Confocal images of circulating tumor cells obtained using a methodology and technology that removes normal cells

The integrated on-chip isolation and detection of circulating tumour cells

Circulating tumour cells (CTCs) are cancer cells shed from a primary tumour which intravasate into the blood stream and have the potential to extravasate into distant tissues, seeding metastatic lesions. As such, they can offer important insight into cancer progression with their presence generally associated with a poor prognosis. The detection and enumeration of CTCs is, therefore, critical to guiding clinical decisions during treatment and providing information on disease state. CTC isolation has been investigated using a plethora of methodologies, of which immunomagnetic capture and microfluidic size-based filtration are the most impactful to date. However, the isolation and detection of CTCs from whole blood comes with many technical barriers, such as those presented by the phenotypic heterogeneity of cell surface markers, with morphological similarity to healthy blood cells, and their low relative abundance (∼1 CTC/1 billion blood cells). At present, the majority of reported methods dissociate CTC isolation from detection, a workflow which undoubtedly contributes to loss from an already sparse population. This review focuses on developments wherein isolation and detection have been integrated into a single-step, microfluidic configuration, reducing CTC loss, increasing throughput, and enabling an on-chip CTC analysis with minimal operator intervention. Particular attention is given to immune-affinity, microfluidic CTC isolation, coupled to optical, physical, and electrochemical CTC detection (quantitative or otherwise).

MnO2 nanosheets and gold nanoparticles supported electrochemical detection of circulating tumor cells

The concentration of circulating tumor cells (CTCs) in peripheral blood is strongly correlated with the progress of certain metastatic cancers. In this study, we have developed a novel and facile electrochemical biosensor for the detection of CTCs based on the use of manganese dioxide nanosheets (MnO2 NSs) and gold nanoparticles (AuNPs). Aptamer sequence of target cell is modified on the surface of AuNPs for specifical recognition. With low-speed centrifugation, numerous AuNPs@DNA can be removed from the supernatant. On the other hand, MnO2 NSs are modified on the electrode surface to capture unreacted AuNPs@DNA. The declined electrochemical signal intensity can be used to reflect the level of CTCs. This biosensor achieves a wide linear range from 10 to 104 cells mL-1 and a limit of detection as low as 3 cells mL-1. Due to the specific aptamer as the recognition element, interfering cells can be successfully distinguished and this method performs satisfactorily in clinical samples. Therefore, it has great potential to be used as a powerful tool benefiting rare cells analysis and the investigation of dynamics of cellular interactions.

Nanomedical detection and downstream analysis of circulating tumor cells in head and neck patients

The establishment of novel biomarkers in liquid biopsies of cancer patients has come more into focus in prognostic and diagnostic research efforts. Due to their prognostic relevance disseminated tumor cells or circulating tumor cells are the subject of intensive research and are discussed as early diagnostic indicators for treatment failure and the formation of micrometastases. A potential association of this early-systemic tumor component with poor prognosis of cancer patients could be already demonstrated for various entities including breast, colon, lung, melanoma, ovarian and prostate cancers. Thus, the detection of circulating tumor cells seems to be also applicable for minimal-invasive monitoring of therapy progress in head and neck cancer patients. A major problem of the use in clinical routine is that circulating tumor cells could not be detected by modern imaging techniques. To overcome these limitations highly sensitive detection methods and techniques for their molecular characterization are urgently needed allowing mechanistic understanding and targeting of circulating tumor cells. Especially the medical application of nanotechnology (nanomedical methods) has made valuable contributions to the field. Here, we want to provide a comprehensive overview on (nanomedical) detection methods for circulating tumor cells and discuss their merits, pitfalls and future perspectives especially for head and neck solid squamous cell carcinoma (HNSCC) patients.

Determination of cell nucleus-to-cytoplasmic ratio using imaging flow cytometry and a combined ultrasound and photoacoustic technique: a comparison study

While the nucleus-to-cytoplasmic (N:C) ratio has traditionally been used for assessing cell malignancy, most N:C measurement techniques are time-consuming and performed on thin histological sections, which prohibit assessment of three-dimensional cell structure. A combined ultrahigh frequency ultrasound (US) and photoacoustic (PA) technique was used to assess the size and N:C ratio of cultured cancer cells in three dimensions (3D). The diameters of the cells and their stained nuclei were obtained by fitting the power spectrum of backscattered US pulses and emitted PA waves, respectively, to well-established theoretical models. For comparison, an imaging flow cytometer (IFC) was also used to determine the two-dimensional cell and nucleus sizes from large cell populations using brightfield and fluorescence images, respectively. An N:C ratio was calculated for each cell using the quotient of the measured nucleus diameter and the total cell diameter. The mean N:C ratios calculated using the sound-based approach were 0.68, 0.66, and 0.54 for MCF-7, PC-3, and MDA-MB-231 cells, respectively, and were in good agreement with the corresponding values of 0.68, 0.67, and 0.68 obtained using the IFC. The combined US and PA technique, which assesses cellular N:C ratio in 3D, has potential applications in the detection of circulating tumor cells in liquid biopsies.

