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

Deciphering cellular complexity: advances and future directions in single-cell protein analysis

Single-cell protein analysis has emerged as a powerful tool for understanding cellular heterogeneity and deciphering the complex mechanisms governing cellular function and fate. This review provides a comprehensive examination of the latest methodologies, including sophisticated cell isolation techniques (Fluorescence-Activated Cell Sorting (FACS), Magnetic-Activated Cell Sorting (MACS), Laser Capture Microdissection (LCM), manual cell picking, and microfluidics) and advanced approaches for protein profiling and protein-protein interaction analysis. The unique strengths, limitations, and opportunities of each method are discussed, along with their contributions to unraveling gene regulatory networks, cellular states, and disease mechanisms. The importance of data analysis and computational methods in extracting meaningful biological insights from the complex data generated by these technologies is also highlighted. By discussing recent progress, technological innovations, and potential future directions, this review emphasizes the critical role of single-cell protein analysis in advancing life science research and its promising applications in precision medicine, biomarker discovery, and targeted therapeutics. Deciphering cellular complexity at the single-cell level holds immense potential for transforming our understanding of biological processes and ultimately improving human health.

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.

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

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

Value of peripheral blood circulating tumor cell detection in the diagnosis of thoracic diseases and the prediction of severity

Circulating tumor cell (CTC) detection, as a noninvasive liquid biopsy method, has been used in the diagnosis, prognostic indication, and monitoring of a variety of cancers. In this study, we aimed to investigate whether CTC detection could be used in the early diagnosis and prediction of severity of thoracic diseases. We enrolled 168 thoracic disease patients, all of whom underwent pathological biopsy. Carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) measurement was also performed in 146 patients. There were 131 cases of malignant thoracic diseases and 37 cases of benign lesions. We detected CTCs in a 5 ml peripheral blood sample with the CTCBiopsy® system and analyzed the value of CTC count for predicting disease severity. Of 131 patients with a diagnosis of thoracic malignancy, CTCs were found in blood samples from 122 patients. However, only 2 out of 37 patients with benign thoracic disease had no detectable CTCs. There was no significant correlation between CTC count and benign and malignant lesions (P = 0.986). However, among 131 patients who had been diagnosed with malignant lesions, 33 had lymph node metastasis or distant metastasis. The presence of CTCs was significantly correlated with metastasis (P = 0.016 OR = 1.14). The area under the receiver operating characteristic (ROC) curve was 0.625 (95% confidence interval (CI), 0.519 to 0.730 P = 0.032). In addition, with stage IA1 as the cutoff, all patients were further divided into an early-stage group and a late-stage group. CTC count was significantly correlated with disease progression (P = 0.031 OR = 1.11), with an area under the curve (AUC) of 0.599 (95% CI, 0.506-0.692 P = 0.47). The sensitivity and specificity of CTC detection for the diagnosis of disease stage were 72.3% and 45.5%, respectively. In addition, the cutoff of 2.5 CTCs was the same when predicting disease metastasis and staging. Furthermore, the combination of CTC count, demographic characteristics and tumor markers had better predictive significance for disease staging. CTC count can effectively indicate the stages and metastasis of thoracic diseases, but it cannot differentiate benign and malignant diseases.

Microfluidic systems for particle capture and release: A review

Microfluidic technology has emerged as a promising tool in various applications, including biosensing, disease diagnosis, and environmental monitoring. One of the notable features of microfluidic devices is their ability to selectively capture and release specific cells, biomolecules, bacteria, and particles. Compared to traditional bulk analysis instruments, microfluidic capture-and-release platforms offer several advantages, such as contactless operation, label-free detection, high accuracy, good sensitivity, and minimal reagent requirements. However, despite significant efforts dedicated to developing innovative capture mechanisms in the past, the release and recovery efficiency of trapped particles have often been overlooked. Many previous studies have focused primarily on particle capture techniques and their efficiency, disregarding the crucial role of successful particle release for subsequent analysis. In reality, the ability to effectively release trapped particles is particularly essential to ensure ongoing, high-throughput analysis. To address this gap, this review aims to highlight the importance of both capture and release mechanisms in microfluidic systems and assess their effectiveness. The methods are classified into two categories: those based on physical principles and those using biochemical approaches. Furthermore, the review offers a comprehensive summary of recent applications of microfluidic platforms specifically designed for particle capture and release. It outlines the designs and performance of these devices, highlighting their advantages and limitations in various target applications and purposes. Finally, the review concludes with discussions on the current challenges faced in the field and presents potential future directions.

