In Vivo Capture of Circulating Tumor Cells Based on Transfusion with a Vein Indwelling Needle

Intravascular elimination of circulating tumor cells and cascaded embolization with multifunctional 3D tubular scaffolds

The primary tumor ("root") and circulating tumor cells (CTCs; "seeds") are vital factors in tumor progression. However, current treatment strategies mainly focus on inhibiting the tumor while ignoring CTCs, resulting in tumor metastasis. Here, we design a multifunctional 3D scaffold with interconnected macropores, excellent photothermal ability and perfect bioaffinity as a blood vessel implantable device. When implanted upstream of the primary tumor, the scaffold intercepts CTCs fleeing back to the primary tumor and then forms "micro-thrombi" to block the supply of nutrients and oxygen to the tumor for embolization therapy. The scaffold implanted downstream of the tumor efficiently captures and photothermally kills the CTCs that escape from the tumor, thereby preventing metastasis. Experiments using rabbits demonstrated excellent biosafety of this scaffold with 86% of the CTC scavenging rate, 99% of the tumor inhibition rate and 100% of CTC killing efficiency. The multifunctional 3D scaffold synergistically inhibits the "root" and eliminates the "seeds" of the tumor, demonstrating its potential for localized cancer therapy with few side effects and high antitumor efficacy.

Advances in circulating tumor cells for early detection, prognosis and metastasis reduction in lung cancer

Globally, lung cancer stands as the leading type of cancer in terms of incidence and is the major source of mortality attributed to cancer. We have outlined the molecular biomarkers for lung cancer that are available clinically. Circulating tumor cells (CTCs) spread from the original location, circulate in the bloodstream, extravasate, and metastasize, forming secondary tumors by invading and establishing a favorable environment. CTC analysis is considered a common liquid biopsy method for lung cancer. We have enumerated both in vivo and ex vivo techniques for CTC separation and enrichment, examined the advantages and limitations of these methods, and also discussed the detection of CTCs in other bodily fluids. We have evaluated the value of CTCs, as well as CTCs in conjunction with other biomarkers, for their utility in the early detection and prognostic assessment of patients with lung cancer. CTCs engage with diverse cells of the metastatic process, interfering with the interaction between CTCs and various cells in metastasis, potentially halting metastasis and enhancing patient prognosis.

Toward Personalized Nanomedicine: The Critical Evaluation of Micro and Nanodevices for Cancer Biomarker Analysis in Liquid Biopsy

Liquid biopsy for the analysis of circulating cancer biomarkers (CBs) is a major advancement toward the early detection of cancer. In comparison to tissue biopsy techniques, liquid biopsy is relatively painless, offering multiple sampling opportunities across easily accessible bodily fluids such as blood, urine, and saliva. Liquid biopsy is also relatively inexpensive and simple, avoiding the requirement for specialized laboratory equipment or trained medical staff. Major advances in the field of liquid biopsy are attributed largely to developments in nanotechnology and microfabrication that enables the creation of highly precise chip-based platforms. These devices can overcome detection limitations of an individual biomarker by detecting multiple markers simultaneously on the same chip, or by featuring integrated and combined target separation techniques. In this review, the major advances in the field of portable and semi-portable micro, nano, and multiplexed platforms for CB detection for the early diagnosis of cancer are highlighted. A comparative discussion is also provided, noting merits and drawbacks of the platforms, especially in terms of portability. Finally, key challenges toward device portability and possible solutions, as well as discussing the future direction of the field are highlighted.

Recent progress of nanostructure-based enrichment of circulating tumor cells and downstream analysis

The isolation and detection of circulating tumor cells (CTCs) play an important role in early cancer diagnosis and prognosis, providing easy access to identify metastatic cells before clinically detectable metastases. In the past 20 years, according to the heterogeneous expression of CTCs on the surface and their special physical properties (size, morphology, electricity, etc.), a series of in vitro enrichment methods of CTCs have been developed based on microfluidic chip technology, nanomaterials and various nanostructures. In recent years, the in vivo detection of CTCs has attracted considerable attention. Photoacoustic flow cytometry and fluorescence flow cytometry were used to detect CTCs in a noninvasive manner. In addition, flexible magnetic wire and indwelling intravascular non-circulating CTCs isolation system were developed for in vivo CTCs study. In the aspect of downstream analysis, gene analysis and drug sensitivity tests of enriched CTCs were developed based on various existing molecular analysis techniques. All of these studies constitute a complete study of CTCs. Although the existing reviews mainly focus on one aspect of capturing CTCs study, a review that includes the in vivo and in vitro capture and downstream analysis study of CTCs is highly needed. This review focuses on not only the classic work and latest research progress in in vitro capture but also includes the in vivo capture and downstream analysis, discussing the advantages and significance of the different research methods and providing new ideas for solving the heterogeneity and rarity of CTCs.

