Cancer stem cell sorting from colorectal cancer cell lines by sedimentation field flow fractionation

Flow field-flow fractionation coupled with multidetector: A robust approach for the separation and characterization of resistant starch

The unique properties of resistant starch (RS) have made it applicable in the formulation of a broad range of functional foods. The physicochemical properties of RS play a crucial role in its applications. Recently, flow field-flow fractionation (FlFFF) has attracted increasing interest in the separation and characterization of different categories of RS. In this review, an overview of the theory behind FlFFF is introduced, and the controllable factors, including FlFFF channel design, sample separation conditions, and the choice of detector, are discussed in detail. Furthermore, the applications of FlFFF for the separation and characterization of RS at both the granule and molecule levels are critically reviewed. The aim of this review is to equip readers with a fundamental understanding of the theoretical principle of FlFFF and to highlight the potential for expanding the application of RS through the valuable insights gained from FlFFF coupled with multidetector analysis.

The Impact of Cancer Stem Cells in Colorectal Cancer

Despite incessant research, colorectal cancer (CRC) is still one of the most common causes of fatality in both men and women worldwide. Over time, advancements in medical treatments have notably enhanced the survival rates of patients with colorectal cancer. Managing metastatic CRC involves a complex tradeoff between the potential benefits and adverse effects of treatment, considering factors like disease progression, treatment toxicity, drug resistance, and the overall impact on the patient's quality of life. An increasing body of evidence highlights the significance of the cancer stem cell (CSC) concept, proposing that CSCs occupy a central role in triggering cancer. CSCs have been a focal point of extensive research in a variety of cancer types, including CRC. Colorectal cancer stem cells (CCSCs) play a crucial role in tumor initiation, metastasis, and therapy resistance, making them potential treatment targets. Various methods exist for isolating CCSCs, and understanding the mechanisms of drug resistance associated with them is crucial. This paper offers an overview of the current body of research pertaining to the comprehension of CSCs in colorectal cancer.

Field-flow fractionation - an excellent tool for fractionation, isolation and/or purification of biomacromolecules

Field-flow fractionation (FFF) with its several variants, has developed into a mature methodology. The scope of the FFF investigations has expanded, covering both a wide range of basic studies and especially a wide range of analytical applications. Special attention of this review is given to the achievements of FFF with reference to recent applications in the fractionation, isolation, and purification of biomacromolecules, and from which especially those of (in alphabetical order) bacteria, cells, extracellular vesicles, liposomes, lipoproteins, nucleic acids, and viruses and virus-like particles. In evaluating the major approaches and trends demonstrated since 2012, the most significant biomacromolecule applications are compiled in tables. It is also evident that asymmetrical flow field-flow fractionation is by far the most dominant technique in the studies. The industry has also shown current interest in FFF and adopted it in some sophisticated fields. FFF, in combination with appropriate detectors, handles biomacromolecules in open channel in a gentle way due to the lack of shear forces and unwanted interactions caused by the stationary phase present in chromatography. In addition, in isolation and purification of biomacromolecules quite high yields can be achieved under optimal conditions.

A concise review on miRNAs as regulators of colon cancer stem cells and associated signalling pathways

Despite recent therapy advances and a better understanding of colon cancer biology, it remains one of the major causes of death. The cancer stem cells, associated with the progression, metastasis, and recurrence of colon cancer, play a major role in promoting the development of tumour and are found to be chemo resistant. The stroma of the tumour, which makes up the bulk of the tumour mass, is composed of the tumour microenvironment. With the advent of theranostic and the development of personalised medicine, miRNAs are becoming increasingly important in the context of colon malignancies. A holistic understanding of the regulatory roles of miRNAs in cancer cells and cancer stem cells will allow us to design effective strategies to regulate miRNAs, which could lead to improved clinical translation and creating a potent colon cancer treatment strategy. In this review paper, we briefly discuss the history of miRNA as well as the mechanisms of miRNA and cancer stem cells that contribute to the tumour growth, apoptosis, and advancement of colon cancer. The usefulness of miRNA in colorectal cancer theranostic is further concisely reviewed. We conclude by holding a stance in addressing the prospects and possibilities for miRNA by the disclosure of recent theranostic approaches aimed at eradicating cancer stem cells and enhancing overall cancer treatment outcomes.

