Name: isolation of stem-like cells from 3-dimensional spheroid cultures
Uploaded: 2019-12-13T13:00:00
Description: Watch this Scientific Journal Video about Isolation of Stem-like Cells from 3-Dimensional Spheroid Cultures at JoVE.com

This study was supported by grants from the National Cancer Institute R01-CA172220 (GSP, WYH), R01-ES02207 (GSP, WYH). We thank the Flow Cytometry Core at the University of Illinois at Chicago for assistance on cell sorting.

All cell handling and media preparations should be performed with aseptic technique in a Class II biological safety cabinet (BSC).
1. Culture and maintenance of HPrEC Cells in 2D
<ol>
	<li>Coat 100 mm culture dishes with 2 mL of 2.5 &#181;g/cm2 fibronectin solution overnight at room temperature (RT). Aspirate the solution and let the culture dishes air dry in the BSC for 45 min. Fibronectin-coated culture dishes can be stored 2&#8211;4 weeks at 4 &#730;C.</li>
	<li>Add 9 mL of the...

<ol>
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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospective+identification+of+tumorigenic+prostate+cancer+stem+cells.">Prospective identification of tumorigenic prostate cancer stem cells.</a> Cancer Research. 65, 10946-10951 (2005).</li><li>Vander Griend, D. J., 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+role+of+CD133+in+normal+human+prostate+stem+cells+and+malignant+cancer-initiating+cells.">The role of CD133 in normal human prostate stem cells and malignant cancer-initiating cells.</a> Cancer Research. 68, 9703-9711 (2008).</li><li>Wang, J., 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=Symmetrical+and+asymmetrical+division+analysis+provides+evidence+for+a+hierarchy+of+prostate+epithelial+cell+lineages.">Symmetrical and asymmetrical division analysis provides evidence for a hierarchy of prostate epithelial cell lineages.</a> Nature Communications. 5, 4758 (2014).</li><li>Neumuller, R. A., Knoblich, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dividing+cellular+asymmetry:+asymmetric+cell+division+and+its+implications+for+stem+cells+and+cancer.">Dividing cellular asymmetry: asymmetric cell division and its implications for stem cells and cancer.</a> Genes and Development. 23, 2675-2699 (2009).</li><li>Cicalese, 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=The+tumor+suppressor+p53+regulates+polarity+of+self-renewing+divisions+in+mammary+stem+cells.">The tumor suppressor p53 regulates polarity of self-renewing divisions in mammary stem cells.</a> Cell. 138, 1083-1095 (2009).</li><li>Klein, A. M., Simons, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Universal+patterns+of+stem+cell+fate+in+cycling+adult+tissues.">Universal patterns of stem cell fate in cycling adult tissues.</a> Development. 138, 3103-3111 (2011).</li><li>Cairns, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutation+selection+and+the+natural+history+of+cancer.">Mutation selection and the natural history of cancer.</a> Nature. 255, 197-200 (1975).</li><li>Karthaus, W. 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=Identification+of+multipotent+luminal+progenitor+cells+in+human+prostate+organoid+cultures.">Identification of multipotent luminal progenitor cells in human prostate organoid cultures.</a> Cell. 159, 163-175 (2014).</li><li>Hu, W. Y., 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+functional+interrogation+of+adult+human+prostate+epithelial+cells+at+single+cell+resolution.">Isolation and functional interrogation of adult human prostate epithelial cells at single cell resolution.</a> Stem Cell Research. 23, 1-12 (2017).</li><li>Bryant, D. M., Stow, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ins+and+outs+of+E-cadherin+trafficking.">The ins and outs of E-cadherin trafficking.</a> Trends in Cell Biology. 14, 427-434 (2004).</li><li>Clevers, H., Loh, K. M., Nusse, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cell+signaling.+An+integral+program+for+tissue+renewal+and+regeneration:+Wnt+signaling+and+stem+cell+control.">Stem cell signaling. An integral program for tissue renewal and regeneration: Wnt signaling and stem cell control.</a> Science. 346, 1248012 (2014).</li><li>Madueke, 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=The+role+of+WNT10B+in+normal+prostate+gland+development+and+prostate+cancer.">The role of WNT10B in normal prostate gland development and prostate cancer.</a> The Prostate. 79 (14), 1692-1704 (2019).</li><li>Guan, J. 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=Autophagy+in+stem+cells.">Autophagy in stem cells.</a> Autophagy. 9, 830-849 (2013).</li></ol>

Flow cytometry using multiple stem cell surface markers is a commonly used approach for stem cell research despite lacking both specificity and selectivity1,5,6. While spheroid formation in a 3D culture system is another useful method in enriching the rare stem cell population from primary epithelial cells, including HPrEC, the resulting spheroids are still a heterogeneous mixture of stem and progenitor cells2<...