Photo-functionalized TiO2 film for facile immobilization of EpCAM antibodies and efficient enrichment of circulating tumor cells

The highly efficient capture of circulating tumor cells (CTCs) in the blood is essential for the screening, treatment, and assessment of the risk of metastasis or recurrence of cancer. Immobilizing specific antibodies, such as EpCAM antibodies, on the material's surface is currently the primary method for efficiently capturing CTCs. However, the strategies for immobilizing antibodies usually have the disadvantages of requiring multiple chemical reagents and a complex pre-treatment process. Herein we developed a simple strategy for the immobilization of EpCAM antibodies without additional chemical reagents. By utilizing the positive charge property of the photo-functionalized titanium dioxide (TiO₂), the negatively charged carboxyl terminal of EpCAM antibodies was immobilized by electrostatic interaction, allowing the antibodies to expose the antigen binding site fully. The experimental results showed that the photo-functionalized TiO₂ surface had a marked positive charge and super-hydrophilic properties that could immobilize large amounts of EpCAM antibodies and keep excellent activity. CTCs capture experiments in vitro showed that the EpCAM antibodies-modified photo-functionalized TiO₂ could efficiently capture CTCs. The results of blood circulation experiments in rabbits showed that the EpCAM antibodies-modified photo-functionalized TiO₂ could accurately capture CTCs from the whole body's blood. It was foreseen that the strategy of simple immobilization of EpCAM antibodies based on photo-functionalized TiO₂ is expected to serve in the efficient capture of CTCs in the future.

An Implantable Magnetic Vascular Scaffold for Circulating Tumor Cell Removal In Vivo

An integrated trapped device (ITD) capable of removal of circulating tumor cells (CTCs) can assuage or even prevent metastasis. However, adhesion repertoires are ordinarily neglected in the design of ITDs, possibly leading to the omission of highly metastatic CTC and treatment failure. Here a vascular-like ITD with adhesive sites and wireless magnetothermal response to remove highly metastatic CTC in vivo is presented. Such a vascular-like ITD comprises circumferential well-aligned fibers and artificial adhesion repertoires and is optimized for magnetothermal integration. Continuous and repeated capture in a dynamic environment increases capture efficiency over time. Meanwhile, the heat generation of the ITD leads to the capture of CTC death owing to cell heat sensitivity. Furthermore, the constructed bioinspired ultrastructure of the ITD prevents vascular blockage and induces potential vascular regeneration. Overall, this work defines an extendable strategy for constructing adhesion repertoires against intravascular shear forces, provides a vascular-like ITD for reducing CTC counts, and is expected to alleviate the risk of cancer recurrence.

Real-Time Detection of Circulating Tumor Cells in Bloodstream Using Plasmonic Fiber Sensors

Circulating tumor cells (CTCs) are single cancer cells or cancer cell clusters that are present in the circulatory system. Assessing CTC levels in patients can aid in the early detection of cancer metastasis and is essential for the purposes of accurate cancer prognosis. However, current in vitro blood tests are limited by the insufficient blood samples and low concentration levels of CTCs, which presents a major challenge for practical biosensing devices. In this work, we propose the first surface plasmon resonance (SPR) fiber probe to work intravenously, which offers a real-time detection of CTCs in bloodstreams. By exposing the protein-functionalized fiber probe to circulating blood, a continuous capture of CTCs ensures a constant increase in enrichment and hence greatly enhances enumeration accuracy. The performance of our plasmonic fiber probe was demonstrated to specifically detect Michigan Cancer Foundation-7 (MCF-7) breast cancer cells in flowing whole mouse blood. Further, a detection limit of ~1.4 cells per microliter was achieved by using an epithelial cell adhesion molecule (EpCAM) antibody-based receptor layer and a 15 minute enrichment period. This pilot study validates real-time CTC detection directly in the bloodstream by using plasmonic fiber probes, which exhibit promising clinical potential for in vivo diagnostic tests involving low concentration biomarkers in circulating blood.