Sedimentation Field-Flow Fractionation: A Diagnostic Tool for Rapid Antimicrobial Susceptibility Testing

Conventional antimicrobial susceptibility testing (AST) methods require 24-48 h to provide results, creating the need for a probabilistic antibiotic therapy that increases the risk of antibiotic resistance emergence. Consequently, the development of rapid AST methods has become a priority. Over the past decades, sedimentation field-flow fractionation (SdFFF) has demonstrated high sensitivity in early monitoring of induced biological events in eukaryotic cell populations. This proof-of-concept study aimed at investigating SdFFF for the rapid assessment of bacterial susceptibility to antibiotics. Three bacterial species were included (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) with two panels of antibiotics tailored to each bacterial species. The results demonstrate that SdFFF, when used in "Hyperlayer" elution mode, enables monitoring of antibiotic-induced morphological changes. The percentage variation of the retention factor (PΔR) was used to quantify the biological effect of antibiotics on bacteria with the establishment of a threshold value of 16.8% to differentiate susceptible and resistant strains. The results obtained with SdFFF were compared to that of the AST reference method, and a categorical agreement of 100% was observed. Overall, this study demonstrates the potential of SdFFF as a rapid method for the determination of antibiotic susceptibility or resistance since it is able to provide results within a shorter time frame than that needed for conventional methods (3-4 h vs 16-24 h, respectively), enabling earlier targeted antibiotic therapy. Further research and validation are necessary to establish the effectiveness and reliability of SdFFF in clinical settings.

Active cell capturing for organ-on-a-chip systems: a review

Organ-on-a-chip (OOC) is an emerging technology that has been proposed as a new powerful cell-based tool to imitate the pathophysiological environment of human organs. For most OOC systems, a pivotal step is to culture cells in microfluidic devices. In active cell capturing techniques, external actuators, such as electrokinetic, magnetic, acoustic, and optical forces, or a combination of these forces, can be applied to trap cells after ejecting cell suspension into the microchannel inlet. This review paper distinguishes the characteristics of biomaterials and evaluates microfluidic technology. Besides, various types of OOC and their fabrication techniques are reported and various active cell capture microstructures are analyzed. Furthermore, their constraints, challenges, and future perspectives are provided.

A Label-Free Cell Sorting Approach to Highlight the Impact of Intratumoral Cellular Heterogeneity and Cancer Stem Cells on Response to Therapies

Cancer stem cells play a crucial role in tumor initiation, metastasis, and resistance to treatment. Cellular heterogeneity and plasticity complicate the isolation of cancer stem cells. The impact of intra-tumor cellular heterogeneity using a label-free approach remains understudied in the context of treatment resistance. Here, we use the sedimentation field–flow fractionation technique to separate, without labeling, cell subpopulations of colorectal cancer cell lines and primary cultures according to their biophysical properties. One of the three sorted cell subpopulations exhibits characteristics of cancer stem cells, including high tumorigenicity in vivo and a higher frequency of tumor-initiating cells compared to the other subpopulations. Due to its chemoresistance, two- and three-dimensional in vitro chemosensitivity assays highlight the therapeutic relevance of this cancer stem cell subpopulation. Thus, our results reveal the major implication of intra-tumor cellular heterogeneity, including cancer stem cells in treatment resistance, thanks to our label-free cell sorting approach. This approach enables—by breaking down the tumor—the study the individualized response of each sorted tumor cell subpopulation and to identify chemoresistance, thus offering new perspectives for personalized therapy.

Characterization of Glioblastoma Cancer Stem Cells Sorted by Sedimentation Field-Flow Fractionation Using an Ultrahigh-Frequency Range Dielectrophoresis Biosensor

Cancer stem cells (CSCs) appear to be an essential target for cancer therapies, in particular, in brain tumors such as Glioblastoma. Nevertheless, their isolation is made difficult by their low content in culture or tumors (<5% of the tumor mass) and is essentially based on the use of fluorescent or magnetic labeling techniques, increasing the risk of differentiation induction. The use of label-free separation methods such as sedimentation field-flow fractionation (SdFFF) is promising, but it becomes necessary to consider a coupling with a detection and characterization method for future identification and purification of CSCs from patient-derived tumors. In this study, we demonstrate for the first time the capability of using an ultrahigh-frequency range dielectrophoresis fluidic biosensor as a detector. This implies an important methodological adaptation of SdFFF cell sorting by the use of a new compatible carrier liquid DEP buffer (DEP-B). After SdFFF sorting, subpopulations derived from U87-MG and LN18 cell lines undergo biological characterization, demonstrating that using DEP-B as a carrier liquid, we sorted by SdFFF subpopulations with specific differentiation characteristics: F1 = differentiated cells/F2 = CSCs. These subpopulations presented high-frequency crossover (HFC) values similar to those measured for standard differentiated (around 110 MHz) and CSC (around 80 MHz) populations. This coupling appeared as a promising solution for the development of an online integration of these two complementary label-free separation/detection technologies.

