The secretome of myocardial telocytes modulates the activity of cardiac stem cells

Telocytes (TCs) are interstitial cells that are present in numerous organs, including the heart interstitial space and cardiac stem cell niche. TCs are completely different from fibroblasts. TCs release extracellular vesicles that may interact with cardiac stem cells (CSCs) via paracrine effects. Data on the secretory profile of TCs and the bidirectional shuttle vesicular signalling mechanism between TCs and CSCs are scarce. We aimed to characterize and understand the in vitro effect of the TC secretome on CSC fate. Therefore, we studied the protein secretory profile using supernatants from mouse cultured cardiac TCs. We also performed a comparative secretome analysis using supernatants from rat cultured cardiac TCs, a pure CSC line and TCs‐CSCs in co‐culture using (i) high‐sensitivity on‐chip electrophoresis, (ii) surface‐enhanced laser desorption/ionization time‐of‐flight mass spectrometry and (iii) multiplex analysis by Luminex‐xMAP. We identified several highly expressed molecules in the mouse cardiac TC secretory profile: interleukin (IL)‐6, VEGF, macrophage inflammatory protein 1α (MIP‐1α), MIP‐2 and MCP‐1, which are also present in the proteome of rat cardiac TCs. In addition, rat cardiac TCs secrete a slightly greater number of cytokines, IL‐2, IL‐10, IL‐13 and some chemokines like, GRO‐KC. We found that VEGF, IL‐6 and some chemokines (all stimulated by IL‐6 signalling) are secreted by cardiac TCs and overexpressed in co‐cultures with CSCs. The expression levels of MIP‐2 and MIP‐1α increased twofold and fourfold, respectively, when TCs were co‐cultured with CSCs, while the expression of IL‐2 did not significantly differ between TCs and CSCs in mono culture and significantly decreased (twofold) in the co‐culture system. These data suggest that the TC secretome plays a modulatory role in stem cell proliferation and differentiation.     

Formation of functional gap junctions in amniotic fluid‐derived stem cells induced by transmembrane co‐culture with neonatal rat cardiomyocytes

Amniotic fluid‐derived stem cells (AFSC) have been reported to differentiate into cardiomyocyte‐like cells and form gap junctions when directly mixed and cultured with neonatal rat ventricular myocytes (NRVM). This study investigated whether or not culture of AFSC on the opposite side of a Transwell membrane from NRVM, allowing for contact and communication without confounding factors such as cell fusion, could direct cardiac differentiation and enhance gap junction formation. Results were compared to shared media (Transwell), conditioned media and monoculture media controls. After a 2‐week culture period, AFSC did not express cardiac myosin heavy chain or troponin T in any co‐culture group. Protein expression of cardiac calsequestrin 2 was up‐regulated in direct transmembrane co‐cultures and media control cultures compared to the other experimental groups, but all groups were up‐regulated compared with undifferentiated AFSC cultures. Gap junction communication, assessed with a scrape‐loading dye transfer assay, was significantly increased in direct transmembrane co‐cultures compared to all other conditions. Gap junction communication corresponded with increased connexin 43 gene expression and decreased phosphorylation of connexin 43. Our results suggest that direct transmembrane co‐culture does not induce cardiomyocyte differentiation of AFSC, though calsequestrin expression is increased. However, direct transmembrane co‐culture does enhance connexin‐43‐mediated gap junction communication between AFSC.     

OPLA scaffold,collagen I,and horse serum induce a higher degree of myogenic differentiation of adult rat cardiac stem cells

In the last few years, a major goal of cardiac research has been to drive stem cell differentiation to replace damaged myocardium. Several research groups have attempted to differentiate potential cardiac stem cells (CSCs) using bi‐ or three‐dimensional systems supplemented with growth factors or molecules acting as differentiating substances. We hypothesize that these systems failed to induce a complete differentiation because they lacked an architectural space. In the present study, we isolated a pool of small proliferating and fibroblast‐like cells from adult rat myocardium. The phenotype of these cells was assessed and the characterized cells were cultured in a collagen I/OPLA scaffold with horse serum to obtain fine myocardial differentiation. C‐Kit^POS/Sca‐1^POS CSCs fully differentiated in vitro when an environment more similar to the CSC niche was created. These experiments demonstrated an important model for the study of the biology of CSCs and the biochemical pathways that lead to myocardial differentiation. The results pave the way for a new surgical approach. J. Cell. Physiol. 221: 729–739, 2009. © 2009 Wiley‐Liss, Inc.     