The Discovery of Novel Circulating Cancer-Related Cells in Circulation Poses New Challenges to Microfluidic Devices for Enrichment and Detection

Circulating tumor cells (CTCs) enumeration has been widely used as a surrogate predictive marker for early diagnoses, the evaluation of chemotherapy efficacy, and cancer prognosis. Microfluidic technologies for CTCs enrichment and detection have been developed and commercialized as automation platforms. Currently, in addition to CTCs, some new types of circulating cancer-related cells (e.g., CCSCs, CTECs, CAMLs, and heterotypic CTC clusters) in circulation are also reported to be correlated to cancer diagnosis, metastasis, or prognosis. And they widely differ from the conventional CTCs in positive markers, cellular morphology, or size, which presents a new technological challenge to microfluidic devices that use affinity-based capture methods or size-based filtration methods for CTCs detection. This review focuses on the biological and physical properties as well as clinical significance of the novel circulating cancer-related cells, and discusses the challenges of their discovery to microfluidic chip for enrichment. Finally, the current challenges of CTCs detection in clinical application and future opportunities are also discussed.

Flexible Electronic Catheter Based on Nanofibers for the In Vivo Elimination of Circulating Tumor Cells

Clearing circulating tumor cells (CTCs) that are closely related to cancer metastasis and recurrence in peripheral blood helps to reduce the probability of cancer recurrence and metastasis. However, conventional therapies aiming at killing CTCs always cause damage to normal blood cells, tissues, and organs. Here, we report a flexible electronic catheter that can capture and kill CTCs via irreversible electroporation (IRE) with high efficiency. The flexible electronic catheter is assembled from nanofibers (NFs) with liquid metal-polymer conductor (MPC) electrodes. The NFs were modified with an epithelial cellular adhesion molecule (EpCAM) antibody on the surface to improve specific biorecognition and cell adhesion. Whole-body blood can be screened by the catheter repeatedly, during which the EpCAM antibody on a nanofiber can enrich CTCs to the surface of the catheter. Taking advantage of the high specific surface area, the capture efficiency of NF-based catheters for CTCs is 25 times higher than previously reported cases. Furthermore, the number of nonspecifically captured WBCs is less than 10 per mm² areas of the catheter, compared to their original large number of 4-11 × 10⁶ mL^-1 of whole blood, showing good specificity of the flexible electronic catheter. The flexible and biocompatible MPC electrodes have a high killing efficiency of 100% for the captured CTCs in a rabbit model. No noticeable hematologic index and morphological changes of the vessels and major organs were observed, indicating that this electronic catheter had good biocompatibility. The present functional electronic catheter offers an alternative strategy for improving the efficiency of clinical cancer therapy.

Very-light alcohol consumption suppresses breast tumor progression in a mouse model

The relationship between alcohol consumption and cancer has no consistent results both in epidemiological studies and animal models. The inaccuracy of alcohol consumption dosage in the experimental design maybe leads to inconsistent results and makes the researchers ignore the effect of very-light alcohol consumption on cancer. To determine the effects of very-light alcohol consumption on cancer, in this study, the manner of gavage was used to control the alcohol consumption accurately. The impacts of age and time of drinking on cancer progression were also evaluated in this study. Here, we find that a certain range of alcohol consumption (from 0.5% w/v to 2.0% w/v) can suppress tumor development in the breast metastasis mouse model by controlling the alcohol consumption dosage accurately. RNA sequencing analyses were performed in primary tumors and related metastases from the NC group and 1.0% w/v group. The results of primary tumors and related metastases indicated that chronic very-light alcohol consumption downregulates breast tumor-associated oncogenes in primary tumors and regulates the immune system and metabolic system in metastatic carcinoma. To provide the public with drinking recommendations, eight commercial alcohol types were investigated at a dosage of 1.0% w/v. Two types of commercial alcohol, red wine (made in France, brand 1) and baijiu (made in China, brand 1), exerted excellent primary tumor and metastasis inhibitory effects. The untargeted metabolomic analysis of commercial alcohol by liquid chromatography-tandem mass spectrometry indicated that baijiu (brand 1) and baijiu (brand 2) exhibited a difference in compositions that can lead to their different anti-cancer effects. These results indicated that a certain range of very light alcohol dosages might have a potential human-cancer inhibition effect.

Evaluation of the Effects of Different Dietary Patterns on Breast Cancer: Monitoring Circulating Tumor Cells

The occurrence and development of breast cancer are closely related to dietary factors, especially dietary patterns. This study was to investigate the effects of dietary patterns on the process of tumor metastasis by in vivo circulating tumor cell (CTC) capture strategy and monitoring changes of CTC numbers in breast tumor mice model. Meanwhile, the effects of different dietary patterns on the development of lung metastases of breast cancer and the volume and weight of carcinoma in situ were investigated. In this study, the increase in the number of CTCs was significantly promoted by dietary patterns such as high-salt diet, high-sugar diet, and high-fat diet, while it was delayed by ketogenic diet, low-fat diet, low-protein diet, diet restriction, and Mediterranean diet. These results indicated that the in vivo capture and detection of CTCs provides a convenient method for real-time cancer metastasis monitoring, and through in-depth study of the effects of different dietary patterns on tumor growth and metastasis, it can expand a new horizon in future cancer treatments.

