Nanostructure embedded microchips for detection, isolation, and characterization of circulating tumor cells

Novel Isolating Approaches to Circulating Tumor Cell Enrichment Based on Microfluidics: A Review

Circulating tumor cells (CTCs), derived from the primary tumor and carrying genetic information, contribute significantly to the process of tumor metastasis. The analysis and detection of CTCs can be used to assess the prognosis and treatment response in patients with tumors, as well as to help study the metastatic mechanisms of tumors and the development of new drugs. Since CTCs are very rare in the blood, it is a challenging problem to enrich CTCs efficiently. In this paper, we provide a comprehensive overview of microfluidics-based enrichment devices for CTCs in recent years. We explore in detail the methods of enrichment based on the physical or biological properties of CTCs; among them, physical properties cover factors such as size, density, and dielectric properties, while biological properties are mainly related to tumor-specific markers on the surface of CTCs. In addition, we provide an in-depth description of the methods for enrichment of single CTCs and illustrate the importance of single CTCs for performing tumor analyses. Future research will focus on aspects such as improving the separation efficiency, reducing costs, and increasing the detection sensitivity and accuracy.

Advances in the role of circulating tumor cell heterogeneity in metastatic small cell lung cancer

Small cell lung cancer (SCLC), a highly aggressive malignancy, is rapidly at an extensive stage once diagnosed and is one of the leading causes of death from malignancy. In the past decade, the treatment of SCLC has largely remained unchanged, and chemotherapy remains the cornerstone of SCLC treatment. The therapeutic value of adding immune checkpoint inhibitors to chemotherapy for SCLC is low, and only a few SCLC patients have shown a response to immune checkpoint inhibitors. Circulating tumor cells (CTCs) are tumor cells shed from solid tumor masses into the peripheral circulation and are key to tumor metastasis. Single-cell sequencing has revealed that the genetic profiles of individual CTCs are highly heterogeneous and contribute to the poor outcome and prognosis of SCLC patients. Theoretically, phenotypic analysis of CTCs may be able to predict the diagnostic significance of new potential targets for metastatic tumors. In this paper, we will discuss in depth the heterogeneity of CTCs in SCLC and the value of CTCs for the diagnosis and prognosis of SCLC and as relevant tumor markers in metastatic SCLC.

Research progress on the multi-omics and survival status of circulating tumor cells

In the dynamic process of metastasis, circulating tumor cells (CTCs) emanate from the primary solid tumor and subsequently acquire the capacity to disengage from the basement membrane, facilitating their infiltration into the vascular system via the interstitial tissue. Given the pivotal role of CTCs in the intricate hematogenous metastasis, they have emerged as an essential resource for a deeper comprehension of cancer metastasis while also serving as a cornerstone for the development of new indicators for early cancer screening and new therapeutic targets. In the epoch of precision medicine, as CTC enrichment and separation technologies continually advance and reach full fruition, the domain of CTC research has transcended the mere straightforward detection and quantification. The rapid advancement of CTC analysis platforms has presented a compelling opportunity for in-depth exploration of CTCs within the bloodstream. Here, we provide an overview of the current status and research significance of multi-omics studies on CTCs, including genomics, transcriptomics, proteomics, and metabolomics. These studies have contributed to uncovering the unique heterogeneity of CTCs and identifying potential metastatic targets as well as specific recognition sites. We also review the impact of various states of CTCs in the bloodstream on their metastatic potential, such as clustered CTCs, interactions with other blood components, and the phenotypic states of CTCs after undergoing epithelial-mesenchymal transition (EMT). Within this context, we also discuss the therapeutic implications and potential of CTCs.

Circulating Tumor Cells: How Far Have We Come with Mining These Seeds of Metastasis?

Circulating tumor cells (CTCs) are cancer cells that slough off from the tumor and circulate in the peripheral blood and lymphatic system as micro metastases that eventually results in macro metastases. Through a simple blood draw, sensitive CTC detection from clinical samples has proven to be a useful tool for determining the prognosis of cancer. Recent technological developments now make it possible to detect CTCs reliably and repeatedly from a simple and straightforward blood test. Multicenter trials to assess the clinical value of CTCs have demonstrated the prognostic value of these cancer cells. Studies on CTCs have filled huge knowledge gap in understanding the process of metastasis since their identification in the late 19th century. However, these rare cancer cells have not been regularly used to tailor precision medicine and or identify novel druggable targets. In this review, we have attempted to summarize the milestones of CTC-based research from the time of identification to molecular characterization. Additionally, the need for a paradigm shift in dissecting these seeds of metastasis and the possible future avenues to improve CTC-based discoveries are also discussed.

Antifouling modification for high-performance isolation of circulating tumor cells

Circulating tumor cells (CTCs), which shed from solid tumor tissue into blood circulatory system, have attracted wide attention as a biomarker in the early diagnosis and prognosis of cancer. Given their potential significance in clinics, many platforms have been developed to separate CTCs. However, the high-performance isolation of CTCs remains significant challenges including achieving the sensitivity and specificity necessary due to their extreme rarity and severe biofouling in blood, such as billions of background cells and various proteins. With the advancement of CTCs detection technologies in recent years, the highly efficient and highly specific detection platforms for CTCs have gradually been developed, resulting in improving CTC capture efficiency, purity and sensitivity. In this review, we systematically describe the current strategies with surface modifications by utilizing the antifouling property of polymer, peptide, protein and cell membrane for high-performance enrichment of CTCs. To wrap up, we discuss the substantial challenges facing by current technologies and the potential directions for future research and development.

Bioorthogonal Microbubbles with Antifouling Nanofilm for Instant and Suspended Enrichment of Circulating Tumor Cells

Integrating clinical rare cell enrichment, culture, and single-cell phenotypic profiling is currently hampered by the lack of competent technologies, which typically suffer from weak cell-interface collision affinity, strong nonspecific adsorption, and the potential uptake. Here, we report cells-on-a-bubble, a bioinspired, self-powered bioorthogonal microbubble (click bubble) that leverages a clickable antifouling nanointerface and a DNA-assembled sucker-like polyvalent cell surface, to enable instant and suspended isolation of circulating tumor cells (CTCs) within minutes. Using this biomimetic engineering strategy, click bubbles achieve a capture efficiency of up to 98%, improved by 20% at 15 times faster over their monovalent counterparts. Further, the buoyancy-activated bubble facilitates self-separation, 3D suspension culture, and in situ phenotyping of the captured single cancer cells. By using a multiantibody design, this fast, affordable micromotor-like click bubble enables suspended enrichment of CTCs in a cohort (n = 42) across three cancer types and treatment response evaluation, signifying its great potential to enable single-cell analysis and 3D organoid culture.

