This study was supported by a grant from the Baden-W&#252;rttemberg Stiftung (Adult Stem Cells Program II) awarded to C.L. We thank Dr. Martina Konantz for critical input and review of the manuscript. We thank Emmanuel Traunecker and Toni Krebs from the DBM FACS Facility (University Hospital Basel) for assistance with FACS sorting.

1. Generation of OVCAR-3 Human ovarian Carcinoma Cells Stably Transduced with Lentiviruses Containing the SOX2 Regulatory Region Reporter Construct
<ol>
	<li>Generate lentiviral particles by transfecting the HEK 293T-packaging cell line with a reporter construct recognizing a SOX2 regulatory region as described10,21. 
	NOTE: The reporter construct further contains a destabilization domain of the ProteoTuner Shield System ahead of the tdTomato fluorescence protein. Shield1 binds to the destabilization domain thereby preventing the proteasome to degrade the fluorescence protein22.</li>
	<li>Transduce OVCAR-3 cells with lentiviral particles over a time period of 24 hr. Afterwards, remove the viral supernatant and wash the cells with phosphate buffered saline (PBS) and cultured in complete medium (RPMI supplemented with 10% FBS, 100 U/ml penicillin, 100 &#956;g/ml streptomycin).</li>
	<li>48 hr later, 10 &#956;g/ml puromycin were added to the cultures and maintained for 5 days to allow selection of properly transduced cells.</li>
</ol>
2. Preparation of Cell Sorting and Plating
<ol>
	<li>Add Shield1 at 1:1,000 dilution 24 hr prior to cell sorting. Use stably transduced OVCAR-3 cells without Shield1 treatment as negative controls (Figure 1). Aspirate media from flask, wash cells with 1x PBS and trypsinize cells with 0.05% Trypsin-EDTA for 3 min.</li>
	<li>Stop trypsin by using complete medium (see above), count cell numbers, centrifuge cells at 300 x g at RT (15 - 25 &#176;C) for 5 min.</li>
	<li>Decant supernatant and resuspend cells carefully in 0.5 - 1 ml sterile PBS.</li>
	<li>Use 40 &#181;m cell strainer cap filter to obtain single-cell suspension.</li>
	<li>Adjust cell count to 5 million cells per ml.</li>
	<li>Prepare ultra low-attachment 96-well plates with 100 &#956;l spheres medium (MEGM supplemented with growth factors, cytokines, and supplements, B-27, heparine-sodium; or DMEM/F12 supplemented with growth factors, cytokines, and supplements, B-27, heparine-sodium with or without addition of 1% methylcellulose, see also Table 1). Optionally add antibiotics to the medium at a concentration of 100 U/ml penicillin and 100 &#956;g/ml streptomycin to minimize the risk of possible contamination.</li>
	<li>Sort RFP+ and RFP- cells into prepared 96-well plates from above, 1 cell per well (single cell-based spheres assay) and 100 cells per well (multi cell-based spheres assay), respectively. Perform sort on commercially available cell sorter (see Materials) using single cell mode, Sort setup: 100 &#956; nozzle, sheath pressure 20 psi, and yield mask 0, purity mask 32, phase mask 16.</li>
	<li>Assess plating efficiency by microscopically scoring wells containing cells (for the single cell-based assay) and by counting cell numbers in individual wells (for the multi cell-based assay; Figure 2).</li>
	<li>Incubate cells under standard conditions in spheres medium (for composition see step 2.6) at 37 &#176;C and 5% CO2. Supplement daily bFGF (20 ng/ml) and EGF (20 ng/ml).</li>
	<li>After one week, count numbers of emerging tumor spheres using a standard microscope with 4X or 10X magnification and a fluorescence microscope to detect fluorescence signal from the integrated reporter system. Count spheres with a diameter exceeding 100 &#956;m as &#8220;large&#8221; spheres, and spheres with a diameter 50 - 100 &#956;m as &#8220;small&#8221; spheres (Figure 3). Be sure that you count real spheres and not cell clusters. 
	NOTE: In single cell-based assays sphere formation is easier to score microscopically after 10 (versus 7) days of culture.</li>
	<li>Calculate the proportion of sphere-forming cells in RFP+ and respectively RFP- cells in single cell-based assays (one 96-well plate for each individual experiment) or multi cell-based spheres assays (one well for each individual experiment) as presented by Shaw et al.16 
	NOTE: Proportion of sphere forming cells (%) = (number of spheres) / (number of seeded cells) x 100</li>
</ol>
3. Serial Passaging of Spheres
<ol>
	<li>Place the content of each well in an appropriate sterile tube and centrifuge at 300 x g for 10 min at RT. For multi cell-based spheres assays, collect together the spheres from one well. Wash the well 3 - 5 times with PBS and centrifuge 2 min longer. For single cell-based spheres assays, collect individual spheres. Due to the low numbers of cells, use 1.5 ml tubes for centrifugation and washing steps.</li>
	<li>Remove supernatant and resuspend pellet in 200 &#181;l of 0.05% Trypsin-EDTA.</li>
	<li>In order to achieve optimal cell separation, incubate the cell suspension at 37 &#176;C for 5 min in a soft shaker. Optimize trypsinization time for your cell line to lower cell death rate: if no large spheres is visible triturate gently using a 100 &#956;l pipette tip. In case large spheres are still present, incubate with trypsin another 3 min and then proceed to the trituration step. In case of single cell-based assays make sure to optimize the time for optimal cell yield of living cells during the trypsinization step.</li>
	<li>To inactivate the trypsin, add 500 &#181;l complete medium and centrifuge at 300 x g for 10 min, in the case of single cell assays, centrifuge for additional 2 min.</li>
	<li>Remove supernatant and resuspend cells carefully in spheres medium.</li>
	<li>Use a 40 &#181;m cell strainer cap filter to obtain a single-cell suspension.</li>
	<li>In the case of using RFP+ and RFP- cells in multi cell-bassed assays, assess the percentage of fluorescent cells in each well after resuspension via flow cytometer analysis.</li>
	<li>For serial replating assays of single cells, seed 1 cell per well into a new ultra low-attachment 96-well plate prepared as detailed above. From one individual sphere, seed approximately 20 individual wells. For replating assays of multi cell-based primary spheres, seed cells obtained from one well of primary spheres into a new 96-well plate and count the cell numbers next day by microscopy.</li>
	<li>Assess the proportion of sphere-forming cells in secondary spheres assays using the formula described in step 2.11.</li>
</ol>
4. Result Analysis
<ol>
	<li>Analyze results from experiments performed in independent triplicates and use two-sided Student&#8217;s t-Test to analyze normally distributed values and otherwise Mann-Whitney-Tests for statistical analysis.</li>
</ol>