Autophagy inhibition reinforces stemness together with exit from dormancy of polydisperse glioblastoma stem cells

Therapeutic resistance and infiltrative capacities justify the aggressiveness of glioblastoma. This is due to cellular heterogeneity, especially the presence of stemness-related cells, i.e. Cancer Stem Cells (CSC). Previous studies focused on autophagy and its role in CSCs maintenance; these studies gave conflicting results as they reported either sustaining or disruptive effects. In the present work, we silenced two autophagy related genes -either Beclin1 or ATG5- by shRNA and we explored the ensuing consequences on CSCs markers’ expression and functionalities. Our results showed that the down regulation of autophagy led to enhancement in expression of CSCs markers, while proliferation and clonogenicity were boosted. Temozolomide (TMZ) treatment failed to induce apoptotic death in shBeclin1-transfected cells, contrary to control. We optimized the cellular subset analysis with the use of Sedimentation Field Flow Fractionation, a biological event monitoring- and cell sorting-dedicated technique. Fractograms of both shBeclin1 and shATG5 cells exhibited a shift of elution peak as compared with control cells, showing cellular dispersion and intrinsic sub-fraction modifications. The classical stemness fraction (i.e. F3) highlighted data obtained with the overall cellular population, exhibiting enhancement of stemness markers and escape from dormancy. Our results contributed to illustrate CSCs polydispersity and to show how these cells develop capacity to bypass autophagy inhibition, thanks to their acute adaptability and plasticity.

The Role of Cancer Stem Cells in Colorectal Cancer: From the Basics to Novel Clinical Trials

The treatment options available for colorectal cancer (CRC) have increased over the years and have significantly improved the overall survival of CRC patients. However, the response rate for CRC patients with metastatic disease remains low and decreases with subsequent lines of therapy. The clinical management of patients with metastatic CRC (mCRC) presents a unique challenge in balancing the benefits and harms while considering disease progression, treatment-related toxicities, drug resistance and the patient's overall quality of life. Despite the initial success of therapy, the development of drug resistance can lead to therapy failure and relapse in cancer patients, which can be attributed to the cancer stem cells (CSCs). Thus, colorectal CSCs (CCSCs) contribute to therapy resistance but also to tumor initiation and metastasis development, making them attractive potential targets for the treatment of CRC. This review presents the available CCSC isolation methods, the clinical relevance of these CCSCs, the mechanisms of drug resistance associated with CCSCs and the ongoing clinical trials targeting these CCSCs. Novel therapeutic strategies are needed to effectively eradicate both tumor growth and metastasis, while taking into account the tumor microenvironment (TME) which plays a key role in tumor cell plasticity.

A New Label-Free Approach to Glioblastoma Cancer Stem Cell Sorting and Detection

Cancer stem cells (CSCs) play critical roles in cancer, making them important targets for new diagnostic and therapeutic approaches. Since CSCs are heterogeneous and not abundant in tumors, and few specific markers for these cells currently exist, new methods to isolate and characterize them are required. To address this issue, we developed a new label-free methodology to isolate, enrich, and identify CSCs from an heterogeneous tumor cell subpopulation using a cell sorting method (sedimentation field flow fractionation, SdFFF) and a biosensor as a detector. Enrichment was optimized using an original protocol and U87-MG glioblastoma cells cultured in a normal (N) or defined (D) medium (± fetal bovine serum, FBS) under normoxic (N, p_O2 = 20%) or hypoxic (H, p_O2 < 2%) conditions to obtain four cell populations: NN, NH, DN, and DH. After elution of CSCs via SdFFF using the hyperlayer mode (inertial elution mode for micrometer-sized species), we isolated eight subpopulations with distinct CSC contents based on phenotypical and functional properties, ranging from NN F1 with a lower CSC content to DH F3 with a higher CSC content. Reflecting biological differences, the intrinsic intracellular dielectric permittivity increased from NN to DH conditions. The largest difference in electromagnetic signature was observed between NN F1 and DH F3, in which the CSC content was lowest and highest, respectively. The results demonstrate that microwave dielectric spectroscopy can be used to reliably and efficiently distinguish stem cell characteristics. This new instrumental and methodological approach is an important innovation that allows both enrichment and detection of CSCs, opening the door to novel diagnostic and therapeutic approaches.