A quantitative proteomics analysis of MCF7 breast cancer stem and progenitor cell populations

Accumulating evidence has demonstrated that breast cancers are initiated and develop from a small population of stem‐like cells termed cancer stem cells (CSCs). These cells are hypothesized to mediate tumor metastasis and contribute to therapeutic resistance. However, the molecular regulatory networks responsible for maintaining CSCs in an undifferentiated state have yet to be elucidated. In this study, we used CSC markers to isolate pure breast CSCs fractions (ALDH+ and CD44+CD24‐ cell populations) and the mature luminal cells (CD49f‐EpCAM+) from the MCF7 cell line. Proteomic analysis was performed on these samples and a total of 3304 proteins were identified. A label‐free quantitative method was applied to analyze differentially expressed proteins. Using the criteria of greater than twofold changes and p value <0.05, 305, 322 and 98 proteins were identified as significantly different in three pairwise comparisons of ALDH+ versus CD44+CD24‐, ALDH+ versus CD49f‐EpCAM+ and CD44+CD24‐ versus CD49f‐EpCAM+, respectively. Pathway analysis of differentially expressed proteins by Ingenuity Pathway Analysis (IPA) revealed potential molecular regulatory networks that may regulate CSCs. Selected differential proteins were validated by Western blot assay and immunohistochemical staining. The use of proteomics analysis may increase our understanding of the underlying molecular mechanisms of breast CSCs. This may be of importance in the future development of anti‐CSC therapeutics.     

Flow cytometry in cancer stem cell analysis and separation

In recent years, a special type of cancer cell--the cancer stem cell (CSC)--has been identified and characterized for different tumors. CSCs may be responsible for the recurrence of a tumor following a primarily successful therapy and are thought to bear a high metastatic potential. For the development of efficient treatment strategies, the establishment of reliable methods for the identification and effective isolation of CSCs is imperative. Similar to their stem cell counterparts in bone marrow or small intestine, different cluster of differentiation surface antigens have been characterized, thus enabling researchers to identify them within the tumor bulk and to determine their degree of differentiation. In addition, functional properties characteristic of stem cells can be measured. Side population analysis is based on the stem cell-specific activity of certain ATP-binding cassette transporter proteins, which are able to transport fluorescent dyes out of the cells. Furthermore, the stem cell-specific presence of aldehyde dehydrogenase isoform 1 can be used for CSC labeling. However, the flow cytometric analysis of these CSC functional features requires specific technical adjustments. This review focuses on the principles and strategies of the flow cytometric analysis of CSCs and provides an overview of current protocols as well as technical requirements and pitfalls. A special focus is set on side population analysis and analysis of ALDH activity. Flow cytometry-based sorting principles and future flow cytometric applications for CSC analysis are also discussed.     

Proteomic profiling of cancer stem cells derived from primary tumors of HER2/Neu transgenic mice

Human epidermal growth factor receptor 2 (HER2) overexpression leads to mammary tumorigenesis and its elevated levels lead to increase in cancer stem cells (CSCs), invasion, and metastasis. CSCs are resistant to radiation/chemotherapeutic drugs and are believed to be responsible for recurrence/relapse of cancer. CSCs are isolated using flow cytometry based sorting, although reliable, this technology hinders the convenient identification of molecular targets of CSCs. Therefore to understand the molecular players of increased CSC through HER2 overexpression and to develop meaningful targets for combination therapy, we isolated and characterized breast CSCs through convenient tumorsphere culture. We identified the altered protein expression in CSC as compared to non‐CSC using LC‐MS/MS and confirmed those results using qRT‐PCR and Western blotting. Ferritin heavy chain 1 (FTH1) was identified as a candidate gene, which is involved in iron metabolism and iron depletion significantly decreased the self‐renewal of CSCs. We further performed in silico analysis of altered genes in tumorsphere and identified a set of genes (PTMA, S100A4, S100A6, TNXRD1, COX‐1, COX‐2, KRT14, and FTH1), representing possible molecular targets, which in combination showed a promise to be used as prognostic markers for breast cancer.     