Hierarchical integration of DNA nanostructures and NanoGold onto a microchip facilitates covalent chemistry-mediated purification of circulating tumor cells in head and neck squamous cell carcinoma

It is well-established that the combined use of nanostructured substrates and immunoaffinity agents can enhance the cell-capture performance of the substrates, thus offering a practical solution to effectively capture circulating tumor cells (CTCs) in peripheral blood. Developing along this strategy, this study first demonstrated a top-down approach for the fabrication of tetrahedral DNA nanostructure (TDN)-NanoGold substrates through the hierarchical integration of three functional constituents at various length-scales: a macroscale glass slide, sub-microscale self-organized NanoGold, and nanoscale self-assembled TDN. The TDN-NanoGold substrates were then assembled with microfluidic chaotic mixers to give TDN-NanoGold Click Chips. In conjunction with the use of copper (Cu)-catalyzed azide-alkyne cycloaddition (CuAAC)-mediated CTC capture and restriction enzyme-triggered CTC release, TDN-NanoGold Click Chips allow for effective enumeration and purification of CTCs with intact cell morphologies and preserved molecular integrity. To evaluate the clinical utility of TDN-NanoGold Click Chips, we used these devices to isolate and purify CTCs from patients with human papillomavirus (HPV)-positive (+) head and neck squamous cell carcinoma (HNSCC). The purified HPV(+) HNSCC CTCs were then subjected to RT-ddPCR testing, allowing for detection of E6/E7 oncogenes, the characteristic molecular signatures of HPV(+) HNSCC. We found that the resulting HPV(+) HNSCC CTC counts and E6/E7 transcript copy numbers are correlated with the treatment responses in the patients, suggesting the potential clinical utility of TDN-NanoGold Click Chips for non-invasive diagnostic applications of HPV(+) HNSCC.

Extracellular Vesicles as Biomarkers in Head and Neck Squamous Cell Carcinoma: From Diagnosis to Disease-Free Survival

Head and neck squamous cell carcinomas (HNSCCs) arising from different anatomical sites present with different incidences and characteristics, which requires a personalized treatment strategy. Despite the extensive research that has conducted on this malignancy, HNSCC still has a poor overall survival rate. Many attempts have been made to improve the outcomes, but one of the bottlenecks is thought to be the lack of an effective biomarker with high sensitivity and specificity. Extracellular vesicles (EVs) are secreted by various cells and participate in a great number of intercellular communications. Based on liquid biopsy, EV detection in several biofluids, such as blood, saliva, and urine, has been applied to identify the existence and progression of a variety of cancers. In HNSCC, tumor-derived EVs exhibit many functionalities by transporting diverse cargoes, which highlights their importance in tumor screening, the determination of multidisciplinary therapy, prediction of prognosis, and evaluation of therapeutic effects. This review illustrates the classification and formation of EV subtypes, the cargoes conveyed by these vesicles, and their respective functions in HNSCC cancer biology, and discloses their potential as biomarkers during the whole process of tumor diagnosis, treatment, and follow-up.

High performance isolation of circulating tumor cells by acoustofluidic chip coupled with ultrasonic concentrated energy transducer

The isolation of circulating tumor cells (CTCs) from whole blood is a challenging task. Although various studies on the separation of CTCs by acoustofluidic devices have been reported, difficulties still persist, such as the complicated equipment, high cost, and difficult operation. Those problems should be resolved urgently. Herein, we developed an acoustofluidic chip separation system coupled with an ultrasonic concentrated energy transducer (UCET) system for efficient separation of CTCs. In the separation system, the acoustically sensitive particles were pre-focused by inertial forces of the PDMS chip channel structure. Then, the particles with different sizes were separated by acoustic radiation forces (ARF). In this study, the circulating tumor cells was simulated (CTCs-like particles) by aminated mesoporous acoustically sensitive particles (MSN@AM) encapsulated carboxylate polystyrene microspheres (PS-COOH). Subsequently, efficient CTCs-like particles separation was achieved by the acoustofluidic chip coupling system. This study effectively separated polystyrene microspheres carrying acoustically sensitive particles (MSN@AM@PS-COOH). However, the MSNs agglomerates and PS microspheres without acoustically sensitive particles did not show phenomenon of separation. This method allows to efficiently separate 2 µm MSNs agglomerates，8.0-8.9 µm PS microspheres and 10-10.5 µm MSN@AM@PS-COOH particles. It is demonstrated that the CTCs-like particles show more sensitive response, longer moving distance, and more obvious separation effect at the condition of the low frequency traveling wave sound field (20 kHz from UCET). This system can maintain the same separation with reduced amount of reagents used for cancer detection. It may provide a reliable basis for sorting out CTCs efficiently from the whole blood of cancer patients.

Near-Infrared Light-Responsive Size-Selective Lateral Flow Chip for Single-Cell Manipulation of Circulating Tumor Cells

Accurately obtaining information on the heterogeneity of CTCs at the single-cell level is a very challenging task that may facilitate cancer pathogenesis research and personalized therapy. However, commonly used multicellular population capture and release assays tend to lose effective information on heterogeneity and cannot accurately assess molecular-level studies and drug resistance assessment of CTCs in different stages of tumor metastasis. Herein, we designed a near-infrared (NIR) light-responsive microfluidic chip for biocompatible single-cell manipulation and study the heterogeneity of CTCs by a combination of the lateral flow microarray (LFM) chip and photothermal response system. First, immunomagnetic labeling and a gradient magnetic field were combined to distribute CTCs in different regions of the chip according to the content of surface markers. Subsequently, the LFM chip achieves high single-cell capture efficiency and purity (even as low as 5 CTCs per milliliter of blood) under the influence of lateral fluid and magnetic fields. Due to the rapid dissolution of the gelatin capture structure at 37 °C and the photothermal properties of gold nanorods, the captured single CTC cell can be recovered in large quantities at physiological temperature or released individually at a specific point by NIR. The multifunctional NIR-responsive LFM chip demonstrates excellent performance in capture and site release of CTCs with high viability, which provides a robust and versatile means for CTCs heterogeneity study at the single-cell level.