The change in circulating tumor cells before and during concurrent chemoradiotherapy is associated with survival in patients with locally advanced head and neck cancer

BACKGROUND

This study aimed to evaluate the role of baseline circulating tumor cells (CTCs) before and during concurrent chemoradiotherapy and attempted to determine the impacts of CTCs on the outcomes in patients with head and neck squamous cell carcinoma.

METHODS

CTCs were detected using a negative selection strategy and flow cytometry protocol.

RESULTS

We observed a significant correlation between baseline CTCs and staging (P = 0.001). The CTC counts were significantly reduced within 2-4 weeks in 47 concurrent chemoradiotherapy responders (P < 0.001). Change of CTC counts correlates with progression-free survival (PFS, P = 0.01) and overall survival (OS, P = 0.01). CTC decline status was an independent prognostic factor in PFS (P = 0.03) and OS (P = 0.05) in multivariate analyses.

CONCLUSION

In chemoradiotherapy responders, CTCs are significantly reduced. CTC decline within the first month indicates a longer PFS and OS, suggesting that the dynamics of CTCs could be more important than CTC number alone.

Circulating Tumour Cells (CTC), Head and Neck Cancer and Radiotherapy; Future Perspectives

Head and neck cancer is the seventh most common cancer in Australia and globally. Despite the current improved treatment modalities, there is still up to 50⁻60% local regional recurrence and or distant metastasis. High-resolution medical imaging technologies such as PET/CT and MRI do not currently detect the early spread of tumour cells, thus limiting the potential for effective minimal residual detection and early diagnosis. Circulating tumour cells (CTCs) are a rare subset of cells that escape from the primary tumour and enter into the bloodstream to form metastatic deposits or even re-establish themselves in the primary site of the cancer. These cells are more aggressive and accumulate gene alterations by somatic mutations that are the same or even greater than the primary tumour because of additional features acquired in the circulation. The potential application of CTC in clinical use is to acquire a liquid biopsy, by taking a reliable minimally invasive venous blood sample, for cell genotyping during radiotherapy treatment to monitor the decline in CTC detectability, and mutational changes in response to radiation resistance and radiation sensitivity. Currently, very little has been published on radiation therapy, CTC, and circulating cancer stem cells (CCSCs). The prognostic value of CTC in cancer management and personalised medicine for head and neck cancer radiotherapy patients requires a deeper understanding at the cellular level, along with other advanced technologies. With this goal, this review summarises the current research of head and neck cancer CTC, CCSC and the molecular targets for personalised radiotherapy response.

Genetic mutations associated with lung cancer metastasis to the brain

Approximately 90% of all cancer deaths arise from the metastatic spread of primary tumours. Of all the processes involved in carcinogenesis, local invasion and the formation of metastases are clinically the most relevant, but they are the least well understood at the molecular level. As a barrier to metastasis, cells normally undergo an apoptotic process known as 'anoikis', in circulation. The recent technological advances in the isolation and characterisation of rare circulating tumour cells (CTCs) will allow a better understanding of anoikis resistance. Detailed molecular and functional analyses of anoikis-resistant cells may provide insight into the biology of cancer metastasis and help identify novel targets for prevention of cancer dissemination. To uncover the molecular changes that govern the transition from a primary lung tumour to a secondary metastasis and specifically the mechanisms by which CTCs survive in circulation, we carried out whole genome sequencing (WGS) of normal lung, primary tumours and the corresponding brain metastases from five patients with progressive metastatic non-small-cell lung carcinoma. We also isolated CTCs from patients with metastatic cancer and subjected them to whole genome amplification and Sanger sequencing of genes of interest. While the primary tumours showed mutations in genes associated with cell adhesion and motility, brain metastases acquired mutations in adaptive, cytoprotective genes involved in response to cellular stress such as Keap-1, Nrf2 and P300, which are key players of the Keap1-Nrf2-ARE survival pathway. Nrf2 is a transcriptional factor that upon stress translocates into the nucleus, binds to the anti-oxidant response elements (ARE) and drives the expression of anti-oxidant genes. The identified mutations affect regulatory domains in all three proteins, suggesting a functional role in providing a survival advantage to CTCs in the peripheral blood allowing their dissemination to distant organs.