The human prostate gland contains luminal epithelium with secretory function and basal cells underlying it along with an unusual neuroendocrine cell component. The epithelial cells, in this case, are generated from a rare population of prostate stem cells that are relatively quiescent in vivo and act as a repair system to maintain glandular homeostasis throughout life1. Despite many advances, the identification and functional isolation of prostate stem cells remains a major challenge in the field. Stem cell biomarkers, including cell surface marker-based methodologies combined with flow cytometry are commonly used for stem cell research2,3,4. However, results for enrichment and isolation vary widely as a function of marker combinations and antibody specificity5,6, raising questions about the identity of the isolated cells. Another widely used approach for stem-like cell enrichment is three-dimensional (3D) spheroid culture2,3,4. While resident stem cells are relatively quiescent in vivo with niche restraints, they undergo cell division in 3D matrix culture (both symmetric and asymmetric), generating both stem and progenitor cells that rapidly reproduce toward the lineage commitment7,8. The formed spheroids are a heterogeneous mixture containing both stem cells and progenitor cells at various stages of lineage commitment, including early and late stage progenitor cells. Thus, assays using the whole spheroids are not stem cell exclusive, making the identification of unique stem cell properties inconclusive. Therefore, it is critical to create assays to identify and separate prostate stem cells from their daughter progenitors. Towards this end, the goal of the current protocol is to establish an assay system that allows for the efficient identification and isolation of stem cells from human prostate tissues followed by robust downstream analysis of their biological functions.
Long-term 5-bromo-2'-deoxyuridine (BrdU) label-retention is widely used for in vivo and in vitro lineage tracing of stem cells based on their prolonged doubling time9,10. The current approach for prostate stem cell identification and isolation described herein is based on their relative quiescent characteristic and label-retention properties within a mixed epithelial population. Furthermore, based on the immortal strand DNA hypothesis, only stem cells can undergo asymmetric cell division. The stem cell represents the daughter cell that contains the older parental DNA while the progenitor cell, which is a committed daughter cell, receives the newly synthesized DNA. The unique stem cell property described above is exploited to perform BrdU labeling in parental stem cells in primary cultures and then track their label following BrdU-washout upon transfer to 3D anchor-free spheroid culture. While the majority of primary prostate epithelial cells retain a basal and transit amplifying phenotype in 2D culture, there is also a rare population of multipotent stem cells replenishing and maintaining the epithelial homeostasis as evidenced by formation of spheroids or fully differentiated organoids with corresponding culture media upon transfer to 3D systems3,12. In our current protocol, by using HPrEC prostate spheroids or prostasphere-based BrdU, CFSE, or Far Red retention assays followed by fluorescence activated cell sorting (FACS), we identify label-retaining stem cells in spheroids at a single cell level13.
Importantly, we further confirmed the stem cell characteristics of label-retaining cells within early-stage spheroids compared to the progenitor cells with lineage commitment. These include stem cell asymmetric division, in vitro spheroid formation ability and in vivo tissue regeneration capacity, elevated autophagy activity, augmented ribosome biogenesis and decreased metabolic activity. Subsequently, RNAseq analysis was performed. Differentially expressed genes in label-retaining spheroid cells were observed that may serve as novel biomarkers for human prostate stem cells. This spheroid-based label-retaining approach can apply to cancer specimens to similarly identify a small number of cancer stem-like cells, thus providing translational opportunities to manage the therapeutic resistant populations13. Presented below is the prostasphere-based label-retention assay using human primary prostate epithelial cells (HPrEC) as an example.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.05% Trypsin-EDTA</td>
			<td>Gibco</td>
			<td>25300-054</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL tuberculin syringes</td>
			<td>Bectin Dickinson</td>
			<td>BD 309625</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL microcentrifuge tubes, sterile</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>100 mm culture dishes</td>
			<td>Corning/Falcon</td>
			<td>353003</td>
			<td></td>
		</tr>
		<tr>
			<td>12-well culture plate</td>
			<td>Corning/Falcon</td>
			<td>353043</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL centrifuge tubes</td>
			<td>Corning/Falcon</td>
			<td>352097</td>
			<td></td>
		</tr>
		<tr>
			<td>22 x 22 mm coverslips, sq</td>
			<td>Corning</td>
			<td>284522</td>
