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 border="0" cellpadding="0" cellspacing="0" width="1035">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:267px;">Name</td>
			<td style="width:297px;">Company</td>
			<td style="width:471px;">Catalog Number</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">DMEM</td>
			<td style="width:297px;">Sigma-Aldrich</td>
			<td style="width:471px;">D5796</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">FBS</td>
			<td style="width:297px;">GIBCO</td>
			<td style="width:471px;">10437</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">Collagen type IA</td>
			<td style="width:297px;">Nitta gelatin Inc.</td>
			<td style="width:471px;">CELL-1A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">Reconstitution buffer</td>
			<td style="width:297px;">Nitta gelatin Inc.</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">Cover slip</td>
			<td style="width:297px;">NUNC</td>
			<td style="width:471px;">174934</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">Silicone grease</td>
			<td style="width:297px;">Dow Corning Toray</td>
			<td style="width:471px;">High vacuum grease</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">Dispase I</td>
			<td style="width:297px;">WAKO</td>
			<td style="width:471px;">386-02271</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">6-well plate</td>
			<td style="width:297px;">BD Falcon</td>
			<td style="width:471px;">353046</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:267px;">Cell strainer (70 &#956;m)</td>
			<td style="width:297px;">BD Falcon</td>
			<td style="width:471px;">352350</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

Experimental Generation of Carcinoma-Associated Fibroblasts (CAFs) from Human Mammary Fibroblasts

Carcinomas are complex tissues comprised of neoplastic cells and a non-cancerous compartment referred to as the 'stroma'. The stroma consists of extracellular matrix (ECM) and a variety of mesenchymal cells, including fibroblasts, myofibroblasts, endothelial cells, pericytes and leukocytes 1-3.
The tumour-associated stroma is responsive to substantial paracrine signals released by neighbouring carcinoma cells. During the disease process, the stroma often becomes populated by carcinoma-associated fibroblasts (CAFs) including large numbers of myofibroblasts. These cells have previously been extracted from many different types of human carcinomas for their in vitro culture. A subpopulation of CAFs is distinguishable through their up-regulation of &alpha;-smooth muscle actin (&alpha;-SMA) expression4,5. These cells are a hallmark of 'activated fibroblasts' that share similar properties with myofibroblasts commonly observed in injured and fibrotic tissues 6. The presence of this myofibroblastic CAF subset is highly related to high-grade malignancies and associated with poor prognoses in patients.
Many laboratories, including our own, have shown that CAFs, when injected with carcinoma cells into immunodeficient mice, are capable of substantially promoting tumourigenesis 7-10. CAFs prepared from carcinoma patients, however, frequently undergo senescence during propagation in culture limiting the extensiveness of their use throughout ongoing experimentation. To overcome this difficulty, we developed a novel technique to experimentally generate immortalised human mammary CAF cell lines (exp-CAFs) from human mammary fibroblasts, using a coimplantation breast tumour xenograft model.
In order to generate exp-CAFs, parental human mammary fibroblasts, obtained from the reduction mammoplasty tissue, were first immortalised with hTERT, the catalytic subunit of the telomerase holoenzyme, and engineered to express GFP and a puromycin resistance gene. These cells were coimplanted with MCF-7 human breast carcinoma cells expressing an activated ras oncogene (MCF-7-ras cells) into a mouse xenograft. After a period of incubation in vivo, the initially injected human mammary fibroblasts were extracted from the tumour xenografts on the basis of their puromycin resistance 11.
We observed that the resident human mammary fibroblasts have differentiated, adopting a myofibroblastic phenotype and acquired tumour-promoting properties during the course of tumour progression. Importantly, these cells, defined as exp-CAFs, closely mimic the tumour-promoting myofibroblastic phenotype of CAFs isolated from breast carcinomas dissected from patients. Our tumour xenograft-derived exp-CAFs therefore provide an effective model to study the biology of CAFs in human breast carcinomas. The described protocol may also be extended for generating and characterising various CAF populations derived from other types of human carcinomas.

Experimental Generation of Carcinoma-Associated Fibroblasts CAFs from Human Mammary Fibroblasts

Carcinoma-associated fibroblasts (CAFs) rich in myofibroblasts present within the tumour stroma, play a major role in driving tumour progression. We developed a coimplantation tumour xengraft model for experimentally generating CAFs from human mammary fibroblasts. The protocol describes how to establish CAF myofibroblasts that acquire an ability to promote tumourigenesis.

Carcinomas are complex tissues comprised of neoplastic cells and a non-cancerous compartment referred to as the 'stroma'. The stroma consists of ...