In vivo flow cytometry reveals a circadian rhythm of circulating tumor cells

Circulating tumor cells (CTCs) is an established biomarker of cancer metastasis. The circulation dynamics of CTCs are important for understanding the mechanisms underlying tumor cell dissemination. Although studies have revealed that the circadian rhythm may disrupt the growth of tumors, it is generally unclear whether the circadian rhythm controls the release of CTCs. In clinical examinations, the current in vitro methods for detecting CTCs in blood samples are based on a fundamental assumption that CTC counts in the peripheral blood do not change significantly over time, which is being challenged by recent studies. Since it is not practical to draw blood from patients repeatedly, a feasible strategy to investigate the circadian rhythm of CTCs is to monitor them by in vivo detection methods. Fluorescence in vivo flow cytometry (IVFC) is a powerful optical technique that is able to detect fluorescent circulating cells directly in living animals in a noninvasive manner over a long period of time. In this study, we applied fluorescence IVFC to monitor CTCs noninvasively in an orthotopic mouse model of human prostate cancer. We observed that CTCs exhibited stochastic bursts over cancer progression. The probability of the bursting activity was higher at early stages than at late stages. We longitudinally monitored CTCs over a 24-h period, and our results revealed striking daily oscillations in CTC counts that peaked at the onset of the night (active phase for rodents), suggesting that the release of CTCs might be regulated by the circadian rhythm.

Circulating tumor-cell-targeting Au-nanocage-mediated bimodal phototherapeutic properties enriched by magnetic nanocores

Metastasis resulting from circulating tumor cells (CTCs) is associated with 90% of all cancer mortality. To disrupt cancer dissemination, therapeutic targeting of CTCs by extracorporeal photodynamic therapy (PDT) has emerged; however, it still remains impractical due to its limited therapeutic window. Herein, we developed a photosensitive and magnetic targeted core-satellite nanomedicine (TCSN) to augment the light-induced damage to the targeted cells. The magnetic nanocore (MNC) with multiple iron oxide nanoparticles stabilized using thiolated polyvinyl alcohol can magnetize the CTCs to achieve magnetic enrichment under a magnetic field. Multiple gold nanocage (AuNC) satellites were conjugated on the MNC to facilitate bimodal photothermal therapy and PDT. Adjusting the thiol content in the MNC allows manipulating the AuNC density on TCSNs, which has been found to demonstrate a density-dependent bimodal phototherapeutic effect under laser irradiation at 808 and 940 nm. Moreover, with the immobilization of anti-epithelial cell adhesion molecule (anti-EpCAM), TCSN exhibited an enhanced affinity toward EpCAM-expressing 4T1 cells. We demonstrate that TCSN-labeled 4T1 cells can be isolated and photo-eradicated in a microfluidic channel with a dynamic flow. Our studies showed that TCSN with the complementary properties of MNC and AuNCs can largely augment the therapeutic window by magnetic enrichment and bimodal phototherapy, serving as an advanced extracorporeal strategy to remove CTCs.

Noninvasive and real-time monitoring of Au nanoparticle promoted cancer metastasis using in vivo flow cytometry

Cancer is the second leading cause of mortality globally, while cancer metastasis, which accounts for about 90% of cancer-related mortality, presents an extremely poor prognosis. Thus, various nanomedicines were designed and synthesized for cancer treatment, but nanomaterials could lead to endothelial leakiness and consequently facilitate intravasation and extravasation of cancer cells to form circulating tumor cells (CTCs), which were regarded as the potential metastatic seeds, possibly accelerating cancer metastasis. Neither possible metastatic sites were observed nor rare CTCs could be measured using common methods at the early stage of cancer metastasis, it is urgent to explore new technology to dynamically monitor nanomedicine promoted cancer metastasis with high sensitivity, which would be beneficial for cancer treatment as well as design and synthesis of nanomedicine. Herein, a novel optical biopsy tool i.e. in vivo flow cytometry (IVFC) was constructed to noninvasively and real-time monitor CTCs of tumor-bearing mice treated with various concentrations of Au nanoparticles. The in vivo experimental results demonstrated the promoted CTCs were Au nanoparticles dose-dependent consistent with the in vitro results, which showed Au nanoparticles induced dose-dependent gaps in the blood vessel endothelial walls to accelerate CTCs formation, making IVFC a promising biopsy tool in fundamental, pre-clinical and clinical investigation of nanomedicine and cancer metastasis.

