Enumeration of circulating tumor cells in the blood of breast cancer patients after filtration enrichment: correlation with disease stage

Single-Cell Isolation Microfluidic Chip Based on Thermal Bubble Micropump Technology

The isolation of single cells is essential for the development of single cell analysis methods, such as single-cell sequencing, monoclonal antibodies, and drug development. Traditional single-cell isolation techniques include flow cytometry (FACS), laser capture microdissection (LCM), micromanipulation, etc., but their operations are complex and have low throughput. Here, we present a microfluidic chip that can isolate individual cells from cell suspension and release them onto a well plate. It uses thermal bubble micropump technology to drive the fluid flow, and single-cell isolation is achieved by matching the flow resistance of the flow channel. Therefore, injection pumps and peristaltic pumps are not required for cell loading. Because of its small size, we can integrate hundreds of single-cell functional modules, which makes high-throughput single-cell isolation possible. For polystyrene beads, the capture rate of the single bead is close to 100%. Finally, the method has been applied to cells, and the capture rate of the single cell is also about 75%. This is a promising method for single-cell isolation.

Circulating Tumor Cell Detection in Lung Cancer Animal Model

BACKGROUND

Metastasis and recurrence of primary cancer are the main causes of cancer mortality. Disseminated tumor cells refer to cancer cells that cause metastasis from primary cancer to other organs. Several recent studies have suggested that circulating tumor cells (CTCs) are associated with the clinical stage, cancer recurrence, cancer metastasis, and prognosis. There are several methods of isolating CTCs from whole blood; in particular, using a membrane filtration system is advantageous due to its cost-effectiveness and availability in clinical settings. In this study, an animal model of lung cancer was established in nude mice using the human large cell lung cancer cell line H460.

METHODS

Six-week-old nude mice were used. The H460 lung cancer cell line was injected subcutaneously into the nude mice. Blood samples were obtained from the orbital area before cell line injection, 2 weeks after injection, and 2 weeks after tumor excision. Blood samples were filtered using a polycarbonate 12-well Transwell membrane (Corning Inc., Corning, NY, USA). An indirect immunofluorescence assay was performed with the epithelial cell adhesion molecule antibody. The number of stained cells was counted using fluorescence microscopy.

RESULTS

The average size of the tumor masses was 35.83 mm. The stained cells were counted before inoculation, 2 weeks after inoculation, and 2 weeks after tumor excision. Cancer cells generally increased after inoculation and decreased after tumor resection.

CONCLUSION

The CTC detection method using the commercial polycarbonate 12-well Transwell (Corning Inc.) membrane is advantageous in terms of cost-effectiveness and convenience.

Inertial-Assisted Immunomagnetic Bioplatform towards Efficient Enrichment of Circulating Tumor Cells

Serving as an effective biomarker in liquid biopsy, circulating tumor cells (CTCs) can provide an accessible source for cancer biology study. For the in-depth evaluation of CTCs in cancer analysis, their efficient enrichment is essential, owing to their low abundance in peripheral blood. In this paper, self-assembled immunomagnetic beads were developed to isolate CTCs from the ordered bundles of cells under the assistance of the spiral inertial effect. Parametric numerical simulations were performed to explore the velocity distribution in the cross section. Based on this chip, rare CTCs could be recovered under the throughput of 500 μL/min, making this device a valuable supplement in cancer analysis, diagnostics, and therapeutics.

Sequential Ensemble-Decision Aliquot Ranking Isolation and Fluorescence In Situ Hybridization Identification of Rare Cells from Blood by Using Concentrated Peripheral Blood Mononuclear Cells

Isolation and analysis of circulating rare cells is a promising approach for early detection of cancer and other diseases and for prenatal diagnosis. Isolation of rare cells is usually difficult due to their heterogeneity as well as their low abundance in peripheral blood. We previously reported a two-stage ensemble-decision aliquot ranking platform (S-eDAR) for isolating circulating tumor cells from whole blood with high throughput, high recovery rate (>90%), and good purity (>70%), allowing detection of low surface antigen-expressing cancer cells linked to metastasis. However, due to the scarcity of these cells, large sample volumes and large quantities of antibodies were required to isolate sufficient cells for downstream analysis. Here, we drastically increased the number of nucleated cells analyzed by first concentrating peripheral blood mononuclear cells (PBMCs) from whole blood by density gradient centrifugation. The S-eDAR platform was capable of isolating rare cells from concentrated PBMCs (10⁸/mL, equivalent to processing ∼20 mL of whole blood in the 1 mL sample volume used by our instrument) at a high recovery rate (>85%). We then applied the S-eDAR platform for isolating rare fetal nucleated red blood cells (fNRBCs) from concentrated PBMCs spiked with umbilical cord blood cells and confirmed fNRBC recovery by immunostaining and fluorescence in situ hybridization, demonstrating the potential of the S-eDAR system for isolating rare fetal cells from maternal PBMCs to improve noninvasive prenatal diagnosis.

A Review on Microdevices for Isolating Circulating Tumor Cells

Cancer metastasis is the primary cause of high mortality of cancer patients. Enumeration of circulating tumor cells (CTCs) in the bloodstream is a very important indicator to estimate the therapeutic outcome in various metastatic cancers. The aim of this article is to review recent developments on the CTC isolation technologies in microdevices. Based on the categories of biochemical and biophysical isolation approaches, a literature review and in-depth discussion will be included to provide an overview of this challenging topic. The current excellent developments suggest promising CTC isolation methods in order to establish a precise indicator of the therapeutic outcome of cancer patients.