Reaching out: junctions between cardiac telocytes and cardiac stem cells in culture

Telocytes (TCs) were previously shown by our group to form a tandem with stem/progenitor cells in cardiac stem cell (CSC) niches, fulfilling various roles in cardiac renewal. Among these, the ability to ‘nurse’ CSCs in situ, both through direct physical contact (junctions) as well as at a distance, by paracrine signalling or through extracellular vesicles containing mRNA. We employed electron microscopy to identify junctions (such as gap or adherens junctions) in a co‐culture of cardiac TCs and CSCs. Gap junctions were observed between TCs, which formed networks, however, not between TCs and CSCs. Instead, we show that TCs and CSCs interact in culture forming heterocellular adherens junctions, as well as non‐classical junctions such as puncta adherentia and stromal synapses. The stromal synapse formed between TCs and CSCs (both stromal cells) was frequently associated with the presence of electron‐dense nanostructures (on average about 15 nm in length) connecting the two opposing membranes. The average width of the synaptic cleft was 30 nm, whereas the average length of the intercellular contact was 5 μm. Recent studies have shown that stem cells fail to adequately engraft and survive in the hostile environment of the injured myocardium, possibly as a result of the absence of the pro‐regenerative components of the secretome (paracrine factors) and/or of neighbouring support cells. Herein, we emphasize the similarities between the junctions described in co‐culture and the junctions identified between TCs and CSCs in situ. Reproducing a CSC niche in culture may represent a viable alternative to mono‐cellular therapies.     

Emerging role of exosome signalling in maintaining cancer stem cell dynamic equilibrium

Cancer stem cells (CSCs) are a small subset of heterogeneous cells existed in tumour tissues or cancer cell lines with self‐renewal and differentiation potentials. CSCs were considered to be responsible for the failure of conventional therapy and tumour recurrence. However, CSCs are not a static cell population, CSCs and non‐CSCs are maintained in dynamic interconversion state by their self‐differentiation and dedifferentiation. Therefore, targeting CSCs for cancer therapy is still not enough,exploring the mechanism of dynamic interconversion between CSCs and non‐CSCs and blocking the interconversion seems to be imperative. Exosomes are 30‐100 nm size in diameter extracellular vesicles (EVs) secreted by multiple living cells into the extracellular space. They contain cell‐state‐specific bioactive materials, including DNA, mRNA, ncRNA, proteins, lipids, etc. with their specific surface markers, such as, CD63, CD81, Alix, Tsg101, etc. Exosomes have been considered as information carriers in cell communication between cancer cells and non‐cancer cells, which affect gene expressions and cellular signalling pathways of recipient cells by delivering their contents. Now that exosomes acted as information carriers, whether they played role in maintaining dynamic equilibrium state between CSCs and non‐CSCs and their mechanism of activity are unknown. This review summarized the current research advance of exosomes’ role in maintaining CSC dynamic interconversion state and their possible mechanism of action, which will provide a better understanding the contribution of exosomes to dedifferentiation and stemness acquisition of non‐CSCs, and highlight that exosomes might be taken as the attractive target approaches for cancer therapeutics.     

Hypoxia followed by reoxygenation induces secretion of cyclophilin A from cultured rat cardiac myocytes

We previously reported that hypoxia followed by reoxygenation (hypoxia/reoxygenation) rapidly activated intracellular signaling such as mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated protein kinase (ERK) 1/2, p38MAPK, and stress-activated protein kinases (SAPKs). To investigate the humoral factors which mediate cardiac response to hypoxia/reoxygenation, we analyzed the conditioned media from cardiac myocytes subjected to hypoxia/reoxygenation by two-dimensional electrophoresis and mass spectrometry. We identified cyclophilin A (CyPA) as one of the proteins secreted from cardiac myocytes in response to hypoxia/reoxygenation. Hypoxia/reoxygenation induced the expression of CyPA and its cell surface receptor CD147 on cardiac myocytes in vitro. This was also confirmed by ischemia/reperfusion in vivo. Recombinant human (rh) CyPA activated ERK1/2, p38MAPK, SAPKs, and Akt in cultured cardiac myocytes. Furthermore, CyPA significantly increased Bcl-2 in cardiac myocytes. These data strongly suggested that CyPA is released from cardiac myocytes in response to hypoxia/reoxygenation and may protect cardiac myocytes from oxidative stress-induced apoptosis.     

EGF signalling pathway regulates colon cancer stem cell proliferation and apoptosis

Objectives

Cancer stem cells (CSCs) compose a subpopulation of cells within a tumour that can self‐renew and proliferate. Growth factors such as epidermal growth factor (EGF) and basic fibroblast growth factor (b‐FGF) promote cancer stem cell proliferation in many solid tumours. This study assesses whether EGF, bFGF and IGF signalling pathways are essential for colon CSC proliferation and self‐renewal.