<ol>
	<li>Pardal, R., Clarke, M. F., Morrison, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applying+the+principles+of+stem-cell+biology+to+cancer.">Applying the principles of stem-cell biology to cancer.</a> Nat Rev Cancer. 3 (12), 895-902 (2003).</li><li>Reya, T., Morrison, S. J., Clarke, M. F., Weissman, I. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cells,+cancer,+and+cancer+stem+cells.">Stem cells, cancer, and cancer stem cells.</a> Nature. 414 (6859), 105-111 (2001).</li><li>Ahmed, N., Abubaker, K., Findlay, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ovarian+cancer+stem+cells:+Molecular+concepts+and+relevance+as+therapeutic+targets.">Ovarian cancer stem cells: Molecular concepts and relevance as therapeutic targets.</a> Mol Aspects Med. 39, 110-125 (2014).</li><li>Silva, I. 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=Aldehyde+dehydrogenase+in+combination+with+CD133+defines+angiogenic+ovarian+cancer+stem+cells+that+portend+poor+patient+survival.">Aldehyde dehydrogenase in combination with CD133 defines angiogenic ovarian cancer stem cells that portend poor patient survival.</a> Cancer Res. 71 (11), 3991-4001 (2011).</li><li>Kryczek, 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=Expression+of+aldehyde+dehydrogenase+and+CD133+defines+ovarian+cancer+stem+cells.">Expression of aldehyde dehydrogenase and CD133 defines ovarian cancer stem cells.</a> Int J Cancer. 130 (1), 29-39 (2012).</li><li>Stewart, J. 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=Phenotypic+heterogeneity+and+instability+of+human+ovarian+tumor-initiating+cells.">Phenotypic heterogeneity and instability of human ovarian tumor-initiating cells.</a> Proc Natl Acad Sci U S A. 108 (16), 6468-6473 (2011).</li><li>Ginestier, 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=ALDH1+is+a+marker+of+normal+and+malignant+human+mammary+stem+cells+and+a+predictor+of+poor+clinical+outcome.">ALDH1 is a marker of normal and malignant human mammary stem cells and a predictor of poor clinical outcome.</a> Cell Stem Cell. 1 (5), 555-567 (2007).</li><li>Chang, B., 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=ALDH1+expression+correlates+with+favorable+prognosis+in+ovarian+cancers.">ALDH1 expression correlates with favorable prognosis in ovarian cancers.</a> Mod Pathol. 22 (6), 817-823 (2009).</li><li>Cannistra, S. 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=CD44+variant+expression+is+a+common+feature+of+epithelial+ovarian+cancer:+lack+of+association+with+standard+prognostic+factors.">CD44 variant expression is a common feature of epithelial ovarian cancer: lack of association with standard prognostic factors.</a> J Clin Oncol. 13 (8), 1912-1921 (1995).</li><li>Bareiss, P. 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=SOX2+expression+associates+with+stem+cell+state+in+human+ovarian+carcinoma.">SOX2 expression associates with stem cell state in human ovarian carcinoma.</a> Cancer Res. 73 (17), 5544-5555 (2013).</li><li>Pham, D. 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=SOX2+expression+and+prognostic+significance+in+ovarian+carcinoma.">SOX2 expression and prognostic significance in ovarian carcinoma.</a> Int J Gynecol Pathol. 32 (4), 358-367 (2013).</li><li>Lengerke, 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=Expression+of+the+embryonic+stem+cell+marker+SOX2+in+early-stage+breast+carcinoma.">Expression of the embryonic stem cell marker SOX2 in early-stage breast carcinoma.</a> BMC Cancer. 11, 42 (2011).</li><li>Lapidot, T., 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=A+cell+initiating+human+acute+myeloid+leukaemia+after+transplantation+into+SCID+mice.">A cell initiating human acute myeloid leukaemia after transplantation into SCID mice.</a> Nature. 367 (6464), 645-648 (1994).</li><li>Reynolds, B. A., Weiss, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+neurons+and+astrocytes+from+isolated+cells+of+the+adult+mammalian+central+nervous+system.">Generation of neurons and astrocytes from isolated cells of the adult mammalian central nervous system.</a> Science. 255 (5052), 1707-1710 (1992).</li><li>Dontu, 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=In+vitro+propagation+and+transcriptional+profiling+of+human+mammary+stem/progenitor+cells.">In vitro propagation and transcriptional profiling of human mammary stem/progenitor cells.</a> Genes Dev. 17 (10), 1253-1270 (2003).</li><li>Shaw, F. 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=A+detailed+mammosphere+assay+protocol+for+the+quantification+of+breast+stem+cell+activity.">A detailed mammosphere assay protocol for the quantification of breast stem cell activity.</a> J Mammary Gland Biol Neoplasia. 17 (2), 111-117 (2012).</li><li>Leis, O., 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=Sox2+expression+in+breast+tumours+and+activation+in+breast+cancer+stem+cells.">Sox2 expression in breast tumours and activation in breast cancer stem cells.</a> Oncogene. 31 (11), 1354-1365 (2012).</li><li>Higgins, D. 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=Brain+tumor+stem+cell+multipotency+correlates+with+nanog+expression+and+extent+of+passaging+in+human+glioblastoma+xenografts.">Brain tumor stem cell multipotency correlates with nanog expression and extent of passaging in human glioblastoma xenografts.</a> Oncotarget. 4 (5), 792-801 (2013).</li><li>Wang, Y. J., Bailey, J. M., Rovira, M., Leach, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sphere-forming+assays+for+assessment+of+benign+and+malignant+pancreatic+stem+cells.">Sphere-forming assays for assessment of benign and malignant pancreatic stem cells.