This study was supported by Yeditepe University. All data and figures used in this article were previously published34.

Written informed consent of the patients was obtained after the approval from the Institutional Ethics Committee.
1. DPSC Isolation and Culture
<ol>
	<li>Transfer wisdom teeth obtained from young adults aged between 17 and 20 to 15 mL tubes containing complete Dulbecco&#39;s Modified Eagle Medium (DMEM) [low glucose DMEM media, supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin/amphotericin (PSA) solution], within 8 h after resection. Keep the tissue material cold ...

<ol>
	<li>Camberlain, G., Fox, J., Ashton, B., Middleton, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells:+their+phenotype,+differentiation+capacity,+immunological+features,+and+potential+for+homing.">Mesenchymal stem cells: their phenotype, differentiation capacity, immunological features, and potential for homing.</a> Stem Cells. 25 (11), 2739-2749 (2007).</li><li>Demirci, S., Do&#287;an, A., &#350;ahin, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Dental Stem Cells. , 109-124 (2016).</li><li>Fox, J. M., Chamberlain, G., Ashton, B. A., Middleton, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+into+the+understanding+of+mesenchymal+stem+cell+trafficking.">Recent advances into the understanding of mesenchymal stem cell trafficking.</a> British journal of haematology. 137 (6), 491-502 (2007).</li><li>Chang, A. I., Schwertschkow, A. H., Nolta, J. A., Wu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Involvement+of+mesenchymal+stem+cells+in+cancer+progression+and+metastases.">Involvement of mesenchymal stem cells in cancer progression and metastases.</a> Current cancer drug targets. 15 (2), 88-98 (2015).</li><li>Dvorak, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumors:+wounds+that+do+not+heal.">Tumors: wounds that do not heal.</a> New England Journal of Medicine. 315 (26), 1650-1659 (1986).</li><li>Lu, Y. -. 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=The+growth+inhibitory+effect+of+mesenchymal+stem+cells+on+tumor+cells+in+vitro+and+in+vivo.">The growth inhibitory effect of mesenchymal stem cells on tumor cells in vitro and in vivo.</a> Cancer biology &amp; therapy. 7 (2), 245-251 (2008).</li><li>Secchiero, P., 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=Human+bone+marrow+mesenchymal+stem+cells+display+anti-cancer+activity+in+SCID+mice+bearing+disseminated+non-Hodgkin's+lymphoma+xenografts.">Human bone marrow mesenchymal stem cells display anti-cancer activity in SCID mice bearing disseminated non-Hodgkin's lymphoma xenografts.</a> PloS one. 5 (6), e11140 (2010).</li><li>Hong, I. -. S., Lee, H. -. Y., Kang, K. -. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+and+cancer:+friends+or+enemies?.">Mesenchymal stem cells and cancer: friends or enemies?.</a> Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis. 768, 98-106 (2014).</li><li>Brennen, W. N., Chen, S., Denmeade, S. R., Isaacs, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+Mesenchymal+Stem+Cells+(MSCs)+at+sites+of+human+prostate+cancer.">Quantification of Mesenchymal Stem Cells (MSCs) at sites of human prostate cancer.</a> Oncotarget. 4 (1), 106 (2013).</li><li>Klopp, A. H., Gupta, A., Spaeth, E., Andreeff, M., Marini, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concise+review:+dissecting+a+discrepancy+in+the+literature:+do+mesenchymal+stem+cells+support+or+suppress+tumor+growth.">Concise review: dissecting a discrepancy in the literature: do mesenchymal stem cells support or suppress tumor growth.</a> Stem cells. 29 (1), 11-19 (2011).</li><li>Albini, A., Sporn, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+tumour+microenvironment+as+a+target+for+chemoprevention.">The tumour microenvironment as a target for chemoprevention.</a> Nature Reviews Cancer. 7 (2), 139 (2007).