Isolation, Detection and Analysis of Circulating Tumour Cells: A Nanotechnological Bioscope

Cancer is one of the dreaded diseases to which a sizeable proportion of the population succumbs every year. Despite the tremendous growth of the health sector, spanning diagnostics to treatment, early diagnosis is still in its infancy. In this regard, circulating tumour cells (CTCs) have of late grabbed the attention of researchers in the detection of metastasis and there has been a huge surge in the surrounding research activities. Acting as a biomarker, CTCs prove beneficial in a variety of aspects. Nanomaterial-based strategies have been devised to have a tremendous impact on the early and rapid examination of tumor cells. This review provides a panoramic overview of the different nanotechnological methodologies employed along with the pharmaceutical purview of cancer. Initiating from fundamentals, the recent nanotechnological developments toward the detection, isolation, and analysis of CTCs are comprehensively delineated. The review also includes state-of-the-art implementations of nanotechnological advances in the enumeration of CTCs, along with future challenges and recommendations thereof.

Circulating tumour cells in patients with lung cancer universally indicate poor prognosis

BACKGROUND

In lung cancer, the relevance of various circulating tumour cell (CTC) subgroups in different lung cancer subtypes is unclear. We performed a comprehensive meta-analysis to assess the prognostic value of CTCs in the different histological types of lung cancer, with particular respect to CTC subtypes, cut-offs and time points of CTC enumeration.

METHODS

We searched MEDLINE, Web of Science and Embase alongside relevant studies evaluating the prognostic value of CTCs in lung cancer patients. A random-effects model was used for meta-analysis, calculating hazard ratios (HRs), 95% confidence intervals and p-values.

RESULTS

27 studies enrolling 2957 patients were included. CTC detection indicates poor prognosis, especially in small cell lung cancer (SCLC) patients (overall survival HR 3.11, 95% CI 2.59-3.73) and predicts a worse outcome compared to nonsmall cell lung cancer patients. Epithelial CTCs predict a worse outcome for lung cancer than mesenchymal CTCs or epithelial-mesenchymal hybrids.

CONCLUSION

CTCs indicate poor prognosis in patients with primary lung cancer, with CTCs in SCLC having a more pronounced prognostic effect. The prognostic value of CTCs detected by different markers varies; most evidence is available for the strong negative prognostic effect of epithelial CTCs.

Recent advances in micro-/nanostructure array integrated microfluidic devices for efficient separation of circulating tumor cells

Circulating tumor cells (CTCs) released from the primary tumor to peripheral blood are promising targets for liquid biopsies. Their biological information is vital for early cancer detection, efficacy assessment, and prognostic monitoring. Despite the tremendous clinical applications of CTCs, development of effective separation techniques are still demanding. Traditional separation methods usually use batch processing for enrichment, which inevitably destroy cell integrity and affect the complete information acquisition. Considering the rarity and heterogeneity of CTCs, it is urgent to develop effective separation methods. Microfluidic chips with precise fluid control at the micron level are promising devices for CTC separation. Their further combination with micro-/nanostructure arrays adds more biomolecule binding sites and exhibit unique fluid barrier effect, which significantly improve the CTC capture efficiency, purity, and sensitivity. This review summarized the recent advances in micro-/nanostructure array integrated microfluidic devices for CTC separation, including microrods, nanowires, and 3D micro-/nanostructures. The mechanisms by which these structures contribute to improved capture efficiency are discussed. Two major categories of separation methods, based on the physical and biological properties of CTCs, are discussed separately. Physical separation includes the design and preparation of micro-/nanostructure arrays, while chemical separation additionally involves the selection and modification of specific capture probes. These emerging technologies are expected to become powerful tools for disease diagnosis in the future.

Fabrication of a Polyvalent Aptamer Network on an Electrode Surface for Capture and Analysis of Circulating Tumor Cells

Capture and analysis of circulating tumor cells (CTCs) from complex matrixes is pivotal for the prediction of cancer metastasis and personalized treatment of cancer. Herein, we propose a strategy for CTC capture by design and fabrication of a polyvalent aptamer network on an electrode surface, which can be further used for the sensitive analysis of CTCs. In our design, the polyvalent aptamer network, which is constructed via a rolling circle amplification reaction, can significantly enhance the cell-binding abilities. Meanwhile, tetrahedral DNA structures previously assembled on the electrode surface will promote the spatial orientation and reduce the steric hindrance effect of the cell capture, thus improving the cell capture efficiency. Importantly, a detectable electrochemical signal can be obtained without additional signal probes by means of target-induced allostery of the DNA hairpin structures. Further studies reveal that the electrochemical response is proportional to the logarithm of the CTC abundance ranging from 10² to 5 × 10⁴ cell mL^-1 with a low limit of detection of 23 cell mL^-1. Moreover, the proposed capture strategy exhibits excellent stability and anti-interference in human whole blood, indicating its promising potential in clinical diagnosis.

Detection of circulating tumor cells: opportunities and challenges

Circulating tumor cells (CTCs) are cells that shed from a primary tumor and travel through the bloodstream. Studying the functional and molecular characteristics of CTCs may provide in-depth knowledge regarding highly lethal tumor diseases. Researchers are working to design devices and develop analytical methods that can capture and detect CTCs in whole blood from cancer patients with improved sensitivity and specificity. Techniques using whole blood samples utilize physical prosperity, immunoaffinity or a combination of the above methods and positive and negative enrichment during separation. Further analysis of CTCs is helpful in cancer monitoring, efficacy evaluation and designing of targeted cancer treatment methods. Although many advances have been achieved in the detection and molecular characterization of CTCs, several challenges still exist that limit the current use of this burgeoning diagnostic approach. In this review, a brief summary of the biological characterization of CTCs is presented. We focus on the current existing CTC detection methods and the potential clinical implications and challenges of CTCs. We also put forward our own views regarding the future development direction of CTCs.

Sensitive CTC analysis and dual-mode MRI/FL diagnosis based on a magnetic core-shell aptasensor

Synergizing the sensitive circulating tumor cell (CTC) capture, detection, release and the specific magnetic resonance/fluorescence (MR/FL) imaging for accurate cancer diagnosis is of great importance for cancer treatment. Herein, EcoR1-responsive complementary pairing of two ssDNA with a fluorescent P₀ aptamer, which can specifically bind with the overexpressed MUC1 protein on cancer cells, was covalently modified to SiO₂@C-coated magnetic nanoparticles for preparing a special nanoparticle-mediated FL turn-on aptasensor (FSC-D-P₀). This aptasensor can selectively capture/enrich CTC and thus achieve sensitive CTC detection/imaging in even the blood due to its stable targeting, unique magnetic properties and the regulated interactions between the quencher and the fluorescent groups. Meanwhile, FSC-D-P₀ can release the captured CTC for further downstream analysis upon the EcoR1 enzyme-triggered cleavage of the double-stranded DNA (dsDNA). Most importantly, this aptasensor can distinctly avoid false positivity of MRI via multiple targeting mechanisms. Thus, the sensitive CTC capture, detection, release and accurate MR/FL imaging were synergistically combined into a single platform with good biocompatibility, promising a robust pattern for clinical tumor diagnosis in vitro and in vivo.