Material and methods

Colon CSCs were cultured in serum‐free medium (SFM) with one of the following growth factors: EGF, bFGF or IGF. Characteristics of CSC gene expression were evaluated by real time PCR. Tumourigenicity of CSCs was determined using a xenograft model in vivo. Effects of EGF receptor inhibitors, Gefitinib and PD153035, on CSC proliferation, apoptosis and signalling were evaluated using fluorescence‐activated cell sorting and western blotting.

Results

Colon cancer cell HCT116 transformed to CSCs in SFM. Compared to other growth factors, EGF was essential to support proliferation of CSCs that expressed higher levels of progenitor genes (Musashi‐1, LGR5) and lower levels of differential genes (CK20). CSCs promoted more rapid tumour growth than regular cancer cells in xenografts. EGFR inhibitors suppressed proliferation and induced apoptosis of CSCs by inhibiting autophosphorylation of EGFR and downstream signalling proteins, such as Akt kinase, extracellular signal‐regulated kinase 1/2 (ERK 1/2).

Conclusions

This study indicates that EGF signalling was essential for formation and maintenance of colon CSCs. Inhibition of the EGF signalling pathway may provide a useful strategy for treatment of colon cancer.     

Breast Cancer Stem Cell Therapeutics,Multiple Strategies Versus Using Engineered Mesenchymal Stem Cells With Notch Inhibitory Properties: Possibilities and Perspectives

Relapse cases of cancers are more vigorous and difficult to control due to the preponderance of cancer stem cells (CSCs). Such CSCs that had been otherwise dormant during the first incidence of cancer gradually appear as radiochemoresistant cancer cells. Hence, cancer therapeutics aimed at CSCs would be an effective strategy for mitigating the cancers during relapse. Alternatively, CSC therapy can also be proposed as an adjuvant therapy, along‐with the conventional therapies. As regenerative stem cells (RSCs) are known for their trophic effects, anti‐tumorogenicity, and better migration toward an injury site, this review aims to address the use of adult stem cells such as dental pulp derived; cord blood derived pure populations of regenerative stem cells for targeting CSCs. Indeed, pro‐tumorogenicity of RSCs is of concern and hence has also been dealt with in relation to breast CSC therapeutics. Furthermore, as notch signaling pathways are upregulated in breast cancers, and anti‐notch antibody based and sh‐RNA based therapies are already in the market, this review focuses the possibilities of engineering RSCs to express notch inhibitory proteins for breast CSC therapeutics. Also, we have drawn a comparison among various possibilities of breast CSC therapeutics, about, notch1 inhibition. J. Cell. Biochem. 119: 141–149, 2018. © 2017 Wiley Periodicals, Inc.     

Vascular endothelial growth factor promotes cardiac stem cell migration via the PI3K/Akt pathway

VEGF is a major inducer of angiogenesis. However, the homing role of VEGF for cardiac stem cells (CSCs) is unclear. In in vitro experiments, CSCs were isolated from the rat hearts, and a cellular migration assay was performed using a 24-well transwell system. VEGF induced CSC migration in a concentration-dependent manner, and SU5416 blocked this. Western blot analysis showed that the phosphorylated Akt was markedly increased in the VEGF-treated CSCs and that inhibition of pAkt activity significantly attenuated the VEGF-induced the migration of CSCs. In in vivo experiments, rat heart myocardial infarction (MI) was induced by left coronary artery ligation. One week after MI, the adenoviral vector expressing hVEGF165 and LacZ genes were injected separately into the infarcted myocardium at four sites before endomyocardial transplantation of 2 × 10⁵ PKH26 labeled CSCs (50 μL) at atrioventricular groove. One week after CSC transplantation, RT-PCR, immunohistochemical staining, Western blot, and ELISA analysis were performed to detect the hVEGF mRNA and protein. The expression of hVEGF mRNA and protein was significantly increased in the infarcted and hVEGF165 transfected rat hearts, accompanied by an enhanced PI3K/Ak activity, a greater accumulation of CSCs in the infarcted region, and an improvement in cardiac function. The CSC accumulation was inhibited by either the VEGF receptor blocker SU5416 or the PI3K/Ak inhibitor wortmannin. VEGF signaling may mediate the migration of CSCs via activation of PI3K/Akt.     

Cervical cancer stem cells

The concept of cancer stem cells (CSC) has been established over the past decade or so, and their role in carcinogenic processes has been confirmed. In this review, we focus on cervical CSCs, including (1) their purported origin, (2) markers used for cervical CSC identification, (3) alterations to signalling pathways in cervical cancer and (4) the cancer stem cell niche. Although cervical CSCs have not yet been definitively identified and characterized, future studies pursuing them as therapeutic targets may provide novel insights for treatment of cervical cancer.     