</a> Methods Mol Biol. 980, 281-290 (2013).</li><li>Li, Y. F., Xiao, B., Tu, S. F., Wang, Y. Y., Zhang, X. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cultivation+and+identification+of+colon+cancer+stem+cell-derived+spheres+from+the+Colo205+cell+line.">Cultivation and identification of colon cancer stem cell-derived spheres from the Colo205 cell line.</a> Braz J Med Biol Res. 45 (3), 197-204 (2012).</li><li>Wu, 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=Identification+of+two+novel+phenotypically+distinct+breast+cancer+cell+subsets+based+on+Sox2+transcription+activity.">Identification of two novel phenotypically distinct breast cancer cell subsets based on Sox2 transcription activity.</a> Cell Signal. 24 (11), 1989-1998 (2012).</li><li>Banaszynski, L. A., Chen, L. C., Maynard-Smith, L. A., Ooi, A. G., Wandless, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid,+reversible,+and+tunable+method+to+regulate+protein+function+in+living+cells+using+synthetic+small+molecules.">A rapid, reversible, and tunable method to regulate protein function in living cells using synthetic small molecules.</a> Cell. 126 (5), 995-1004 (2006).</li><li>Kawase, Y., Yanagi, Y., Takato, T., Fujimoto, M., Okochi, H. <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+multipotent+adult+stem+cells+from+the+skin:+transforming+growth+factor-beta+(TGF-beta)+facilitates+cell+growth.">Characterization of multipotent adult stem cells from the skin: transforming growth factor-beta (TGF-beta) facilitates cell growth.</a> Exp Cell Res. 295 (1), 194-203 (2004).</li><li>Walia, V., 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=Loss+of+breast+epithelial+marker+hCLCA2+promotes+epithelial-to-mesenchymal+transition+and+indicates+higher+risk+of+metastasis.">Loss of breast epithelial marker hCLCA2 promotes epithelial-to-mesenchymal transition and indicates higher risk of metastasis.</a> Oncogene. 31 (17), 2237-2246 (2012).</li><li>Leung, E. 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=Non-small+cell+lung+cancer+cells+expressing+CD44+are+enriched+for+stem+cell-like+properties.">Non-small cell lung cancer cells expressing CD44 are enriched for stem cell-like properties.</a> PLoS One. 5 (11), e14062 (2010).</li><li>Bertolini, 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=Highly+tumorigenic+lung+cancer+CD133++cells+display+stem-like+features+and+are+spared+by+cisplatin+treatment.">Highly tumorigenic lung cancer CD133+ cells display stem-like features and are spared by cisplatin treatment.</a> Proc Natl Acad Sci U S A. 106 (38), 16281-16286 (2009).</li><li>Ma, L., Lai, D., Liu, T., Cheng, W., Guo, L. <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-like+cells+can+be+isolated+with+drug+selection+in+human+ovarian+cancer+cell+line+SKOV3.">Cancer stem-like cells can be isolated with drug selection in human ovarian cancer cell line SKOV3.</a> Acta Biochim Biophys Sin (Shanghai). 42 (9), 593-602 (2010).</li><li>Wang, H., Zhang, Y., Du, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ovarian+and+breast+cancer+spheres+are+similar+in+transcriptomic+features+and+sensitive+to+fenretinide).">Ovarian and breast cancer spheres are similar in transcriptomic features and sensitive to fenretinide).</a> Biomed Res Int. 2013, 510905 (2013).</li><li>Du, 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=Effects+and+mechanisms+of+anti-CD44+monoclonal+antibody+A3D8+on+proliferation+and+apoptosis+of+sphere-forming+cells+with+stemness+from+human+ovarian+cancer.">Effects and mechanisms of anti-CD44 monoclonal antibody A3D8 on proliferation and apoptosis of sphere-forming cells with stemness from human ovarian cancer.</a> Int J Gynecol Cancer. 23 (8), 1367-1375 (2013).</li><li>Xiang, T., 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=Interleukin-17+produced+by+tumor+microenvironment+promotes+self-renewal+of+CD133+cancer+stem-like+cells+in+ovarian+cancer.">Interleukin-17 produced by tumor microenvironment promotes self-renewal of CD133 cancer stem-like cells in ovarian cancer.</a> Oncogene. , (2013).</li><li>Liu, T., Cheng, W., Lai, D., Huang, Y., Guo, L. <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+primary+ovarian+cancer+cells+in+different+culture+systems.">Characterization of primary ovarian cancer cells in different culture systems.</a> Oncol Rep. 23 (5), 1277-1284 (2010).</li><li>Soritau, O., 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=Enhanced+chemoresistance+and+tumor+sphere+formation+as+a+laboratory+model+for+peritoneal+micrometastasis+in+epithelial+ovarian+cancer.">Enhanced chemoresistance and tumor sphere formation as a laboratory model for peritoneal micrometastasis in epithelial ovarian cancer.</a> Rom J Morphol Embryol. 51 (2), 259-264 (2010).</li><li>Shi, M. 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=Identification+of+cancer+stem+cell-like+cells+from+human+epithelial+ovarian+carcinoma+cell+line.">Identification of cancer stem cell-like cells from human epithelial ovarian carcinoma cell line.</a> Cell Mol Life Sci. 67 (22), 3915-3925 (2010).</li><li>Zhang, S., 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=Identification+and+characterization+of+ovarian+cancer-initiating+cells+from+primary+human+tumors.">Identification and characterization of ovarian cancer-initiating cells from primary human tumors.</a> Cancer Res. 68 (11), 4311-4320 (2008).</li><li>Liang, D., 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+hypoxic+microenvironment+upgrades+stem-like+properties+of+ovarian+cancer+cells.">The hypoxic microenvironment upgrades stem-like properties of ovarian cancer cells.</a> BMC Cancer. 12, 201 (2012).</li></ol>