Application of Microfluidics in Detection of Circulating Tumor Cells

Tumor metastasis is one of the main causes of cancer incidence and death worldwide. In the process of tumor metastasis, the isolation and analysis of circulating tumor cells (CTCs) plays a crucial role in the early diagnosis and prognosis of cancer patients. Due to the rarity and inherent heterogeneity of CTCs, there is an urgent need for reliable CTCs separation and detection methods in order to obtain valuable information on tumor metastasis and progression from CTCs. Microfluidic technology is increasingly used in various studies of CTCs separation, identification and characterization because of its unique advantages, such as low cost, simple operation, less reagent consumption, miniaturization of the system, rapid detection and accurate control. This paper reviews the research progress of microfluidic technology in CTCs separation and detection in recent years, as well as the potential clinical application of CTCs, looks forward to the application prospect of microfluidic technology in the treatment of tumor metastasis, and briefly discusses the development prospect of microfluidic biosensor.

Discovery and characterization of circulating tumor cell clusters in neuroendocrine tumor patients using nanosubstrate-embedded microchips

Circulating tumor cell (CTC) clusters are present in cancer patients with severe metastasis, resulting in poor clinical outcomes. However, CTC clusters have not been studied as extensively as single CTCs, and the clinical utility of CTC clusters remains largely unknown. In this study, we aim sought to explore the feasibility of NanoVelcro Chips to simultaneously detect both single CTCs and CTC clusters with negligible perturbation to their intrinsic properties in neuroendocrine tumors (NETs). We discovered frequent CTC clusters in patients with advanced NETs and examined their potential roles, together with single NET CTCs, as novel biomarkers of patient response following peptide receptor radionuclide therapy (PRRT). We observed dynamic changes in both total NET CTCs and NET CTC cluster counts in NET patients undergoing PRRT which correlated with clinical outcome. These preliminary findings suggest that CTC clusters, along with single CTCs, offer a potential non-invasive option to monitor the treatment response in NET patients undergoing PRRT.

Microfluidic-Based Technologies for CTC Isolation: A Review of 10 Years of Intense Efforts towards Liquid Biopsy

The selection of circulating tumor cells (CTCs) directly from blood as a real-time liquid biopsy has received increasing attention over the past ten years, and further analysis of these cells may greatly aid in both research and clinical applications. CTC analysis could advance understandings of metastatic cascade, tumor evolution, and patient heterogeneity, as well as drug resistance. Until now, the rarity and heterogeneity of CTCs have been technical challenges to their wider use in clinical studies, but microfluidic-based isolation technologies have emerged as promising tools to address these limitations. This review provides a detailed overview of latest and leading microfluidic devices implemented for CTC isolation. In particular, this study details must-have device performances and highlights the tradeoff between recovery and purity. Finally, the review gives a report of CTC potential clinical applications that can be conducted after CTC isolation. Widespread microfluidic devices, which aim to support liquid-biopsy-based applications, will represent a paradigm shift for cancer clinical care in the near future.

A review of enrichment methods for circulating tumor cells: from single modality to hybrid modality

Circulating tumor cell (CTC) analysis as a liquid biopsy can be used for early diagnosis of cancer, evaluating cancer progression, and assessing treatment efficacy. The enrichment of CTCs from patient blood is important for CTC analysis due to the extreme rarity of CTCs. This paper updates recent advances in CTC enrichment methods. We first review single-modality methods, including biophysical and biochemical methods. Hybrid-modality methods, combining at least two single-modality methods, are gaining increasing popularity for their improved performance. Then this paper reviews hybrid-modality methods, which are categorized into integrated and sequenced hybrid-modality methods. The state of the art indicates that the CTC capture efficiencies of integrated hybrid-modality methods can reach 85% or higher by taking advantage of the superimposed and enhanced capture effects from multiple single-modality methods. Moreover, a hybrid method integrating biophysical with biochemical methods is characterized by both high processing rate and high specificity.

Specific capture and intact release of breast cancer cells using a twin-layer vein-shaped microchip with a self-assembled surface

Breast cancer is the most fatal disease among female cancers yet its detection still relies on needle biopsy. The unique physical and immune characteristics of breast cancer cells different from blood cells make them suitable to be employed as excellent biomarkers in liquid biopsy, through which breast cancer cells are collected from peripheral blood for further cancer diagnosis, medical treatment monitoring, and drug screening. Although the separation and enrichment of breast cancer cells from peripheral blood have been studied for years, there are still two problems to be solved in these methods: the low efficiency of on-chip immunologic capture in the flow state and the influence of the conjugated antibodies for the following analyses during cell release. In this paper, a vein-shaped microchip with self-assembled surface was developed for the specific and robust capture (91.2%) of breast cancer cells in the flow state. A protein-recovery process was proposed, in which trypsin served as a mild release reagent, releasing 92% of cells with high viability (96%), normal adherent proliferation, and complete proteins on the cell membrane, avoiding disturbance of the conjugated chemical molecules in the following clinical study. The excellent performance demonstrated in isolating free breast cancer cells from real peripheral blood sample, originating from the orthotopic 4T1 breast cancer metastatic models, suggest the microchip could be utilized as a multiple circulating tumor cell capture and release platform that could allow providing more reliable information in liquid biopsies.

Reversible capturing and voltammetric determination of circulating tumor cells using two-dimensional nanozyme based on PdMo decorated with gold nanoparticles and aptamer

A novel cytosensor was constructed for the ultrasensitive detection and nondestructive release of circulating tumor cells (CTCs) by combining Au nanoparticles-loaded two-dimensional bimetallic PdMo (2D Au@PdMo) nanozymes and electrochemical reductive desorption. The 2D Au@PdMo nanozymes possessed high-efficiency peroxidase-like activity and were assembled with an aptamer composed of a thiol-modified epithelial specific cell adhesion molecule (EpCAM) to strengthen CTCs adhesion. Moreover, the electrode surface was decorated with highly fractal Au nanostructures (HFAuNSs) composites due to the similarity in fractal nanostructure with the CTCs membrane to enhance the CTCs anchoring efficiency and release capability. The captured CTCs could be further efficiently dissociated and nondestructively released from the modified electrodes upon electrochemical reductive desorption. The designed cytosensor showed an excellent analytical performance, with a wide linear range from 2 to 1 × 10⁵ cells mL^-1 and low limit of detection (LOD) of 2 cells mL^-1 (S/N = 3) at the working potential in the range  -0.6 to 0.2 V. A satisfactory CTCs release reaching a range of 93.7-97.4% with acceptable RSD from 3.55 to 6.41% and good cell viability was obtained. Thus, the developed cytosensor might provide a potential alternative to perform CTC-based liquid biopsies, with promising applications in early diagnosis of tumors. Preparation and mechanism of desorption of the cytosensor based on 2D Au@PdMo nanozymes and electrochemical reductive desorption for the detection and release of CTCs. A Preparation procedure of the Apt/Au@PbMo bioconjugates. B Fabrication process of the sandwich-type cytosensor. C Electrochemical signal produced by the Au@PdMo nanozymes. D Mechanism of electrochemical reductive desorption for CTCs release.

