We thank members of our laboratory for their helpful discussions and support. Our research on breast cancer stem cells and the tumor microenvironment is funded by grants from the Canadian Cancer Research Society Research Institute and the U.S. Army Department of Defense Breast Cancer Program (Grant # BC160912). V.B. is supported by a Western Postdoctoral Fellowship (Western University), and both A.L.A. and V.B. are supported by the Breast Cancer Society of Canada. C.L. is supported by a Vanier Canada Graduate Scholarship from the Government of Canada.

The authors have nothing to disclose.

Breast cancer metastasis and resistance to therapy have become major cause of mortality in women worldwide. The existence of a sub-population of breast cancer stem cells (BCSCs) contributes to enhanced metastasis26,43,44,45,46 and therapy resistance21,47,48. Therefore...

Understanding the cellular and molecular mechanisms of human breast cancer stem cells (BCSCs) is crucial for addressing the challenges encountered in breast cancer treatment. The emergence of the BCSC concept dates back to the early 21st century, where a small population of CD44+CD24-/low breast cancer cells were found to be capable of generating heterogenous tumors in mice1,2. Subsequently, it was observed that human breast cancer cells with high enzymatic activity of aldehyde dehydrogenase (ALDHhigh) also displayed similar stem cell-like properties3. These BCSCs represent a small population of cells capable of self-renewal and differentiation, contributing to the heterogenous nature of bulk tumors1,2,3. Accumulating evidence suggest that alterations in evolutionarily conserved signaling pathways drive BCSC survival and maintenance4,5,6,7,8,9,10,11,12,13,14. In addition, the cell extrinsic microenvironment has been shown to play a pivotal role in dictating different BCSC functions15,16,17. These molecular pathways and the external factors regulating BCSC function contribute to breast cancer relapse, metastasis18 and development of resistance to therapies19,20,21, with the residual existence of BCSCs post-treatment posing a major challenge to the overall survival of breast cancer patients22,23. Pre-clinical evaluation of these factors is therefore very important for identifying BCSC-targeting therapies that could be beneficial for achieving better treatment outcomes and improved overall survival in breast cancer patients.
Several in vitro human breast cancer cell line models and in vivo human xenograft models have been used to characterize BCSCs24,25,26,27,28,29. The ability of cell lines to continuously repopulate after every successive passage makes these an ideal model system to perform omics-based and pharmacogenomic studies. However, cell lines often fail to recapitulate the heterogeneity observed in patient samples. Hence, it is important to complement cell line data with patient-derived samples. Isolation of BCSCs in their purest form is important for enabling detailed characterization of BCSCs. Achieving this purity depends on the selection of phenotypic markers that are specific to BCSCs. Currently, the ALDHhighCD44+CD24- cell phenotype is most commonly used to distinguish and isolate human BCSCs from bulk breast cancer cell populations using fluorescence activated cell sorting (FACS) for maximum purity1,3,26. Furthermore, the properties of isolated BCSCs such as self-renewal, proliferation, and differentiation can be evaluated using in vitro and in vivo techniques.
For example, in vitro colony forming assays can be used to assess the ability of a single cell to self-renew to form a colony of 50 cells or more in presence of different treatment conditions30. Mammosphere assays can also be used to assess the self-renewal potential of breast cancer cells under anchorage-independent conditions. This assay measures the ability of single cells to generate and grow as spheres (mixture of BCSCs and non-BCSCs) at each successive passage in serum-free non-adherent culture conditions31. Additionally, 3-Dimensional (3D) culture models can be used to assess BCSC function, including cell-cell and cell-matrix interactions that closely recapitulate the in vivo microenvironment and allow investigation of the activity of potential BCSC-targeted therapies32. Despite the diverse applications of in vitro models, it is difficult to model the complexity of in vivo conditions using only in vitro assays. This challenge can be overcome by use of mouse xenograft models to evaluate BCSC behavior in vivo. In particular, such models serve as an ideal system for assessing breast cancer metastasis33, investigating interactions with the microenvironment during disease progression34, in vivo imaging35, and for predicting patient-specific toxicity and efficacy of antitumor agents34.
This protocol provides a detailed description for the isolation of human ALDHhighCD44+CD24- BCSCs at maximum purity from bulk populations of heterogenous breast cancer cells. We also provide a detailed description of three in vitro techniques (colony forming assay, mammosphere assay, and 3D culture model) and an in vivo tumor xenograft assay that can be used to assess different functions of BCSCs. These methods would be appropriate for use by investigators interested in isolating and characterizing BCSCs from human breast cancer cell lines or primary-patient derived breast cancer cells and tumor tissue for the purposes of understanding BCSC biology and/or investigating novel BCSC-targeting therapies.