Functional Diagnostic and Therapeutic Nanoconstructs for Efficient Probing of Circulating Tumor Cells

The circulation of tumor cells in peripheral blood is mostly recognized as a prerequisite for cancer progression or systemic invasion, and it correlates with the pivotal hallmark of malignancies known as metastasis. Multiple detection schemes for circulating tumor cells (CTCs) have emerged as the most discerning criteria for monitoring the outcome of anticancer therapy. Therefore, there has been a tremendous increase in the use of robust nanostructured platforms for observation of these mobile tumor cells through various simultaneous diagnosis and treatment regimens developed from conventional techniques. This review seeks to give detailed information about the nature of CTCs as well as techniques for exploiting specific biomarkers to help monitor cancer via detection, capturing, and analysis of unstable tumor cells. We will further discuss nanobased diagnostic interventions and novel platforms which have recently been developed from versatile nanomaterials such as polymer nanocomposites, metal organic frameworks, bioderived nanomaterials and other physically responsive particles with desirable intrinsic and external properties. Herein, we will also include in vivo nanotheranostic platforms which have received a lot of attention because of their enormous clinical potential. In all, this review sums up the general potential of key promising nanoinspired systems as well as other advanced strategies under research and those in clinical use.

Impact of label-free technologies in head and neck cancer circulating tumour cells

Background

The ability to identify high risk head and neck cancer (HNC) patients with disseminated disease prior to presenting with clinically detectable metastases holds remarkable potential. A fraction of circulating tumour cells (CTCs) are invasive cancer cells which mediate metastasis by intravasation, survival and extravasation from the blood stream to metastatic sites. CTCs have been cleared by the FDA for use as surrogate markers of overall survival and progression free survival for breast, prostate and colorectal cancers using the CellSearch^® system. However, the clinical significance of CTCs in head and neck cancer patients has yet to be determined. There has been a significant shift in CTC enrichment platforms, away from exclusively single marker selection, to epitope-independent systems.

Methods

The aim of this study was to screen advanced stage HNC patients by the CellSearch^® platform and utilise two other epitope-independent approaches, ScreenCell^® (microfiltration device) and RosetteSep^™ (negative enrichment), to determine how a shift to such methodologies would enable CTC enrichment and detection.

Results

In advanced stage HNC patients, single CTCs were detected in 8/43 (18.6%) on CellSearch^®, 13/28 (46.4%) on ScreenCell^® and 16/25 (64.0%) by RosetteSep™ (the latter could also detect CTC clusters). Notably, in patients with suspicious lung nodules, too small to biopsy, CTCs were found upon presentation. Moreover, CTCs were readily detected in advanced stage HNC patients.

Conclusion

The epitope-independent platforms detected higher CTC numbers and clusters. Further studies are needed to ascertain whether CTCs can be used as independent prognostic markers for HNCs.

A Collective Route to Head and Neck Cancer Metastasis

Distant metastasis (DM) from head and neck cancers (HNC) portends a poor patient prognosis. Despite its important biological role, little is known about the cells which seed these DM. Circulating tumour cells (CTCs) represent a transient cancer cell population, which circulate in HNC patients’ peripheral blood and seed at distant sites. Capture and analysis of CTCs offers insights into tumour metastasis and can facilitate treatment strategies. Whilst the data on singular CTCs have shown clinical significance, the role of CTC clusters in metastasis remains limited. In this pilot study, we assessed 60 treatment naïve HNC patients for CTCs with disease ranging from early to advanced stages, for CTC clusters utilizing spiral CTC enrichment technology. Single CTCs were isolated in 18/60–30% (Ranging from Stage I-IV), CTC clusters in 15/60–25% (exclusively Stage IV) with 3/15–20% of CTC clusters also containing leukocytes. The presence of CTC clusters associated with the development of distant metastatic disease(P = 0.0313). This study demonstrates that CTC clusters are found in locally advanced patients, and this may be an important prognostic marker. In vivo and in vitro studies are warranted to determine the role of these CTC clusters, in particular, whether leukocyte involvement in CTC clusters has clinical relevance.

Enrichment of circulating head and neck tumour cells using spiral microfluidic technology

Whilst locoregional control of head and neck cancers (HNCs) has improved over the last four decades, long-term survival has remained largely unchanged. A possible reason for this is that the rate of distant metastasis has not changed. Such disseminated disease is reflected in measurable levels of cancer cells in the blood of HNC patients, referred to as circulating tumour cells (CTCs). Numerous marker-independent techniques have been developed for CTC isolation and detection. Recently, microfluidics-based platforms have come to the fore to avoid molecular bias. In this pilot, proof of concept study, we evaluated the use of the spiral microfluidic chip for CTC enrichment and subsequent detection in HNC patients. CTCs were detected in 13/24 (54%) HNC patients, representing both early to late stages of disease. Importantly, in 7/13 CTC-positive patients, CTC clusters were observed. This is the first study to use spiral microfluidics technology for CTC enrichment in HNC.