Engineering Peptide-Functionalized Biomimetic Nanointerfaces for Synergetic Capture of Circulating Tumor Cells in an EpCAM-Independent Manner

Broad-spectrum detection and long-term monitoring of circulating tumor cells (CTCs) remain challenging due to the extreme rarity, heterogeneity, and dynamic nature of CTCs. Herein, a dual-affinity nanostructured platform was developed for capturing different subpopulations of CTCs and monitoring CTCs during treatment. Stepwise assembly of fibrous scaffolds, a ligand-exchangeable spacer, and a lysosomal protein transmembrane 4 β (LAPTM4B)-targeting peptide creates biomimetic, stimuli-responsive, and multivalent-binding nanointerfaces, which enable harvest of CTCs directly from whole blood with high yield, purity, and viability. The stable overexpression of the target LAPTM4B protein in CTCs and the enhanced peptide-protein binding facilitate the capture of rare CTCs in patients at an early stage, detection of both epithelial-positive and nonepithelial CTCs, and tracking of therapeutic responses. The reversible release of CTCs allows downstream molecular analysis and identification of specific liver cancer genes. The consistency of the information with clinical diagnosis presents the prospect of this platform for early diagnosis, metastasis prediction, and prognosis assessment.

Ultradense Erythrocyte Bionic Layer Used to Capture Circulating Tumor Cells and Plasma-Assisted High-Purity Release

The isolation and detection of rare circulating tumor cells (CTCs) from patient peripheral blood can help early diagnosis of cancer and evaluation of therapeutic outcomes. At present, most of the available strategies for enriching CTCs face serious problems with purity due to the nonspecific interactions between the capture medium and leukocytes. Inspired by the immune evasion ability of homologous red blood cells (RBCs), we modified the tumor-targeting molecule folic acid (FA) on the surface of RBCs by hydrophobic interactions. Under the treatment of polybrene, the charges on the surface of RBCs are neutralized, which reduces the mutual repulsion force. Furthermore, RBCs treated with polyethylene also have excellent deformability, thereby enabling engineered RBCs to form a dense bionic layer on the adhesive glass slide, which can greatly inhibit the nonspecific adhesion of leukocytes. The bionic layer can achieve high-purity enrichment of tumor cells in phosphate-buffered saline (PBS), and we can achieve high-activity release in plasma. The cell count showed over 80% capture efficiency and over 70% release rate, and the purity of CTCs obtained in the artificial blood sample after release was higher than 90%. The RBC bionic surface coating is notably cost-effective and highly applicable for CTC isolation in clinic practice, and thus provides new prospects for designing cell-material interfaces for advanced cell-based biomedical studies in the future.

Circulating tumor cell profiling for precision oncology

Analysis of circulating tumor cells (CTCs) collected from patient's blood offers a broad range of opportunities in the field of precision oncology. With new advances in profiling technology, it is now possible to demonstrate an association between the molecular profiles of CTCs and tumor response to therapy. In this Review, we discuss mechanisms of tumor resistance to therapy and their link to phenotypic and genotypic properties of CTCs. We summarize key technologies used to isolate and analyze CTCs and discuss recent clinical studies that examined CTCs for genomic and proteomic predictors of responsiveness to therapy. We also point out current limitations that still hamper the implementation of CTCs into clinical practice. We finally reflect on how these shortcomings can be addressed with the likely contribution of multiparametric approaches and advanced data analytics.

A circulating tumor cell-based digital assay for the detection of EGFR T790M mutation in advanced non-small cell lung cancer

Determining the status of epidermal growth factor receptor (EGFR) T790M mutation is crucial for guiding further treatment intervention in advanced non-small cell lung cancer (NSCLC) patients who develop acquired resistance to initial EGFR tyrosine kinase inhibitor (TKI) treatment. Circulating tumor cells (CTCs) which contain plentiful copies of well-preserved RNA offer an ideal source for noninvasive detection of T790M mutation in NSCLC. We developed a CTC-based digital assay which synergistically integrates NanoVelcro Chips for enriching NSCLC CTCs and reverse-transcription droplet digital PCR (RT-ddPCR) for quantifying T790M transcripts in the enriched CTCs. We collected 46 peripheral arterial and venous blood samples from 27 advanced NSCLC patients for testing this CTC-based digital assay. The results showed that the T790M mutational status observed by the CTC-based digital assay matched with those observed by tissue-based diagnostic methods. Furthermore, higher copy numbers of T790M transcripts were observed in peripheral arterial blood than those detected in the matched peripheral venous blood. In short, our results demonstrated the potential of the NanoVelcro CTC-digital assay for noninvasive detection of the T790M mutation in NSCLC, and suggested that peripheral arterial blood sampling may offer a more abundant CTC source than peripheral venous blood in advanced NSCLC patients.

Selective recognition of tumor cells by molecularly imprinted polymers

Molecularly imprinted polymers, developed 50 years ago, have garnered enormous attention as receptor-like materials. Lately, molecularly imprinted polymers have been employed as a specific target tool in favor of cancer diagnosis and therapy by the selective recognition of tumor cells. Although the molecular imprinting technology has been well-innovated recently, the cell still remains the most challenging target for imprinting. In this review, we summarize the advances in the synthesis of molecularly imprinted polymers suitable for the selective recognition of tumor cells. Through a sustained effort, three strategies have been developed including peptide-imprinting, polysaccharide-imprinting, and whole-cell imprinting, which have resulted in inspiring applications in effective cancer diagnosis and therapy. The major challenges and perspectives on the further directions related to the synthesis of molecularly imprinted polymers were also outlined.