Isolating Rare Cells and Circulating Tumor Cells with High Purity by Sequential eDAR

Isolation and analysis of circulating tumor cells (CTCs) from the blood of patients at risk of metastatic cancers is a promising approach to improving cancer treatment. However, CTC isolation is difficult due to low CTC abundance and heterogeneity. Previously, we reported an ensemble-decision aliquot ranking (eDAR) platform for the rare cell and CTC isolation with high throughput, greater than 90% recovery, and high sensitivity, allowing detection of low surface antigen-expressing cells linked to metastasis. Here we demonstrate a sequential eDAR platform capable of isolating rare cells from whole blood with high purity. This improvement in purity is achieved by using a sequential sorting and flow stretching design in which whole blood is sorted and fluid elements are stretched using herringbone features and the parabolic flow profile being sorted a second time. This platform can be used to collect single CTCs in a multiwell plate for downstream analysis.

Separation detection of different circulating tumor cells in the blood using an electrochemical microfluidic channel modified with a lipid-bonded conducting polymer

Different circulating tumor cells (CTCs) in blood were separated and detected through the decoration of anti-cancer drug on the target cells, along with chemical modification of the microfluidic channel walls using a lipid attached covalently to the conducting polymer. The working principle of the electrochemical microfluidic device was evaluated with experimental parameters affecting on the separation, in terms of mass and surface charge of target species, fluid flow rate, AC amplitude, and AC frequency. The separated CTCs were selectively detected via the oxidation of daunomycin adsorbed specifically at the cells using an electrochemical sensor installed at the channel end. The fluorescence microscopic examination also confirmed the separation of CTCs in the channel. To evaluate the reliability of the method, blood samples from 37 cancer patients were tested. The device was able to separate the CTCs with 92.0 ± 0.5 % efficiency and 90.9% detection rate.

A microfluidic platform for high-purity separating circulating tumor cells at the single-cell level

Circulating tumor cells (CTCs) are rare cancer cells that are shed from the tumors into the peripheral blood and are instrumental in distant metastasis. Early detection of CTCs can therefore improve prognoses and help design patient-specific treatment regimen. However, the current CTC isolation techniques have poor efficacy and selectivity, owing to the rarity and heterogeneity of the CTCs. We designed a microchip for integrated single-cell isolation of CTCs - based on cell size and immuno-phenotype - and analysis. Each isolation unit consisted of a trap channel, a bypass channel, and a release channel. The larger cells were preferentially captured at the trap channels and flushed out selectively via release microvalves according to their immuno-phenotype. The average recovery rate and purity of lung cancer cells isolated from a spiked WBC population were respectively 92.5% and 94% using the microchip, which were significantly higher compared to that obtained using anti-CD45 magnetic beads. In addition, the isolated cancer cells were analyzed on chip for the surface markers of epithelial mesenchymal transition. Taken together, the integrated microchip is a promising tool for the isolation and analysis of CTCs in the clinical setting.

Filtration based assessment of CTCs and CellSearch® based assessment are both powerful predictors of prognosis for metastatic breast cancer patients

Background

The assessment of circulating tumor cells (CTCs) has been shown to enable monitoring of treatment response and early detection of metastatic breast cancer (MBC) recurrence. The aim of this study was to compare a well-established CTC detection method based on immunomagnetic isolation with a new, filtration-based platform.

Methods

In this prospective study, two 7.5 ml blood draws were obtained from 60 MBC patients and CTC enumeration was assessed using both the CellSearch® and the newly developed filtration-based platform. We analyzed the correlation of CTC-positivity between both methods and their ability to predict prognosis. Overall survival (OS) was calculated and Kaplan-Meier curves were estimated with thresholds of ≥1 and ≥5 detected CTCs.

Results

The CTC positivity rate of the CellSearch® system was 56.7% and of the filtration-based platform 66.7%. There was a high correlation of CTC enumeration obtained with both methods. The OS for patients without detected CTCs, regardless of the method used, was significantly higher compared to patients with one or more CTCs (p < 0.001). The median OS of patients with no CTCs vs. ≥ 1 CTC assessed by CellSearch® was 1.83 years (95% CI: 1.63–2.02) vs. 0.74 years (95% CI: 0.51–1.52). If CTCs were detected by the filtration-based method the median OS times were 1.88 years (95% CI: 1.74–2.03) vs. 0.59 years (95% CI: 0.38–0.80).

Conclusions

The newly established EpCAM independently filtration-based system is a suitable method to determine CTC counts for MBC patients. Our study confirms CTCs as being strong predictors of prognosis in our population of MBC patients.

Separation and Analysis of Adherent and Non-Adherent Cancer Cells Using a Single-Cell Microarray Chip

A new single-cell microarray chip was designed and developed to separate and analyze single adherent and non-adherent cancer cells. The single-cell microarray chip is made of polystyrene with over 60,000 microchambers of 10 different size patterns (31–40 µm upper diameter, 11–20 µm lower diameter). A drop of suspension of adherent carcinoma (NCI-H1650) and non-adherent leukocyte (CCRF-CEM) cells was placed onto the chip, and single-cell occupancy of NCI-H1650 and CCRF-CEM was determined to be 79% and 84%, respectively. This was achieved by controlling the chip design and surface treatment. Analysis of protein expression in single NCI-H1650 and CCRF-CEM cells was performed on the single-cell microarray chip by multi-antibody staining. Additionally, with this system, we retrieved positive single cells from the microchambers by a micromanipulator. Thus, this system demonstrates the potential for easy and accurate separation and analysis of various types of single cells.