			<td>For MatTek 35 mm culture dish</td>
		</tr>
		<tr>
			<td>24 x 50 mm coverslips</td>
			<td>Corning</td>
			<td>2975245</td>
			<td></td>
		</tr>
		<tr>
			<td>26G x 1.5 inch hypodermic needle</td>
			<td>Monoject</td>
			<td>1188826112</td>
			<td></td>
		</tr>
		<tr>
			<td>2N HCl</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>35 mm culture dish with cover glass bottom</td>
			<td>MatTek Corp</td>
			<td>P35G-0-10-C</td>
			<td>Glass bottom No. 0, uncoated, <img src="files/ftp_upload/60357/60357img1.jpg"/> irradiated</td>
		</tr>
		<tr>
			<td>40 &#181;m pore nylon cell strainer</td>
			<td>Corning</td>
			<td>352340</td>
			<td></td>
		</tr>
		<tr>
			<td>5% CO2 culture incubator, 37 &#176;C</td>
			<td>Forma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL centrifuge tubes</td>
			<td>Corning/Falcon</td>
			<td>352098</td>
			<td></td>
		</tr>
		<tr>
			<td>5mL Polystyrene Round-Bottom Tube with strainer snap cap</td>
			<td>Corning</td>
			<td>352235</td>
			<td>35 &#181;m nylon mesh</td>
		</tr>
		<tr>
			<td>6-well culture plates</td>
			<td>Corning</td>
			<td>353046</td>
			<td></td>
		</tr>
		<tr>
			<td>8-well chamber slides</td>
			<td>Millipore Sigma</td>
			<td>PEZGS0816</td>
			<td></td>
		</tr>
		<tr>
			<td>Aqueous mounting medium containing DAPI</td>
			<td>Vector Laboratories</td>
			<td>H-1200</td>
			<td>A nuclear fluorescent dye</td>
		</tr>
		<tr>
			<td>Biological safety cabinet, Level 2 certified</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BrdU (5-bromo-2'-deoxyuridine)</td>
			<td>Sigma-Aldrich</td>
			<td>B5002</td>
			<td>1 mM stock solution in DMSO</td>
		</tr>
		<tr>
			<td>Centrifuge for 1.5 mL microcentrifuge tubes</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge for 15 mL tubes</td>
			<td>Beckman Coulter</td>
			<td></td>
			<td>Allegra 6</td>
		</tr>
		<tr>
			<td>CFSE (carboxyfluorescein succinimidyl ester)</td>
			<td>Thermo Fisher Scientific</td>
			<td>C34554</td>
			<td>5 mM stock solution in DMSO</td>
		</tr>
		<tr>
			<td>cytochalasin D</td>
			<td>Thermo Fisher Scientific</td>
			<td>PHZ1063</td>
			<td></td>
		</tr>
		<tr>
			<td>Dispase 1U/mL</td>
			<td>StemCell Technologies</td>
			<td>07923</td>
			<td></td>
		</tr>
		<tr>
			<td>FACS CellSorter MoFlo XDP</td>
			<td>Beckman Coulter</td>
			<td>s</td>
			<td></td>
		</tr>
		<tr>
			<td>Far-Red pro-dye</td>
			<td>Thermo Fisher</td>
			<td>C34564</td>
			<td>5 mM stock solution in DMSO</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fibronectin</td>
			<td>Sigma-Aldrich</td>
			<td>F0895</td>
			<td>For coating 100 mm culture dishes</td>
		</tr>
		<tr>
			<td>Fluorescent microscope with color digital camera</td>
			<td>Carl Zeiss</td>
			<td></td>
			<td>Axioskop 20 fluorescent microscope; color digital Axiocamera</td>
		</tr>
		<tr>
			<td>Goat anti-Mouse IgG (H+L) Highly Cross-Adsorbed Secondary Antibody, Alexa Fluor 488</td>
			<td>Thermo Fisher</td>
			<td>A-11029</td>
			<td></td>
		</tr>
		<tr>
			<td>HPrEC (Primary normal human prostate epithelial cells)</td>
			<td>Lifeline Cell Technology</td>
			<td>FC-0038</td>
			<td>Pooled from 3 young (19-21yr od) disease-free organ donors; 1 x 105 cells/mL; stored in liquid nitrogen</td>
		</tr>
		<tr>
			<td>ice bucket and ice</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted microsope with digital camera</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel, low growth factor, phenol-red free</td>
			<td>Corning</td>
			<td>356239</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Corning</td>
			<td>A452-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse anti-BrdU antibody</td>
			<td>Cell Signaling</td>
			<td>5292S</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse IgG antibody (negative control)</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-2025</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal goat serum</td>
			<td>Vector Laboratories</td>
			<td>S-1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS), pH 7.4</td>
			<td>Sigma-Aldrich</td>
			<td>P5368-10PAK</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipettors and tips, various sizes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PrEGM (ProstaLife Epithelial Cell Growth Medium)</td>
			<td>Lifeline Cell Technology</td>
			<td>LL-0041</td>
			<td></td>
		</tr>
		<tr>
			<td>Propidium Iodide (PI)</td>
			<td>R &#38; D Systems</td>
			<td>5135/10</td>
			<td>10 &#956;g/mL PI in PBS stored at 4 &#176;C in the dark</td>
		</tr>
		<tr>
			<td>Serological pipets, various sizes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Software for sphere counting and size measurements</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Software: 3D images using Imaris an imageing software with freeform drawing capabilities</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Millipore Sigma</td>
			<td>T8787</td>
			<td></td>
		</tr>
		<tr>
			<td>Water bath, 37 &#176;C</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>z-stack images using a transmitted light inverted fluorescent confocal microscope</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of stem-like cells from 3-dimensional spheroid cultures