<table><tbody><tr><td>7-Aminoactinomycin D (7AAD)</td><td>BD</td><td>51-68981E</td><td>suggested: 0.25 &amp;micro;g/1x10&lt;sup&gt;6&lt;/sup&gt; cells</td></tr><tr><td>Acetone</td><td>Fisher</td><td>A18-1</td><td></td></tr><tr><td>Aldehyde dehydrogenase (ALDH) substrate</td><td>Stemcell Technologies</td><td>1700</td><td>Sold commerically as part of the ALDEFLOUR Assay kit; follow manufacturer&#039;s instructions for ALDH substrate preparation</td></tr><tr><td>Basement membrane extract (BME)</td><td>Corning</td><td>354234</td><td>Sold under the commercial name Matrigel</td></tr><tr><td>Cell culture plates: 6 well</td><td>Corning</td><td>877218</td><td></td></tr><tr><td>Cell culture plates: 60mm</td><td>Corning</td><td>353002</td><td></td></tr><tr><td>Cell culture plates: 96-well ultra low attachment</td><td>Corning</td><td>3474</td><td></td></tr><tr><td>Cell strainer: 40 micron</td><td>BD</td><td>352340</td><td></td></tr><tr><td>Collagen</td><td>Stemcell Technologies</td><td>7001</td><td>Prepare 1:30 dilution of 3 mg/mL collagen in PBS</td></tr><tr><td>Collagenase</td><td>Sigma</td><td>11088807001</td><td>1x</td></tr><tr><td>Conical tubes: 50 mL</td><td>Fisher scientific</td><td>05-539-7</td><td></td></tr><tr><td>Crystal violet</td><td>Sigma</td><td>C6158</td><td>Use 0.05% crystal violet solution in water for staining</td></tr><tr><td>Dispase</td><td>Stemcell Technologies</td><td>7913</td><td>5U/mL</td></tr><tr><td>DMEM:F12</td><td>Gibco</td><td>11330-032</td><td>1x, With L-glutamine and 15 mM HEPES</td></tr><tr><td>DNAse</td><td>Sigma</td><td>D5052</td><td>0.1 mg/mL final concentration</td></tr><tr><td>FBS</td><td>Avantor Seradigm Lifescience</td><td>97068-085</td><td>&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;</td></tr><tr><td>Flow tubes: 5ml</td><td>BD</td><td>352063</td><td>Polypropylene round-bottom tubes</td></tr><tr><td>Methanol</td><td>Fisher</td><td>84124</td><td></td></tr><tr><td>mouse anti-Human CD24 antibody</td><td>BD</td><td>561646</td><td>R-phycoerythrin and Cyanine dye conjugated Clone: ML5</td></tr><tr><td>mouse anti-Human CD44 antibody</td><td>BD</td><td>555479</td><td>R-phycoerythrin conjugated, Clone: G44-26</td></tr><tr><td>N,N-diethylaminobenzaldehyde (DEAB)</td><td>Stemcell Technologies</td><td>1700</td><td>Sold commerically as part of the ALDEFLOUR Assay kit; follow manufacturer&#039;s instructions DEAB preparation</td></tr><tr><td>PBS</td><td>Wisent Inc</td><td>311-425-CL</td><td>1x, Without calcium and magnesium</td></tr><tr><td>Trypsin-EDTA</td><td>Gibco</td><td>25200-056</td><td></td></tr><tr><td></td><td></td><td></td><td></td></tr><tr><td>&lt;strong&gt;Mammosphere Media Composition&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>B27</td><td>Gibco</td><td>17504-44</td><td>1x</td></tr><tr><td>bFGF</td><td>Sigma</td><td>F2006</td><td>10 ng/mL</td></tr><tr><td>BSA</td><td>Bioshop</td><td>ALB003</td><td>04%</td></tr><tr><td>DMEM:F12</td><td>Gibco</td><td>11330-032</td><td>1x, With L-glutamine and 15 mM HEPES</td></tr><tr><td>EGF</td><td>Sigma</td><td>E9644</td><td>20 ng/mL</td></tr><tr><td>Insulin</td><td>Sigma</td><td>16634</td><td>5 &amp;micro;g/mL</td></tr><tr><td></td><td></td><td></td><td></td></tr><tr><td>&lt;strong&gt;3D Organoid Media Composition&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>A8301</td><td>Tocris</td><td>2939</td><td>500 nM</td></tr><tr><td>B27</td><td>Gibco</td><td>17504-44</td><td>1x</td></tr><tr><td>DMEM:F12</td><td>Gibco</td><td>11330-032</td><td>1x, With L-glutamine and 15 mM HEPES</td></tr><tr><td>EGF</td><td>Sigma</td><td>E9644</td><td>5 ng/mL</td></tr><tr><td>FGF10</td><td>Peprotech</td><td>100-26</td><td>20 ng/mL</td></tr><tr><td>FGF7</td><td>Peprotech</td><td>100-19</td><td>5 ng/mL</td></tr><tr><td>GlutaMax</td><td>Invitrogen</td><td>35050-061</td><td>1x</td></tr><tr><td>HEPES</td><td>Gibco</td><td>15630-080</td><td>10 mM</td></tr><tr><td>N-acetylcysteine</td><td>Sigma</td><td>A9165</td><td>1.25 mM</td></tr><tr><td>Neuregulin &amp;beta;1</td><td>Peprotech</td><td>100-03</td><td>5 nM</td></tr><tr><td>Nicotinamide</td><td>Sigma</td><td>N0636</td><td>5 mM</td></tr><tr><td>Noggin</td><td>Peprotech</td><td>120-10C</td><td>100 ng/mL</td></tr><tr><td>R-spondin3</td><td>R&amp;amp;D</td><td>3500</td><td>250 ng/mL</td></tr><tr><td>SB202190</td><td>Sigma</td><td>S7067</td><td>500 nM</td></tr><tr><td>Y-27632</td><td>Tocris</td><td>1254</td><td>5 &amp;micro;M</td></tr></tbody></table>