Materials and microfluidics: enabling the efficient isolation and analysis of circulating tumour cells

We present a critical review of microfluidic technologies and material effects on the analyses of circulating tumour cells (CTCs) selected from the peripheral blood of cancer patients. CTCs are a minimally invasive source of clinical information that can be used to prognose patient outcome, monitor minimal residual disease, assess tumour resistance to therapeutic agents, and potentially screen individuals for the early diagnosis of cancer. The performance of CTC isolation technologies depends on microfluidic architectures, the underlying principles of isolation, and the choice of materials. We present a critical review of the fundamental principles used in these technologies and discuss their performance. We also give context to how CTC isolation technologies enable downstream analysis of selected CTCs in terms of detecting genetic mutations and gene expression that could be used to gain information that may affect patient outcome.

Isolation of circulating tumor cells in pancreatic cancer patients by immunocytochemical assay

BACKGROUND

The patients diagnosed with pancreatic cancer have the possibilities of getting the cancer again even after resection. The tumor cells identified from blood can be related to different stages of tumor.

METHODS

In this study, we used an immunoassay to detect circulating tumor cells in blood and bone marrow samples. About 120 patients' blood and bone marrow samples were used in this study along with controls. The presence of tumor cells was evaluated with different stages of cancer classified by UICC. The survival rate at each stages of tumor was also analyzed.

RESULTS

The tumor cells were isolated both in blood (29%) and bone marrow samples (25%). The prevalence of tumor cells increased with increase in stages of tumor in blood samples.

CONCLUSION

The survival of the patients considerably related to different stages of tumor but it cannot be taken a parameter alone for the patients' survival.

Enrichment, Isolation and Molecular Characterization of EpCAM-Negative Circulating Tumor Cells

The presence of EpCAM-positive circulating tumor cells (CTCs) in the peripheral blood is associated with poor clinical outcomes in breast, colorectal and prostate cancer, as well as the prognosis of other tumor types. In addition, recent studies have suggested that the presence of CTCs undergoing epithelial-to-mesenchymal transition and, as such, may exhibit reduced or no expression of epithelial proteins e.g. EpCAM, might be related to disease progression in metastatic breast cancer (MBC) patients. Analyzing the neoplastic nature of this EpCAM-low/negative (EpCAM-neg) subpopulation remains an open issue as the current standard detection methods for CTCs are not efficient at identifying this subpopulation of cells. The possible association of EpCAM-neg CTCs with EpCAM-positive (EpCAM-pos) CTCs and role in the clinicopathological features and prognosis of MBC patients has still to be demonstrated. Several technologies have been developed and are currently being tested for the identification and the downstream analyses of EpCAM-pos CTCs. These technologies can be adapted and implemented into workflows to isolate and investigate EpCAM-neg cells to understand their biology and clinical relevance. This chapter will endeavour to explain the rationale behind the identification and analyses of all CTC subgroups, as well as to review the current strategies employed to enrich, isolate and characterize EpCAM-negative CTCs. Finally, the latest findings in the field will briefly be discussed with regard to their clinical relevance.

Adhesion-based simple capture and recovery of circulating tumor cells using a blood-compatible and thermo-responsive polymer-coated substrate

Circulating tumor cells (CTCs) have been a focus of study for metastatic cancer diagnostics, in in vitro anti-cancer drug screening to decide the chemotherapeutic course, and cancer biology research.

Honeycomb-shaped magnetic multilayer thin films for cell trapping

Honeycomb-shaped magnetic thin films with domain wall (DW) pinning geometry are designed to actively trap magnetically labeled cells.

Interaction between circulating cancer cells and platelets: clinical implication

Metastasis is the main cause of cancer-associated mortality. During this complicated process, some cancer cells, also called circulating tumor cells (CTCs), detach from primary sites, enter bloodstream and extravasate at metastatic site. Thrombocytosis is frequently observed in patients with metastatic cancers suggesting the important role of platelets in metastasis. Therefore this review focuses on how platelets facilitate the generation of CTCs, protect them from various host attacks, such as immune assaults, apoptosis and shear stress, and regulate CTCs intravasation/extravasation. Platelet-derived cytokines and receptors are involved in this cascade. Identification the mechanisms underlie platelet-CTCs interactions could lead to the development of new platelet-targeted therapeutic strategy to reduce metastasis.

Effects of Nanotexture on Electrical Profiling of Single Tumor Cell and Detection of Cancer from Blood in Microfluidic Channels

Microfluidic channels have been implemented to detect cancer cells from blood using electrical measurement of each single cell from the sample. Every cell provided characteristic current profile based on its mechano-physical properties. Cancer cells not only showed higher translocation time and peak amplitude compared to blood cells, their pulse shape was also distinctively different. Prevalent microfluidic channels are plain but we created nanotexture on the channel walls using micro reactive ion etching (micro-RIE). The translocation behaviors of the metastatic renal cancer cells through plain and nanotextured PDMS microchannels showed clear differences. Nanotexture enhanced the cell-surface interactions and more than 50% tumor cells exhibited slower translocation through nanotextured channels compared to plain devices. On the other hand, most of the blood cells had very similar characteristics in both channels. Only 7.63% blood cells had slower translocation in nanotextured microchannels. The tumor cell detection efficiency from whole blood increased by 14% in nanotextured microchannels compared to plain channels. This interesting effect of nanotexture on translocation behavior of tumor cells is important for the early detection of cancer.