Effects of dietary patterns combined with dietary phytochemicals on breast cancer metastasis

AIMS

Dietary phytochemicals and diet types (e.g., the Mediterranean diet) have been shown to have anti-cancer properties. However, the effects of combined treatment with dietary phytochemicals and different diet types on primary and metastatic tumor growth have yet to be investigated. The purpose of this study is to investigate the effects of phytochemicals combined with diet types on breast cancer metastasis.

MAIN METHODS

The inhibitory effects on breast cancer metastasis of three phytochemicals (allicin, hesperidin, astragalus polysaccharides) and two diet types (Mediterranean diet, restricted diet), separately or in combination, were evaluated based on: (i) detection of circulating tumor cells (CTCs) using an in vivo capture method; and (ii) primary tumor growth.

KEY FINDINGS

All dietary factors significantly inhibited the growth of primary tumors and metastases, with combinations showing enhancing the effects.

SIGNIFICANCE

Dietary phytochemicals and diet types should be further evaluated as adjunct therapies and lifestyle modifications in cancer patients. Furthermore, the in vivo CTC capture method allows dynamic monitoring of cancer metastasis over time, providing a useful approach to evaluating treatment effects in real-time.

High‑throughput and continuous flow isolation of rare circulating tumor cells and clusters in gastric cancer from human whole blood samples using electromagnetic vibration‑based filtration

Circulating tumor cells (CTCs) or CTC clusters are considered as suitable and relevant targets for liquid biopsy as they more accurately indicate cancer progression, the therapeutic effects of treatment and allows for monitoring of cancer metastasis in real-time. Among the various methods for isolating CTCs, size-based filtration is one of the most convenient methods. However, cell clogging makes the filtration process less efficient. In the present study, an electromagnetic vibration-based filtration (eVBF) device was developed that efficiently isolated rare CTCs and CTC clusters from clinical blood samples of patients with gastric cancer. Using human blood samples spiked with human gastric cancer cells, the parameters of this device such as vibrating amplitude and flow rate were optimized. Putative CTCs were detected using a conventional filtration method and the eVBF device from the peripheral blood samples of patients with gastric cancer. Continuous flow isolation of CTCs was evaluated by a simulated blood flow system. The eVBF device utilized the electromagnetic force to generate a periodic vibration that prevented the cell clogging and improved the filtering efficiency. The optimized eVBF device with the high-amplitude vibration exhibited a recovery efficiency of 80–90% from whole blood samples spiked with 100 or 1,000 gastric cancer cells per ml. Using the eVBF device, CTCs were detected in 100% of patients (10/10) with gastric cancer, and the positive detection rate of the eVBF device was 30% higher compared with the conventional filtration method. Furthermore, CTC clusters were detected in 40% (4/10) of CTC-positive patient samples, and the integrity of CTC clusters was preserved using the eVBF device. The eVBF device allowed for high-throughput (1 ml/min) and continuous flow isolation of CTCs without the addition of any antibodies, any chemical reagents or any pretreatment processes. Thus, the eVBF device provides an efficient tool for isolating rare CTCs and CTC clusters from patients with cancer, highlighting its potential for use in cancer diagnosis, treatment and cancer biology research.

Flexible Three-Dimensional Net for Intravascular Fishing of Circulating Tumor Cells

Current strategies for in vitro isolation of circulating tumor cells (CTCs) fail to detect extremely rare CTCs heterogeneously distributed in blood. It is possible to devise methods for in vivo capture of CTCs based on processing almost all of the blood in the human body to improve detection sensitivity, but the complicated manipulation, biosafety concerns, and limited capture efficiency of conventional detection strategies prohibit their implementation in the clinic. Herein, we present a flexible three-dimensional (3-D) CTC-Net probe for intravascular collection of CTCs. The CTC-Net, consisting of a 3-D elastic scaffold with an interconnected, spatially distributed network accommodates a large quantity of immobilized antibodies and provides an enhanced substrate-cell contact frequency, which results in an enhanced capture efficiency and effective detection of heterogeneous CTCs. The as-prepared CTC-Net can be readily compressed and injected into blood vessels and fully unfolded to form a 3-D "fishing-net" structure for capture of the CTCs, and then retracted for imaging and downstream gene analysis of the captured CTCs. Significant advantages for the CTC-Net over currently available in vitro and in vivo procedures are demonstrated for detection of extremely rare CTCs from wild-type rats and successful capture of CTCs and CTC clusters before metastasis in the case of tumor-bearing rats. Our research demonstrates for the first time the use of a 3-D scaffold CTC-Net probe for in vivo capture of CTCs. The method shows exceptional performance for cell capture, which is readily implemented and holds great potential in the clinic for early diagnosis of cancer.