Covalent Chemistry-Mediated Multimarker Purification of Circulating Tumor Cells Enables Noninvasive Detection of Molecular Signatures of Hepatocellular Carcinoma

Transcriptomic profiling of tumor tissues introduces a large database, which has led to improvements in the ability of cancer diagnosis, treatment, and prevention. However, performing tumor transcriptomic profiling in the clinical setting is very challenging since the procurement of tumor tissues is inherently limited by invasive sampling procedures. Here, we demonstrated the feasibility of purifying hepatocellular carcinoma (HCC) circulating tumor cells (CTCs) from clinical patient samples with improved molecular integrity using Click Chips in conjunction with a multimarker antibody cocktail. The purified CTCs were then subjected to mRNA profiling by NanoString nCounter platform, targeting 64 HCC-specific genes, which were generated from an integrated data analysis framework with 8 tissue-based prognostic gene signatures from 7 publicly available HCC transcriptomic studies. After bioinformatics analysis and comparison, the HCC CTC-derived gene signatures showed high concordance with HCC tissue-derived gene signatures from TCGA database, suggesting that HCC CTCs purified by Click Chips could enable the translation of HCC tissue molecular profiling into a noninvasive setting.

A Three-Dimensional Conductive Scaffold Microchip for Effective Capture and Recovery of Circulating Tumor Cells with High Purity

Effective acquirement of highly pure circulating tumor cells (CTCs) is very important for CTC-related research. However, it is a great challenge since abundant white blood cells (WBCs) are always co-collected with CTCs because of nonspecific bonding or low depletion rate of WBCs in various CTC isolation platforms. Herein, we designed a three-dimensional (3D) conductive scaffold microchip for highly effective capture and electrochemical release of CTCs with high purity. The conductive 3D scaffold was prepared by dense immobilization of gold nanotubes (Au NTs) on porous polydimethylsiloxane and was functionalized with a CTC-specific biomolecule facilitated by a Au-S bond before embedding into a microfluidic device. The spatially distributed 3D macroporous structure compelled cells to change migration from linear to chaotic and the densely covered Au NTs enhanced the topographic interaction between cells and the substrate, thus synergistically improving the CTC capture efficiency. The Au NT-coated 3D scaffold had good electrical conductivity and the Au-S bond was breakable by voltage exposure so that captured CTCs could be specifically released by electrochemical stimulation while nonspecifically bonded WBCs were not responsive to this process, facilitating recovery of CTCs with high purity. The 3D conductive scaffold microchip was successfully applied to obtain highly pure CTCs from cancer patients' blood, benefiting the downstream analysis of CTCs.

Microfluidics-Based Sensing of Biospecies

Over the past decades, microfluidic devices based on many advanced techniques have aroused widespread attention in the fields of chemical, biological, and analytical applications. Integration of microdevices with a variety of chip designs will facilitate promising functionality. Notably, the combination of microfluidics with functional nanomaterials may provide creative ideas to achieve rapid and sensitive detection of various biospecies. In this review, focused on the microfluids and microdevices in terms of their fabrication, integration, and functions, we summarize the up-to-date developments in microfluidics-based analysis of biospecies, where biomarkers, small molecules, cells, and pathogens as representative biospecies have been explored in-depth. The promising applications of microfluidic biosensors including clinical diagnosis, food safety control, and environmental monitoring are also discussed. This review aims to highlight the importance of microfluidics-based biosensors in achieving high throughput, highly sensitive, and low-cost analysis and to promote microfluidics toward a wider range of applications.

Aptamer-Functionalized Microdevices for Bioanalysis

Aptamers have drawn great attention in the field of biological research and disease diagnosis for the remarkable advantages as recognition elements. They show unique superiority for facile selection, desirable thermal stability, flexible engineering, and low immunogenicity, complementing the use of conventional antibodies. Aptamer-functionalized microdevices offer promising properties for bioanalysis applications because of the compact sizes, minimal reaction volume, high throughput, operational feasibility, and controlled preciseness. In this review, we first introduce the innovative technologies in the selection of aptamers with microdevices and then highlight some advanced applications of aptamer-functionalized microdevices in bioanalysis field for diverse targets. Aptamer-functionalized microfluidic devices, microarrays, and paper-based and other interface-based microdevices are all bioanalysis platforms with huge potential in the near future. Finally, the major challenges of these microdevices applied in bioanalysis are discussed and future perspectives are also envisioned.

Recent Advances in Nano-Bio-Sensing Fabrication Technology for the Detection of Oral Cancer

Nanotechnology-based miniaturized devices have been a breakthrough in the pre-clinical and clinical research areas, e.g. drug delivery, personalized medicine. They have revolutionized the discovery and development of biomarker-based diagnostic devices for detection of various diseases such as tuberculosis, malaria and cancer. Nanomaterials (NMs) hold tremendous diagnostic potential due to their high surface-to-volume ratio and quantum confinement phenomenon, improving the detection limit of clinically relevant biomolecules in bio-fluids. Thus, they are helpful in the translation of bench-on platform to point-of-care (POC) screening device. The nanomaterial-based biosensor fabrication technology has also simplified and improved oral cancer (OC) or oral squamous cell carcinomas (OSCC) diagnosis. The fabrication of nano-bio sensors involves application specific modifications of NMs. The unique properties functionalized NMs have augmented their application on the nano-biosensing platform for the detection of clinically relevant biomolecules in bio-fluids. Therefore, this article summarizes the recent advancements in the process of fabrication of nano-biosensors for detection of OC.

A Reusable Column Method Using Glycopolymer-Functionalized Resins for Capture-Detection of Proteins and Escherichia coli

The use of glycopolymer-functionalized resins (Resin-Glc), as a solid support, in column mode for bacterial/protein capture and quantification is explored. The Resin-Glc is synthesized from commercially available chloromethylated polystyrene resin and glycopolymer, and is characterized by fourier transform infrared spectroscopy, thermogravimetry, and elemental analysis. The percentage of glycopolymer functionalized on Resin-Glc is accounted to be 5 wt%. The ability of Resin-Glc to selectively capture lectin, Concanavalin A, over Peanut Agglutinin, reversibly, is demonstrated for six cycles of experiments. The bacterial sequestration study using SYBR (Synergy Brands, Inc.) Green I tagged Escherichia coli/Staphylococcus aureus reveals the ability of Resin-Glc to selectively capture E. coli over S. aureus. The quantification of captured cells in the column is carried out by enzymatic colorimetric assay using methylumbelliferyl glucuronide as the substrate. The E. coli capture studies reveal a consistent capture efficiency of 10⁵  CFU (Colony Forming Units) g^-1 over six cycles. Studies with spiked tap water samples show satisfactory results for E. coli cell densities ranging from 10² to 10⁷  CFU mL^-1 . The method portrayed can serve as a basis for the development of a reusable solid support in capture and detection of proteins and bacteria.