TrkB-containing exosomes promote the transfer of glioblastoma aggressiveness to YKL-40-inactivated glioblastoma cells

The neurotrophin receptors are known to promote growth and proliferation of glioblastoma cells. Their functions in spreading glioblastoma cell aggressiveness to the microenvironment through exosome release from glioblastoma cells are unknown. Considering previous reports demonstrating that YKL-40 expression is associated with undifferentiated glioblastoma cancer stem cells, we used YKL-40-silenced cells to modulate the U87-MG differentiated state and their biological aggressiveness. Herein, we demonstrated a relationship between neurotrophin-receptors and YKL-40 expression in undifferentiated cells. Differential functions of cells and derived-exosomes were evidenced according to neurotrophin receptor content and differentiated cell state by comparison with control pLKO cells. YKL-40 silencing of glioblastoma cells impairs proliferation, neurosphere formation, and their ability to induce endothelial cell (HBMEC) migration. The modulation of differentiated cell state in YKL-40-silenced cells induces a decrease of TrkB, sortilin and p75NTR cellular expressions, associated with a low-aggressiveness phenotype. Interestingly, TrkB expressed in exosomes derived from control cells was undetectable in exosomes from YKL-40 -silenced cells. The transfer of TrkB-containing exosomes in YKL-40-silenced cells contributed to restore cell proliferation and promote endothelial cell activation. Interestingly, in U87 MG xenografted mice, TrkB-depleted exosomes from YKL-40-silenced cells inhibited tumor growth in vivo. These data highlight that TrkB-containing exosomes play a key role in the control of glioblastoma progression and aggressiveness. Furthermore, TrkB expression was detected in exosomes isolated from plasma of glioblastoma patients, suggesting that this receptor may be considered as a new biomarker for glioblastoma diagnosis.

Time-lapse microscopic observation of non-dividing cells in cultured human osteosarcoma MG-63 cell line

Cancer stem cells resemble normal tissue-specific stem cells in many aspects, such as self-renewal and plasticity. Like their non-malignant counterparts, cancer stem cells are suggested to exhibit a relative quiescence. The established cancer cell lines reportedly harbor slow-proliferating cells that are positive for some cancer stem cells markers. However, the fate of these cells and their progeny remains unknown. We used time-lapse microscopy and the contrast-based segmentation algorithm to identify and monitor actively dividing and non-dividing cells in human osteosarcoma MG-63 cell line. Within the monitored field of view the non-dividing cells were represented by three cells that never divided, and one cell that attempted to divide, but failed cytokinesis, and later, after significantly prolonged division, produced the progeny with enlarged segmented nuclei, thus pointing to a possible mitotic catastrophe. Together, these cells initially constituted about 6.2% of the total number of seeded cells, yet only 0.02% of all cells at the end of the observation period when cells became confluent. Non-dividing cells were characterized by rounded shape, dark nuclei, random cytoplasmic streaming and subtle oscillatory movement, however, they did not migrate and rarely formed cell-cell contacts as compared to actively dividing cells. Our data indicate that the observed non-dividing MG-63 cells do not have a growth advantage over other cells and, therefore, they do not contribute to the cancer stem cells pool.

The extracellular domain of E cadherin linked to invasiveness in colorectal cancer: a new resistance and relapses monitoring serum-bio marker?

PURPOSE

Multiple studies have attempted to demonstrate the interest of the cell adhesion marker, E cadherin, as a diagnostic and prognosis marker in colorectal cancer (CRC). However, it was considered non specific.

MATERIALS AND METHODS

Studies were carried out with CRC cell lines and patients' cohort operated for CRC. The expression of E cadherin was studied after 5 fluorouracil (5FU) treatment and correlated to CRC relapse, chemo-resistance and survival.

RESULTS

In CRC cell lines derived from high tumor stages, extracellular domain of E cadherin expression decreased after 5FU treatment whereas it increased in supernatants. Interestingly, only specific cleaved forms at 55 kDa of E cadherin were detected in supernatants. In CRC surgical patients, more importantly concerning extracellular E cadherin domain, a decreased expression was observed in tissues in function of CRC stages whereas an increased expression was found in sera. Moreover, there is an increasing trend of survival with weak serum E cadherin secretion, reinforcing the implication of this protein in CRC evolution.

DISCUSSION

The extracellular domain can be defined as a 5FU resistance marker and allow CRC monitoring.