The authors have nothing to disclose.

Spheres cultures are a widely used method to assay cancer stem cell potential and enrich for stem-like cells in a wide range of human tumor cells15,25,26. Under these culture conditions, cancer cells that lack self-renewal ability are expected to differentiate and eventually undergo cell death. Although they may initially form cell clusters or even tumor spheres especially in primary assays, they are not able to sustain sphere-forming ability upon serial replating due to lack of self-renewing properties. Spher...

There is increasing evidence that ovarian carcinomas are comprised of heterogeneous mixtures of cells and harbor so-called &#8220;cancer stem cells&#8221; (CSCs) responsible for disease initiation, maintenance and relapse after conventional cytotoxic therapies1-3. Therefore, the development of molecular strategies targeting ovarian CSCs is an important goal and promises to improve the therapy of ovarian cancer patients.
A pre-requisite for the understanding of the molecular features of CSCs is their reliable isolation from the non-CSCs. However, identification of ovarian CSCs appears challenging. While CD133 expression and aldehyde dehydrogenase (ALDH) activity4,5 have been reported to mark ovarian CSCs, some data indicate that these markers are unstable6. Consistently, in ovarian cancer, other than for example in breast carcinoma7, expression of ALDH1 associates with favorable outcome8 and expression of the proposed stem cell marker CD44 variant has no prognostic value9. More recently, we have shown that expression of the embryonic stem cell protein SOX2 confers stemness to ovarian carcinoma cells10 and high SOX2 expression associates with clinically aggressive ovarian and breast carcinomas11,12. Therefore, in this report we use a lentiviral reporter construct containing a red fluorescence protein (RFP) whose expression is controlled by a SOX2 regulatory region, as a method to isolate putative ovarian CSCs.
By definition, CSCs can both self-renew and differentiate, giving rise to all tumor cell types. Putative CSC populations need to be analyzed in functional assays performed in vivo. For obvious reasons, in human cells such functional tests are confined to xenograft assays, comprising mostly transplantation of human tumor cells into immuno-compromised mice10,13.
An alternative in vitro method was offered by Brent Reynolds and Sam Weiss who firstly reported the so-called neurosphere assay as a surrogate assay evaluating stem potential in neural cells14. Dontu and colleagues later confirmed the use of this assay for evaluation of stem cell potential in breast cells15,16. Here, human mammary cells were plated in different numbers in serum-free medium supplemented with epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), B-27 and heparin and cultured under non-adherent conditions for seven to ten days before sphere formation was scored by microscopy. Following this protocol with some adjustments in cell numbers, growth medium and supplements, several groups have explored in vitro stem cell potential from several cancer types such as breast17, brain18, pancreas19 and colon20 tumors. In ovarian carcinoma, we have recently reported feasibility of the spheres assay and compared its results to those collected in in vivo murine xenograft models10. We found that overexpression of the stem cell protein SOX2 enhanced both in vitro sphere formation as well as in vivo tumorigenicity of human ovarian carcinoma cells10. However, the frequency of sphere-initiating cells was higher than the frequency of tumor-initiating cells measured in vivo10 suggesting that either the sphere assay may lead to false positive results due to technical reasons or, alternatively, the in vivo assay may be inefficient and result in false negative results.
In this report, we analyze multi cell-based ovarian spheres assays in more detail, review the different protocols available in the literature and compare them to a single cell-based assay. We show that the single cell-based assay provides more accurate and reproducible results than multi cell-based assays, which can be highly influenced by the density of plated cells unless methylcellulose is added to the cultures to immobilize cells. However, also in single cell-based assays, in vitro sphere-initiating potential is observed at higher frequency than in vivo tumor-initiating potential.