An integrated microfluidic chip for alginate microsphere generation and 3D cell culture

Three-dimensional (3D) hydrogel microspheres have attracted increasing attention as cell culture carriers. The system of hydrogel microspheres provides great advantages for cell growth owing to its high surface-to-volume ratio and biocompatible environment. However, an integrated system that includes microsphere generation, microsphere capture and in situ culture together has not been realized yet. Here we present a multifunctional microfluidic device to accomplish the overall process including cell-laden microsphere generation, online demulsification and dynamic-culture. The microfluidic device can produce massive monodispersed alginate microspheres and allows us to immobilize the alginate microspheres and record bacterial growth. Moreover, the microspheres provide a suitable environment through the mechanical properties of soft tissues, leading to high cell viability, proliferation, activity and biocompatibility. We believe that this versatile and biocompatible platform will provide a more reliable analysis tool for tissue engineering and cell therapy.

Advanced Devices for Tumor Diagnosis and Therapy

At present, tumor diagnosis is performed using common procedures, which are slow, costly, and still presenting difficulties in diagnosing tumors at their early stage. Tumor therapeutic methods also mainly rely on large-scale equipment or non-intelligent treatment approaches. Thus, an early and accurate tumor diagnosis and personalized treatment may represent the best treatment option for a successful result, and the efforts in finding them are still in progress and mainly focusing on non-destructive, integrated, and multiple technologies. These objectives can be achieved with the development of advanced devices and smart technology that represent the topic of the current investigations. Therefore, this review summarizes the progress in tumor diagnosis and therapy and briefly explains the advantages and disadvantages of the described microdevices, finally proposing advanced micro smart devices as the future development trend for tumor diagnosis and therapy.

Computational and experimental studies of a cell-imprinted-based integrated microfluidic device for biomedical applications

It has been proved that cell-imprinted substrates molded from template cells can be used for the re-culture of that cell while preserving its normal behavior or to differentiate the cultured stem cells into the template cell. In this study, a microfluidic device was presented to modify the previous irregular cell-imprinted substrate and increase imprinting efficiency by regular and objective cell culture. First, a cell-imprinted substrate from template cells was prepared using a microfluidic chip in a regular pattern. Another microfluidic chip with the same pattern was then aligned on the cell-imprinted substrate to create a chondrocyte-imprinted-based integrated microfluidic device. Computational fluid dynamics (CFD) simulations were used to obtain suitable conditions for injecting cells into the microfluidic chip before performing experimental evaluations. In this simulation, the effect of input flow rate, number per unit volume, and size of injected cells in two different chip sizes were examined on exerted shear stress and cell trajectories. This numerical simulation was first validated with experiments with cell lines. Finally, chondrocyte was used as template cell to evaluate the chondrogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) in the chondrocyte-imprinted-based integrated microfluidic device. ADSCs were positioned precisely on the chondrocyte patterns, and without using any chemical growth factor, their fibroblast-like morphology was modified to the spherical morphology of chondrocytes after 14 days of culture. Both immunostaining and gene expression analysis showed improvement in chondrogenic differentiation compared to traditional imprinting methods. This study demonstrated the effectiveness of cell-imprinted-based integrated microfluidic devices for biomedical applications.

Immunomagnetic separation of circulating tumor cells with microfluidic chips and their clinical applications

Circulating tumor cells (CTCs) are tumor cells detached from the original lesion and getting into the blood and lymphatic circulation systems. They potentially establish new tumors in remote areas, namely, metastasis. Isolation of CTCs and following biological molecular analysis facilitate investigating cancer and coming out treatment. Since CTCs carry important information on the primary tumor, they are vital in exploring the mechanism of cancer, metastasis, and diagnosis. However, CTCs are very difficult to separate due to their extreme heterogeneity and rarity in blood. Recently, advanced technologies, such as nanosurfaces, quantum dots, and Raman spectroscopy, have been integrated with microfluidic chips. These achievements enable the next generation isolation technologies and subsequent biological analysis of CTCs. In this review, we summarize CTCs' separation with microfluidic chips based on the principle of immunomagnetic isolation of CTCs. Fundamental insights, clinical applications, and potential future directions are discussed.

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.