Engulfment of ceramic particles by fibroblasts does not alter cell behavior

Despite many studies, the impact of ceramic particles on cell behavior remains unclear. The aim of the present study was to investigate the effects of nano-sized ceramic particles on fibroblastic cells. Fibroblasts (dermal fibroblasts freshly isolated from skin samples and WI26 fibroblastic cells) were cultured in a monolayer in the presence of alumina or cerium-zirconia particles (≈50 nm diameter) at two concentrations (100 or 500 μg ml^-1). Fluorescent alumina particles were also used. The following properties were analyzed: cell morphology, cytoplasmic ceramic incorporation (using confocal and transmission electron microscopy) and migration (using a silicon insert). Sedimentation field-flow fractionation (SdFFF) was also used to evaluate the rate of incorporation of ceramic particles into the cells. Finally, after treatment with various concentrations of ceramic particles, fibroblasts were also included in a collagen type I lattice constituting a dermal equivalent (DE), and the collagen lattice retraction and cell proliferation were evaluated. In monolayer conditions, the presence of both alumina and cerium-zirconia ceramic particles did not cause any deleterious effects on cultured cells (dermal fibroblast and WI26 cells) and cell fate was not affected in any way by the presence of ceramic particles in the cytoplasm. Confocal (using fluorescent alumina particles) and electron microscopy (using both alumina and cerium-zirconia particles) showed that ceramic particles were internalized in the WI26 cells. Using fluorescent membrane labeling and fluorescent alumina particles, a membrane was observed around the particle-containing vesicles present in the cytoplasm. Electron microscopy on WI26 cells showed the presence of a classical bilayer membrane around the ceramic particles. Interestingly, SdFFF confirmed that some dermal fibroblasts contained many alumina ceramic particles while others contained very few; in WI26 cells, the uptake of alumina ceramic was more homogeneous. In DE, collagen lattice retraction and cell proliferation were unchanged when WI26 fibroblastic cells contained alumina or cerium-zirconia ceramic particles. Our data suggest that ceramic particles are internalized in the cells by endocytosis. The presence of ceramic particles in the cytoplasm has no affect on cell behavior, confirming the excellent biocompatibility of this material and anticipating a minimal harmful effect of potential wear debris.

New Method for Sorting Endothelial and Neural Progenitors from Human Induced Pluripotent Stem Cells by Sedimentation Field Flow Fractionation

Human induced pluripotent stem cells (hiPSc) are a very useful solution to create and observe the behavior of specific and usually inaccessible cells, such as human motor neurons. Obtained from a patient biopsy by reprograming dermal fibroblasts (DF), hiPSc present the same properties as embryonic stem cells and can generate any cell type after several weeks of differentiation. Today, there are numerus protocols which aim to control hiPSC differentiation. The principal challenge is to obtain a sufficiently enriched specific cell population to study disease pathophysiology and to provide a good model for further investigation and drug screening. The differentiation process is very costly and time-consuming, because many specific factors and different culture media must be used. In this study, we used Sedimentation Field Flow Fractionation (SdFFF) to prepare enriched populations derived from hiPSc after only 10 days of culture in a classical medium. Based on phenotypic and proteomic characterization, "hyperlayer" elution resulted in a fraction expressing markers of endothelial progenitors while another fraction expressed markers of neural progenitors. The isolation of subpopulations representing various differentiation lineages is of major interest for the production of specialized, cell-enriched fractions and in the preparation of increasingly complex models for the development of new therapeutic tools.

In vivo relevant mixed urolithins and ellagic acid inhibit phenotypic and molecular colon cancer stem cell features: A new potentiality for ellagitannin metabolites against cancer

Colon cancer stem cells (CSCs) offer a novel paradigm for colorectal cancer (CRC) treatment and dietary polyphenols may contribute to battle these cells. Specifically, polyphenol-derived colon metabolites have the potential to interact with and affect colon CSCs. We herein report the effects against colon CSCs of two mixtures of ellagitannin (ET) metabolites, ellagic acid (EA) and the gut microbiota-derived urolithins (Uro) at concentrations detected in the human colon tissues following the intake of ET-containing products (pomegranate, walnuts). These mixtures reduce phenotypic and molecular features in two models of colon CSCs: Caco-2 cells and primary tumour cells from a patient with CRC. The mixture containing mostly Uro-A (85% Uro-A, 10% Uro-C, 5% EA) was most effective at inhibiting the number and size of colonospheres and aldehyde dehydrogenase activity (ALDH, a marker of chemoresistance) whereas the mixture containing less Uro-A but IsoUro-A and Uro-B (30% Uro-A, 50% IsoUro-A, 10% Uro-B, 5% Uro-C, 5% EA) had some effects on the number and size of colonospheres but not on ALDH. These data support a role for polyphenols metabolites in the control of colon cancer chemoresistance and relapse and encourage the research on the effects of polyphenols against CSCs.

CD133 Expression at the Metastatic Site Predicts Patients' Outcome in Colorectal Cancer with Synchronous Liver Metastasis

BACKGROUND

CD133 is a transmembrane protein that is proposed to be a stem cell marker of colorectal cancer (CRC); however, the correlation between CD133 expression and survival of CRC patients with liver metastasis has not been fully examined.

METHODS

CD133 expression was evaluated immunohistochemically, both in primary tumors and synchronous liver metastases of 88 consecutive CRC patients, as well as recurrent lesions in the remnant liver of 27 of these 88 patients. The relationship between CD133 expression and clinicopathological characteristics, recurrence-free survival, and overall survival (OS) was analyzed.