<table border="0" cellpadding="0" cellspacing="0" width="636">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Name of Material/ Equipment</td>
			<td style="width:112px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:189px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">low-Attachment-plate&#160;</td>
			<td>Corning</td>
			<td style="width:119px;">3474</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEGM</td>
			<td>Lonza</td>
			<td>CC-3151</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Insulin</td>
			<td>Lonza</td>
			<td style="width:119px;">CC-4136</td>
			<td>SingleQuots&#8482; Kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Hydrocortison</td>
			<td>Lonza</td>
			<td style="width:119px;">CC-4136</td>
			<td>SingleQuots&#8482; Kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">EGF</td>
			<td>Lonza</td>
			<td style="width:119px;">CC-4136</td>
			<td>SingleQuots&#8482; Kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EGF</td>
			<td>Sigma</td>
			<td>E9644</td>
			<td>end concentration: 20 ng/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FGF</td>
			<td>PeproTech</td>
			<td>100-18B</td>
			<td>end concentration: 20 ng/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">B-27</td>
			<td>Invitrogen/ Gibco</td>
			<td>17504-044</td>
			<td>end concentration: 1x</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Heparin-Natrium-25000 IE</td>
			<td>Ratiopharm</td>
			<td style="width:119px;">N68542.02</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pen/Strep</td>
			<td>Gibco</td>
			<td style="width:119px;">15140-122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FCS&#160;</td>
			<td>Gibco</td>
			<td style="width:119px;">10500-064</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RPMI 1640</td>
			<td>Gibco</td>
			<td style="width:119px;">21875-034</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin-EDTA&#160;</td>
			<td>Gibco</td>
			<td style="width:119px;">25300-054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s PBS (1x)</td>
			<td>Gibco</td>
			<td style="width:119px;">14190-094</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Shield1&#160;</td>
			<td>Clontech</td>
			<td style="width:119px;">632189</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DMEM/F12</td>
			<td>Gibco</td>
			<td style="width:119px;">21041-025</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DMEM/F12 (powder)</td>
			<td>Gibco</td>
			<td style="width:119px;">42400-010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Methyl cellulose</td>
			<td style="width:112px;">Sigma</td>
			<td style="width:119px;">M0387</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Puromycin dihydrochloride</td>
			<td>applichem</td>
			<td style="width:119px;">A2856</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">cell sorter&#160;</td>
			<td style="width:112px;">BD</td>
			<td style="width:119px;"></td>
			<td>Aria III cell sorter&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">FACS analyser</td>
			<td style="width:112px;">BD</td>
			<td style="width:119px;"></td>
			<td>accuri c6 flow cytometer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">microscope</td>
			<td style="width:112px;">Olympus&#160;</td>
			<td style="width:119px;"></td>
			<td>IX50 Osiris</td>
		</tr>
	</tbody>
</table>

evaluation of stem cell properties in human ovarian carcinoma cells using multi and single cell-based spheres assays

Years of research indicates that ovarian cancers harbor a heterogeneous mixture of cells including a subpopulation of so-called &#8220;cancer stem cells&#8221; (CSCs) responsible for tumor initiation, maintenance and relapse following conventional chemotherapies. Identification of ovarian CSCs is therefore an important goal. A commonly used method to assess CSC potential in vitro is the spheres assay in which cells are plated under non-adherent culture conditions in serum-free medium supplemented with growth factors and sphere formation is scored after a few days. Here, we review currently available protocols for human ovarian cancer spheres assays and perform a side-by-side analysis between commonly used multi cell-based assays and a more accurate system based on single cell plating. Our results indicate that both multi cell-based as well as single cell-based spheres assays can be used to investigate sphere formation in vitro. The more laborious and expensive single cell-based assays are more suitable for functional assessment of individual cells and lead to overall more accurate results while multi cell-based assays can be strongly influenced by the density of plated cells and require titration experiments upfront. Methylcellulose supplementation to multi cell-based assays can be effectively used to reduce mechanical artifacts.

In conventional spheres assays, nearly 40% of RFP+ OVCAR-3 cells vs. 20% of RFP- cells gave rise to an individual tumor sphere in the primary spheres assay (Figure 4A). Moreover, spheres formed by RFP+ cells were larger in size than those formed by RFP- cells.
When plated in single cell-based assays, RFP+ cells also formed more spheres than RFP- cells, confirming the results above. However, there was a tendency towards generation of fewer spheres per plated in the single versu...

Watch this Scientific Journal Video about Evaluation of Stem Cell Properties in Human Ovarian Carcinoma Cells Using Multi and Single Cell-based Spheres Assays at JoVE.com

Evaluation of Stem Cell Properties in Human Ovarian Carcinoma Cells Using Multi and Single Cell-based Spheres Assays

In vitro spheres assays are commonly used to identify cancer stem cells. Here we compare single with multi cell-based spheres assays. The more laborious single cell-based assays or methylcellulose supplementation give more accurate results while multi cell-based assays performed in liquid medium can be highly influenced by cell density.

Years of research indicates that ovarian cancers harbor a heterogeneous mixture of cells including a subpopulation of so-called &#8220;cancer stem ...

evaluation-stem-cell-properties-human-ovarian-carcinoma-cells-using

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9.5K vistas.  University Hospital Basel. In vitro spheres assays are commonly used to identify cancer stem cells. Here we compare single with multi cell-based spheres assays. The more laborious single cell-based assays or methylcellulose supplementation give more accurate results while multi cell-based assays performed in liquid medium can be highly influenced by cell density.

Video: Evaluation of Stem Cell Properties in Human Ovarian Carcinoma Cells Using Multi and Single Cell-based Spheres Assays

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.

A comprehensive overview of the techniques involved in generating a mouse model of oral cancer and quantitative monitoring of tumor invasion within the tongue through multi-photon microscopy of labeled cells is presented. This system can serve as a useful platform for the molecular assessment and drug efficacy of anti-invasive compounds.

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient ...