An electrochemical biosensor for the detection of epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is critically involved in a variety of biological processes. Electrochemical sensing offers potential to develop more effective technology for EMT detection. In this study, by using the unique performance of quantum dot (QD)-nanocomposite materials, we establish an electrochemical biosensor that can specifically detect the change of E-cadherin and analyze different stages of EMT. The signal for EMT is largely magnified due to the transmission of molecular information to the electronic device. In addition, differential pulse voltammetry reveals that the response of the electrochemical signals is rapid and sensitive, due to the synergistic effect of QDs and carbon nanotube-gold nanoparticles. Our study thus suggests that electrochemical sensing is an effective technology for detecting EMT and may have broad applications in analyzing various cell type transitions.

Magnetic Chip Based Extracorporeal Circulation: A New Tool for Circulating Tumor Cell in Vivo Detection

In vivo detection of circulating tumor cells (CTCs) which inspect all of the circulating blood in body seems to have more advantages on cell capture, especially in earlier cancer diagnosis. Herein, based on in vivo microfluidic chip detection system (IV-chip-system), an extracorporeal circulation was constructed to effectively detect and monitor CTCs in vivo. Combined with microfluidic chip and immunomagnetic nanosphere (IMN), this system not only acts as a window for CTC monitoring but also serves as a collector for further cancer diagnosis and research on CTCs. Compared with the current in vivo detection method, this system can capture and detect CTCs in the bloodstream without any pretreatments, and it also has a higher CTC capture efficiency. It is worth mentioning that this system is stable and biocompatible without any irreversible damage to living animals. Taking use of this system, the mimicked CTC cleanup process in the blood vessel is monitored, which may open new insights in cancer research and early cancer diagnosis.

A platform for primary tumor origin identification of circulating tumor cells via antibody cocktail-based in vivo capture and specific aptamer-based multicolor fluorescence imaging strategy

Circulating tumor cells (CTCs) are expected to serve as a blood-based biomarker in the diagnosis of cancers at an early stage, providing an opportunity to increase the survival of cancer patients. Current techniques for CTC detection were designed for some particular types of cancer with confirmed primary tumor origin. In this work, a platform for the detection of two cancer types and the identification of the primary tumor origin of CTCs was established to meet the requirement of cancer diagnosis and clinical application. A combined strategy based on in vivo capture method using antibody cocktail and multicolor fluorescence imaging using aptamer was designed to achieve the high-efficiency capture of CTCs and the accurate location of the primary tumor. An antibody cocktail of epithelial cell adhesion molecule (EpCAM) and epidermal growth factor receptor (EGFR) was applied to capture breast cancer CTCs and hepatocellular CTCs in vivo. The capture efficiency of hepatocellular CTCs was significantly increased from 3.17% to 26.67% and the capture efficiency of breast cancer CTCs slightly increased from 27.00% to 29.84% compared with EpCAM-based capture of CTCs. Meanwhile, the primary tumor origins of breast cancer CTCs and hepatocellular CTCs were simultaneously distinguished by specific aptamer-based fluorescence probes without any signal crosstalk. The results of in vivo experiments using the dual tumor-bearing mouse model confirmed the feasibility of this method to capture CTCs and identify primary tumor origins. This simple and efficient approach has potential for future applications in cancer diagnosis and prognosis.

Microfluidic technologies for circulating tumor cell isolation

Metastasis is the main cause of tumor-related death, and the dispersal of tumor cells through the circulatory system is a critical step in the metastatic process. Early detection and analysis of circulating tumor cells (CTCs) is therefore important for early diagnosis, prognosis, and effective treatment of cancer, enabling favorable clinical outcomes in cancer patients. Accurate and reliable methods for isolating and detecting CTCs are necessary to obtain this clinical information. Over the past two decades, microfluidic technologies have demonstrated great potential for isolating and detecting CTCs from blood. The present paper reviews current advanced microfluidic technologies for isolating CTCs based on various biological and physical principles, and discusses their fundamental advantages and drawbacks for subsequent cellular and molecular assays. Owing to significant genetic heterogeneity among CTCs, microfluidic technologies for isolating individual CTCs have recently been developed. We discuss these single-cell isolation methods, as well as approaches to overcoming the limitations of current microfluidic CTC isolation technologies. Finally, we provide an overview of future innovative microfluidic platforms.