RESULTS

CD133 expression in liver metastases (mCD133) was detected in 50 of 88 patients (56.8 %), and had significant correlation with CD133 expression in primary lesions (pCD133) (p < 0.001). CD133 expression in liver recurrent lesions (recCD133) also had a significant correlation with mCD133 (p < 0.001). mCD133+ patients had significantly longer disease-free survival (p = 0.043) and OS (p = 0.014) than mCD133- patients. In addition, mCD133+ patients had a significantly lower rate of extrahepatic recurrence (p < 0.001).

CONCLUSIONS

Patients without CD133 expression in liver metastasis had significantly shorter survival, perhaps because mCD133- patients had a significantly higher rate of extrahepatic recurrence.

New ex-ovo colorectal-cancer models from different SdFFF-sorted tumor-initiating cells

Despite effective treatments, relapse of colorectal cancer (CRC) is frequent, in part caused by the existence of tumor-initiating cells (TICs). Different subtypes of TICs, quiescent and activated, coexist in tumors, defining the tumor aggressiveness and therapeutic response. These subtypes have been sorted by hyperlayer sedimentation field-flow fractionation (SdFFF) from WiDr and HCT116 cell lines. On the basis of a new strategy, including TIC SdFFF sorting, 3D Matrigel amplification, and grafting of corresponding TIC colonies on the chick chorioallantoic membrane (CAM), specific tumor matrices could be obtained. If tumors had similar architectural structure with vascularization by the host system, they had different proliferative indices in agreement with their initial quiescent or activated state. Protein analysis also revealed that tumors obtained from a population enriched for "activated" TICs lost "stemness" properties and became invasive. In contrast, tumors obtained from a population enriched for "quiescent" TICs kept their stemness properties and seemed to be less proliferative and invasive. Then, it was possible to produce different kinds of tumor which could be used as selective supports to study carcinogenesis and therapy sensitivity.

Mutational analysis of circulating tumor cells from colorectal cancer patients and correlation with primary tumor tissue

Circulating tumor cells (CTCs) provide a non-invasive accessible source of tumor material from patients with cancer. The cellular heterogeneity within CTC populations is of great clinical importance regarding the increasing number of adjuvant treatment options for patients with metastatic carcinomas, in order to eliminate residual disease. Moreover, the molecular profiling of these rare cells might lead to insight on disease progression and therapeutic strategies than simple CTCs counting. In the present study we investigated the feasibility to detect KRAS, BRAF, CD133 and Plastin3 (PLS3) mutations in an enriched CTCs cell suspension from patients with colorectal cancer, with the hypothesis that these genes` mutations are of great importance regarding the generation of CTCs subpopulations. Subsequently, we compared CTCs mutational status with that of the corresponding primary tumor, in order to access the possibility of tumor cells characterization without biopsy. CTCs were detected and isolated from blood drawn from 52 colorectal cancer (CRC) patients using a quantum-dot-labelled magnetic immunoassay method. Mutations were detected by PCR-RFLP or allele-specific PCR and confirmed by direct sequencing. In 52 patients, discordance between primary tumor and CTCs was 5.77% for KRAS, 3.85% for BRAF, 11.54% for CD133 rs3130, 7.69% for CD133 rs2286455 and 11.54% for PLS3 rs6643869 mutations. Our results support that DNA mutational analysis of CTCs may enable non-invasive, specific biomarker diagnostics and expand the scope of personalized medicine for cancer patients.

Surface free energy activated high-throughput cell sorting

Cell sorting is an important screening process in microbiology, biotechnology, and clinical research. Existing methods are mainly based on single-cell analysis as in flow cytometric and microfluidic cell sorters. Here we report a label-free bulk method for sorting cells by differentiating their characteristic surface free energies (SFEs). We demonstrated the feasibility of this method by sorting model binary cell mixtures of various bacterial species, including Pseudomonas putida KT2440, Enterococcus faecalis ATCC 29212, Salmonella Typhimurium ATCC 14028, and Escherichia coli DH5α. This method can effectively separate 10(10) bacterial cells within 30 min. Individual bacterial species can be sorted with up to 96% efficiency, and the cell viability ratio can be as high as 99%. In addition to its capacity of sorting evenly mixed bacterial cells, we demonstrated the feasibility of this method in selecting and enriching cells of minor populations in the mixture (presenting at only 1% in quantity) to a purity as high as 99%. This SFE-activated method may be used as a stand-alone method for quickly sorting a large quantity of bacterial cells or as a prescreening tool for microbial discrimination. Given its advantages of label-free, high-throughput, low cost, and simplicity, this SFE-activated cell sorting method has potential in various applications of sorting cells and abiotic particles.