Microfluidics for research and applications in oncology

Cancer is currently one of the top non-communicable human diseases, and continual research and developmental efforts are being made to better understand and manage this disease. More recently, with the improved understanding in cancer biology as well as the advancements made in microtechnology and rapid prototyping, microfluidics is increasingly being explored and even validated for use in the detection, diagnosis and treatment of cancer. With inherent advantages such as small sample volume, high sensitivity and fast processing time, microfluidics is well-positioned to serve as a promising platform for applications in oncology. In this review, we look at the recent advances in the use of microfluidics, from basic research such as understanding cancer cell phenotypes as well as metastatic behaviors to applications such as the detection, diagnosis, prognosis and drug screening. We then conclude with a future outlook on this promising technology.

The potential for liquid biopsies in the precision medical treatment of breast cancer

Currently the clinical management of breast cancer relies on relatively few prognostic/predictive clinical markers (estrogen receptor, progesterone receptor, HER2), based on primary tumor biology. Circulating biomarkers, such as circulating tumor DNA (ctDNA) or circulating tumor cells (CTCs) may enhance our treatment options by focusing on the very cells that are the direct precursors of distant metastatic disease, and probably inherently different than the primary tumor's biology. To shift the current clinical paradigm, assessing tumor biology in real time by molecularly profiling CTCs or ctDNA may serve to discover therapeutic targets, detect minimal residual disease and predict response to treatment. This review serves to elucidate the detection, characterization, and clinical application of CTCs and ctDNA with the goal of precision treatment of breast cancer.

Sensitive and Specific Biomimetic Lipid Coated Microfluidics to Isolate Viable Circulating Tumor Cells and Microemboli for Cancer Detection

Here we presented a simple and effective membrane mimetic microfluidic device with antibody conjugated supported lipid bilayer (SLB) "smart coating" to capture viable circulating tumor cells (CTCs) and circulating tumor microemboli (CTM) directly from whole blood of all stage clinical cancer patients. The non-covalently bound SLB was able to promote dynamic clustering of lipid-tethered antibodies to CTC antigens and minimized non-specific blood cells retention through its non-fouling nature. A gentle flow further flushed away loosely-bound blood cells to achieve high purity of CTCs, and a stream of air foam injected disintegrate the SLB assemblies to release intact and viable CTCs from the chip. Human blood spiked cancer cell line test showed the ~95% overall efficiency to recover both CTCs and CTMs. Live/dead assay showed that at least 86% of recovered cells maintain viability. By using 2 mL of peripheral blood, the CTCs and CTMs counts of 63 healthy and colorectal cancer donors were positively correlated with the cancer progression. In summary, a simple and effective strategy utilizing biomimetic principle was developed to retrieve viable CTCs for enumeration, molecular analysis, as well as ex vivo culture over weeks. Due to the high sensitivity and specificity, it is the first time to show the high detection rates and quantity of CTCs in non-metastatic cancer patients. This work offers the values in both early cancer detection and prognosis of CTC and provides an accurate non-invasive strategy for routine clinical investigation on CTCs.

Alternating current electrohydrodynamics in microsystems: Pushing biomolecules and cells around on surfaces

Electrohydrodynamics (EHD) deals with the fluid motion induced by an electric field. This phenomenon originally developed in physical science, and engineering is currently experiencing a renaissance in microfluidics. Investigations by Taylor on Gilbert's theory proposed in 1600 have evolved to include multiple contributions including the promising effects arising from electric field interactions with cells and particles to influence their behaviour on electrode surfaces. Theoretical modelling of electric fields in microsystems and the ability to determine shear forces have certainly reached an advanced state. The ability to deftly manipulate microscopic fluid flow in bulk fluid and at solid/liquid interfaces has enabled the controlled assembly, coagulation, or removal of microstructures, nanostructures, cells, and molecules on surfaces. Furthermore, the ability of electrohydrodynamics to generate fluid flow using surface shear forces generated within nanometers from the surface and their application in bioassays has led to recent advancements in biomolecule, vesicle and cellular detection across different length scales. With the integration of Alternating Current Electrohydrodynamics (AC-EHD) in cellular and molecular assays proving to be highly fruitful, challenges still remain with respect to understanding the discrepancies between each of the associated ac-induced fluid flow phenomena, extending their utility towards clinical diagnostic development, and utilising them in tandem as a standard tool for disease monitoring. In this regard, this article will review the history of electrohydrodynamics, followed by some of the recent developments in the field including a new dimension of electrohydrodynamics that deals with the utilization of surface shear forces for the manipulation of biological cells or molecules on electrode surfaces. Recent advances and challenges in the use of electrohydrodynamic forces such as dielectrophoresis and ac electrosmosis for the detection of biological analytes are also reviewed. Additionally, the fundamental mechanisms of fluid flow using electrohydrodynamics forces, which are still evolving, are reviewed. Challenges and future directions are discussed from the perspective of both fundamental understanding and potential applications of these nanoscaled shear forces in diagnostics.