Recent advances in microfluidic technologies for circulating tumor cells: enrichment, single-cell analysis, and liquid biopsy for clinical applications

Circulating tumor cells (CTCs) detach from primary or metastatic lesions and circulate in the peripheral blood, which is considered to be the cause of distant metastases. CTC analysis in the form of liquid biopsy, enumeration and molecular analysis provide significant clinical information for cancer diagnosis, prognosis and therapeutic strategies. Despite the great clinical value, CTC analysis has not yet entered routine clinical practice due to lack of efficient technologies to perform CTC isolation and single-cell analysis. Taking the rarity and inherent heterogeneity of CTCs into account, reliable methods for CTC isolation and detection are in urgent demand for obtaining valuable information on cancer metastasis and progression from CTCs. Microfluidic technology, featuring microfabricated structures, can precisely control fluids and cells at the micrometer scale, thus making itself a particularly suitable method for rare CTC manipulation. Besides the enrichment function, microfluidic chips can also realize the analysis function by integrating multiple detection technologies. In this review, we have summarized the recent progress in CTC isolation and detection using microfluidic technologies, with special attention to emerging direct enrichment and enumeration in vivo. Further, few insights into single CTC molecular analysis are also demonstrated. We have provided a review of potential clinical applications of CTCs, ranging from early screening and diagnosis, tumor progression and prognosis, treatment and resistance monitoring, to therapeutic evaluation. Through this review, we conclude that the clinical utility of CTCs will be expanded as the isolation and analysis techniques are constantly improving.

Field enhancement in microfluidic semiconductor nanowire array

Nano-material integrated microfluidic platforms are increasingly being considered to accelerate biological sample preparation and molecular diagnostics. A major challenge in this context is the generation of high electric fields for electroporation of cell membranes. In this paper, we have studied a novel mechanism of generating a high electric field in the microfluidic channels by using an array of semiconductor nanowires. When an electrostatic field is applied across a semiconductor nanowire array, the electric field is localized near the nanowires and the field strength is higher than what was reported previously with various other micro-geometries. Nanowires made of ZnO, Si, and Si-SiO₂ and their orientation and array spacing are considered design parameters. It is observed that for a given ratio of the spacing between nanowires to the diameter, the electric field enhancement near the edges of ZnO nanowires is nearly 30 times higher compared to Si or Si-SiO₂ nanowire arrays. This enhancement is a combined effect of the unique geometry with a pointed tip with a hexagonal cross section, the piezoelectric and the spontaneous polarization in the ZnO nanowires, and the electro-kinetics of the interface fluid. Considering the field localization phenomena, the trajectories of E. coli cells in the channel are analyzed. For a given inter-nanowire spacing and an applied electric field, the channels with ZnO nanowire arrays have a greater probability of cell lysis in comparison to Si-based nanowire arrays. Detailed correlations between the cell lysis probability with the inter-nanowire spacing and the applied electric field are reported.

Hepatocellular Carcinoma-Circulating Tumor Cells Expressing PD-L1 Are Prognostic and Potentially Associated With Response to Checkpoint Inhibitors

Hepatocellular carcinoma (HCC) is a leading cause of mortality. Checkpoint inhibitors of programmed cell death protein-1 (PD-1) and programmed death-ligand 1 (PD-L1) have shown great efficacy, but lack biomarkers that predict response. Circulating tumor cells (CTCs) have promise as a liquid-biopsy biomarker; however, data on HCC CTCs expressing PD-L1 have not been reported. We sought to detect PD-L1-expressing HCC-CTCs and investigated their role as a prognostic and predictive biomarker. Using an antibody-based platform, CTCs were enumerated/phenotyped from a prospective cohort of 87 patients with HCC (49 early-stage, 22 locally advanced, and 16 metastatic), 7 patients with cirrhosis, and 8 healthy controls. Immunocytochemistry identified total HCC CTCs (4',6-diamidino-2-phenylindole-positive [DAPI+]/cytokeratin-positive [CK+]/clusters of differentiation 45-negative [CD45-]) and a subpopulation expressing PD-L1 (DAPI+/CK+/PD-L1+/CD45-). PD-L1+ CTCs were identified in 4 of 49 (8.2%) early-stage patients, but 12 of 22 (54.5%) locally advanced and 15 of 16 (93.8%) metastatic patients, accurately discriminating early from locally advanced/metastatic HCC (sensitivity = 71.1%, specificity = 91.8%, area under the receiver operating characteristic curve = 0.807; P < 0.001). Compared to patients without PD-L1+ CTCs, patients with PD-L1+ CTCs had significantly inferior overall survival (OS) (median OS = 14.0 months vs. not reached, hazard ratio [HR] = 4.0, P = 0.001). PD-L1+ CTCs remained an independent predictor of OS (HR = 3.22, P = 0.010) even after controlling for Model for End-Stage Liver Disease score (HR = 1.14, P < 0.001), alpha-fetoprotein (HR = 1.55, P < 0.001), and overall stage/tumor burden (beyond University of California, San Francisco, HR = 7.19, P < 0.001). In the subset of 10 patients with HCC receiving PD-1 blockade, all 5 responders demonstrated PD-L1+ CTCs at baseline, compared with only 1 of 5 nonresponders, all of whom progressed within 4 months of starting treatment. Conclusion: We report a CTC assay for the phenotypic profiling of HCC CTCs expressing PD-L1. PD-L1+ CTCs are predominantly found in advanced-stage HCC, and independently prognosticate OS after controlling for Model for End-Stage Liver Disease, alpha-fetoprotein, and tumor stage. In patients with HCC receiving anti-PD-1 therapy, there was a strong association with the presence of PD-L1+ CTCs and favorable treatment response. Prospective validation in a larger cohort will better define the utility of PD-L1+ CTCs as a prognostic and predictive biomarker in HCC.

Direct Analysis of Rare Circulating Tumor Cells in Whole Blood Based on Their Controlled Capture and Release on Electrode Surface

The development of a simple, sensitive, and effective method for the analysis of circulating tumor cells (CTCs) is essential for cancer diagnosis and metastasis prediction. In this work, we have proposed an enzyme-free electrochemical method for specific capture, sensitive quantification, and efficient release of CTCs. To achieve this, the specific interaction between CTCs and the corresponding aptamer designed to be located in the identification probe (IP) will unfold the hairpin structure of IP. Consequently, IP will initiate a hybridization reaction to produce a duplex, which will further trigger the hybridization chain reaction (HCR) process to form a composite product of CTCs and double-stranded DNA polymers. Therefore, a significantly amplified signal readout can be obtained. Moreover, the composite product can be brought to the electrode surface by tetrahedral DNA nanostructures to achieve the purpose of capturing and quantifying CTCs. More significantly, these captured CTCs can be controlled released without compromising cell viability via a simple strand displacement reaction. Taking the breast cancer cell MCF-7 as a representative, the newly developed approach led to an ultralow detection limit of 3 cells mL^-1, which is superior to several studies previously reported. The current method has also been demonstrated to analyze CTCs in human whole blood and hence revealed a great potential in the future.