High-resolution imaging for the detection and characterisation of circulating tumour cells from patients with oesophageal, hepatocellular, thyroid and ovarian cancers

Interest has increased in the potential role of circulating tumour cells in cancer management. Most cell‐based studies have been designed to determine the number of circulating tumour cells in a given volume of blood. Ability to understand the biology of the cancer cells would increase the clinical potential. The purpose of this study was to develop and validate a novel, widely applicable method for detection and characterisation of circulating tumour cells. Cells were imaged with an ImageStream^X imaging flow cytometer which allows detection of expression of multiple biomarkers on each cell and produces high‐resolution images. Depletion of haematopoietic cells was by red cell lysis, leukocyte common antigen CD45 depletion and differential centrifugation. Expression of epithelial cell adhesion molecule, cytokeratins, tumour‐type‐specific biomarkers and CD45 was detected by immunofluorescence. Nuclei were identified with DAPI or DRAQ5 and brightfield images of cells were collected. The method is notable for the dearth of cell damage, recoveries greater than 50%, speed and absence of reliance on the expression of a single biomarker by the tumour cells. The high‐quality images obtained ensure confidence in the specificity of the method. Validation of the methodology on samples from patients with oesophageal, hepatocellular, thyroid and ovarian cancers confirms its utility and specificity. Importantly, this adaptable method is applicable to all tumour types including those of nonepithelial origin. The ability to measure simultaneously the expression of multiple biomarkers will facilitate analysis of the cancer cell biology of individual circulating tumour cells.

What's new?

Circulating tumour cells (CTCs) are disseminated malignant cells from which biological and therapeutic information may be obtained non‐invasively. Detection of small CTC populations within the large number of normal blood cells is a challenge. This study describes a novel method for the detection and high‐resolution imaging of CTCs. Unlike most other studies, CTC detection is not reliant upon expression of a single biomarker. The method is applicable to all cancers; the authors present preliminary results from four tumour types. The high quality of the images allows biological characterisation of the tumour cells and increases the clinical potential of the approach.

Microfluidic platform for negative enrichment of circulating tumor cells

Negative enrichment is the preferred approach for tumor cell isolation as it does not rely on biomarker expression. However, size-based negative enrichment methods suffer from well-known recovery/purity trade-off. Non-size based methods have a number of processing steps that lead to compounded cell loss due to extensive sample processing and handling which result in a low recovery efficiency. We present a method that performs negative enrichment in two steps from 2 ml of whole blood in a total assay processing time of 60 min. This negative enrichment method employs upstream immunomagnetic depletion to deplete CD45-positive WBCs followed by a microfabricated filter membrane to perform chemical-free RBC depletion and target cells isolation. Experiments of spiking two cell lines, MCF-7 and NCI-H1975, in the whole blood show an average of >90 % cell recovery over a range of spiked cell numbers. We also successfully recovered circulating tumor cells from 15 cancer patient samples.

Isolation of viable cancer cells in antibody-functionalized microfluidic devices

Microfluidic devices functionalized with EpCAM antibodies were utilized for the capture of target cancer cells representing circulating tumor cells (CTCs). The fraction of cancer cells captured from homogeneous suspensions is mainly a function of flow shear rate, and can be described by an exponential function. A characteristic shear rate emerges as the most dominant parameter affecting the cell attachment ratio. Utilizing this characteristic shear rate as a scaling factor, all attachment ratio results for various combinations of receptor and ligand densities collapsed onto a single curve described by the empirical formula. The characteristic shear rate increases with both cell-receptor and surface-ligand densities, and empirical formulae featuring a product of two independent cumulative distributions described well these relationships. The minimum detection limit in isolation of target cancer cells from binary mixtures was experimentally explored utilizing microchannel arrays that allow high-throughput processing of suspensions about 0.5 ml in volume, which are clinically relevant, within a short time. Under a two-step attachment/detachment flow rate, both high sensitivity (almost 1.0) and high specificity (about 0.985) can be achieved in isolating target cancer cells from binary mixtures even for the lowest target/non-target cell concentration ratio of 1:100 000; this is a realistic ratio between CTCs and white blood cells in blood of cancer patients. Detection of CTCs from blood samples was also demonstrated using whole blood from healthy donors spiked with cancer cells. Finally, the viability of target cancer cells released after capture was confirmed by observing continuous cell growth in culture.

Circulating Tumor Cells Count and Morphological Features in Breast, Colorectal and Prostate Cancer

Background

Presence of circulating tumor cells (CTC) in patients with metastatic breast, colorectal and prostate cancer is indicative for poor prognosis. An automated CTC (aCTC) algorithm developed previously to eliminate the variability in manual counting of CTC (mCTC) was used to extract morphological features. Here we validated the aCTC algorithm on CTC images from prostate, breast and colorectal cancer patients and investigated the role of quantitative morphological parameters.

Methodology

Stored images of samples from patients with prostate, breast and colorectal cancer, healthy controls, benign breast and colorectal tumors were obtained using the CellSearch system. Images were analyzed for the presence of aCTC and their morphological parameters measured and correlated with survival.