Despite advances in adult stem cell research, identification and isolation of stem cells from tissue specimens remains a major challenge. While resident stem cells are relatively quiescent with niche restraints in adult tissues, they enter the cell cycle in anchor-free three-dimensional (3D) culture and undergo both symmetric and asymmetric cell division, giving rise to both stem and progenitor cells. The latter proliferate rapidly and are the major cell population at various stages of lineage commitment, forming heterogeneous spheroids. Using primary normal human prostate epithelial cells (HPrEC), a spheroid-based, label-retention assay was developed that permits the identification and functional isolation of the spheroid-initiating stem cells at a single cell resolution.
HPrEC or cell lines are two-dimensionally (2D) cultured with BrdU for 10 days to permit its incorporation into the DNA of all dividing cells, including self-renewing stem cells. Wash out commences upon transfer to the 3D culture for 5 days, during which stem cells self-renew through asymmetric division and initiate spheroid formation. While relatively quiescent daughter stem cells retain BrdU-labeled parental DNA, the daughter progenitors rapidly proliferate, losing the BrdU label. BrdU can be substituted with CFSE or Far Red pro-dyes, which permit live stem cell isolation by FACS. Stem cell characteristics are confirmed by in vitro spheroid formation, in vivo tissue regeneration assays, and by documenting their symmetric/asymmetric cell divisions. The isolated label-retaining stem cells can be rigorously interrogated by downstream molecular and biologic studies, including RNA-seq, ChIP-seq, single cell capture, metabolic activity, proteome profiling, immunocytochemistry, organoid formation, and in vivo tissue regeneration. Importantly, this marker-free functional stem cell isolation approach identifies stem-like cells from fresh cancer specimens and cancer cell lines from multiple organs, suggesting wide applicability. It can be used to identify cancer stem-like cell biomarkers, screen pharmaceuticals targeting cancer stem-like cells, and discover novel therapeutic targets in cancers.