Magnetic nanoparticles in nanomedicine: a review of recent advances

Nanomaterials, in addition to their small size, possess unique physicochemical properties that differ from bulk materials, making them ideal for a host of novel applications. Magnetic nanoparticles (MNPs) are one important class of nanomaterials that have been widely studied for their potential applications in nanomedicine. Due to the fact that MNPs can be detected and manipulated by remote magnetic fields, it opens a wide opportunity for them to be used in vivo. Nowadays, MNPs have been used for diverse applications including magnetic biosensing (diagnostics), magnetic imaging, magnetic separation, drug and gene delivery, and hyperthermia therapy, etc. Specifically, we reviewed some emerging techniques in magnetic diagnostics such as magnetoresistive (MR) and micro-Hall (μHall) biosensors, as well as the magnetic particle spectroscopy, magnetic relaxation switching and surface enhanced Raman spectroscopy (SERS)-based bioassays. Recent advances in applying MNPs as contrast agents in magnetic resonance imaging and as tracer materials in magnetic particle imaging are reviewed. In addition, the development of high magnetic moment MNPs with proper surface functionalization has progressed exponentially over the past decade. To this end, different MNP synthesis approaches and surface coating strategies are reviewed and the biocompatibility and toxicity of surface functionalized MNP nanocomposites are also discussed. Herein, we are aiming to provide a comprehensive assessment of the state-of-the-art biological and biomedical applications of MNPs. This review is not only to provide in-depth insights into the different synthesis, biofunctionalization, biosensing, imaging, and therapy methods but also to give an overview of limitations and possibilities of each technology.

Dynamic Halbach array magnet integrated microfluidic system for the continuous-flow separation of rare tumor cells

Circulating tumor cells (CTCs), the most representative rare cells in peripheral blood, have received great attention due to their clinical utility in liquid biopsy. The downstream analysis of intact CTCs isolated from peripheral blood provides important clinical information for personalized medicine. However, current CTC isolation and detection methods have been challenged by their extreme rarity and heterogeneity. In this study, we developed a novel microfluidic system with a continuously moving Halbach array magnet (dHAMI microfluidic system) for negative isolation CTCs from whole blood, which aimed to capture non-target white blood cells (WBCs) and elute target CTCs. The dynamic and continuous movement of the Halbach array magnet generated a continuous magnetic force acting on the magnetic bead-labelled WBCs in the continuous-flow fluid to negatively exclude the WBCs from the CTCs. Furthermore, the continuously moving magnetic field effectively eliminated the effect of magnetic bead aggregation on the fluid flow to realize the continuous-flow separation of the CTCs without a sample loading volume limitation. The experimental procedure for CTC negative isolation using the dHAMI microfluidic system could be completed within 40 min. Under the optimized experimental conditions of the dHAMI microfluidic system, including the flow rate and concentration of the immunomagnetic bead, the average CTC capture rate over a range of spiked cell numbers (50–1000 cancer cells per mL) was up to 91.6% at a flow rate of 100 μL min⁻¹. Finally, the CTCs were successfully detected in 10 of 10 (100%) blood samples from patients with cancer. Therefore, the dHAMI microfluidic system could effectively isolate intact and heterogeneous CTCs for downstream cellular and molecular analyses, and this robust microfluidic platform with an excellent magnetic manipulation performance also has great application potential for the separation of other rare cells.

We develop a dynamic Halbach array magnet integrated microfluidic system for continuous-flow separation of circulating tumor cells from whole blood.

An Integrated Microfluidic Chip and Its Clinical Application for Circulating Tumor Cell Isolation and Single-Cell Analysis

Circulating tumor cells (CTCs) represent invasive tumor cell populations and provide a noninvasive solution to the clinical management and research of tumors. Characterization of CTCs at single-cell resolution enables the comprehensive understanding of tumor heterogeneity and may benefit the diagnosis and treatment of cancer patients. However, most efforts have been made on enumeration and detection of CTCs, while little focus has been directed to single-cell study. Herein, an integrated microfluidic platform for single-cell isolation and analysis was established. After validating this platform on lung cancer cell lines, we detected and isolated single CTCs from the peripheral blood samples of 20 cancer patients before and after one treatment cycle. Furthermore, we performed single-cell whole-exome DNA sequencing on a single CTC from the peripheral blood sample of a representative early stage lung cancer patient. Among the blood samples of 20 patients, 15 of them were positive for CTC detection (75.0% detectable rate). Single-cell analysis revealed detailed genetic variations of the CTC, while six new gene mutations were detected in both single CTC and surgical specimen. This study provides a useful tool for the isolation and analysis of single CTCs from peripheral blood samples, which not only facilitates the early diagnosis of cancers but also helps to unravel the genetic information of tumor at a single-cell level. © 2019 International Society for Advancement of Cytometry.