Secreted proteins as a fundamental source for biomarker discovery

The proteins secreted by various cells (the secretomes) are a potential rich source of biomarkers as they reflect various states of the cells at real time and at given conditions. To have accessible, sufficient and reliable protein markers is desirable as they mark various stages of disease development and their presence/absence can be used for diagnosis, prognosis, risk stratification and therapeutic monitoring. As direct analysis of blood/plasma, a common and noninvasive patient screening method, can be difficult for candidate protein biomarker identification, the alternative/complementary approaches are required, one of them is the analysis of secretomes in cell conditioned media in vitro. As the proteins secreted by cells as a response to various stimuli are most likely secreted into blood/plasma, the identification and pre-selection of candidate protein biomarkers from cell secretomes with subsequent validation of their presence at higher levels in serum/plasma is a promising approach. In this review, we discuss the proteins secreted by three progenitor cell types (smooth muscle, endothelial and cardiac progenitor cells) and two adult cell types (neonatal rat ventrical myocytes and smooth muscle cells) which can be relevant to cardiovascular research and which have been recently published in the literature. We found, at least for secretome studies included in this review, that secretomes of progenitor and adult cells overlap by 48% but the secretomes are very distinct among progenitor cell themselves as well as between adult cells. In addition, we compared secreted proteins to protein identifications listed in the Human Plasma PeptideAtlas and in two reports with cardiovascular-related proteins and we performed the extensive literature search to find if any of these secreted proteins were identified in a biomarker study. As expected, many proteins have been identified as biomarkers in cancer but 18 proteins (out of 62) have been tested as biomarkers in cardiovascular diseases as well.     

Local activation of cardiac stem cells for post‐myocardial infarction cardiac repair

The prognosis of patients with myocardial infarction (MI) and resultant chronic heart failure remains extremely poor despite continuous advancements in optimal medical therapy and interventional procedures. Animal experiments and clinical trials using adult stem cell therapy following MI have shown a global improvement of myocardial function. The emergence of stem cell transplantation approaches has recently represented promising alternatives to stimulate myocardial regeneration. Regarding their tissue‐specific properties, cardiac stem cells (CSCs) residing within the heart have advantages over other stem cell types to be the best cell source for cell transplantation. However, time‐consuming and costly procedures to expanse cells prior to cell transplantation and the reliability of cell culture and expansion may both be major obstacles in the clinical application of CSC‐based transplantation therapy after MI. The recognition that the adult heart possesses endogenous CSCs that can regenerate cardiomyocytes and vascular cells has raised the unique therapeutic strategy to reconstitute dead myocardium via activating these cells post‐MI. Several strategies, such as growth factors, mircoRNAs and drugs, may be implemented to potentiate endogenous CSCs to repair infarcted heart without cell transplantation. Most molecular and cellular mechanism involved in the process of CSC‐based endogenous regeneration after MI is far from understanding. This article reviews current knowledge opening up the possibilities of cardiac repair through CSCs activation in situ in the setting of MI.     

Sca-1+ cardiac stem cells mediate acute cardioprotection via paracrine factor SDF-1 following myocardial ischemia/reperfusion

Background

Cardiac stem cells (CSCs) promote myocardial recovery following ischemia through their regenerative properties. However, little is known regarding the implication of paracrine action by CSCs in the setting of myocardial ischemia/reperfusion (I/R) injury although it is well documented that non-cardiac stem cells mediate cardioprotection via the production of paracrine protective factors. Here, we studied whether CSCs could initiate acute protection following global myocardial I/R via paracrine effect and what component from CSCs is critical to this protection.

Methodology/Principal Findings

A murine model of global myocardial I/R was utilized to investigate paracrine effect of Sca-1+ CSCs on cardiac function. Intracoronary delivery of CSCs or CSC conditioned medium (CSC CM) prior to ischemia significantly improved myocardial function following I/R. siRNA targeting of VEGF in CSCs did not affect CSC-preserved myocardial function in response to I/R injury. However, differentiation of CSCs to cardiomyocytes (DCSCs) abolished this protection. Through direct comparison of the protein expression profiles of CSCs and DCSCs, SDF-1 was identified as one of the dominant paracrine factors secreted by CSCs. Blockade of the SDF-1 receptor by AMD3100 or downregulated SDF-1 expression in CSCs by specific SDF-1 siRNA dramatically impaired CSC-induced improvement in cardiac function and increased myocardial damage following I/R. Of note, CSC treatment increased myocardial STAT3 activation after I/R, whereas downregulation of SDF-1 action by blockade of the SDF-1 receptor or SDF-1 siRNA transfection abolished CSC-induced STAT3 activation. In addition, inhibition of STAT3 activation attenuated CSC-mediated cardioprotection following I/R. Finally, post-ischemic infusion of CSC CM was shown to significantly protect I/R-caused myocardial dysfunction.