Sedimentation field flow fractionation monitoring of in vitro enrichment in cancer stem cells by specific serum-free culture medium

The development of methods to enrich cell populations for cancer stem cells (CSC) is urgently needed to help understand tumor progression, therapeutic escape and to evaluate new drugs, in particular for colorectal cancer (CRC). In this work, we describe the in vitro use of OncoMiD for colon, a CRC-specific primary cell culture medium, to enrich CRC cell lines in CSC. Sedimentation field flow fractionation (SdFFF) was used to monitor the evolution of subpopulations composition. In these models, medium induced a loss of adherence properties associated with a balance between proliferation and apoptosis rates and, more important, an increased expression of relevant CSC markers, leading to specific SdFFF elution profile changes.

Hallmarks in colorectal cancer: Angiogenesis and cancer stem-like cells

Carcinogenesis is a multistep process that requires the accumulation of various genetic and epigenetic aberrations to drive the progressive malignant transformation of normal human cells. Two major hallmarks of carcinogenesis that have been described are angiogenesis and the stem cell characteristic of limitless replicative potential. These properties have been targeted over the past decade in the development of therapeutic treatments for colorectal cancer (CRC), one of the most commonly diagnosed and lethal cancers worldwide. The treatment of solid tumor cancers such as CRC has been challenging due to the heterogeneity of the tumor itself and the chemoresistance of the malignant cells. Furthermore, the same microenvironment that maintains the pool of intestinal stem cells that contribute to the continuous renewal of the intestinal epithelia also provides the necessary conditions for proliferative growth of cancer stem-like cells. These cancer stem-like cells are responsible for the resistance to therapy and cancer recurrence, though they represent less than 2.5% of the tumor mass. The stromal environment surrounding the tumor cells, referred to as the tumor niche, also supports angiogenesis, which supplies the oxygen and nutrients needed for tumor development. Anti-angiogenic therapy, such as with bevacizumab, a monoclonal antibody against vascular-endothelial growth factor, significantly prolongs the survival of metastatic CRC patients. However, such treatments are not completely curative, and a large proportion of patient tumors retain chemoresistance or show recurrence. This article reviews the current knowledge regarding the molecular phenotype of CRC cancer cells, as well as discusses the mechanisms contributing to their maintenance. Future personalized therapeutic approaches that are based on the interaction of the carcinogenic hallmarks, namely angiogenic and proliferative attributes, could improve survival and decrease adverse effects induced by unnecessary chemotherapy.

Distribution of bone-marrow-derived endothelial and immune cells in a murine colitis-associated colorectal cancer model

Inflammatory bowel disease (IBD) can lead to an increased risk of developing colorectal cancer (CRC). The aim of this study was to establish a model for combined bone marrow transplantation (BMT) and colitis-associated colorectal cancer (CAC) and to define the contribution of BM-derived cells during the inflammation associated with carcinogenesis. We established a model for BMT using green fluorescent protein (GFP) transgenic mice, followed by AOM/DSS-induced CAC, and performed confocal microscopy analysis on in vivo living tissue and frozen tumor sections. Our imaging analyses showed that GFP-positive cells extensively infiltrated the tumor stroma and that some WGA and GFP or CD31 and GFP double-positive cells were observed in the lining of tumor vessels. Flow cytometry analysis of the tumor-infiltrating cells showed that the GFP-positive CD11c+ DCs cells were one-third of the GFP+/CD11C- cells, and that half of these DCs (0.96% vs 1.02%) were GFP-positive BM-derived cells. The majority of CD4⁺ T cells were GFP-negative (12.02% vs 1.9%), and we discovered a novel CD4⁺ CD11c⁺ DC subset (0.34% vs 1.64%). In conclusion, we defined the distribution of BM-derived endothelial cells, CD11c⁺ DCs and CD4⁺ T cells in tumors. This model might be useful for elucidating the diverse BM-derived cell types and functions during the progression of colitis-associated colorectal cancer.

Prognostic value of CD166 expression in cancers of the digestive system: a systematic review and meta-analysis

Objective

Many studies have reported the prognostic predictive value of CD166 as a cancer stem cell marker in cancers of the digestive system; however, its predictive value remains controversial. Here, we investigate the correlation between CD166 positivity in digestive system cancers and clinicopathological features using meta-analysis.

Methods

A comprehensive search in PubMed and ISI Web of Science through March of 2013 was performed. Only articles containing CD166 antigen immunohistochemical staining in cancers of the digestive system were included,including pancreatic cancer, esophageal cancer, gastric cancer and colorectal cancer. Data comparing 3- and 5-year overall survival along with other clinicopathological features were collected.