Primary normal human prostate epithelial cells are placed into fibronectin-coated culture dishes and cell growth is maintained in 2D culture (Figure 1a). Upon transfer into 3D culture with a basement membrane matrix, differentiated epithelial cells slowly die out. Only prostate stem cells can survive in an anchor-free culture and form spheroids in 5 days (Figure 1b).
Dual labeling of prostate epitheli...

Watch this Scientific Journal Video about Isolation of Stem-like Cells from 3-Dimensional Spheroid Cultures at JoVE.com

Isolation of Stem-like Cells from 3-Dimensional Spheroid Cultures

Using human primary prostate epithelial cells, we report a novel biomarker-free method of functional characterization of stem-like cells by a spheroid-based label-retention assay. A step-by-step protocol is described for BrdU, CFSE, or Far Red 2D cell labeling; three-dimensional spheroid formation; label-retaining stem-like cell identification by immunocytochemistry; and isolation by FACS.

Despite advances in adult stem cell research, identification and isolation of stem cells from tissue specimens remains a major challenge. While resident ...

Stem cell isolation remains a major challenge due to co-isolation of progenitor cells using current methods. We developed a novel biomarker-free assay to isolate quiescent stem cells from mixed progenitors. The main advantage of this spheroid-based, label-retention assay, it can expand and isolate live stem cells from their daughter progenitors by FACS using CFSE or Far Red labeling.While conventional therapies eradicate most prostate cancer cells, cancer stem cells remain due to therapeutic resistance, thus driving disease progression. Stem-like cell isolation will permit identification of novel genes that can be therapeutically co-targeted for effective disease remission. Our label-retention assay's applicable for normal stem cell isolation from various tissues and cells, and for cancer stem cell research.Importantly, this assay's applicable to other epithelial cell cancers, such as breast and colorectal cancers. Begin by coating 100-millimeter culture dishes with two milliliters of 2.5 microgram fibronectin solution and incubate them overnight at room temperature. Then aspirate the solution and let the culture dishes air dry in the biosafety cabinet for 45 minutes.Add nine milliliters of the prostate epithelial cell growth medium to a fibronectin-coated dish and keep it warm in carbon dioxide incubator at 37 degrees Celsius. Thaw one vial of frozen human prostate epithelial cells in a 37 degrees Celsius water bath, and resuspend the cells in 10 milliliters of warm medium. Centrifuge the cell suspension at 500 times g for five minutes.Then aspirate and discard the supernatant. Resuspend the cells in one milliliter of warm culture medium and transfer one milliliter of the suspension directly to the fibronectin-coated dish with the pre-warmed medium. Then incubate the dish in the carbon dioxide incubator at 37 degrees Celsius.If co-labeling the cells, prepare BrdU-labeled cells in 10-days 2D culture as described in the text manuscript. Then add five micromolar CFSE or Far Red and incubate the cells for 30 minutes. After the incubation, carefully aspirate the medium with the dye and wash the cells twice with five milliliters of warm PBS.Next, perform enzymatic digestion with 05%trypsin EDTA according to the manuscript directions. Centrifuge the cells at 500 times g for five minutes and discard the supernatant. Cells were resuspended in ice-cold, one-to-one basement membrane matrix and culture medium mix for 3D prostasphere formation.To prepare prostasphere culture in a 3D basement matrix system, thaw the basement membrane matrix at four degrees Celsius overnight and keep it on ice prior to use. Then gently add one milliliter of ice-cold basement membrane matrix into an equal volume of ice-cold culture medium. Pipette up and down to mix, taking care to not introduce air bubbles.Resuspend five times 10 to 1/4 human prostate epithelial cells in ice-cold one-to-one basement membrane matrix and culture media mix for total volume of 500 microliters. Pipette the solution to the bottom rim of each well and swirl the plate to evenly distribute the mixture. Place the plate in a 37 degrees Celsius carbon dioxide incubator for 30 minutes to allow the matrix to solidify.Then cover it with one milliliter of warm culture medium per well, making sure to not disturb the ring. To harvest the CFSE-labeled prostaspheres replace the medium with two milliliters dispase and pipette up and down to mix several times. Incubate the plate at 37 degrees Celsius for 30 minutes to digest the matrix, then collect the sphere mixture into a 15-milliliter centrifuge tube.Centrifuge the spheres at 500 times g for five minutes and discard the supernatant. Resuspend the pellet in 500 microliters of warm 05%trypsin EDTA, and transfer them into a 1.5-milliliter centrifuge tube. Incubate the spheres at 37 degrees Celsius for five minutes, then add 500 microliters of warm PBS with 10%FBS.Pass them through a one-milliliter syringe with a 26-gauge needle to completely dissociate the spheres. Centrifuge the cells at 500 times g for five minutes. Then aspirate and discard the supernatant.Resuspend the cells in one milliliter of warm culture medium with one microgram per milliliter propidium iodide to stain the dead cells and incubate them for one minute at room temperature. Repeat the centrifugation, and discard the supernatant. Then wash the cells with one milliliter of warm medium.Repeat the centrifugation, and discard the supernatant. Resuspend the cells in one milliliter of warm culture medium and collect the cells in five-milliliter polystyrene round bottom tubes by filtering them through 35-micron pore size cell strainer snap caps. Perform FACS analysis of trypsin-dispersed CFSE-labeled prostasphere cells.Using non-labeled cells as a negative control and CFSE-labeled cells as a positive control to set the gates, run the sample to sort and collect the subpopulations of fractionated CFSE-high and CFSE-low cells. Primary normal human prostate epithelial cells were placed into fibronectin-coated culture dishes and cell growth was maintained in 2D culture. Upon transfer into a 3D culture with a basement membrane matrix, differentiated epithelial cells slowly died out and only prostate stem cells remained.Dual-labeling of prostate epithelial cells in 2D culture followed by spheroid formation in 3D culture showed colocalization of BrdU, CFSE, and Far Red in the same label-retaining cells. Dual immunostaining showed that label-retaining cells exhibit lower levels of cytokeratin protein keratin 14, decreased cell junction protein E-cadherin, increased stem cell early marker proteins Wnt10b and ALDH1A1, increased autophagy protein LC3, and increased myosin IIB. Furthermore, the spheroid-based, label-retention assay successfully detects cancer stem-like cells in prostate cancer specimens.CFSE-labeled retaining stem-like cancer cells and spheroids derived from human prostate cancer specimens exhibited reduced E-cadherin protein relative to the non-labeled progenitor cells. When attempting this protocol, it is important to maintain matrix in liquid form for culture medium preparation. Store it overnight at four degrees, and chill pipette tips in ice-cold PBS prior to dispensing matrix.Following isolation of stem cells using the spheroid-based label-retention assay, single-cell RNA sequencing and proteomic analysis can be performed to identify specific genes and novel biomarkers in stem cells. Isolation of live cancer stem cells by the spheroid-based label-retention assay makes it possible for researchers to grow cancer stem cell-derived tumoroids in vitro and to screen novel anti-cancer drugs.

isolation-of-stem-like-cells-from-3-dimensional-spheroid-cultures

Research

JoVE Journal

Cancer Research

Establishment of Cancer Stem Cell Cultures from Human Conventional Osteosarcoma

The current improvements in therapy against osteosarcoma (OS) have prolonged the lives of cancer patients, but the survival rate of five years remains poor when metastasis has occurred. The Cancer Stem Cell (CSC) theory holds that there is a subset of tumor cells within the tumor that have stem-like characteristics, including the capacity to maintain the tumor and to resist multidrug chemotherapy. Therefore, a better understanding of OS biology and pathogenesis is needed in order to advance the development of targeted therapies to eradicate this particular subset and to reduce morbidity and mortality among patients. Isolating CSCs, establishing cell cultures of CSCs, and studying their biology are important steps to improving our understanding of OS biology and pathogenesis. The establishment of human-derived OS-CSCs from biopsies of OS has been made possible using several methods, including the capacity to create 3-dimensional stem cell cultures under nonadherent conditions. Under these conditions, CSCs are able to create spherical floating colonies formed by daughter stem cells; these colonies are termed &#34;cellular spheres&#34;. Here, we describe a method to establish CSC cultures from primary cell cultures of conventional OS obtained from OS biopsies. We clearly describe the several passages required to isolate and characterize CSCs.