Human Neuroendocrine Tumor Cell Lines as a Three-Dimensional Model for the Study of Human Neuroendocrine Tumor Therapy

Neuroendocrine tumors (NETs) are rare tumors, with an incidence of two per 100,&#x200A;000 individuals per year, and they account for 0.5% of all human malignancies.1 Other than surgery for the minority of patients who present with localized disease, there is little or no survival benefit of systemic therapy. Therefore, there is a great need to better understand the biology of NETs, and in particular define new therapeutic targets for patients with nonresectable or metastatic neuroendocrine tumors. 3D cell culture is becoming a popular method for drug screening due to its relevance in modeling the in vivo tumor tissue organization and microenvironment.2,3 The 3D multicellular spheroids could provide valuable information in a more timely and less expensive manner than directly proceeding from 2D cell culture experiments to animal (murine) models.
To facilitate the discovery of new therapeutics for NET patients, we have developed an in vitro 3D multicellular spheroids model using the human NET cell lines. The NET cells are plated in a non-adhesive agarose-coated 24-well plate and incubated under physiological conditions (5% CO2, 37 &deg;C) with a very slow agitation for 16-24 hr after plating. The cells form multicellular spheroids starting on the 3rd or 4th day. The spheroids become more spherical by the 6th day, at which point the drug treatments are initiated. The efficacy of the drug treatments on the NET spheroids is monitored based on the morphology, shape and size of the spheroids with a phase-contrast light microscope. The size of the spheroids is estimated automatically using a custom-developed MATLAB program based on an active contour algorithm. Further, we demonstrate a simple method to process the HistoGel embedding on these 3D spheroids, allowing the use of standard histological and immunohistochemical techniques. 
This is the first report on generating 3D spheroids using NET cell lines to examine the effect of therapeutic drugs. We have also performed histology on these 3D spheroids, and displayed an example of a single drug's effect on growth and proliferation of the NET spheroids. Our results support that the NET spheroids are valuable for further studies of NET biology and drug development.

We present a simple agarose overlay platform to grow 3D multicellular spheroids using neuroendocrine cancer cell lines. This method provides a very convenient way to examine the effect of therapeutic drugs on the neuroendocrine tumor cells. It could also help us establish human neuroendocrine tumor spheroids for cancer therapy.

Neuroendocrine tumors (NETs) are rare tumors, with an incidence of two per 100,&#x200A;000 individuals per year, and they account for 0.5% of all human ...

A Three-dimensional Tissue Culture Model to Study Primary Human Bone Marrow and its Malignancies

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods rely on the ability of cells either to attach to a solid substratum of a tissue culture dish or to grow in suspension in liquid medium. Multiple immortal cell lines have been created and grown using such approaches, however, these methods frequently fail when primary cells need to be grown ex vivo. Such failure has been attributed to the absence of the appropriate extracellular matrix components of the tissue microenvironment from the standard systems where tissue culture plastic is used as a surface for cell growth. Extracellular matrix is an integral component of the tissue microenvironment and its presence is crucial for the maintenance of physiological functions such as cell polarization, survival, and proliferation. Here we present a 3-dimensional tissue culture method where primary bone marrow cells are grown in extracellular matrix formulated to recapitulate the microenvironment of the human bone (rBM system). Embedded in the extracellular matrix, cells are supplied with nutrients through the medium supplemented with human plasma, thus providing a comprehensive system where cell survival and proliferation can be sustained for up to 30 days while maintaining the cellular composition of the primary tissue. Using the rBM system we have successfully grown primary bone marrow cells from normal donors and patients with amyloidosis, and various hematological malignancies. The rBM system allows for direct, in-matrix real time visualization of the cell behavior and evaluation of preclinical efficacy of novel therapeutics. Moreover, cells can be isolated from the rBM and subsequently used for in vivo transplantation, cell sorting, flow cytometry, and nucleic acid and protein analysis. Taken together, the rBM method provides a reliable system for the growth of primary bone marrow cells under physiological conditions.

In standard culture methods cells are taken out of their physiological environment and grown on the plastic surface of a dish. To study the behavior of primary human bone marrow cells we created a 3-D culture system where cells are grown under conditions recapitulating the native microenvironment of the tissue.

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods ...

Quantification of Breast Cancer Cell Invasiveness Using a Three-dimensional (3D) Model

It is now well known that the cellular and tissue microenvironment are critical regulators influencing tumor initiation and progression. Moreover, the extracellular matrix (ECM) has been demonstrated to be a critical regulator of cell behavior in culture and homeostasis in vivo. The current approach of culturing cells on two-dimensional (2D), plastic surfaces results in the disturbance and loss of complex interactions between cells and their microenvironment. Through the use of three-dimensional (3D) culture assays, the conditions for cell-microenvironment interaction are established resembling the in vivo microenvironment. This article provides a detailed methodology to grow breast cancer cells in a 3D basement membrane protein matrix, exemplifying the potential of 3D culture in the assessment of cell invasion into the surrounding environment. In addition, we discuss how these 3D assays have the potential to examine the loss of signaling molecules that regulate epithelial morphology by immunostaining procedures. These studies aid to identify important mechanistic details into the processes regulating invasion, required for the spread of breast cancer.