isolation and functional assessment of human breast cancer stem cells from cell and tissue samples

Breast cancer stem cells (BCSCs) are cancer cells with inherited or acquired stem cell-like characteristics. Despite their low frequency, they are major contributors to breast cancer initiation, relapse, metastasis and therapy resistance. It is imperative to understand the biology of breast cancer stem cells in order to identify novel therapeutic targets to treat breast cancer. Breast cancer stem cells are isolated and characterized based on expression of unique cell surface markers such as CD44, CD24 and enzymatic activity of aldehyde dehydrogenase (ALDH). These ALDHhighCD44+CD24- cells constitute the BCSC population and can be isolated by fluorescence-activated cell sorting (FACS) for downstream functional studies. Depending on the scientific question, different in vitro and in vivo methods can be used to assess the functional characteristics of BCSCs. Here, we provide a detailed experimental protocol for isolation of human BCSCs from both heterogenous populations of breast cancer cells as well as primary tumor tissue obtained from breast cancer patients. In addition, we highlight downstream in vitro and in vivo functional assays including colony forming assays, mammosphere assays, 3D culture models and tumor xenograft assays that can be used to assess BCSC function.

The described protocol allows isolation of human BCSCs from a heterogenous population of breast cancer cells, either from cell lines or from dissociated tumor tissue. For any given cell line or tissue sample, it is crucial to generate a uniform single cell suspension to isolate BCSCs at maximum purity as contaminating non-BCSC populations could result in variable cellular responses, especially if the study aim is to evaluate the efficacy of therapeutic agents targeting BCSCs. Application of a stringent sorting strategy w...

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Isolation and Functional Assessment of Human Breast Cancer Stem Cells from Cell and Tissue Samples

This experimental protocol describes the isolation of BCSCs from breast cancer cell and tissue samples as well as the in vitro and in vivo assays that can be used to assess BCSC phenotype and function.

Breast cancer stem cells (BCSCs) are cancer cells with inherited or acquired stem cell-like characteristics. Despite their low frequency, they are major ...

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Research

JoVE Journal

Cancer Research

4.5K Views.  London Regional Cancer Program. Dit experimentele protocol beschrijft de isolatie van BCSC's uit borstkankercel- en weefselmonsters, evenals de in vitro en in vivo assays die kunnen worden gebruikt om bcsc-fenotype en -functie te beoordelen.

Video: Isolation and Functional Assessment of Human Breast Cancer Stem Cells from Cell and Tissue Samples

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 ...

Synthesis and Characterization of an Aspirin-fumarate Prodrug that Inhibits NF&#954;B Activity and Breast Cancer Stem Cells

Inflammation is a cancer hallmark that underlies cancer incidence and promotion, and eventually progression to metastasis. Therefore, adding an anti-inflammatory drug to standard cancer regiments may improve patient outcome. One such drug, aspirin (acetylsalicylic acid, ASA), has been explored for cancer chemoprevention and anti-tumor activity. Besides inhibiting the cyclooxygenase 2-prostaglandin axis, ASA&#39;s anti-cancer activities have also been attributed to nuclear factor &#312;B (NF&#312;B) inhibition. Because prolonged ASA use may cause gastrointestinal toxicity, a prodrug strategy has been implemented successfully. In this prodrug design the carboxylic acid of ASA is masked and additional pharmacophores are incorporated.
This protocol describes how we synthesized an aspirin-fumarate prodrug, GTCpFE, and characterized its inhibition of the NF&#312;B pathway in breast cancer cells and attenuation of the cancer stem-like properties, an important NF&#312;B-dependent phenotype. GTCpFE effectively inhibits the NF&#312;B pathway in breast cancer cell lines whereas ASA lacks any inhibitory activity, indicating that adding fumarate to ASA structure significantly contributes to its activity. In addition, GTCpFE shows significant anti-cancer stem cell activity by blocking mammosphere formation and attenuating the cancer stem cell associated CD44+CD24- immunophenotype. These results establish a viable strategy to develop improved anti-inflammatory drugs for chemoprevention and cancer therapy.

This procedure will demonstrate how we synthesized and characterized the anti-NF&#954;B and anti-cancer stem cell activity of an aspirin-fumarate prodrug.

Inflammation is a cancer hallmark that underlies cancer incidence and promotion, and eventually progression to metastasis. Therefore, adding an ...

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 ...