Construction of carbon nanotube based nanoarchitectures for selective impedimetric detection of cancer cells in whole blood

A carbon nanotube (CNT) based nanoarchitecture is developed for rapid, sensitive and specific detection of cancer cells by using real time electrical impedance sensing. The sensor is constructed with carbon nanotube (CNT) multilayers and EpCAM (epithelial cell adhesion molecule) antibodies, which are assembled on an indium tin oxide (ITO) electrode surface. The binding of tumor cells to EpCAM antibodies causes increase of the electron-transfer resistance. The electrochemical impedance of the prepared biosensors is linear with the logarithm of concentration of the liver cancer cell line (HepG2) within the concentration range of 10 to 10(5) cells per mL. The detection limit for HepG2 cells is 5 cells per mL. The proposed impedimetric sensing devices allow for sensitive and specific detection of cancer cells in whole-blood samples without any sample pretreatment steps.

Enrichment of circulating melanoma cells (CMCs) using negative selection from patients with metastatic melanoma

Circulating tumor cells have emerged as prognostic biomarkers in the treatment of metastatic cancers of epithelial origins viz., breast, colorectal and prostate. These tumors express Epithelial Cell Adhesion Molecule (EpCAM) on their cell surface which is used as an antigen for immunoaffinity capture. However, EpCAM capture technologies are of limited utility for non-epithelial cancers such as melanoma. We report a method to enrich Circulating Melanoma Cells (CMCs) that does not presuppose malignant cell characteristics. CMCs were enriched by centrifugation of blood samples from healthy (N = 10) and patient (N = 11) donors, followed by RBC lysis and immunomagnetic depletion of CD45-positive leukocytes in a specialized magnetic separator. CMCs were identified by immunocytochemistry using Melan-A or S100B as melanoma markers and enumerated using automated microscopy image analyses. Separation was optimized for maximum sensitivity and recovery of CMCs. Our results indicate large number of CMCs in Stage IV melanoma patients. Analysis of survival suggested a trend toward decreased survival with increased number of CMCs. Moreover, melanoma-associated miRs were found to be higher in CMC-enriched fractions in two patients when compared with the unseparated samples, validating this method as applicable for molecular analyses. Negative selection is a promising approach for isolation of CMCs and other EpCAM -negative CTCs, and is amenable to molecular analysis of CMCs. Further studies are required to validate its efficacy at capturing specific circulating cells for genomic analysis, and xenograft studies.

Blood-based analyses of cancer: circulating tumor cells and circulating tumor DNA

The ability to study nonhematologic cancers through noninvasive sampling of blood is one of the most exciting and rapidly advancing fields in cancer diagnostics. This has been driven both by major technologic advances, including the isolation of intact cancer cells and the analysis of cancer cell-derived DNA from blood samples, and by the increasing application of molecularly driven therapeutics, which rely on such accurate and timely measurements of critical biomarkers. Moreover, the dramatic efficacy of these potent cancer therapies drives the selection for additional genetic changes as tumors acquire drug resistance, necessitating repeated sampling of cancer cells to adjust therapy in response to tumor evolution. Together, these advanced noninvasive diagnostic capabilities and their applications in guiding precision cancer therapies are poised to change the ways in which we select and monitor cancer treatments.

SIGNIFICANCE

Recent advances in technologies to analyze circulating tumor cells and circulating tumor DNA are setting the stage for real-time, noninvasive monitoring of cancer and providing novel insights into cancer evolution, invasion, and metastasis.

High-purity separation of cancer cells by optically induced dielectrophoresis

Detecting and concentrating cancer cells in peripheral blood is of great importance for cancer diagnosis and prognosis. Optically induced dielectrophoresis (ODEP) can achieve high resolution and low optical intensities, and the electrode pattern can be dynamically changed by varied light patterns. By changing the projected light pattern, it is demonstrated to separate high-purity gastric cancer cell lines. Traditionally, the purity of cancer cell isolation by negative selection is 0.9% to 10%; by positive selection it is 50% to 62%. An ODEP technology is proposed to enhance the purity of cancer cell isolation to about 77%.

Heterogeneous atypical cell populations are present in blood of metastatic breast cancer patients

INTRODUCTION

Circulating tumor cells (CTCs) are commonly isolated from the blood by targeting the epithelial cell adhesion molecule (EpCAM) through positive selection. However, EpCAM can be downregulated during metastatic progression, or it can be initially not present. We designed the present prospective trial to characterize CTCs as well as other circulating cell populations in blood samples from women with metastatic breast cancer without EpCAM-dependent enrichment and/or isolation technology.