Results

Nine studies with 2553 patients who met the inclusion criteria were included for the analysis. The median rate of CD166 immunohistochemical staining expression was 56% (25.4%–76.3%). In colorectal cancer specifically, the results of a fixed-effects model indicated that CD166-positive expression was an independent marker associated with a smaller tumor burden (T category; RR = 0.93, 95%, CI: 0.88–0.98) but worse spread to nearby lymph nodes (N category; RR = 1.17, 95% CI: 1.05–1.30). The 5-year overall survival rate was showed relationship with cytoplasmic positive staining of CD166 (RR = 1.47 95% 1.21–1.79), but no significant association was found in the pool or any other stratified analysis with 3- or 5- year overall survival rate.

Conclusion

Based on the published studies, different cellular location of CD166 has distinct prognostic value and cytoplasmic positive expression is associated with worse prognosis outcome. Besides, our results also find CD166 expression indicate advanced T category and N-positive status in colorectal cancer specifically.

Recent advances in microfluidic cell separations

The isolation and sorting of cells has become an increasingly important step in chemical and biological analyses. As a unit operation in more complex analyses, isolating a phenotypically pure cell population from a heterogeneous sample presents unique challenges. Microfluidic systems are ideal platforms for performing cell separations, enabling integration with other techniques and enhancing traditional separation modalities. In recent years there have been several techniques that use surface antigen affinity, physical interactions, or a combination of the two to achieve high separation purity and efficiency. This review discusses methods including magnetophoretic, acoustophoretic, sedimentation, electric, and hydrodynamic methods for physical separations. We also discuss affinity methods, including magnetic sorting, flow sorting, and affinity capture.

CD133: A cancer stem cells marker, is used in colorectal cancers

Colorectal cancer is one of the most common malignant tumors worldwide. A model of cancer development involving cancer stem cells has been put forward because it provides a possible explanation of tumor hierarchy. Cancer stem cells are characterized by their proliferation, tumorigenesis, differentiation, and self-renewal capacities, and chemoradiotherapy resistance. Due to the role of cancer stem cells in tumor initiation and treatment failure, studies of cancer stem cell markers, such as CD133, have been of great interest. CD133, a five-transmembrane glycoprotein, is widely used as a marker to identify and isolate colorectal cancer stem cells. This marker has been investigated to better understand the characteristics and functions of cancer stem cells. Moreover, it can also be used to predict tumor progression, patient survival, chemoradiotherapy resistance and other clinical parameters. In this review, we discuss the use of CD133 in the identification of colorectal cancer stem cell, which is currently controversial. Although the function of CD133 is as yet unclear, we have discussed several possible functions and associated mechanisms that may partially explain the role of CD133 in colorectal cancers. In addition, we focus on the prognostic value of CD133 in colorectal cancers. Finally, we predict that CD133 may be used as a possible target for colorectal cancer treatment.

A tag-less method for direct isolation of human umbilical vein endothelial cells by gravitational field-flow fractionation

The analysis of cellular and molecular profiles represents a powerful tool in many biomedical applications to identify the mechanisms underlying the pathological changes. The improvement of cellular starting material and the maintenance of the physiological status in the sample preparation are very useful. Human umbilical vein endothelial cells (HUVEC) are a model for prediction of endothelial dysfunction. HUVEC are enzymatically removed from the umbilical vein by collagenase. This method provides obtaining a good sample yield. However, the obtained cells are often contaminated with blood cells and fibroblasts. Methods based on negative selection by in vitro passages or on the use of defined marker are currently employed to isolate target cells. However, these approaches cannot reproduce physiological status and they require expensive instrumentation. Here we proposed a new method for an easy, tag-less and direct isolation of HUVEC from raw umbilical cord sample based on the gravitational field-flow fractionation (GrFFF). This is a low-cost, fully biocompatible method with low instrumental and training investments for flow-assisted cell fractionation. The method allows obtaining pure cells without cell culture procedures as starting material for further analysis; for example, a proper amount of RNA can be extracted. The approach can be easily integrated into clinical and biomedical procedures.

Colon cancer stem cells--from basic to clinical application

Based on cancer stem cell (CSC) concept of carcinogenesis, tumors represent complex heterogeneous organ-like systems with a hierarchical cellular organization, and only minority phenotypic subpopulations with stem-like properties possess a dual ability to self-renew indefinitely and produce all the heterogeneous cell phenotypes comprising the bulk tumor cells. Large experimental and clinical data indicate that conventional anti-cancer therapies cannot eradicate CSCs, and moreover, they usually increase their number leading to cancer recurrence and further drug resistance. In this review, several current controversies in the CSC field and recent studies, which help to shed light on their origin, are discussed. The emerging necessity for the development of complex, multimodal CSC-targeted treatment strategies, which combine conventional therapeutics with promising pathway-specific modulators, and natural compounds, which can improve the efficacy of conventional anti-cancer therapeutics and decrease their undesirable side effects is presented. Also, novel requirements and criteria necessary for evaluation of the CSC-targeted drug efficacy and relevant experimental models are discussed.