</li><li>Quante, 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=Bone+marrow-derived+myofibroblasts+contribute+to+the+mesenchymal+stem+cell+niche+and+promote+tumor+growth.">Bone marrow-derived myofibroblasts contribute to the mesenchymal stem cell niche and promote tumor growth.</a> Cancer cell. 19 (2), 257-272 (2011).</li><li>Gronthos, S., Mankani, M., Brahim, J., Robey, P. G., Shi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postnatal+human+dental+pulp+stem+cells+(DPSCs)+in+vitro+and+in+vivo.">Postnatal human dental pulp stem cells (DPSCs) in vitro and in vivo.</a> Proceedings of the National Academy of Sciences. 97 (25), 13625-13630 (2000).</li><li>Mori, G., 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=Dental+pulp+stem+cells:+osteogenic+differentiation+and+gene+expression.">Dental pulp stem cells: osteogenic differentiation and gene expression.</a> Annals of the new York Academy of Sciences. 1237 (1), 47-52 (2011).</li><li>Mori, G., 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=Osteogenic+properties+of+human+dental+pulp+stem+cells.">Osteogenic properties of human dental pulp stem cells.</a> Journal of biological regulators and homeostatic agents. 24 (2), 167-175 (2010).</li><li>Kerkis, I., 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=Isolation+and+characterization+of+a+population+of+immature+dental+pulp+stem+cells+expressing+OCT-4+and+other+embryonic+stem+cell+markers.">Isolation and characterization of a population of immature dental pulp stem cells expressing OCT-4 and other embryonic stem cell markers.</a> Cells Tissues Organs. 184 (3-4), 105-116 (2006).</li><li>Potdar, P. D., Jethmalani, Y. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+dental+pulp+stem+cells:+applications+in+future+regenerative+medicine.">Human dental pulp stem cells: applications in future regenerative medicine.</a> World journal of stem cells. 7 (5), 839 (2015).</li><li>Ahmed, N. E. -. M. B., Murakami, M., Hirose, Y., Nakashima, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutic+potential+of+dental+pulp+stem+cell+secretome+for+Alzheimer's+disease+treatment:+an+in+vitro+study.">Therapeutic potential of dental pulp stem cell secretome for Alzheimer's disease treatment: an in vitro study.</a> Stem cells international. 2016, (2016).</li><li>Gorin, 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=Priming+dental+pulp+stem+cells+with+fibroblast+growth+factor-2+increases+angiogenesis+of+implanted+tissue-engineered+constructs+through+hepatocyte+growth+factor+and+vascular+endothelial+growth+factor+secretion.">Priming dental pulp stem cells with fibroblast growth factor-2 increases angiogenesis of implanted tissue-engineered constructs through hepatocyte growth factor and vascular endothelial growth factor secretion.</a> Stem cells translational medicine. 5 (3), 392-404 (2016).</li><li>Wakayama, H., 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=Factors+secreted+from+dental+pulp+stem+cells+show+multifaceted+benefits+for+treating+acute+lung+injury+in+mice.">Factors secreted from dental pulp stem cells show multifaceted benefits for treating acute lung injury in mice.</a> Cytotherapy. 17 (8), 1119-1129 (2015).</li><li>Do&#287;an, 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=Differentiation+of+human+stem+cells+is+promoted+by+amphiphilic+pluronic+block+copolymers.">Differentiation of human stem cells is promoted by amphiphilic pluronic block copolymers.</a> International Journal of Nanomedicine. 7, 4849 (2012).</li><li>Ta&#351;l&#305;, P. N., Do&#287;an, A., Demirci, S., &#350;ahin, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Boron+enhances+odontogenic+and+osteogenic+differentiation+of+human+tooth+germ+stem+cells+(hTGSCs)+in+vitro.">Boron enhances odontogenic and osteogenic differentiation of human tooth germ stem cells (hTGSCs) in vitro.</a> Biological trace element research. 153 (1-3), 419-427 (2013).