Future directions and management of liquid biopsy in non-small cell lung cancer

Lung cancer represents the world’s most common cause of cancer death. In recent years, we moved from a generic therapeutic strategy to a personalized approach, based on the molecular characterization of the tumor. In this view, liquid biopsy is becoming an important tool for assessing the progress or onset of lung disease. Liquid biopsy is a non-invasive procedure able to isolate circulating tumor cells, tumor educated platelets, exosomes and free circulating tumor DNA from body fluids. The characterization of these liquid biomarkers can help to choose the therapeutic strategy for each different case. In this review, the authors will analyze the main aspects of lung cancer and the applications currently in use focusing on the benefits associated with this approach for predicting the prognosis and monitoring the clinical conditions of lung cancer disease.

Nanotechnology-Assisted Isolation and Analysis of Circulating Tumor Cells on Microfluidic Devices

Circulating tumor cells (CTCs), a type of cancer cell that spreads from primary tumors into human peripheral blood and are considered as a new biomarker of cancer liquid biopsy. It provides the direction for understanding the biology of cancer metastasis and progression. Isolation and analysis of CTCs offer the possibility for early cancer detection and dynamic prognosis monitoring. The extremely low quantity and high heterogeneity of CTCs are the major challenges for the application of CTCs in liquid biopsy. There have been significant research endeavors to develop efficient and reliable approaches to CTC isolation and analysis in the past few decades. With the advancement of microfabrication and nanomaterials, a variety of approaches have now emerged for CTC isolation and analysis on microfluidic platforms combined with nanotechnology. These new approaches show advantages in terms of cell capture efficiency, purity, detection sensitivity and specificity. This review focuses on recent progress in the field of nanotechnology-assisted microfluidics for CTC isolation and detection. Firstly, CTC isolation approaches using nanomaterial-based microfluidic devices are summarized and discussed. The different strategies for CTC release from the devices are specifically outlined. In addition, existing nanotechnology-assisted methods for CTC downstream analysis are summarized. Some perspectives are discussed on the challenges of current methods for CTC studies and promising research directions.

Prospects and Opportunities for Microsystems and Microfluidic Devices in the Field of Otorhinolaryngology

Microfluidic systems can be used to control picoliter to microliter volumes in ways not possible with other methods of fluid handling. In recent years, the field of microfluidics has grown rapidly, with microfluidic devices offering possibilities to impact biology and medicine. Microfluidic devices populated with human cells have the potential to mimic the physiological functions of tissues and organs in a three-dimensional microenvironment and enable the study of mechanisms of human diseases, drug discovery and the practice of personalized medicine. In the field of otorhinolaryngology, various types of microfluidic systems have already been introduced to study organ physiology, diagnose diseases, and evaluate therapeutic efficacy. Therefore, microfluidic technologies can be implemented at all levels of otorhinolaryngology. This review is intended to promote understanding of microfluidic properties and introduce the recent literature on application of microfluidic-related devices in the field of otorhinolaryngology.

Vertical nanowire array-based biosensors: device design strategies and biomedical applications

Biosensors have been extensively studied in the areas of biology, electronics, chemistry, biotechnology, medicine, and various engineering fields. The interdisciplinarity creates an ideal platform for scientists to analyze biological species and chemical materials in a direct, efficient, and sensitive manner; this is expected to revolutionize the life sciences, basic medicine, and the healthcare industry. To carry out high-performance biosensing, nanoprobes - with specific nanoscale properties - have been proposed for ultrasensitive and in situ monitoring/detection of tracer biomolecules, cellular behavior, cellular microenvironments, and electrophysiological activity. Here, we review the development of vertical nanowire (VNW) array-based devices for the effective collection of biomedical information at the molecular level, extracellular level, and intracellular level. In particular, we summarize VNW-based technologies in the aspects of detecting biochemical information, cellular information, and bioelectrical information, all of which facilitate the understanding of fundamental biology and development of therapeutic techniques. Finally, we present a conclusion and prospects for the development of VNW platforms in practical biomedical applications, and we identify the challenges and opportunities for VNW-based biosensor systems in future biological research.

Somatic copy number profiling from hepatocellular carcinoma circulating tumor cells

Somatic copy number alterations (SCNAs) are important genetic drivers of many cancers. We investigated the feasibility of obtaining SCNA profiles from circulating tumor cells (CTCs) as a molecular liquid biopsy for hepatocellular carcinoma (HCC). CTCs from ten HCC patients underwent SCNA profiling. The Cancer Genome Atlas (TCGA) SCNA data were used to develop a cancer origin classification model, which was then evaluated for classifying 44 CTCs from multiple cancer types. Sequencing of 18 CTC samples (median: 4 CTCs/sample) from 10 HCC patients using a low-resolution whole-genome sequencing strategy (median: 0.88 million reads/sample) revealed frequent SCNAs in previously reported HCC regions such as 8q amplifications and 17p deletions. SCNA profiling revealed that CTCs share a median of 80% concordance with the primary tumor. CTCs had SCNAs not seen in the primary tumor, some with prognostic implications. Using a SCNA profiling model, the tissue of origin was correctly identified for 32/44 (73%) CTCs from 12/16 (75%) patients with different cancer types.

Recent Advances in Cancer Plasticity: Cellular Mechanisms, Surveillance Strategies, and Therapeutic Optimization

The processes of recurrence and metastasis, through which cancer relapses locally or spreads to distant sites in the body, accounts for more than 90% of cancer-related deaths. At present there are very few treatment options for patients at this stage of their disease. The main obstacle to successfully treat advanced cancer is the cells' ability to change in ways that make them resistant to treatment. Understanding the cellular mechanisms that mediate this cancer cell plasticity may lead to improved patient survival. Epigenetic reprogramming, together with tumor microenvironment, drives such dynamic mechanisms favoring tumor heterogeneity, and cancer cell plasticity. In addition, the development of new approaches that can report on cancer plasticity in their native environment have profound implications for studying cancer biology and monitoring tumor progression. We herein provide an overview of recent advancements in understanding the mechanisms regulating cell plasticity and current strategies for their monitoring and therapy management.

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.