Evaluation of Cancer Stem Cell Migration Using Compartmentalizing Microfluidic Devices and Live Cell Imaging

In the last 40 years, the United States invested over 200 billion dollars on cancer research, resulting in only a 5% decrease in death rate. A major obstacle for improving patient outcomes is the poor understanding of mechanisms underlying cellular migration associated with aggressive cancer cell invasion, metastasis and therapeutic resistance1. Glioblastoma Multiforme (GBM), the most prevalent primary malignant adult brain tumor2, exemplifies this difficulty. Despite standard surgery, radiation and chemotherapies, patient median survival is only fifteen months, due to aggressive GBM infiltration into adjacent brain and rapid cancer recurrence2. The interactions of aberrant cell migratory mechanisms and the tumor microenvironment likely differentiate cancer from normal cells3. Therefore, improving therapeutic approaches for GBM require a better understanding of cancer cell migration mechanisms. Recent work suggests that a small subpopulation of cells within GBM, the brain tumor stem cell (BTSC), may be responsible for therapeutic resistance and recurrence. Mechanisms underlying BTSC migratory capacity are only starting to be characterized1,4.
Due to a limitation in visual inspection and geometrical manipulation, conventional migration assays5 are restricted to quantifying overall cell populations. In contrast, microfluidic devices permit single cell analysis because of compatibility with modern microscopy and control over micro-environment6-9.
We present a method for detailed characterization of BTSC migration using compartmentalizing microfluidic devices. These PDMS-made devices cast the tissue culture environment into three connected compartments: seeding chamber, receiving chamber and bridging microchannels. We tailored the device such that both chambers hold sufficient media to support viable BTSC for 4-5 days without media exchange. Highly mobile BTSCs initially introduced into the seeding chamber are isolated after migration though bridging microchannels to the parallel receiving chamber. This migration simulates cancer cellular spread through the interstitial spaces of the brain. The phase live images of cell morphology during migration are recorded over several days. Highly migratory BTSC can therefore be isolated, recultured, and analyzed further. 
Compartmentalizing microfluidics can be a versatile platform to study the migratory behavior of BTSCs and other cancer stem cells. By combining gradient generators, fluid handling, micro-electrodes and other microfluidic modules, these devices can also be used for drug screening and disease diagnosis6. Isolation of an aggressive subpopulation of migratory cells will enable studies of underlying molecular mechanisms.

A compartmentalizing microfluidic device for investigating cancer stem cell migration is described. This novel platform creates a viable cellular microenvironment and enables microscopic visualization of live cell locomotion. Highly motile cancer cells are isolated to study molecular mechanisms of aggressive infiltration, potentially leading to more effective future therapies.

In the last 40 years, the United States invested over 200 billion dollars on cancer research, resulting in only a 5% decrease in death rate. A major ...

Stem Cell Transplantation in an in vitro Simulated Ischemia/Reperfusion Model

Stem cell transplantation protocols are finding their way into clinical practice1,2,3. Getting better results, making the protocols more robust, and finding new sources for implantable cells are the focus of recent research4,5. Investigating the effectiveness of cell therapies is not an easy task and new tools are needed to investigate the mechanisms involved in the treatment process6. We designed an experimental protocol of ischemia/reperfusion in order to allow the observation of cellular connections and even subcellular mechanisms during ischemia/reperfusion injury and after stem cell transplantation and to evaluate the efficacy of cell therapy. H9c2 cardiomyoblast cells were placed onto cell culture plates7,8. Ischemia was simulated with 150 minutes in a glucose free medium with oxygen level below 0.5%. Then, normal media and oxygen levels were reintroduced to simulate reperfusion. After oxygen glucose deprivation, the damaged cells were treated with transplantation of labeled human bone marrow derived mesenchymal stem cells by adding them to the culture. Mesenchymal stem cells are preferred in clinical trials because they are easily accessible with minimal invasive surgery, easily expandable and autologous. After 24 hours of co-cultivation, cells were stained with calcein and ethidium-homodimer to differentiate between live and dead cells. This setup allowed us to investigate the intercellular connections using confocal fluorescent microscopy and to quantify the survival rate of postischemic cells by flow cytometry. Confocal microscopy showed the interactions of the two cell populations such as cell fusion and formation of intercellular nanotubes. Flow cytometry analysis revealed 3 clusters of damaged cells which can be plotted on a graph and analyzed statistically. These populations can be investigated separately and conclusions can be drawn on these data on the effectiveness of the simulated therapeutical approach.

Stem Cell Transplantation in an in vitro Simulated Ischemia/Reperfusion Model

We demonstrate how to set up an in vitro ischemia/reperfusion model and how to evaluate the effect of stem cell therapy on postischemic cardiac cells.

Stem cell transplantation protocols are finding their way into clinical practice1,2,3. Getting better results, making the protocols more robust, and ...

Processing of Primary Brain Tumor Tissue for Stem Cell Assays and Flow Sorting

Brain tumors are typically comprised of morphologically diverse cells that express a variety of neural lineage markers. Only a relatively small fraction of cells in the tumor with stem cell properties, termed brain tumor initiating cells (BTICs), possess an ability to differentiate along multiple lineages, self-renew, and initiate tumors in vivo. We applied culture conditions originally used for normal neural stem cells (NSCs) to a variety of human brain tumors and found that this culture method specifically selects for stem-like populations. Serum-free medium (NSC) allows for the maintenance of an undifferentiated stem cell state, and the addition of bFGF and EGF allows for the proliferation of multi-potent, self-renewing, and expandable tumorspheres.
To further characterize each tumor's BTIC population, we evaluate cell surface markers by flow cytometry. We may also sort populations of interest for more specific characterization. Self-renewal assays are performed on single BTICs sorted into 96 well plates; the formation of tumorspheres following incubation at 37 &deg;C indicates the presence of a stem or progenitor cell. Multiple cell numbers of a particular population can also be sorted in different wells for limiting dilution analysis, to analyze self-renewal capacity. We can also study differential gene expression within a particular cell population by using single cell RT-PCR.
The following protocols describe our procedures for the dissociation and culturing of primary human samples to enrich for BTIC populations, as well as the dissociation of tumorspheres. Also included are protocols for staining for flow cytometry analysis or sorting, self-renewal assays, and single cell RT-PCR.