Results

Overall survival hazard ratio was not significantly different for aCTC and mCTC. The number of CTC correlated strongest with survival, whereas CTC size, roundness and apoptosis features reached significance in univariate analysis, but not in multivariate analysis. One aCTC/7.5 ml of blood was found in 7 of 204 healthy controls and 9 of 694 benign tumors. In one patient with benign tumor 2 and another 9 aCTC were detected.

Significance of the study

CTC can be identified and morphological features extracted by an algorithm on images stored by the CellSearch system and strongly correlate with clinical outcome in metastatic breast, colorectal and prostate cancer.

Enrichment, detection and clinical significance of circulating tumor cells

Circulating Tumor Cells (CTCs) are shed from primary or secondary tumors into blood circulation. Accessing and analyzing these cells provides a non-invasive alternative to tissue biopsy. CTCs are estimated to be as few as 1 cell among a few million WBCs and few billion RBCs in 1 ml of patient blood and are rarely found in healthy individuals. CTCs are FDA approved for prognosis of the major cancers, namely, Breast, Colon and Prostate. Currently, more than 400 clinical trials are ongoing to establish their clinical significance beyond prognosis, such as, therapy selection and companion diagnostics. Understanding the clinical relevance of CTCs typically involves isolation, detection and molecular characterization of cells, ideally at single cell level. The need for highly reliable, standardized and robust methodologies for isolating and analyzing CTCs has been widely expressed by clinical thought leaders. In the last decade, numerous academic and commercial technology platforms for isolation and analysis of CTCs have been reported. A recent market report highlighted the presence of more than 100 companies offering products and services related to CTCs. This review aims to capture the state of the art and examines the technical merits and limitations of contemporary technologies for clinical use.

Filtration parameters influencing circulating tumor cell enrichment from whole blood

Filtration can achieve circulating tumor cell (CTC) enrichment from blood. Key parameters such as flow-rate, applied pressure, and fixation, vary largely between assays and their influence is not well understood. Here, we used a filtration system, to monitor these parameters and determine their relationships. Whole blood, or its components, with and without spiked tumor cells were filtered through track-etched filters. We characterize cells passing through filter pores by their apparent viscosity; the viscosity of a fluid that would pass with the same flow. We measured a ratio of 5·10(4)∶10(2)∶1 for the apparent viscosities of 15 µm diameter MDA-231 cells, 10 µm white cells and 90 fl red cells passing through a 5 µm pore. Fixation increases the pressure needed to pass cells through 8 µm pores 25-fold and halves the recovery of spiked tumor cells. Filtration should be performed on unfixed samples at a pressure of ∼10 mbar for a 1 cm(2) track-etched filter with 5 µm pores. At this pressure MDA-231 cells move through the filter in 1 hour. If fixation is needed for sample preservation, a gentle fixative should be selected. The difference in apparent viscosity between CTC and blood cells is key in optimizing recovery of CTC.

An automated high-throughput counting method for screening circulating tumor cells in peripheral blood

Enumeration of circulating tumor cells (CTCs) has proved valuable for early detection and prognosis in cancer treatment. This paper describes an automated high-throughput counting method for CTCs based on microfluidics and line-confocal microscopy. Peripheral blood was directly labeled with multiple antibodies, each conjugated with a different fluorophore, pneumatically pumped through a microfluidic channel, and interrogated by a line-confocal microscope. On the basis of the fluorescence signals and labeling schemes, the count of CTCs was automatically reported. Due to the high flow rate, 1 mL of whole blood can be analyzed in less than 30 min. We applied this method in analyzing CTCs from 90 stage IV breast cancer patient samples and performed a side-by-side comparison with the results of the CellSearch assay, which is the only method approved by the U.S. Food and Drug Administration at present for enumeration of CTCs. This method has a recovery rate for cultured breast cancer cells of 94% (n = 9), with an average of 1.2 counts/mL of background level of detected CTCs from healthy donors. It detected CTCs from breast cancer patients ranging from 15 to 3375 counts/7.5 mL. Using this method, we also demonstrate the ability to enumerate CTCs from breast cancer patients that were positive for Her2 or CD44(+)/CD24(-), which is a putative cancer stem cell marker. This automated method can enumerate CTCs from peripheral blood with high throughput and sensitivity. It could potentially benefit the clinical diagnosis and prognosis of cancer.

Continual collection and re-separation of circulating tumor cells from blood using multi-stage multi-orifice flow fractionation

Circulating tumor cells (CTCs) are highly correlated with the invasive behavior of cancer; as such, the ability to isolate and quantify CTCs is of great biomedical importance. This research presents a multi-stage multi-orifice flow fractionation (MS-MOFF) device formed by combining three single-stage multi-orifice segments designed for separating breast cancer cells from blood. The structure and dimensions of the MS-MOFF were determined by hydrodynamic principles to have consistent Reynolds numbers (Re) at each multi-orifice segment. From this device, we achieved improved separation efficiency by collecting and re-separating non-selected target cells in comparison with the single-stage multi-orifice flow fractionation (SS-MOFF). The recovery of breast cancer cells increased from 88.8% to greater than 98.9% through the multi-stage multi-orifice segments. This device can be utilized to isolate rare cells from human blood, such as CTCs, in a label-free manner solely through the use of hydrodynamic forces.