METHODS

A total of 32 patients with metastatic breast cancer were enrolled, and blood samples were processed using a previously described negative depletion immunomagnetic methodology. Samples from healthy volunteers were run as controls (n = 5). Multistep sequential labeling was performed to label and fix cell-surface markers followed by permeabilization for cytokeratins (CK) 8, 18 and 19. Multiparametric flow cytometry (FCM) analysis was conducted using a BD LSR II flow cytometer or a BD FACSAria II or FACSAria III cell sorter. Immunocytochemical staining on postenrichment specimens for DAPI, EpCAM, CD45, CK, epidermal growth factor receptor and vimentin was performed. Expression of these markers was visualized using confocal microscopy (CM).

RESULTS

CD45-negative/CK-positive (CD45- CK+) populations with EpCAM + and EpCAM - expression were identified with both FCM and CM from the negatively enriched patient samples. In addition, EpCAM + and EpCAM - populations that were CK + and coexpressing the pan-hematopoietic marker CD45 were also noted. There were more CK + EpCAM - events/ml than CK + EpCAM + events/ml in both the CD45- and CD45+ fractions (both statistically significant at P ≤ 0.0005). The number of CK + CD45- and CK + CD45+ events per milliliter in blood samples (regardless of EpCAM status) was higher in patient samples than in normal control samples (P ≤ 0.0005 and P ≤ 0.026, respectively). Further, a significant fraction of the CK + CD45+ events also expressed CD68, a marker associated with tumor-associated macrophages. Higher levels of CD45-CK + EpCAM - were associated with worse overall survival (P = 0.0292).

CONCLUSIONS

Metastatic breast cancer patients have atypical cells that are CK + EpCAM - circulating in their blood. Because a substantial number of these patients do not have EpCAM + CTCs, additional studies are needed to evaluate the role of EpCAM - circulating cells as a prognostic and predictive marker.

Isolation and mutational analysis of circulating tumor cells from lung cancer patients with magnetic sifters and biochips

Detection and characterization of circulating tumor cells (CTCs) may reveal insights into the diagnosis and treatment of malignant disease. Technologies for isolating CTCs developed thus far suffer from one or more limitations, such as low throughput, inability to release captured cells, and reliance on expensive instrumentation for enrichment or subsequent characterization. We report a continuing development of a magnetic separation device, the magnetic sifter, which is a miniature microfluidic chip with a dense array of magnetic pores. It offers high efficiency capture of tumor cells, labeled with magnetic nanoparticles, from whole blood with high throughput and efficient release of captured cells. For subsequent characterization of CTCs, an assay, using a protein chip with giant magnetoresistive nanosensors, has been implemented for mutational analysis of CTCs enriched with the magnetic sifter. The use of these magnetic technologies, which are separate devices, may lead the way to routine preparation and characterization of "liquid biopsies" from cancer patients.

New generation of ensemble-decision aliquot ranking based on simplified microfluidic components for large-capacity trapping of circulating tumor cells

Ensemble-decision aliquot ranking (eDAR) is a sensitive and high-throughput method to analyze circulating tumor cells (CTCs) from peripheral blood. Here, we report the next generation of eDAR, where we designed and optimized a new hydrodynamic switching scheme for the active sorting step in eDAR, which provided fast cell sorting with an improved reproducibility and stability. The microfluidic chip was also simplified by incorporating a functional area for subsequent purification using microslits fabricated by standard lithography method. Using the reported second generation of eDAR, we were able to analyze 1 mL of whole-blood samples in 12.5 min, with a 95% recovery and a zero false positive rate (n = 15).

Filter characteristics influencing circulating tumor cell enrichment from whole blood

A variety of filters assays have been described to enrich circulating tumor cells (CTC) based on differences in physical characteristics of blood cells and CTC. In this study we evaluate different filter types to derive the properties of the ideal filter for CTC enrichment. Between 0.1 and 10 mL of whole blood spiked with cells from tumor cell lines were passed through silicon nitride microsieves, polymer track-etched filters and metal TEM grids with various pore sizes. The recovery and size of 9 different culture cell lines was determined and compared to the size of EpCAM+CK+CD45−DNA+ CTC from patients with metastatic breast, colorectal and prostate cancer. The 8 µm track-etched filter and the 5 µm microsieve had the best performance on MDA-231, PC3-9 and SKBR-3 cells, enriching >80% of cells from whole blood. TEM grids had poor recovery of ∼25%. Median diameter of cell lines ranged from 10.9–19.0 µm, compared to 13.1, 10.7, and 11.0 µm for breast, prostate and colorectal CTC, respectively. The 11.4 µm COLO-320 cell line had the lowest recovery of 17%. The ideal filter for CTC enrichment is constructed of a stiff, flat material, is inert to blood cells, has at least 100,000 regularly spaced 5 µm pores for 1 ml of blood with a ≤10% porosity. While cell size is an important factor in determining recovery, other factors must be involved as well. To evaluate a filtration procedure, cell lines with a median size of 11–13 µm should be used to challenge the system.