</li><li>Yalvac, 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=Isolation+and+characterization+of+stem+cells+derived+from+human+third+molar+tooth+germs+of+young+adults:+implications+in+neo-vascularization,+osteo-,+adipo-and+neurogenesis.">Isolation and characterization of stem cells derived from human third molar tooth germs of young adults: implications in neo-vascularization, osteo-, adipo-and neurogenesis.</a> The pharmacogenomics journal. 10 (2), 105 (2010).</li><li>Do&#287;an, 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=Sodium+pentaborate+pentahydrate+and+pluronic+containing+hydrogel+increases+cutaneous+wound+healing+in+vitro+and+in+vivo.">Sodium pentaborate pentahydrate and pluronic containing hydrogel increases cutaneous wound healing in vitro and in vivo.</a> Biological trace element research. 162 (1-3), 72-79 (2014).</li><li>Do&#287;an, A., Yalva&#231;, M. E., Y&#305;lmaz, A., Rizvanov, A., &#350;ahin, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+F68+on+cryopreservation+of+mesenchymal+stem+cells+derived+from+human+tooth+germ.">Effect of F68 on cryopreservation of mesenchymal stem cells derived from human tooth germ.</a> Applied biochemistry and biotechnology. 171 (7), 1819-1831 (2013).</li><li>Rizvanov, A. 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=Interaction+and+self-organization+of+human+mesenchymal+stem+cells+and+neuro-blastoma+SH-SY5Y+cells+under+co-culture+conditions:+A+novel+system+for+modeling+cancer+cell+micro-environment.">Interaction and self-organization of human mesenchymal stem cells and neuro-blastoma SH-SY5Y cells under co-culture conditions: A novel system for modeling cancer cell micro-environment.</a> European Journal of Pharmaceutics and Biopharmaceutics. 76 (2), 253-259 (2010).</li><li>Troiano, L., 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=Multiparametric+analysis+of+cells+with+different+mitochondrial+membrane+potential+during+apoptosis+by+polychromatic+flow+cytometry.">Multiparametric analysis of cells with different mitochondrial membrane potential during apoptosis by polychromatic flow cytometry.</a> Nature protocols. 2 (11), 2719 (2007).</li><li>Melzer, C., von der Ohe, J., Lehnert, H., Ungefroren, H., Hass, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+stem+cell+niche+models+and+contribution+by+mesenchymal+stroma/stem+cells.">Cancer stem cell niche models and contribution by mesenchymal stroma/stem cells.</a> Molecular cancer. 16 (1), 28 (2017).</li><li>Aguirre, A., Planell, J., Engel, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+of+bone+marrow-derived+endothelial+progenitor+cell/mesenchymal+stem+cell+interaction+in+co-culture+and+its+implications+in+angiogenesis.">Dynamics of bone marrow-derived endothelial progenitor cell/mesenchymal stem cell interaction in co-culture and its implications in angiogenesis.</a> Biochemical and biophysical research communications. 400 (2), 284-291 (2010).</li><li>Bogdanowicz, D. R., Lu, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biomimetics and Stem Cells. , 29-36 (2013).</li><li>Plotnikov, E., 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=Cell-to-cell+cross-talk+between+mesenchymal+stem+cells+and+cardiomyocytes+in+co-culture.">Cell-to-cell cross-talk between mesenchymal stem cells and cardiomyocytes in co-culture.</a> Journal of cellular and molecular. 12 (5a), 1622-1631 (2008).</li><li>Bogdanowicz, D. R., Lu, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studying+cell-cell+communication+in+co-culture.">Studying cell-cell communication in co-culture.</a> Biotechnology journal. 8 (4), 395-396 (2013).</li><li>Brunetti, G., 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=High+expression+of+TRAIL+by+osteoblastic+differentiated+dental+pulp+stem+cells+affects+myeloma+cell+viability.">High expression of TRAIL by osteoblastic differentiated dental pulp stem cells affects myeloma cell viability.</a> Oncology reports. 39 (4), 2031-2039 (2018).</li><li>Do&#287;an, A., Demirci, S., Apdik, H., Apdik, E. 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The authors have nothing to disclose.