Medicine

Obtaining Cancer Stem Cell Spheres from Gynecological and Breast Cancer Tumors

Cancer stem cells (CSC) are a small population with self-renewal and plasticity which are responsible for tumorigenesis, resistance to treatment and recurrent disease. This population can be identified by surface markers, enzymatic activity and a functional profile. These approaches per se are limited, due to phenotypic heterogeneity and CSC plasticity. Here, we update the sphere-forming protocol to obtain CSC spheres from breast and gynecological cancers, assessing functional properties, CSC markers and protein expression. The spheres are obtained with single-cell seeding at low density in suspension culture, using a semi-solid methylcellulose medium to avoid migration and aggregates. This profitable protocol can be used in cancer cell lines but also in primary tumors. The tridimensional non-adherent suspension culture thought to mimic the tumor microenvironment, particularly the CSC-niche, is supplemented with epidermal growth factor and basic fibroblast growth factor to ensure CSC signaling. Aiming for robust identification of CSC, we propose a complementary approach, combining functional and phenotypic evaluation. Sphere-forming capacity, self-renewal and sphere projection area establish CSC functional properties. Additionally, characterization comprises flow cytometry evaluation of the markers, represented by CD44+/CD24- and CD133, and Western blot, considering ALDH. The presented protocol was also optimized for primary tumor samples, following a sample digestion procedure, useful for translational research.

The aim of this methodology is to identify cancer stem cells (CSC) in cancer cell lines and primary human tumor samples with the sphere-forming protocol, in a robust manner, using functional assays and phenotypic characterization with flow cytometry and Western blot.

Cancer stem cells (CSC) are a small population with self-renewal and plasticity which are responsible for tumorigenesis, resistance to treatment and ...

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.

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 ...

Patient Derived Cell Culture and Isolation of CD133+ Putative Cancer Stem Cells from Melanoma

Despite improved treatments options for melanoma available today, patients with advanced malignant melanoma still have a poor prognosis for progression-free and overall survival. Therefore, translational research needs to provide further molecular evidence to improve targeted therapies for malignant melanomas. In the past, oncogenic mechanisms related to melanoma were extensively studied in established cell lines. On the way to more personalized treatment regimens based on individual genetic profiles, we propose to use patient-derived cell lines instead of generic cell lines. Together with high quality clinical data, especially on patient follow-up, these cells will be instrumental to better understand the molecular mechanisms behind melanoma progression.
Here, we report the establishment of primary melanoma cultures from dissected fresh tumor tissue. This procedure includes mincing and dissociation of the tissue into single cells, removal of contaminations with erythrocytes and fibroblasts as well as primary culture and reliable verification of the cells' melanoma origin.
Recent reports revealed that melanomas, like the majority of tumors, harbor a small subpopulation of cancer stem cells (CSCs), which seem to exclusively fuel tumor initiation and progression towards the metastatic state. One of the key markers for CSC identification and isolation in melanoma is CD133. To isolate CD133+ CSCs from primary melanoma cultures, we have modified and optimized the Magnetic-Activated Cell Sorting (MACS) procedure from Miltenyi resulting in high sorting purity and viability of CD133+ CSCs and CD133- bulk, which can be cultivated and functionally analyzed thereafter.

Patient Derived Cell Culture and Isolation of CD133+ Putative Cancer Stem Cells from Melanoma

This article describes the preparation of freshly obtained melanoma tissue into primary cell cultures, and how to remove contaminations of erythrocytes and fibroblasts from the tumor cells. Finally, we describe how CD133+ putative melanoma stem cells are sorted from the CD133- bulk using Magnetic Activated Cell Sorting (MACS).

Despite improved treatments options for melanoma available today, patients with advanced malignant melanoma still have a poor prognosis for ...

Isolation of Cancer Stem Cells From Human Prostate Cancer Samples

The cancer stem cell (CSC) model has been considerably revisited over the last two decades. During this time CSCs have been identified and directly isolated from human tissues and serially propagated in immunodeficient mice, typically through antibody labeling of subpopulations of cells and fractionation by flow cytometry. However, the unique clinical features of prostate cancer have considerably limited the study of prostate CSCs from fresh human tumor samples. We recently reported the isolation of prostate CSCs directly from human tissues by virtue of their HLA class I (HLAI)-negative phenotype. Prostate cancer cells are harvested from surgical specimens and mechanically dissociated. A cell suspension is generated and labeled with fluorescently conjugated HLAI and stromal antibodies. Subpopulations of HLAI-negative cells are finally isolated using a flow cytometer. The principal limitation of this protocol is the frequently microscopic and multifocal nature of primary cancer in prostatectomy specimens. Nonetheless, isolated live prostate CSCs are suitable for molecular characterization and functional validation by transplantation in immunodeficient mice.