High-purity and label-free isolation of circulating tumor cells (CTCs) in a microfluidic platform by using optically-induced-dielectrophoretic (ODEP) force

Negative selection-based circulating tumor cell (CTC) isolation is believed valuable to harvest more native, and in particular all possible CTCs without biases relevant to the properties of surface antigens on the CTCs. Under such a cell isolation strategy, however, the CTC purity is normally compromised. To address this issue, this study reports the integration of optically-induced-dielectrophoretic (ODEP) force-based cell manipulation, and a laminar flow regime in a microfluidic platform for the isolation of untreated, and highly pure CTCs after conventional negative selection-based CTC isolation. In the design, six sections of moving light-bar screens were continuously and simultaneously exerted in two parallel laminar flows to concurrently separate the cancer cells from the leukocytes based on their size difference and electric properties. The separated cell populations were further partitioned, delivered, and collected through the two flows. With this approach, the cancer cells can be isolated in a continuous, effective, and efficient manner. In this study, the operating conditions of ODEP for the manipulation of prostate cancer (PC-3) and human oral cancer (OEC-M1) cells, and leukocytes with minor cell aggregation phenomenon were first characterized. Moreover, performances of the proposed method for the isolation of cancer cells were experimentally investigated. The results showed that the presented CTC isolation scheme was able to isolate PC-3 cells or OEC-M1 cells from a leukocyte background with high recovery rate (PC-3 cells: 76-83%, OEC-M1 cells: 61-68%), and high purity (PC-3 cells: 74-82%, OEC-M1 cells: 64-66%) (set flow rate: 0.1 μl min(-1) and sample volume: 1 μl). The latter is beyond what is currently possible in the conventional CTC isolations. Moreover, the viability of isolated cancer cells was evaluated to be as high as 94 ± 2%, and 95 ± 3% for the PC-3, and OEC-M1 cells, respectively. Furthermore, the isolated cancer cells were also shown to preserve their proliferative capability. As a whole, this study has presented an ODEP-based microfluidic platform that is capable of isolating CTCs in a continuous, label-free, cell-friendly, and particularly highly pure manner. All these traits are found particularly meaningful for exploiting the harvested CTCs for the subsequent cell-based, or biochemical assays.

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.

Multiparameter analysis, including EMT markers, on negatively enriched blood samples from patients with squamous cell carcinoma of the head and neck

Epithelial to mesenchymal transition (EMT) has been hypothesized as a mechanism by which cells change phenotype during carcinogenesis, as well as tumor metastasis. Whether EMT is involved in cancer metastasis has a specific, practical impact on the field of circulating tumor cells (CTCs). Since the generally accepted definition of a CTC includes the expression of epithelial surface markers, such as EpCAM, if a cancer cell loses its epithelial surface markers (which is suggested in EMT), it will not be separated and/or identified as a CTC. We have developed, and previously reported on the use of, a purely negative enrichment technology enriching for CTCs in the blood of squamous cell carcinoma of the head and neck (SCCHN). This methodology does not depend on the expression of surface epithelial markers. Using this technology, our initial data on SCCHN patient blood indicates that the presence of CTCs correlates with worse disease-free survival. Since our enrichment is not dependent on epithelial markers, we have initiated investigation of the presence of mesenchymal markers in these CTC cells to include analysis of: vimentin, epidermal growth factor receptor, N-cadherin, and CD44. With the aid of confocal microscopy, we have demonstrated not only presumed CTCs that express and/or contain: a nucleus, cytokeratins, vimentin, and either EGFR, CD44, or N-cadherin, but also cells that contain all of the aforementioned proteins except cytokeratins, suggesting that the cells have undergone the EMT process. We suggest that our negative depletion enrichment methodology provides a more objective approach in identifying and evaluating CTCs, as opposed to positive selection approaches, as it is not subjective to a selection bias and can be tailored to accommodate a variety of cytoplasmic and surface markers which can be evaluated to identify a multitude of phenotypic patterns within CTCs from individual patients, including so-called EMT as presented here.