Contribution of MSCs to tumor environment is regulated by several interactions including hybrid cell generation via cell fusions, entosis or cytokine and chemokine activities between stem cells and cancer cells28. Structural organization, cell-cell interactions, and secreted factors determine cancer cell behavior in terms of tumor promotion, progression, and metastasis to surrounding tissue. Proper ex vivo model systems to investigate the mechanisms behind the interactions of res...

Mesenchymal stem cells (MSCs), with&#160;the ability of differentiation and contribution to regeneration of mesenchymal tissues such as bone, cartilage, muscle, ligament, tendon, and adipose, have been isolated from almost all tissues in the adult body1,2. Other than providing tissue homeostasis by producing resident cells in case of chronic inflammation or an injury, they produce vital cytokines and growth factors to orchestrate angiogenesis, immune system, and tissue remodeling3. The interaction of MSCs with cancer tissue is not well-understood, but accumulating evidence suggests that MSCs might promote tumor initiation, progression, and metastasis4.
The homing ability of MSCs to the injured or chronically inflamed area makes them a valuable candidate for stem cell-based therapies. However, cancer tissues, &#34;never healing wounds&#34;, also release inflammatory cytokines, pro-angiogenic molecules, and vital growth factors, which attract MSCs to the cancerogenous area5. While there are limited reports showing inhibitory effects of MSCs on cancer growth6,7, their cancer progression and metastasis promoting effects have been extensively reported8. MSCs directly or indirectly affect carcinogenesis in different ways including suppressing immune cells, secreting growth factors/cytokines that support cancer cell proliferation and migration, enhancing angiogenic activity, and regulating epithelial-mesenchymal transition (EMT)9,10. Tumor environment consists of several cell types including cancer-associated fibroblasts (CAFs) and/or myofibroblasts, endothelial cells, adipocytes, and immune cells11. Of those, CAFs are the most abundant cell type in the tumor area that secrete various chemokines promoting cancer growth and metastasis8. It has been shown that bone marrow-derived MSCs can differentiate into CAFs in the tumor stroma12.
Dental pulp stem cells (DPSCs), characterized as the first dental tissue-derived MSCs by Gronthos et al.13 in 2000 and then widely investigated by others14,15, express pluripotency markers such as Oct4, Sox2, and Nanog16 and can differentiate into various cell linages17. Gene and protein expression analysis proved that DPSCs produce comparable levels of growth factors/cytokines with other MSCs such as vascular endothelial growth factor (VEGF), angiogenin, fibroblast growth factor 2 (FGF2), interleukin-4 (IL-4), IL-6, IL-10, and stem cell factor (SCF), as well as fms-like tyrosine kinase-3 ligand (Flt-3L) that might promote angiogenesis, modulate immune cells, and support cancer cell proliferation and migration18,19,20. While the interactions of MSCs with cancer environment have been well-documented in the literature, the relationship between DPSCs and cancer cells has not been evaluated yet. In the present study, we established co-culture and condition medium treatment strategies for a highly metastatic prostate cancer cell line, PC-3, and DPSCs to propose potential action of mechanism of dental MSCs in cancer progression and metastasis.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>DMEM</td>
			<td>Invitrogen</td>
			<td>11885084</td>
			<td>For cell culture</td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Invitrogen</td>
			<td>16000044</td>
			<td>For cell culture</td>
		</tr>
		<tr>
			<td>PSA</td>
			<td>Lonza</td>
			<td>17-745E</td>
			<td>For cell culture</td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Invitrogen</td>
			<td>25200056</td>
			<td>For cell dissociation</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Invitrogen</td>
			<td>10010023</td>
			<td>For washes</td>
		</tr>
		<tr>
			<td>Dexamethasone</td>
			<td>Sigma</td>
			<td>D4902</td>
			<td>Component of differentiation media</td>
		</tr>
		<tr>
			<td>&#946;-Glycerophosphate</td>
			<td>Sigma</td>
			<td>G9422</td>
			<td>Component of osteogenic differentiation medium</td>
		</tr>
		<tr>
			<td>Ascorbic acid</td>
			<td>Sigma</td>
			<td>A4544</td>
			<td>Component of osteo- and chondro-genic differentiation medium</td>
		</tr>
		<tr>
			<td>Insulin-Transferrin-Selenium (ITS &#8722;G)</td>
			<td>Invitrogen</td>
			<td>41400045</td>
			<td>Component of chondrogenic differentiation medium</td>
		</tr>
		<tr>
			<td>TGF-&#946;</td>
			<td>Sigma</td>
			<td>SRP3171</td>
			<td>Component of chondrogenic differentiation medium</td>
		</tr>
		<tr>
			<td>Insulin</td>
			<td>Sigma</td>
			<td>I6634</td>
			<td>Component of adipogenic differentiation medium</td>
		</tr>
		<tr>
			<td>Isobutyl-1-methylxanthine (IBMX)</td>
			<td>Sigma</td>
			<td>I7018</td>
			<td>Component of adipogenic differentiation medium</td>
		</tr>
		<tr>
			<td>Indomethacin</td>
			<td>Sigma</td>
			<td>I7378</td>
			<td>Component of adipogenic differentiation medium</td>
		</tr>
		<tr>
			<td>MTS Reagent</td>
			<td>Promega</td>
			<td>G3582</td>
			<td>Cell viability analyses</td>
		</tr>
		<tr>
			<td>TUNEL Assay</td>
			<td>Sigma</td>
			<td>11684795910</td>
			<td>Apoptotic analyses</td>
		</tr>
		<tr>
			<td>24-well plate inserts</td>
			<td>Corning</td>
			<td>3396</td>
			<td>For trans-well migration assay</td>
		</tr>
		<tr>
			<td>PKH67</td>
			<td>Sigma</td>
			<td>PKH67GL</td>
			<td>For co-culture cell staining</td>
		</tr>
		<tr>
			<td>PKH26</td>
			<td>Sigma</td>
			<td>PKH26GL</td>
			<td>For co-culture cell staining</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma</td>
			<td>P6148</td>
			<td>For cell fixation</td>
		</tr>
		<tr>
			<td>von Kossa Kit</td>
			<td>BioOptica</td>
			<td>04-170801.A</td>
			<td>For cell staining (differentiation)</td>
		</tr>
		<tr>
			<td>Alcian blue</td>
			<td>Sigma</td>
			<td>A2899</td>
			<td>For cell staining (differentiation)</td>
		</tr>
	</tbody>
</table>