The presence of cancer stem cells (CSCs) in bone sarcomas has recently been linked to their pathogenesis. In this article, we present the isolation of CSCs from primary cell cultures obtained from human biopsies of conventional osteosarcoma (OS) using the ability of CSCs to grow under nonadherent conditions.

The current improvements in therapy against osteosarcoma (OS) have prolonged the lives of cancer patients, but the survival rate of five years remains ...

Utilizing Functional Genomics Screening to Identify Potentially Novel Drug Targets in Cancer Cell Spheroid Cultures

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery of the next generation of novel drug targets. It is becoming apparent that more complex models of cancer are required to fully appreciate the contributing factors that drive tumorigenesis in vivo and increase the efficacy of novel therapies that make the transition from pre-clinical models to clinical trials.
Here we present a methodology for generating uniform and reproducible tumor spheroids that can be subjected to siRNA functional screening. These spheroids display many characteristics that are found in solid tumors that are not present in traditional two-dimension culture. We show that several commonly used breast cancer cell lines are amenable to this protocol. Furthermore, we provide proof-of-principle data utilizing the breast cancer cell line BT474, confirming their dependency on amplification of the epidermal growth factor receptor HER2 and mutation of phosphatidylinositol-4,5-biphosphate 3-kinase (PIK3CA) when grown as tumor spheroids. Finally, we are able to further investigate and confirm the spatial impact of these dependencies using immunohistochemistry.

Identifying novel drug targets that transition from pre-clinical testing to human trials is a scientific priority. To that end, here we describe a functional genomics approach for examining the impact of gene depletion on cancer cell line spheroids, which more appropriately model human cancers in vivo.

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery ...

Preparation and Metabolic Assay of 3-dimensional Spheroid Co-cultures of Pancreatic Cancer Cells and Fibroblasts

Many cancer types, including pancreatic cancer, have a dense fibrotic stroma that plays an important role in tumor progression and invasion. Activated cancer associated fibroblasts are a key component of the tumor stroma that interact with cancer cells and support their growth and survival. Models that recapitulate the interaction of cancer cells and activated fibroblasts are important tools for studying the stromal biology and for development of antitumor agents. Here, a method is described for the rapid generation of robust 3-dimensional (3D) spheroid co-culture of pancreatic cancer cells and activated pancreatic fibroblasts that can be used for subsequent biological studies. Additionally, described is the use of 3D spheroids in carrying out functional metabolic assays to probe cellular bioenergetics pathways using an extracellular flux analyzer paired with a spheroid microplate. Pancreatic cancer cells (Patu8902) and activated pancreatic fibroblast cells (PS1) were co-cultured and magnetized using a biocompatible nanoparticle assembly. Magnetized cells were rapidly bioprinted using magnetic drives in a 96 well format, in growth media to generate spheroids with a diameter ranging between 400-600 &#181;m within 5-7 days of culture. Functional metabolic assays using Patu8902-PS1 spheroids were then carried out using the extracellular flux technology to probe cellular energetic pathways. The method herein is simple, allows consistent generation of cancer cell-fibroblast spheroid co-cultures and can be potentially adapted to other cancer cell types upon optimization of the current described methodology.

Here, a method is described for the preparation of 3-dimensional (3D) spheroid co-culture of pancreatic cancer cells and fibroblasts, followed by measurement of metabolic functions using an extracellular flux analyzer.

Many cancer types, including pancreatic cancer, have a dense fibrotic stroma that plays an important role in tumor progression and invasion. Activated ...

Isolation and Characterization of Tumor-initiating Cells from Sarcoma Patient-derived Xenografts

The existence and importance of tumor-initiating cells (TICs) have been supported by increasing evidence during the past decade. These TICs have been shown to be responsible for tumor initiation, metastasis, and drug resistance. Therefore, it is important to develop specific TIC-targeting therapy in addition to current chemotherapy strategies, which mostly focus on the bulk of non-TICs. In order to further understand the mechanism behind the malignancy of TICs, we describe a method to isolate and to characterize TICs in human sarcomas. Herein, we show a detailed protocol to generate patient-derived xenografts (PDXs) of human sarcomas and to isolate TICs by fluorescence-activated cell sorting (FACS) using human leukocyte antigen class I (HLA-1) as a negative marker. Also, we describe how to functionally characterize these TICs, including a sphere formation assay and a tumor formation assay, and to induce differentiation along mesenchymal pathways. The isolation and characterization of PDX TICs provide clues for the discovery of potential targeting therapy reagents. Moreover, increasing evidence suggests that this protocol may be further extended to isolate and characterize TICs from other types of human cancers.