The identification of brain tumor initiating cells (BTICs), the rare cells within a heterogeneous tumor possessing stem cell properties, provides new insights into human brain tumor pathogenesis. We have refined specific culture conditions to enrich for BTICs, and we routinely use flow cytometry to further enrich these populations. Self-renewal assays and transcript analysis by single cell RT-PCR can subsequently be performed on these isolated cells.

Brain tumors are typically comprised of morphologically diverse cells that express a variety of neural lineage markers. Only a relatively small fraction ...

Isolation, Characterization and Comparative Differentiation of Human Dental Pulp Stem Cells Derived from Permanent Teeth by Using Two Different Methods

Developing wisdom teeth are easy-accessible source of stem cells during the adulthood which could be obtained by routine orthodontic treatments. Human pulp-derived stem cells (hDPSCs) possess high proliferation potential with multi-lineage differentiation capacity compare to the ordinary source of adult stem cells1-8; therefore, hDPSCs could be the good candidates for autologous transplantation in tissue engineering and regenerative medicine. Along with these benefits, possessing the mesenchymal stem cells (MSC) features, such as immunolodulatory effect, make hDPSCs more valuable, even in the case of allograft transplantation6,9,10. Therefore, the primary step for using this source of stem cells is to select the best protocol for isolating hDPSCs from pulp tissue. In order to achieve this goal, it is crucial to investigate the effect of various isolation conditions on different cellular behaviors, such as their common surface markers &amp; also their differentiation capacity.
Thus, here we separate human pulp tissue from impacted third molar teeth, and then used both existing protocols based on literature, for isolating hDPSCs,11-13 i.e. enzymatic dissociation of pulp tissue (DPSC-ED) or outgrowth from tissue explants (DPSC-OG). In this regards, we tried to facilitate the isolation methods by using dental diamond disk. Then, these cells characterized in terms of stromal-associated Markers (CD73, CD90, CD105 &amp; CD44), hematopoietic/endothelial Markers (CD34, CD45 &amp; CD11b), perivascular marker, like CD146 and also STRO-1. Afterwards, these two protocols were compared based on the differentiation potency into odontoblasts by both quantitative polymerase chain reaction (QPCR) &amp; Alizarin Red Staining. QPCR were used for the assessment of the expression of the mineralization-related genes (alkaline phosphatase; ALP, matrix extracellular phosphoglycoprotein; MEPE &amp; dentin sialophosphoprotein; DSPP).14

The method described isolation and characterization of human Dental Pulp Stem Cells (hDPSCs) by using either enzymatic dissociation of pulp (DPSC-ED) or direct outgrowth of stem cells from pulp tissue explants (DPSC-OG). Then followed by in vitro comparative differentiation of both types of hDPSCs into odontoblasts.

Developing wisdom teeth are easy-accessible source of stem cells during the adulthood which could be obtained by routine orthodontic treatments. Human ...

Cell-based Assay Protocol for the Prognostic Prediction of Idiopathic Scoliosis Using Cellular Dielectric Spectroscopy

This protocol details the experimental and analytical procedure for a cell-based assay developed in our laboratory as a functional test to predict the prognosis of idiopathic scoliosis in asymptomatic and affected children. The assay consists of the evaluation of the functional status of Gi and Gs proteins in peripheral blood mononuclear cells (PBMCs) by cellular dielectric spectroscopy (CDS), using an automated CDS-based instrument, and the classification of children into three functional groups (FG1, FG2, FG3) with respect to the profile of imbalance between the degree of response to Gi and Gs proteins stimulation. The classification is further confirmed by the differential effect of osteopontin (OPN) on response to Gi stimulation among groups and the severe progression of disease is referenced by FG2. Approximately, a volume of 10 ml of blood is required to extract PBMCs by Ficoll-gradient and cells are then stored in liquid nitrogen. The adequate number of PBMCs to perform the assay is obtained after two days of cell culture. Essentially, cells are first incubated with phytohemmaglutinin (PHA). After 24 hr incubation, medium is replaced by a PHA-free culture medium for an additional 24 hr prior to cell seeding and OPN treatment. Cells are then spectroscopically screened for their responses to somatostatin and isoproterenol, which respectively activate Gi and Gs proteins through their cognate receptors. Both somatostatin and isoproterenol are simultaneously injected with an integrated fluidics system and the cells&#39; responses are monitored for 15 min. The assay can be performed with fresh or frozen PBMCs and the procedure is completed within 4 days.

A structured protocol is presented for a cell-based assay as a functional test to predict the prognosis of idiopathic scoliosis using cellular dielectric spectroscopy (CDS). The assay can be performed with fresh or frozen peripheral blood mononuclear cells (PBMCs) and the procedure is completed within 4 days.

This protocol details the experimental and analytical procedure for a cell-based assay developed in our laboratory as a functional test to predict the ...

RNAscope for In situ Detection of Transcriptionally Active Human Papillomavirus in Head and Neck Squamous Cell Carcinoma

The &#39;gold standard&#39; for oncogenic HPV detection is the demonstration of transcriptionally active high-risk HPV in tumor tissue. However, detection of E6/E7 mRNA by quantitative reverse transcription polymerase chain reaction (qRT-PCR) requires RNA extraction which destroys the tumor tissue context critical for morphological correlation and has been difficult to be adopted in routine clinical practice. Our recently developed RNA in situ hybridization technology, RNAscope, permits direct visualization of RNA in formalin-fixed, paraffin-embedded (FFPE) tissue with single molecule sensitivity and single cell resolution, which enables highly sensitive and specific in situ analysis of any RNA biomarker in routine clinical specimens. The RNAscope HPV assay was designed to detect the E6/E7 mRNA of seven high-risk HPV genotypes (HPV16, 18, 31, 33, 35, 52, and 58) using a pool of genotype-specific probes. It has demonstrated excellent sensitivity and specificity against the current &#39;gold standard&#39; method of detecting E6/E7 mRNA by qRT-PCR. HPV status determined by RNAscope is strongly prognostic of clinical outcome in oropharyngeal cancer patients.