Current detection technologies for circulating tumor cells

Circulating tumor cells (CTCs) are cancer cells that circulate in the blood stream after being naturally shed from original or metastatic tumors, and can lead to a new fatal metastasis. CTCs have become a hotspot research field during the last decade. Detection of CTCs, as a liquid biopsy of tumors, can be used for early diagnosis of cancers, earlier evaluation of cancer recurrence and chemotherapeutic efficacy, and choice of individual sensitive anti-cancer drugs. Therefore, CTC detection is a crucial tool to fight against cancer. Herein, we classify the currently reported CTC detection technologies, introduce some representative samples for each technology, conclude the advantages and limitations, and give a future perspective including the challenges and opportunities of CTC detection.

Advances in isolation and detection of circulating tumor cells based on microfluidics

Circulating tumor cells (CTCs) are the cancer cells that circulate in the peripheral blood after escaping from the original or metastatic tumors. CTCs could be used as non-invasive source of clinical information in early diagnosis of cancer and evaluation of cancer development. In recent years, CTC research has become a hotspot field wherein many novel CTC detection technologies based on microfluidics have been developed. Great advances have been made that exhibit obvious technical advantages, but cannot yet satisfy the current clinical requirements. In this study, we review the main advances in isolation and detection methods of CTC based on microfluidics research over several years, propose five technical indicators for evaluating these methods, and explore the application prospects. We also discuss the concepts, issues, approaches, advantages, limitations, and challenges with an aim of stimulating a broader interest in developing microfluidics-based CTC detection technology.

Self-Sterilizing and Regeneratable Microchip for the Precise Capture and Recovery of Viable Circulating Tumor Cells from Patients with Cancer

Cancer cells metastasize and are transported in the bloodstream, easily reaching any site in the body through the blood circulation. A method designed to assess the number of circulating tumor cells (CTCs) should be validated as a clinical tool for predicting the response to therapy and monitoring the disease progression in patients with cancer. Although CTCs are detectable in many cases, they remain unavailable for clinic usage because of their high testing cost, tedious operation, and poor clinical relevance. Herein, we developed a regeneratable microchip for isolating CTCs, which is available for robust cell heterogeneity assays on-site without the need for a sterile environment. The ivy-like hierarchical roughened zinc oxide (ZnO) nanograss interface was synthesized and directly integrated into the microfluidic devices and enables effective CTC capture and flexible, nontoxic CTC release during incubation in a mildly acidic solution, thus enabling cellular and molecular analyses. The microchip can be regenerated and recycled to capture CTCs with the remaining ZnO without affecting the efficiency, even after countless cycles of cell release. Moreover, microbial infection is avoided during its storage, distribution, and even in the open space usage, which ideally appeals to the demands of point-of-care (POC) and home testing and meets to the requirements for blood examinations in undeveloped or resource-limited settings. Furthermore, the findings generated using this platform based on the cocktail of antiepithelial cell adhesion molecule and antivimentin antibodies indicate that CTC capture was more precise and reasonable for patients with advanced cancer.

[Current progress in research of circulating tumor cells]

Circulating tumor cells are tumor cells that spontaneously or, following operations, migrate into the peripheral blood circulation from the primary tumor or metastatic tumor. As diagnostic, prognostic and predictive biomarkers in many types of cancers including breast cancer, lung cancer, pancreatic cancer and colorectal cancer, circulating tumor cells contribute to the early diagnosis of cancers, drug resistance monitoring, prognostic assessment, survival analysis, detection of tumor recurrence and evaluation of drug efficacy to assist in treatment decision?making and adjustment of treatment plans. However, the current approaches to the detection of circulating tumor cells still have limitations, and the development of new detection methods with higher sensitivity and specificity will be helpful for better use of these cells. Herein the authors review the research progress in circulating tumor cells in terms of the detection techniques, clinical applications of circulating tumor cells, and their prospects in future clinical practice.