We describe a detailed protocol for the isolation of tumor-initiating cells from human sarcoma patient-derived xenografts by fluorescence-activated cell sorting, using human leukocyte antigen-1 (HLA-1) as a negative marker, and for the further validation and characterization of these HLA-1-negative tumor-initiating cells.

The existence and importance of tumor-initiating cells (TICs) have been supported by increasing evidence during the past decade. These TICs have been ...

Isolation of Human Endothelial Cells from Normal Colon and Colorectal Carcinoma - An Improved Protocol

Primary cells isolated from human carcinomas are valuable tools to identify pathogenic mechanisms contributing to disease development and progression. In particular, endothelial cells (EC) constituting the inner surface of vessels, directly participate in oxygen delivery, nutrient supply, and removal of waste products to and from tumors, and are thereby prominently involved in the constitution of the tumor microenvironment (TME). Tumor endothelial cells (TECs) can be used as cellular biosensors of the intratumoral microenvironment established by communication between tumor and stromal cells. TECs also serve as targets of therapy. Accordingly, in culture these cells allow studies on mechanisms of response or resistance to anti-angiogenic treatment. Recently, it was found that TECs isolated from human colorectal carcinoma (CRC) exhibit memory-like effects based on the specific TME they were derived from. Moreover, these TECs actively contribute to the establishment of a specific TME by the secretion of different factors. For example, TECs in a prognostically favorable Th1-TME secrete the anti-angiogenic tumor-suppressive factor secreted protein, acidic and rich in cysteine-like 1 (SPARCL1). SPARCL1 regulates vessel homeostasis and inhibits tumor cell proliferation and migration. Hence, cultures of pure, viable TECs isolated from human solid tumors are a valuable tool for functional studies on the role of the vascular system in tumorigenesis. Here, a new up-to-date protocol for the isolation of primary EC from the normal colon as well as CRC is described. The technique is based on mechanical and enzymatic tissue digestion, immunolabeling, and fluorescence activated cell sorting (FACS)-sorting of triple-positive cells (CD31, VE-cadherin, CD105). With this protocol, viable TEC or normal endothelial cell (NEC) cultures could be isolated from colon tissues with a success rate of 62.12% when subjected to FACS-sorting (41 pure EC cultures from 66 tissue samples). Accordingly, this protocol provides a robust approach to isolate human EC cultures from normal colon and CRC.

Tumor endothelial cells are important determinants of the tumor microenvironment and the course of the disease. Here, a protocol for the isolation of pure and viable endothelial cells from human colorectal carcinoma and normal colon to be used in drug testing and pathogenesis research is described.

Primary cells isolated from human carcinomas are valuable tools to identify pathogenic mechanisms contributing to disease development and progression. In ...

A Spheroid Killing Assay by CAR T Cells

Immunotherapy has become a field of growing interest in the fight against cancer otherwise untreatable. Among all immunotherapeutic methods, chimeric antigen receptor (CAR) redirected T cells obtained the most spectacular results, in particular with pediatric B-acute lymphoblastic leukemia (B-ALL). Classical validation methods of CAR T cells rely on the use of specificity and functionality assays of the CAR T cells against target cells in suspension and in xenograft models. Unfortunately, observations made in vitro are often decoupled from results obtained in vivo and a lot of effort and animals could be spared by adding another step: the use of 3D culture. The production of spheroids out of potential target cells that mimic the 3D structure of the tumor cells when they are engrafted into the animal model represents an ideal alternative. Here, we report an affordable, reliable and easy method to produce spheroids from a transduced colorectal cell line as a validation tool for adoptive cell therapy (exemplified here by CD19 CAR T cells). This method is coupled with an advanced live imaging system that can follow spheroid growth, effector cells cytotoxicity and tumor cell apoptosis.

This protocol is designed to assess immunotherapeutic redirected T-cell (CAR T-cell) cytotoxicity against 3D structured cancerous cells (spheroids) in real time.

Immunotherapy has become a field of growing interest in the fight against cancer otherwise untreatable. Among all immunotherapeutic methods, chimeric ...

Mimicking and Manipulating Pancreatic Acinar-to-Ductal Metaplasia in 3-dimensional Cell Culture

The differentiation of acinar cells to ductal cells during pancreatitis and in the early development of pancreatic cancer is a key process that requires further study. To understand the mechanisms regulating acinar-to-ductal metaplasia (ADM), ex vivo 3D culture and differentiation of primary acinar cells to ductal cells offers many advantages over other systems. With the technique herein, modulation of protein expression is simple and quick, requiring only one day to isolate, stimulate or virally infect, and begin culturing primary acinar cells to investigate the ADM process. In contrast to using basement membrane matrix, the seeding of acinar cell clusters in collagen I extracellular matrix, allows acinar cells to retain their acinar identity before manipulation. This is vital when testing the contribution of various components to the induction of ADM. Not only are the effects of cytokines or other ectopically administered factors testable through this technique, but the contribution of common mutations, increased protein expression, or knockdown of protein expression is testable via viral infection of primary acinar cells, using adenoviral or lentiviral vectors. Moreover, cells can be re-isolated from collagen or basement membrane matrix at the endpoint and analyzed for protein expression.