The isolation of cancer stem cells (CSCs) directly from human tissues is requisite for their biological characterization. This manuscript describes a methodology for the isolation of prostate CSCs from human tissues, while also providing tips on troubleshooting difficult steps.

The cancer stem cell (CSC) model has been considerably revisited over the last two decades. During this time CSCs have been identified and directly ...

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 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 ...

Isolation of Stem Cells from Human Pancreatic Cancer Xenografts

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal and produce differentiated progeny1. These properties allow CSCs to recapitulate the original tumor when injected into immunocompromised mice. CSCs within an epithelial malignancy were first described in breast cancer and found to display specific cell surface antigen expression (CD44+CD24low/-)2. Since then, CSCs have been identified in an increasing number of other human malignancies using CD44 and CD24 as well as a number of other surface antigens. Physiologic properties, including aldehyde dehydrogenase (ALDH) activity, have also been used to isolate CSCs from malignant tissues3-5.
Recently, we and others identified CSCs from pancreatic adenocarcinoma based on
ALDH activity and the expression of the cell surface antigens CD44 and CD24, and CD1336-8. These highly tumorigenic populations may or may not be overlapping and display other functions. We found that ALDH+ and CD44+CD24+ pancreatic CSCs are similarly tumorigenic, but ALDH+ cells are relatively more invasive8. In this protocol we describe a method to isolate viable pancreatic CSCs from low-passage human
xenografts9. Xenografted tumors are harvested from mice and made into a single-cell suspension. Tissue debris and dead cells are separated from live cells and then stained using antibodies against CD44 and CD24 and using the ALDEFLUOR reagent,
a fluorescent substrate of ALDH10. CSCs are then isolated by fluorescence activated cell sorting. Isolated CSCs can then be used for analytical or functional assays requiring viable cells.

Cancer stem cells (CSCs) have been identified in a number of malignancies. In this protocol we describe a flow cytometric method utilizing aldehyde dehydrogenase activity and CD44 and CD24 expression to isolate CSCs from human pancreatic adenocarcinoma xenografts. These viable cells can then be used in functional and analytical studies.

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal ...

Biology

Mammosphere Formation Assay from Human Breast Cancer Tissues and Cell Lines

Similar to healthy tissues, many blood and solid malignancies are now thought to be organised hierarchically, with a subset of stem-like cancer cells that self-renew while giving rise to more differentiated progeny. Understanding and targeting these cancer stem cells in breast cancer, which may possess enhanced chemo- and radio-resistance compared to the non-stem tumor bulk, has become an important research area. Markers including CD44, CD24, and ALDH activity can be assessed using fluorescence activated cell sorting (FACS) to prospectively isolate cells that display enhanced tumorigenicity when implanted into immunocompromised mice: the mammosphere assay has also become widely used for its ability to retrospectively identify sphere-forming cells that develop from single stem cell-like clones. Here we outline approaches for the appropriate culturing of mammospheres from cell lines or primary patient samples, their passaging, and calculations to estimate sphere forming efficiency (SFE). First we discuss key considerations and pitfalls in the appropriate planning and interpretation of mammosphere experiments.

Floating mammosphere assays can investigate the subset of stem-like breast cancer cells that survive in suspension conditions and show enhanced tumorigenesis when implanted into mice. This protocol provides a convenient in vitro measure of sphere-forming ability, a proxy for in vivo tumorigenesis, while facilitating analysis of the stem-associated transcriptional landscape.

Similar to healthy tissues, many blood and solid malignancies are now thought to be organised hierarchically, with a subset of stem-like cancer cells that ...

Isolation and Functional Assessment of Human Breast Cancer Stem Cells from Cell and Tissue Samples

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