to its close similarity to the native in vivo tissue or organ. We developed a 3D cell culture system using two compartments, namely (i) a central compartment containing cancer cells embedded in a collagen gel acting as a pseudo-primary macrospherical tumor and (ii) a peripheral cell-free compartment made of a fibrin gel, i.e. an extracellular matrix component different from that used in the center, in which cancer cells can migrate (invasion front) and/or form microspherical tumors representing secondary or satellite tumors. The formation of satellite tumors in the peripheral compartment is remarkably correlated to the known aggressiveness or metastatic origin of the native tumor cells, which makes this 3D culture system unique. This cell culture approach might be considered to assess cancer cell invasiveness and motility, cell-extracellular matrix interactions and as a method to evaluate anti-cancer drug properties.

Cancer cells are embedded in a collagen gel and then sandwiched in an acellular fibrin gel to generate a 3D culture system in which the invasiveness and formation of satellite tumors may be monitored.

Mammalian cell culture in monolayers is widely used to study various physiological and molecular processes. However, this approach to study growing cells ...

Isolation of Mammary Epithelial Cells from Three-dimensional Mixed-cell Spheroid Co-culture

While enormous efforts have gone into identifying signaling pathways and molecules involved in normal and malignant cell behaviors1-2, much of this work has been done using classical two-dimensional cell culture models, which allow for easy cell manipulation. It has become clear that intracellular signaling pathways are affected by extracellular forces, including dimensionality and cell surface tension3-4. Multiple approaches have been taken to develop three-dimensional models that more accurately represent biologic tissue architecture3. While these models incorporate multi-dimensionality and architectural stresses, study of the consequent effects on cells is less facile than in two-dimensional tissue culture due to the limitations of the models and the difficulty in extracting cells for subsequent analysis.
The important role of the microenvironment around tumors in tumorigenesis and tumor behavior is becoming increasingly recognized4. Tumor stroma is composed of multiple cell types and extracellular molecules. During tumor development there are bidirectional signals between tumor cells and stromal cells5. Although some factors participating in tumor-stroma co-evolution have been identified, there is still a need to develop simple techniques to systematically identify and study the full array of these signals6. Fibroblasts are the most abundant cell type in normal or tumor-associated stromal tissues, and contribute to deposition and maintenance of basement membrane and paracrine growth factors7.
Many groups have used three dimensional culture systems to study the role of fibroblasts on various cellular functions, including tumor response to therapies, recruitment of immune cells, signaling molecules, proliferation, apoptosis, angiogenesis, and invasion8-15. We have optimized a simple method for assessing the effects of mammary fibroblasts on mammary epithelial cells using a commercially available extracellular matrix model to create three-dimensional cultures of mixed cell populations (co-cultures)16-22. With continued co-culture the cells form spheroids with the fibroblasts clustering in the interior and the epithelial cells largely on the exterior of the spheroids and forming multi-cellular projections into the matrix. Manipulation of the fibroblasts that leads to altered epithelial cell invasiveness can be readily quantified by changes in numbers and length of epithelial projections23. Furthermore, we have devised a method for isolating epithelial cells out of three-dimensional co-culture that facilitates analysis of the effects of fibroblast exposure on epithelial behavior. We have found that the effects of co-culture persist for weeks after epithelial cell isolation, permitting ample time to perform multiple assays. This method is adaptable to cells of varying malignant potential and requires no specialized equipment. This technique allows for rapid evaluation of in vitro cell models under multiple conditions, and the corresponding results can be compared to in vivo animal tissue models as well as human tissue samples.

A simple method is described for analyzing effects of tissue fibroblasts on associated epithelial cells. The combination of this method and three-dimensional tissue culture can facilitate analysis of cells after isolation from 3D. The technique is applicable to cells of varying malignant potential, allowing systematic study of effects of tumor-associated stroma on tumor cells.

While enormous efforts have gone into identifying signaling pathways and molecules involved in normal and malignant cell behaviors1-2, much of this work ...

Biology

3D Co-culture of Lung Cancer Cells with CAFs: An In Vitro Model System to Study Tumor Progression

Source: Chen, S., et al. <a href="https://www.jove.com/v/60644/multidimensional-coculture-system-to-model-lung-squamous-carcinoma">Multidimensional Coculture System to Model Lung Squamous Carcinoma Progression.</a>&#160;J. Vis. Exp.&#160;(2020)
This video describes the two invitro model systems to capture the tissue architectural changes during lung squamous carcinoma progression in a 3-dimensional (3D) co-culture with cancer-associated fibroblasts. This system provides a unique platform to investigate the role of intrinsic and extrinsic changes that affect the tumor phenotype.

Three-dimensional Co-culture Model for Tumor-stromal Interaction

Summary

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Chapters in this video

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

Multidimensional Coculture System to Model Lung Squamous Carcinoma Progression

A Novel Stromal Fibroblast-Modulated 3D Tumor Spheroid Model for Studying Tumor-Stroma Interaction and Drug Discovery

Monitoring Cancer Cell Invasion and T-Cell Cytotoxicity in 3D Culture

A Three-Dimensional Spheroid Model to Investigate the Tumor-Stromal Interaction in Hepatocellular Carcinoma

Preparation and Analysis of In Vitro Three Dimensional Breast Carcinoma Surrogates

Heteromulticellular Stromal Cells in Scaffold-free 3D Cultures of Epithelial Cancer Cells to Drive Invasion

Three-Dimensional Culture Assay to Explore Cancer Cell Invasiveness and Satellite Tumor Formation

Isolation of Mammary Epithelial Cells from Three-dimensional Mixed-cell Spheroid Co-culture

3D Co-culture of Lung Cancer Cells with CAFs: An In Vitro Model System to Study Tumor Progression