Conclusions/Significance

This study suggests that CSCs acutely improve post-ischemic myocardial function through paracrine factor SDF-1 and up-regulated myocardial STAT3 activation.     

Critical role of Lin28‐TNFR2 signalling in cardiac stem cell activation and differentiation

Tumour necrotic factor receptor‐2 (TNFR2) has been to be cardiac‐protective and is expressed in cardiac progenitor cells. Our goal is to define the mechanism for TNFR2‐mediated cardiac stem cell activation and differentiation. By employing a protocol of in vitro cardiac stem cell (CSC) differentiation from human inducible pluripotent stem cell (hiPSC), we show that expression of TNFR2 precedes expression of CSC markers followed by expression of mature cardiomyocyte proteins. Activation of TNFR2 by a specific agonist promotes whereas inhibition of TNFR2 by neutralizing antibody diminishes hiPSC‐based CSC differentiation. Interestingly, pluripotent cell factor RNA‐binding protein Lin28 enhances TNFR2 protein expression in early CSC activation by directly binding to a conserved Lin28‐motif within the 3'UTR of Tnfr2 mRNA. Furthermore, inhibition of Lin28 blunts TNFR2 expression and TNFR2‐dependent CSC activation and differentiation. Our study demonstrates a critical role of Lin28‐TNFR2 axis in CSC activation and survival, providing a novel strategy to enhance stem cell‐based therapy for the ischaemic heart diseases.     

CD133 positive embryonal rhabdomyosarcoma stem-like cell population is enriched in rhabdospheres

Cancer stem cells (CSCs) have been identified in a number of solid tumors, but not yet in rhabdomyosarcoma (RMS), the most frequently occurring soft tissue tumor in childhood. Hence, the aim of this study was to identify and characterize a CSC population in RMS using a functional approach. We found that embryonal rhabdomyosarcoma (eRMS) cell lines can form rhabdomyosarcoma spheres (short rhabdospheres) in stem cell medium containing defined growth factors over several passages. Using an orthotopic xenograft model, we demonstrate that a 100 fold less sphere cells result in faster tumor growth compared to the adherent population suggesting that CSCs were enriched in the sphere population. Furthermore, stem cell genes such as oct4, nanog, c-myc, pax3 and sox2 are significantly upregulated in rhabdospheres which can be differentiated into multiple lineages such as adipocytes, myocytes and neuronal cells. Surprisingly, gene expression profiles indicate that rhabdospheres show more similarities with neuronal than with hematopoietic or mesenchymal stem cells. Analysis of these profiles identified the known CSC marker CD133 as one of the genes upregulated in rhabdospheres, both on RNA and protein levels. CD133(+) sorted cells were subsequently shown to be more tumorigenic and more resistant to commonly used chemotherapeutics. Using a tissue microarray (TMA) of eRMS patients, we found that high expression of CD133 correlates with poor overall survival. Hence, CD133 could be a prognostic marker for eRMS. These experiments indicate that a CD133(+) CSC population can be enriched from eRMS which might help to develop novel targeted therapies against this pediatric tumor.     

Three‐dimensional cell culture model utilization in cancer stem cell research

Three‐dimensional (3D) cell culture models are becoming increasingly popular in contemporary cancer research and drug resistance studies. Recently, scientists have begun incorporating cancer stem cells (CSCs) into 3D models and modifying culture components in order to mimic in vivo conditions better. Currently, the global cell culture market is primarily focused on either 3D cancer cell cultures or stem cell cultures, with less focus on CSCs. This is evident in the low product availability officially indicated for 3D CSC model research. This review discusses the currently available commercial products for CSC 3D culture model research. Additionally, we discuss different culture media and components that result in higher levels of stem cell subpopulations while better recreating the tumor microenvironment. In summary, although progress has been made applying 3D technology to CSC research, this technology could be further utilized and a greater number of 3D kits dedicated specifically to CSCs should be implemented.