mesenchymal stem cell isolation from pulp tissue and co-culture with cancer cells to study their interactions

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

Figure 1 depicts the general MSC characteristics of DPSCs under culture conditions. DPSCs exert fibroblast-like cell morphology after plating (Figure 1B). MSC surface antigens (CD29, CD73, CD90, CD105, and CD166) are highly expressed while hematopoietic markers (CD34, CD45, and CD14) are negative (Figure 1C). Changes at the morphological and molecular level related to osteo-, chondro-, and adipo-geni...

Watch this Scientific Journal Video about Mesenchymal Stem Cell Isolation from Pulp Tissue and Co-Culture with Cancer Cells to Study Their Interactions at JoVE.com

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

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

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

This method can help answer key questions in the stem cell field about the role of adult stem cells in the regulation of cancer cell behavior. The main advantage of this technique is that it allows the evaluation of cancer cell and stem cell interactions in vitro without the use of living organisms. This technique has potential for cancer metastasis as it models the promoting role of adult stem cells in cancer metastasis to hard tissues such as bone.Demonstration of the procedure will be carried out by Huseyin Apdik, a post-doctoral in my laboratory. Begin by using sterile extraction forceps to remove the pulp tissue from the center of wisdom teeth obtained from young adults aged 17 to 20 years old. Place the tissue in cold complete DMEM in 10-centimeter tissue culture dishes and use a scalpel to mince the samples into two to three-millimeter fragments.Transfer the pieces from each dish into individual wells of a tissue culture treated six-well plate and cover the tissues in each well with 200 microliters of complete DMEM. Allow the tissues to attach to the well bottoms with an at least two-hour incubation in a humidified, 37 degree Celsius and 5%CO2 cell culture incubator. At the end of the incubation, feed the tissues with two to 2.5 milliliters of fresh complete medium and culture the cells for an additional eight to nine days.When the culture has reached 80%confluency, wash each well with two milliliters of PBS followed by detachment of the cells with two milliliters of trypsin at 37 degrees Celsius. After two minutes, stop the reaction with two milliliters of complete DMEM per well and collect the cells by centrifugation. Then, resuspend the pellets in 15 milliliters of fresh complete medium per two wells of cells and passage the cells into T75 flasks for their subsequent culture.After at least eight passages, visualize the cells by light microscopy. The dental pulp stem cells should have attached to the culture dishes and should display a spindle-like cell morphology. For surface marker analysis, after trypsinization is demonstrated, fix the cells with 4%paraformaldehyde for 20 minutes at room temperature in 1.5-milliliter tubes followed by three washes in 500 microliters of PBS per wash.After the last wash, label the cells with the appropriate antibodies of interest in 100 microliters of PBS per tube for one hour at four degrees Celsius. At the end of the incubation, wash the cells three times in PBS as demonstrated and label the cells with the appropriate secondary antibodies in 100 microliters of PBS per tube for 30 minutes at four degrees Celsius. Then wash the samples three times in PBS and analyze the cells by flow cytometry according to standard protocols.For differentiation of the dental pulp stem cells, seed one times 10 to the four cells into individual wells of 24-well plates in 500 microliters of complete DMEM for a 24-hour incubation in the cell culture incubator. The next day, replace the medium in each well with the appropriate differentiation medium and return the cells to the incubator, refreshing the medium twice a week for two weeks. Differentiation can be confirmed by von Kossa and Alcian blue staining according to standard protocols.After two to four passages, collect the conditioned medium supernatants from the cultured dental pulp stem cells when the cultures reach 80%confluency. Then, centrifuge the collected medium to remove any waste tissue material and cell debris and store the medium at negative 20 degrees Celsius until use. For cancer cell treatment, seed one times 10 to the five tumor cells into individual wells of a 12-well plate for overnight incubation at 37 degrees Celsius and 5%CO2.The next morning, use a sterile 200-microliter tip to