Selective capture and collection of live target cells using a photoreactive silicon wafer device modified with antibodies via a photocleavable linker

A device for the capture and recollection of live target cells is described. The platform was a silicon (Si) wafer modified with an anti-HEL antibody (anti-HEL-IgG, HEL = hen egg lysozyme) through a photocleavable 3-amino-3-(2-nitrophenyl)propionic acid (ANP) linker. The modification processes of the Si wafer surface were monitored by Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and fast-scanning atomic force microscopy (FS-AFM). The attachment of IgG and its release reaction on the Si surface via the photochemical cleavage of the ANP linker were observed directly by FS-AFM. The results of an enzyme-linked immunosorbent assay (ELISA) indicated that the photorelease of the complex of anti-HEL-IgG with the secondary antibody-alkaline phosphatase hybrid (secondary IgG-AP) from the Si surface occurs with minimum damage. Furthermore, it was possible to collect SP2/O cells selectively that express HEL on their cell membranes (SP2/O-HEL) on the Si wafer device. Photochemical cleavage of the ANP linker facilitated the effective release of living SP2/O cells whose viability was verified by staining experiments using tripan blue. Moreover, it was possible to reculture the recovered cells. This methodology represents an effective strategy for isolating intact target cells in the biological and medicinal sciences and related fields.

Electrical fingerprinting, 3D profiling and detection of tumor cells with solid-state micropores

Solid-state micropores can provide direct information of ex vivo or in vitro cell populations. Micropores are used to detect and discriminate cancer cells based on the translocation behavior through micropores. The approach provides rapid detection of cell types based on their size and mechano-physical properties like elasticity, viscosity and stiffness. Use of a single micropore device enables detection of tumor cells from whole blood efficiently, at 70% CTC detection efficiency. The CTCs show characteristic electrical signals which easily distinguish these from other cell types. The approach provides a gentle and inexpensive instrument that can be used for specific blood analysis in a lab-on-a-chip setting. The device does not require any preprocessing of the blood sample, particles/beads attachment, surface functionalization or fluorescent tags and provides quantitative and objective detection of cancer cells.

Identification and quantification of concentration-dependent biomarkers in MCF-7/BOS cells exposed to 17β-estradiol by 2-D DIGE and label-free proteomics

This paper reports the identification of biomarkers resulting from the exposure of MCF-7/BOS cells to 17β-estradiol (E(2)). The biomarkers were identified using 2 independent and complementary techniques, 2-D DIGE/MALDI-TOF peptide mass fingerprint, and 2-D UPLC-ESI MS/MS. They were identified from the cytosolic fractions of cells treated for 24h with mitogenic concentrations of 1, 30 and 500 pM of 17β-estradiol. Five biomarkers were up-regulated proteins, namely HSP 74, EF2, FKBP4, EF1 and GDIB and one was a down-regulated protein, namely K2C8. Three of these proteins, EF2, FKBP4 and K2C8 are implicated in a network centered on the estrogen receptors ESR1 and ESR2 as well as on AKT1. After the discovery phase, three biomarkers were selected to test the presence of estrogens using selected reaction monitoring (SRM). They were monitored using SRM after incubation of MCF-7/BOS in the presence of E(2) for confirmation or selected xenoestrogens. Daidzein, coumestrol and enterolactone induced an up-regulation of EF2 and FKPB4 proteins, while tamoxifen and resveratrol induced a down-regulation. The exposure of all phytoestrogens induced the down-regulation of K2C8. These markers form a preliminary molecular signature that can be used when testing the estrogenic activity of xenobiotics, either pure or in mixtures.

A high-performance microsystem for isolating circulating tumor cells

A unique flow field pattern in a bio-functional microchannel is utilized to significantly enhance the performance of a microsystem developed for selectively isolating circulating tumor cells from cell suspensions. For high performance of such systems, disposal of maximum non-target species is just as important as retention of maximum target species; unfortunately, most studies ignore or fail to report this aspect. Therefore, sensitivity and specificity are introduced as quantitative criteria to evaluate the system performance enabling a direct comparison among systems employing different techniques. The newly proposed fluidic scheme combines a slow flow field, for maximum target-cell attachment, followed by a faster flow field, for maximum detachment of non-target cells. Suspensions of homogeneous or binary mixtures of circulating breast tumor cells, with varying relative concentrations, were driven through antibody-functionalized microchannels. Either EpCAM or cadherin-11 transmembrane receptors were targeted to selectively capture target cells from the suspensions. Cadherin-11-expressing MDA-MB-231 cancer cells were used as target cells, while BT-20 cells were used as non-target cells as they do not express cadherin-11. The attachment and detachment of these two cell lines are characterized, and a two-step attachment/detachment flow field pattern is implemented to enhance the system performance in capturing target cells from binary mixtures. While the system sensitivity remains high, above 0.95, the specificity increases from about 0.85 to 0.95 solely due to the second detachment step even for a 1 : 1000 relative concentration of the target cells.

Cytokeratin-19 and mammaglobin gene expression in circulating tumor cells from metastatic breast cancer patients enrolled in North Central Cancer Treatment Group trials, N0234/336/436/437

PURPOSE

To investigate the associations between baseline and posttreatment circulating tumor cell (CTC) gene expression and outcome of patients enrolled in four North Central Cancer Treatment Group metastatic breast cancer (MBC) trials in which specimens were shipped (at 4°C) from community-based sites to a reference laboratory (Mayo Clinic, Rochester, MN).