Microchip-based immunomagnetic detection of circulating tumor cells

Screening for circulating tumor cells (CTCs) in blood has been an object of interest for evidence of progressive disease, status of disease activity, recognition of clonal evolution of molecular changes and for possible early diagnosis of cancer. We describe a new method of microchip-based immunomagnetic CTC detection, in which the benefits of both immunomagnetic assay and the microfluidic device are combined. As the blood sample flows through the microchannel closely above arrayed magnets, cancer cells labeled with magnetic nanoparticles are separated from blood flow and deposited at the bottom wall of the glass coverslip, which allows direct observation of captured cells with a fluorescence microscope. A polydimethylsiloxane (PDMS)-based microchannel fixed on a glass coverslip was used to screen blood samples. The thin, flat dimensions of the microchannel, combined with the sharp magnetic field gradient in the vicinity of arrayed magnets with alternate polarities, lead to an effective capture of labeled cells. Compared to the commercially available CellSearch™ system, fewer (25%) magnetic particles are required to achieve a comparable capture rate, while the screening speed (at an optimal blood flow rate of 10 mL h(-1)) is more than five times faster than those reported previously with a microchannel-based assay. For the screening experiment, blood drawn from healthy subjects into CellSave™ tubes was spiked with cultured cancer cell lines of COLO205 and SKBR3. The blood was then kept at room temperature for 48 hours before the screening, emulating the actual clinical cases of blood screening. Customized Fe(3)O(4) magnetic nanoparticles (Veridex Ferrofluid™) conjugated to anti-epithelial cell adhesion molecule (EpCAM) antibodies were introduced into the blood samples to label cancer cells, and the blood was then run through the microchip device to capture the labelled cells. After capture, the cells were stained with fluorescent labelled anti-cytokeratin, DAPI and anti-CD45. Subsequent immunofluorescence images were taken for the captured cells, followed by comprehensive computer aided analysis based on fluorescence intensities and cell morphology. Rare cancer cells (from ∼1000 cells down to ∼5 cells per mL) with very low tumor cell to blood cell ratios (about 1 : 10(7) to 10(9), including red blood cells) were successfully detected. Cancer cell capture rates of 90% and 86% were demonstrated for COLO205 and SKBR3 cells, respectively.

Circulating tumor cell isolation and diagnostics: toward routine clinical use

From February 7-11, 2011, the multidisciplinary Lorentz Workshop Circulating Tumor Cell (CTC) Isolation and Diagnostics: Toward Routine Clinical Use was held in Leiden (The Netherlands) to discuss progress and define challenges and potential solutions for development of clinically useful circulating tumor cell (CTC) diagnostics. CTCs, captured as "liquid biopsy" from blood, for counting and characterization using pathology and molecular assays, are expected to replace metastatic tissue biopsies to be used to predict drug response and resistance and to monitor therapy response and cancer recurrence. CTCs are highly heterogeneous; therefore, cancer type-specific isolation technologies, as well as complex clinical interpretation software, are required.

Circulating tumor cells: approaches to isolation and characterization

Circulating tumor cells (CTCs) shed from primary and metastatic cancers are admixed with blood components and are thus rare, making their isolation and characterization a major technological challenge. CTCs hold the key to understanding the biology of metastasis and provide a biomarker to noninvasively measure the evolution of tumor genotypes during treatment and disease progression. Improvements in technologies to yield purer CTC populations amenable to better cellular and molecular characterization will enable a broad range of clinical applications, including early detection of disease and the discovery of biomarkers to predict treatment responses and disease progression.

Significance of circulating tumor cells in patients with squamous cell carcinoma of the head and neck: initial results

OBJECTIVES

to present and discuss a high-performance negative depletion method for the isolation of circulating tumor cells (CTCs) in the blood of patients with head and neck cancer and to determine the correlation between the presence of CTCs and early clinical outcome in these patients.

DESIGN

prospective clinical follow-up study of patients with squamous cell carcinoma of the head and neck (SCCHN) undergoing surgical intervention, who had peripheral blood examined for the presence of CTCs.

PATIENTS

the study population comprised 48 patients diagnosed as having SCCHN and undergoing surgical intervention.

INTERVENTION

a negative depletion process to isolate and quantify CTCs from the blood of patients with SCCHN using immunomagnetic separation was developed and validated. Immunostaining for cytokeratin was performed on the enriched samples to determine the number of CTCs extracted from each patient's blood sample. Correlation of the presence of CTCs, tumor stage, nodal status, clinical characteristics, and outcome was made.

MAIN OUTCOME MEASURE

disease-free survival.

RESULTS

our initial data, that have a mean follow-up of 19.0 months, suggest that patients with no detectable CTCs per milliliter of blood had a significantly higher probability of disease-free survival (P = .01). There was no correlation between the presence of CTCs with regard to age, sex, tumor site, stage, or nodal involvement.

CONCLUSIONS

our enrichment technology, based on the removal of normal cells, has been used on the peripheral blood of patients with head and neck cancer for which follow-up data were collected. If no CTCs were present, a statistically significant improved disease-free survival was observed in SCCHN. A blood test with such a prognostic capability could have important implications in the treatment of patients with head and neck cancer.

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.