make a scratch injury in each well and immediately replace the supernatant in each well with fresh medium containing various concentrations of conditioned medium. Then, immediately observe the scratches under an inverted microscope and obtain images of the injured cultures at regular time intervals. At the end of the analysis, measure the scratch closure over time in ImageJ.To assess dental pulp stem cell migration, first seed three times 10 to the four dental pulp stem cells onto individual 24-well plate inserts with 0.4 micron pores in 250 microliters of DMEM and incubate the inserts overnight at 37 degrees Celsius. Next, seed five times 10 the four tumor cells into individual wells of a 24-well plate in 500 microliters of DMEM for overnight incubation at 37 degrees Celsius. The next morning, scratch the tumor cells as demonstrated.Replace the supernatants with 500 microliters of fresh DMEM and place one dental pulp stem cell seeded insert into each well fed with fresh medium. Then immediately observe cells on an inverted microscope and image the cells at regular intervals to assess dental pulp stem cell migration. To assess the direct interactions of dental pulp stem cells with cancer cells, trypsinize each labeled culture to obtain single-cell suspensions and collect the dissociated cells by centrifugation.Resuspend the pellets in distinct cell linker dye solutions prepared in diluent C buffer, supplied according to the manufacturer's instructions, and incubate the cells are room temperature for 10 minutes. Terminate the staining reaction with 100 microliters of fetal bovine serum and collect the cells by centrifugation. Then centrifuge the cells with complete growth medium before plating five times 10 to the four dental pulp stem cell and tumor cells per well in a six-well plate at a one to one ratio in two milliliters of complete medium.Collect the cells after 24 or 48 hours of incubation by centrifugation followed by a wash in PBS. Then, resuspend the cells in 300 microliters of fluorescence-activated cell sorting buffer in five-milliliter round-bottom flow cytometry tubes and vortex to disperse any cell aggregates before analyzing the cells according to standard flow cytometric analysis protocols. Dental pulp stem cells exhibit a fibroblast-like cell morphology after plating and express mesenchymal stem cell surface antigens but not hematopoietic cell markers.Changes at the morphological and molecular level related to osteo, chondro, and adipogenic differentiation are also observed in the dental pulp stem cell cultures following the appropriate differentiation cocktail application. The treatment of scratch-injured tumor cell cultures with 10 and 20%concentrations of conditioned medium increases the scratch closure significantly compared to control-medium-treated tumor cell cultures. Secreted molecules from dental pulp stem cell insert co-cultures also increased scratch closure in injured tumor cells compared to control cell co-cultures.Fluorescence microscope analysis of the interactions of dental pulp stem and tumor cell within an in vitro cell culture reveals the creation of a well-organized structure within which tumor cells rapidly proliferate after 48 hours. While attempting this procedure, it's important to remember to keep two tissue samples in cold medium and immediately transport samples to the laboratory to minimize cell death. After its development, this technique paved the way for researchers in the stem cell fields in exploring adult stem cell cancer interactions in humans.Following this procedure, other methods like immune cell tracing for differential labeled cells of various stem cell and cancer types can be performed to answer additional question about how adult stem cells interact with cancer cells and control cancer metastasis. Don't forget that working with the human samples can be dangerous and that precautions such as analyzing patient samples for infectious diseases and obtaining written patient consent should always be implemented when performing this procedure.

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Cancer Research

10.2K vues.  Yeditepe University. Cette méthode peut aider à répondre à des questions clés dans le domaine des cellules souches sur le rôle des cellules souches adultes dans la régulation du comportement des cellules cancéreuses. Le principal avantage de cette technique est qu’elle permet l’évaluation in vitro des interactions des cellules cancéreuses et des cellules souches sans l’utilisation d’organismes vivants. Cette technique a un potentiel de métastase du cancer car elle modèle le rôle de promotion ...