EXPERIMENTAL DESIGN

Blood was collected at treating sites from MBC patients before (baseline), during, and at the end of treatment with erlotinib + gemcitabine (N0234), sorafenib (N0336), irinotecan + cetuximab (N0436), or paclitaxel-poliglumex + capecitabine (N0437). CTCs from 10 mL of EDTA blood were enriched with CD45 depletion, 24 to 30 hours postblood collection. Reverse transcription/quantitative PCR was used to determine cytokeratin-19 (CK19) and mammaglobin (MGB1) mRNA levels in CTCs from up to 13 (N0234), 16 (N0336), 18 (N0436), and 39 (N0437) patients. The gene expressions were normalized to β(2)-microglobulin and calibrated to healthy blood using the 2(-ΔΔCq) algorithm; positivity was defined as 2 or more.

RESULTS

CK19+mRNA cells were detected in 56% to 75% and MGB1+mRNA cells in 23% to 38% of 86 patients at baseline. CK19+mRNA cells were detected in 30% to 67% and MGB1+mRNA cells in 14% to 64% of 110 postbaseline serial samples. The presence of baseline CK19+mRNA cells (P = 0.01) but not MGB1+mRNA cells (P = 0.14) was significantly associated with shorter overall survival. A decrease in MGB1+mRNA levels (baseline-week 8) seemed to be associated with clinical response (P = 0.05).

CONCLUSIONS

CTC gene expression analysis conducted by a reference laboratory is feasible when blood is collected from treating sites and processed 24 to 30 hours postcollection. The presence of baseline CK19+mRNA CTCs was associated with poor prognosis; a decrease in MGB1+mRNA CTCs may help predict response to therapy of MBC patients.

3D microfilter device for viable circulating tumor cell (CTC) enrichment from blood

Detection of circulating tumor cells has emerged as a promising minimally invasive diagnostic and prognostic tool for patients with metastatic cancers. We report a novel three dimensional microfilter device that can enrich viable circulating tumor cells from blood. This device consists of two layers of parylene membrane with pores and gap precisely defined with photolithography. The positions of the pores are shifted between the top and bottom membranes. The bottom membrane supports captured cells and minimize the stress concentration on cell membrane and sustain cell viability during filtration. Viable cell capture on device was investigated with scanning electron microscopy, confocal microscopy, and immunofluorescent staining using model systems of cultured tumor cells spiked in blood or saline. The paper presents and validates this new 3D microfiltration concept for circulation tumor cell enrichment application. The device provides a highly valuable tool for assessing and characterizing viable enriched circulating tumor cells in both research and clinical settings.

Continuous separation of breast cancer cells from blood samples using multi-orifice flow fractionation (MOFF) and dielectrophoresis (DEP)

Circulating tumor cells (CTCs) are highly correlated with the invasive behavior of cancer, so their isolations and quantifications are important for biomedical applications such as cancer prognosis and measuring the responses to drug treatments. In this paper, we present the development of a microfluidic device for the separation of CTCs from blood cells based on the physical properties of cells. For use as a CTC model, we successfully separated human breast cancer cells (MCF-7) from a spiked blood cell sample by combining multi-orifice flow fractionation (MOFF) and dielectrophoretic (DEP) cell separation technique. Hydrodynamic separation takes advantage of the massive and high-throughput filtration of blood cells as it can accommodate a very high flow rate. DEP separation plays a role in precise post-processing to enhance the efficiency of the separation. The serial combination of these two different sorting techniques enabled high-speed continuous flow-through separation without labeling. We observed up to a 162-fold increase in MCF-7 cells at a 126 µL min(-1) flow rate. Red and white blood cells were efficiently removed with separation efficiencies of 99.24% and 94.23% respectively. Therefore, we suggest that our system could be used for separation and detection of CTCs from blood cells for biomedical applications.

Direct serum assay for microRNA-21 concentrations in early and advanced breast cancer

BACKGROUND

MicroRNAs (miRs) are a class of small noncoding RNAs whose expression changes have been associated with cancer development and progression. Current techniques to isolate miRs for expression analysis from blood are inefficient. We developed a reverse-transcription quantitative real-time PCR (RT-qPCR) assay for direct detection of circulating miRs in serum. We hypothesized that serum concentrations of miR-21, a biomarker increased in breast tumors, would correlate with the presence and extent of breast cancer.

METHODS

The RT-qPCR applied directly in serum (RT-qPCR-DS) assay for circulating miR-21 was tested in sera from 102 patients with different stages of breast cancer and 20 healthy female donors.

RESULTS

The assay was sensitive for detection of miR-21 in 0.625 μL of serum from breast cancer patients. For differentiation of samples from patients with locoregional breast cancer from those from healthy donors, the odds ratio was 1.796 and the area under the curve was 0.721. In a multivariate analysis that included standard clinicopathologic prognostic factors, high circulating miR-21 concentrations correlated significantly (P < 0.001) with visceral metastasis.

CONCLUSIONS

A novel RT-qPCR-DS can improve the efficiency of miR assessment. Use of this assay to detect circulating miR-21 has diagnostic and prognostic potential in breast cancer.