Primary acinar cell isolation, protein expression or activity modulation, culture, and down-stream applications are abundantly useful in the ex vivo study of acinar-to-ductal metaplasia (ADM), an early event in the development of pancreatic cancer.

The differentiation of acinar cells to ductal cells during pancreatitis and in the early development of pancreatic cancer is a key process that requires ...

Assessing Cell Viability and Death in 3D Spheroid Cultures of Cancer Cells

Three-dimensional spheroids of cancer cells are important tools for both cancer drug screens and for gaining mechanistic insight into cancer cell biology. The power of this preparation lies in its ability to mimic many aspects of the in vivo conditions of tumors while being fast, cheap, and versatile enough to allow relatively high-throughput screening. The spheroid culture conditions can recapitulate the physico-chemical gradients in a tumor, including the increasing extracellular acidity, increased lactate, and decreasing glucose and oxygen availability, from the spheroid periphery to its core. Also, the mechanical properties and cell-cell interactions of in vivo tumors are in part mimicked by this model. The specific properties and consequently the optimal growth conditions, of 3D spheroids, differ widely between different types of cancer cells. Furthermore, the assessment of cell viability and death in 3D spheroids requires methods that differ in part from those employed for 2D cultures. Here we describe several protocols for preparing 3D spheroids of cancer cells, and for using such cultures to assess cell viability and death in the context of evaluating the efficacy of anticancer drugs.

Here, we present several simple methods for evaluating viability and death in 3D cancer cell spheroids, which mimic the physico-chemical gradients of in vivo tumors much better than the 2D culture. The spheroid model, therefore, allows evaluation of the cancer drug efficacy with improved translation to in vivo conditions.

Three-dimensional spheroids of cancer cells are important tools for both cancer drug screens and for gaining mechanistic insight into cancer cell biology. ...

Discovery of Driver Genes in Colorectal HT29-derived Cancer Stem-Like Tumorspheres

Cancer stem cells play a vital role against clinical therapies, contributing to tumor relapse. There are many oncogenes involved in tumorigenesis and the initiation of cancer stemness properties. Since gene expression in the formation of colorectal cancer-derived tumorspheres is unclear, it takes time to discover the mechanisms working on one gene at a time. This study demonstrates a method to quickly discover the driver genes involved in the survival of the colorectal cancer stem-like cells in vitro. Colorectal HT29 cancer cells that express the LGR5 when cultured as spheroids and accompany an increase CD133 stemness markers were selected and used in this study. The protocol presented is used to perform RNAseq with available bioinformatics to quickly uncover the overexpressed driver genes in the formation of colorectal HT29-derived stem-like tumorspheres. The methodology can quickly screen and discover potential driver genes in other disease models.

Presented here is a protocol to discover the overexpressed driver genes maintaining the established cancer stem-like cells derived from colorectal HT29 cells. RNAseq with available bioinformatics was performed to investigate and screen gene expression networks for elucidating a potential mechanism involved in the survival of targeted tumor cells.

Cancer stem cells play a vital role against clinical therapies, contributing to tumor relapse. There are many oncogenes involved in tumorigenesis and the ...

Evaluating Cell Death Using Cell-Free Supernatant of Probiotics in Three-Dimensional Spheroid Cultures of Colorectal Cancer Cells

This manuscript describes a protocol to evaluate cancer cell deaths in three dimensional (3D) spheroids of multicellular types of cancer cells using supernatants from Lactobacillus fermentum cell culture, considered as probiotics cultures. The use of 3D cultures to test Lactobacillus cell-free supernatant (LCFS) are a better option than testing in 2D monolayers, especially as L. fermentum can produce anti-cancer effects within the gut. L. fermentum supernatant was identified to possess increased anti-proliferative effects against several colorectal cancer (CRC) cells in 3D culture conditions. Interestingly, these effects were strongly related to the culture model, demonstrating the notable ability of L. fermentum to induce cancer cell death. Stable spheroids were generated from diverse CRCs (colorectal cancer cells) using the protocol presented below. This protocol of generating 3D spheroid is time saving and cost effective. This system was developed to easily investigate the anti-cancer effects of LCFS in multiple types of CRC spheroids. As expected, CRC spheroids treated with LCFS strongly induced cell death during the experiment and expressed specific apoptosis molecular markers as analyzed by qRT-PCR, western blotting, and FACS analysis. Therefore, this method is valuable for exploring cell viability and evaluating the efficacy of anti-cancer drugs.

Here methods are presented to understand anti-cancer effects of Lactobacillus cell-free supernatant (LCFS). Colorectal cancer cell lines show cell deaths when treated with LCFS in 3D cultures. The process of generating spheroids can be optimized depending on the scaffold and the analysis methods presented are useful for evaluating the involved signaling pathways.

This manuscript describes a protocol to evaluate cancer cell deaths in three dimensional (3D) spheroids of multicellular types of cancer cells using ...