Quantification of Breast Cancer Cell Invasiveness Using a Three-dimensional 3D Model

This article provides detailed methodologies for the use of three-dimensional (3D) assays to quantify breast cancer cell invasion. Specifically, we discuss the procedures required to set up such assays, quantification, and data analysis, as well as methods to examine the loss of membrane integrity that occurs when cells invade.

It is now well known that the cellular and tissue microenvironment are critical regulators influencing tumor initiation and progression. Moreover, the ...

Three-Dimensional (3D) Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in particular (e.g., brain tumors such as glioblastoma multiforme and squamous cell carcinoma of the head and neck &#8211; SCCHN) it is a cause of severe morbidity and can be life-threatening even in the absence of distant metastases. In addition, cancers which have relapsed following treatment unfortunately often present with a more aggressive phenotype. Therefore, there is an opportunity to target the process of invasion to provide novel therapies that could be complementary to standard anti-proliferative agents. Until now, this strategy has been hampered by the lack of robust, reproducible assays suitable for a detailed analysis of invasion and for drug screening. Here we provide a simple micro-plate method (based on uniform, self-assembling 3D tumor spheroids) which has great potential for such studies. We exemplify the assay platform using a human glioblastoma cell line and also an SCCHN model where the development of resistance against targeted epidermal growth factor receptor (EGFR) inhibitors is associated with enhanced matrix-invasive potential. We also provide two alternative methods of semi-automated quantification: one using an imaging cytometer and a second which simply requires standard microscopy and image capture with digital image analysis.

Three-Dimensional 3D Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is a defining characteristic of malignant tumors. We provide here a simple, semi-automated micro-plate assay of invasion into a natural 3D biomatrix that has been exemplified with a number of models of advanced human cancers.

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in ...

Three-dimensional Alginate-bead Culture of Human Pituitary Adenoma Cells

A three-dimensional culture method is described in which primary pituitary adenoma cells are grown in alginate beads. Alginate is a polymer derived from brown sea algae. Briefly, the tumor tissue is cut into small pieces and submitted to an enzymatic digestion with collagenase and trypsin. Next, a cell suspension is obtained. The tumor cell suspension is mixed with 1.2% sodium alginate and dropped into a CaCl2 solution, and the alginate/cell suspension is gelled on contact with the CaCl2 to form spherical beads. The cells embedded in the alginate beads are supplied with nutrients provided by the culture media enriched with 20% FBS. Three-dimensional culture in alginate beads maintains the viability of adenoma cells for long periods of time, up to four months. Moreover, the cells can be liberated from the alginate by washing the beads with sodium citrate and seeded on glass coverslips for further immunocytochemical analyses. The use of a cell culture model allows for the fixation and visualization of the actin cytoskeleton with minimal disorganization. In summary, alginate beads provide a reliable culture system for the maintenance of pituitary adenoma cells.

Three-dimensional culture in alginate beads, due to its simplicity and reproducibility, was chosen to maintain the pituitary adenoma cells. The procedures included an initial enzymatic digestion and mechanical dissociation of the tumor tissue, and the subsequent cell suspension was encapsulated in alginate beads.

A three-dimensional culture method is described in which primary pituitary adenoma cells are grown in alginate beads. Alginate is a polymer derived from ...

Three-Dimensional Printing of a Complex Aortic Anomaly

Complex congenital aortic anomalies include diverse types of malformations that may be clinically asymptomatic or present with respiratory or esophageal symptoms. These anomalies may be associated with other congenital heart diseases. It is hard to identify the accurate anatomic vessel location from two-dimensional imaging data, such as computed tomography. As an additive manufacturing method, three-dimensional (3-D) printing can covert the acquired imaging data into 3-D physical models. This protocol describes the procedure for modeling the volumetric DICOM imaging into 3-D data and printing it as an anatomically realistic 3-D model. Using this model, surgeons can identify the vessel location of complex aortic anomalies, which is helpful for pre-operative planning and intra-operative guidance.

Here, we present a protocol to use three dimensional printed models for pre-operative planning and intra-operative reorganization of complicated vascular locations when handling a congenital aortic anomaly.

Complex congenital aortic anomalies include diverse types of malformations that may be clinically asymptomatic or present with respiratory or esophageal ...

Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty (PVP)

Percutaneous vertebroplasty (PVP) is considered an effective treatment for the back pain caused by osteoporotic vertebral compression fracture. The accuracy of PVP mainly depends on the surgeons&#39; experience and multiple fluoroscopes during a traditional procedure. Puncture related complications were reported all over the world. To make the surgical procedure more precise and decrease the rate of puncture-related complications, our team applied a three-dimensional printing guide template to PVP to modify the traditional procedure. This protocol introduces how to model target vertebrae DICOM imaging data into three-dimensions in the software, how to simulate operation in this 3-D model, and how to use all of the surgical data to reconstruct a patient specific template for application. Using this template, surgeons can identify suitable puncture points accurately to improve the accuracy of the operation. The whole protocol includes: 1) diagnosis of the osteoporotic vertebral compression fracture; 2) acquisition of CT imaging of the target vertebra; 3) simulation of the operation in the software; 4) design and fabrication of the 3-D printing guide template; and 5) application of the template into an operation procedure.

Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty PVP

Herein, we present a three-dimensional printing guide template for percutaneous vertebraplasty. A patient with a T11 vertebral compression fracture was selected as a case study.

Percutaneous vertebroplasty (PVP) is considered an effective treatment for the back pain caused by osteoporotic vertebral compression fracture. The ...

High-Resolution Three-Dimensional Imaging of the Footpad Vasculature in a Murine Hindlimb Gangrene Model

Peripheral arterial disease (PAD) is a significant cause of morbidity resulting from chronic exposure to atherosclerotic risk factors. Patients suffering from its most severe form, chronic limb-threatening ischemia (CLTI), face substantial impairments to daily living, including chronic pain, limited walking distance without pain, and nonhealing wounds. Preclinical models have been developed in various animals to study PAD, but mouse hindlimb ischemia remains the most widely used. There can be significant variation in response to ischemic insult in these models depending on the mouse strain used and the site, number, and means of arterial disruption. This protocol describes a unique method combining femoral artery and vein electrocoagulation with the administration of a nitric oxide synthase (NOS) inhibitor to reliably induce footpad gangrene in Friend Virus B (FVB) mice that resembles the tissue loss of CLTI. While traditional means of assessing reperfusion such as laser Doppler perfusion imaging (LDPI) are still recommended, intracardiac perfusion of the lipophilic dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) is used to label the vasculature. Subsequent whole-mount confocal laser scanning microscopy allows for high-resolution, three-dimensional (3D) reconstruction of footpad vascular networks that complements traditional means of assessing reperfusion in hindlimb ischemia models.

The present protocol describes a unique, clinically relevant model of peripheral arterial disease that combines femoral artery and vein electrocoagulation with the administration of a nitric oxide synthase inhibitor to induce hindlimb gangrene in FVB mice. Intracardiac DiI perfusion is then used for high-resolution, three-dimensional imaging of the footpad vasculature.

Peripheral arterial disease (PAD) is a significant cause of morbidity resulting from chronic exposure to atherosclerotic risk factors. Patients suffering ...

Guided Endodontics: Three-Dimensional Planning and Template-Aided Preparation of Endodontic Access Cavities

Pulp canal obliterations (PCO) are often a consequence of dental trauma, such as luxation injuries. Even though dentin apposition is a sign of vital pulp, pulpitis or apical periodontitis may develop in the long term. Root canal treatment of teeth with severe PCO and pulpal or periapical pathosis is challenging for general practitioners and even for well-equipped endodontic specialists. To ensure detection of the calcified root canal and avoid excessive loss of tooth structure or root perforation, static navigation using templates ("Guided Endodontics") was introduced a few years ago. The general workflow includes three-dimensional imaging using cone-beam computed tomography (CBCT), a digital surface scan, and superimposition of both in a planning software. This is followed by virtual planning of the access cavity and the design of a template that will guide the drill to the desired target point. To do this, a true-to-scale virtual image of the drill must be placed in a way that the tip of the drill reaches the orifice of the calcified root canal. Once the template has been fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM) or a 3D printer, guided preparation of the access cavity can be performed clinically. For research purposes, a postoperative CBCT image can be used to quantify the accuracy of the access cavity performed. This work aims to present the technique of static guided endodontics from imaging to clinical implementation.

Guided endodontics describes a template-aided approach for access cavity preparation. The procedure requires cone-beam computed tomography and a surface scan to produce a template. An incorporated sleeve guides the drill to the target point. This allows the preparation of minimally invasive endodontic access cavities in calcified teeth.

Pulp canal obliterations (PCO) are often a consequence of dental trauma, such as luxation injuries. Even though dentin apposition is a sign of vital pulp, ...