Micro- and nanotechnology approaches for capturing circulating tumor cells

Circulating tumor cells (CTC) are cells that have detached from primary tumors and circulate in the bloodstream where they are carried to other organs, leading to seeding of new tumors and metastases. CTC have been known to exist in the bloodstream for more than a century. With recent progress in the area of micro- and nanotechnology, it has been possible to adopt new approaches in CTC research. Microscale and nanoscale studies can throw some light on the time course of CTC appearance in blood and CTC overexpression profiles for cancer-related markers and galvanize the development of drugs to block metastases. CTC counts could serve as endpoint biomarkers and as prognostic markers for patients with a metastatic disease. This paper reviews some of the recent researches on using micro- and nanotechnology to capture and profile CTC.

Deformability considerations in filtration of biological cells

Biological cells are highly sensitive to variation in local pressure because cellular membranes are not rigid. Unlike microbeads, cells deform under pressure or even lyse. In isolating or enriching cells by mechanical filtration, pressure-induced lysis is exacerbated when high local fluidic velocity is present or when a filter reaches its intended capacity. Microfabrication offers new possibilities to design fluidic environments to reduce cellular stress during the filtration process. We describe the underlying biophysics of cellular stress and general solutions to scale up filtration processes for biological cells.

Significance of Circulating Tumor Cells Detected by the CellSearch System in Patients with Metastatic Breast Colorectal and Prostate Cancer

The increasing number of treatment options for patients with metastatic carcinomas has created a concomitant need for new methods to monitor their use. Ideally, these modalities would be noninvasive, be independent of treatment, and provide quantitative real-time analysis of tumor activity in a variety of carcinomas. Assessment of circulating tumor cells (CTCs) shed into the blood during metastasis may satisfy this need. We developed the CellSearch System to enumerate CTC from 7.5 mL of venous blood. In this review we compare the outcomes from three prospective multicenter studies investigating the use of CTC to monitor patients undergoing treatment for metastatic breast (MBC), colorectal (MCRC), or prostate cancer (MPC) and review the CTC definition used in these studies. Evaluation of CTC at anytime during the course of disease allows assessment of patient prognosis and is predictive of overall survival.

Long term survival following the detection of circulating tumour cells in head and neck squamous cell carcinoma

BACKGROUND

Techniques for detecting circulating tumor cells in the peripheral blood of patients with head and neck cancers may identify individuals likely to benefit from early systemic treatment.

METHODS

Reconstruction experiments were used to optimise immunomagnetic enrichment and RT-PCR detection of circulating tumor cells using four markers (ELF3, CK19, EGFR and EphB4). This method was then tested in a pilot study using samples from 16 patients with advanced head and neck carcinomas.

RESULTS

Seven patients were positive for circulating tumour cells both prior to and after surgery, 4 patients were positive prior to but not after surgery, 3 patients were positive after but not prior to surgery and 2 patients were negative. Two patients tested positive for circulating cells but there was no other evidence of tumor spread. Given this patient cohort had mostly advanced disease, as expected the detection of circulating tumour cells was not associated with significant differences in overall or disease free survival.

CONCLUSION

For the first time, we show that almost all patients with advanced head and neck cancers have circulating cells at the time of surgery. The clinical application of techniques for detection of spreading disease, such as the immunomagnetic enrichment RT-PCR analysis used in this study, should be explored further.

Circulating tumour cell detection: a direct comparison between the CellSearch System, the AdnaTest and CK-19/mammaglobin RT-PCR in patients with metastatic breast cancer

BACKGROUND

The detection, enumeration and isolation of circulating tumour cells (CTCs) have considerable potential to influence the clinical management of patients with breast cancer. There is, however, substantial variability in the rates of positive samples using existing detection techniques. The lack of standardisation of technology hampers the implementation of CTC measurement in clinical routine practice.

METHODS

This study was designed to directly compare three techniques for detecting CTCs in blood samples taken from 76 patients with metastatic breast cancer (MBC) and from 20 healthy controls: the CellSearch CTC System, the AdnaTest Breast Cancer Select/Detect and a previously developed real-time qRT-PCR assay for the detection of CK-19 and mammaglobin transcripts.

RESULTS

As a result, 36% of patients with MBC were positive by the CellSearch System, 22% by the AdnaTest, 26% using RT-PCR for CK-19 and 54% using RT-PCR for mammaglobin. Samples were significantly more likely to be positive for at least one mRNA marker using RT-PCR than using the CellSearch System (P=0.001) or the AdnaTest (P<0.001).

CONCLUSION

We observed a substantial variation in the detection rates of CTCs in blood from breast cancer patients using three different techniques. A higher rate of positive samples was observed using a combined qRT-PCR approach for CK-19 and mammaglobin, which suggests that this is currently the most sensitive technique for detecting CTCs.

Microdevice for the isolation and enumeration of cancer cells from blood

Cancer metastasis is the main attribute to cancer-related deaths. Furthermore, clinical reports have shown a strong correlation between the disease development and number of circulating tumor cells (CTCs) in the peripheral blood of cancer patients. Here, we present a label-free microdevice capable of isolating cancer cells from whole blood via their distinctively different physical properties such as deformability and size. The isolation efficiency is at least 80% for tests performed on breast and colon cancer cells. Viable isolated cells are also obtained which may give further insights to the understanding of the metastatic process. Contrasting with conventional biochemical techniques, the uniqueness of this microdevice lies in the mechanistic and efficient means of isolating viable cancer cells in blood. The microdevice has the potential to be used for routine monitoring of cancer development and cancer therapy in a clinical setting.