RNAscope for In situ Detection of Transcriptionally Active Human Papillomavirus in Head and Neck Squamous Cell Carcinoma

The presence of high-risk HPV in head and neck tumor tissue is associated with favorable outcomes. The recently developed RNA in situ hybridization technique called RNAscope allows direct visualization of HPV E6/E7 mRNA in FFPE tissue sections.

The &#39;gold standard&#39; for oncogenic HPV detection is the demonstration of transcriptionally active high-risk HPV in tumor tissue. However, detection ...

Multi-electrode Array Recordings of Human Epileptic Postoperative Cortical Tissue

Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which disrupt normal brain function. Despite treatment with currently available antiepileptic drugs targeting neuronal functions, one third of patients with epilepsy are pharmacoresistant. In this condition, surgical resection of the brain area generating seizures remains the only alternative treatment. Studying human epileptic tissues has contributed to understand new epileptogenic mechanisms during the last 10 years. Indeed, these tissues generate spontaneous interictal epileptic discharges as well as pharmacologically-induced ictal events which can be recorded with classical electrophysiology techniques. Remarkably, multi-electrode arrays (MEAs), which are microfabricated devices embedding an array of spatially arranged microelectrodes, provide the unique opportunity to simultaneously stimulate and record field potentials, as well as action potentials of multiple neurons from different areas of the tissue. Thus MEAs recordings offer an excellent approach to study the spatio-temporal patterns of spontaneous interictal and evoked seizure-like events and the mechanisms underlying seizure onset and propagation. Here we describe how to prepare human cortical slices from surgically resected tissue and to record with MEAs interictal and ictal-like events ex vivo.

We here describe how to perform multi-electrode array recordings of human epileptic cortical tissue. Epileptic tissue resection, slice preparation and multi-electrode array recordings of interictal and ictal events are demonstrated in detail.

Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which ...

Enrichment for Chemoresistant Ovarian Cancer Stem Cells from Human Cell Lines

Cancer stem cells (CSCs) are defined as a subset of slow cycling and undifferentiated cells that divide asymmetrically to generate highly proliferative, invasive, and chemoresistant tumor cells. Therefore, CSCs are an attractive population of cells to target therapeutically. CSCs are predicted to contribute to a number of types of malignancies including those in the blood, brain, lung, gastrointestinal tract, prostate, and ovary. Isolating and enriching a tumor cell population for CSCs will enable researchers to study the properties, genetics, and therapeutic response of CSCs. We generated a protocol that reproducibly enriches for ovarian cancer CSCs from ovarian cancer cell lines (SKOV3 and OVCA429). Cell lines are treated with 20 &#181;M cisplatin for 3 days. Surviving cells are isolated and cultured in a serum-free stem cell media containing cytokines and growth factors. We demonstrate an enrichment of these purified CSCs by analyzing the isolated cells for known stem cell markers Oct4, Nanog, and Prom1 (CD133) and cell surface expression of CD177 and CD133. The CSCs exhibit increased chemoresistance. This method for isolation of CSCs is a useful tool for studying the role of CSCs in chemoresistance and tumor relapse.

Cancer stem cells (CSCs) are&#160;implicated in tumor relapse due to chemoresistance. We have optimized a protocol for selection and expansion of CSCs from ovarian cancer cell lines. By treating cells with the chemotherapeutic cisplatin and culturing&#160;in a stem cell promoting media we enrich for non-adherent CSC cultures.

Cancer stem cells (CSCs) are defined as a subset of slow cycling and undifferentiated cells that divide asymmetrically to generate highly proliferative, ...

Isolation of Human Lymphatic Endothelial Cells by Multi-parameter Fluorescence-activated Cell Sorting

Lymphatic system disorders such as primary lymphedema, lymphatic malformations and lymphatic tumors are rare conditions that cause significant morbidity but little is known about their biology. Isolating highly pure human lymphatic endothelial cells (LECs) from diseased and healthy tissue would facilitate studies of the lymphatic endothelium at genetic, molecular and cellular levels. It is anticipated that these investigations may reveal targets for new therapies that may change the clinical management of these conditions. A protocol describing the isolation of human foreskin LECs and lymphatic malformation lymphatic endothelial cells (LM LECs) is presented. To obtain a single cell suspension tissue was minced and enzymatically treated using dispase II and collagenase II. The resulting single cell suspension was then labelled with antibodies to cluster of differentiation (CD) markers CD34, CD31, Vascular Endothelial Growth Factor-3 (VEGFR-3) and PODOPLANIN. Stained viable cells were sorted on a fluorescently activated cell sorter (FACS) to separate the CD34LowCD31PosVEGFR-3PosPODOPLANINPos LM LEC population from other endothelial and non-endothelial cells. The sorted LM LECs were cultured and expanded on fibronectin-coated flasks for further experimental use.

The goal of this protocol is to isolate lymphatic endothelial cells lining human lymphatic malformation cyst-like vessels and foreskins using fluorescence-activated cell sorting (FACS). Subsequent cell culturing and expansion of these cells permits a new level of experimental sophistication for genetic, proteomic, functional and cell differentiation studies.

Lymphatic system disorders such as primary lymphedema, lymphatic malformations and lymphatic tumors are rare conditions that cause significant morbidity ...