Transferrin-navigation Nano Artificial Antibody Fluorescence Recognition of Circulating Tumor Cells

Specific recognition of circulating tumor cells (CTCs) is of great significance for cancer diagnosis and personalized therapy. The antibodies and aptamer are commonly used for recognition of CTCs, but they often suffer from low stability and high cost. Therefore, chemically stable and low-cost artificial recognition elements are still highly demanded. Herein, we prepared nano artificial antibody based on molecular imprinting and applied for fluorescence recognition of CTCs. Surface imprinting was employed to construct a transferrin (TRA)-imprinted layer on the surface of rhodamine doped silica nanoparticles. Take advantage of the specific interaction between TRA and TRA receptor (overexpressed on cancer cells), the as-prepared TRA-imprinted artificial antibody was allowed for specific targeting cancer cells mediated by TRA. And the average recognition efficiency of the artificial antibody for the cancer cells was 88% through flow cytometry. Finally, the nano artificial antibody was successfully applied to specific identify mimetic CTCs, under the same conditions, the recognition ability of artificial antibody for CTCs was 8 times higher than the white blood cells.

A Novel Pathogen Capturing Device for Removal and Detection

A simple technique that employs an antibody coated polydimethylsiloxane tube is used for effective capturing of bloodborne and foodborne pathogens. By recirculating the entire sample through the antibody coated tube, accumulation of target pathogens is achieved, thereby delivering a higher concentration of pathogens in a small volume. The described method can provide an effective and economical solution to microbiology techniques that rely on enrichment, thereby expediting diagnostics. Using this method 80.3 ± 5.6% of Staphylococcus aureus with a starting concentration of ~10⁷ CFU/mL and 95.4 ± 1.0% of Methicillin-resistant Staphylococcus aureus with starting concentration of ~10⁴ CFU/mL were removed from 5 mL blood in a few hours. This concept was extended to live rats with an induced bloodstream S. aureus infection. A reduction of two orders of magnitude in the bacterial load of the rats was observed within a few hours. The same technique was used to capture a food pathogen, Salmonella typhimurium, with starting concentrations as low as ~10⁰ CFU, from 100 or 250 mL of culture broth within similar timeframes as above. The feasibility for food pathogen testing applications was additionally confirmed by capturing and detecting S. typhimurium in ground chicken and ground beef.

Rhein and polydimethylsiloxane functionalized carbon/carbon composites as prosthetic implants for bone repair applications

A major issue in bone tissue engineering is the selection of biocompatible materials for implants, to reduce unwanted inflammatory reactions and promote cell adhesion. Bone tissue growth on suitable biomedical implants can shorten recovery and hospitalization after surgery. Therefore, a method to improve tissue-implant integration and healing would be of scientific and clinical interest. In this work, we permeated polydimethylsiloxane (PDMS) into carbon/carbon (C/C) composites (PDMS-C/C) and then coated it with 4,5-dihydroxyanthraquinone-2-carboxylic acid (rhein) to create rhein-PDMS-C/C to increase its biocompatibility and reduce the occurrence of inflammatory reactions. We measured in vitro adhesion and proliferation of MC3T3-E1 cells and bacteria to evaluate the biocompatibility and antimicrobial properties of C/C, PDMS-C/C, and rhein-PDMS-C/C. In vivo, x-ray and micro-CT evaluation three, six and nine weeks after surgery revealed that rhein-PDMS-C/C was more effective than PDMS-C/C and C/C composite in terms of antibacterial activity, cell adhesion and tissue growth. Compared with C/C and PDMS-C/C, rhein-PDMS-C/C could be suitable for clinical applications for bone tissue engineering.

Highly Selective Capture Surfaces on Medical Wires for Fishing Tumor Cells in Whole Blood

The detection of circulating tumor cells (CTCs) in the blood of cancer patients is a challenging task. CTCs are, especially at the early stages of cancer development, extremely rare cells hidden in a vast background of regular blood cells. We describe a new strategy for the isolation of CTCs from whole blood. The key component is a medical wire coated with a multilayer assembly that allows highly specific capture of EpCAM (epithelial cell adhesion molecule) positive CTCs from blood. The assembly is generated in a layer-by-layer fashion through photochemically induced C,H insertion reactions and consists of a protective layer, which shields the contacting solution from the metal, a protein resistant layer, which prevents nonspecific interactions with proteins and a layer containing the EpCAM antibodies. In vitro experiments show that these surfaces can capture tumor cells from whole blood with enrichment factors (specifically vs nonspecifically bound cells) of up to about 3000 compared to the number of leucocytes in the blood. The purity of the isolated cells is greater than 90%. After "fishing" them from the blood, the cells, still bound to the wire, can be genetically analyzed. This demonstrates that this strategy might prove useful for next generation sequencing.

The effect of selected food phytochemicals on breast cancer metastasis based on in vivo capture of circulating tumor cells

The number of CTCs revealed dietary factor effects on cancer metastasis using a newin vivoCTC detection method.