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

Colorimetric detection of circulating tumor cells in breast cancer based on ladder-branch hybridization chain reaction and DFs/AuNCs nanozyme

Breast cancer is the most common malignant tumor in women, which accounts for 6.9% of all cancer-related deaths. Early diagnosis is crucial for making the best clinical decision and improving the prognosis of patients. Circulating tumor cells (CTCs) have been regarded as significant tumor biomarkers. Herein, we designed a colorimetric biosensor for breast cancer CTCs quantification based on ladder-branch hybridization chain reaction (HCR) and DNA flowers/gold nanoclusters (DFs/AuNCs) nanozyme. With the assistance of complementary DNA labeled on magnetic beads (MBs), the cleavage products of RNA-cleaving DNAzymes (RCDs) could be rapidly captured, subsequently triggering ladder-branch HCR. In addition, the DFs/AuNCs nanozyme was applied for colorimetric analysis, which further improved the sensitivity for the detection of target CTCs. Benefiting from specific RCDs, ladder-branch HCR and DFs/AuNCs, we achieved a superior detection limit of 3 cells/mL as well as a broad linear range of 10 cells/mL to 104 cells/mL. Conclusively, this colorimetric biosensor achieved sensitively and selectively detection of breast cancer CTCs without the participation of enzymes at room temperature, which might provide new insight into the early detection of breast cancer.

A hydrodynamic-based dual-function microfluidic chip for high throughput discriminating tumor cells

A hydrodynamic-based microfluidic chip consisted of two function units that could not only separate tumor cells (TCs) from whole blood but also remove residual blood cells was designed. The separation of TCs was achieved by a straight contraction-expansion array (CEA) microchannel on the front end of the chip. The addition of contractive structure brought a micro-vortex like Dean vortex that promoted cell focusing in the channel, while when cells entered the dilated region, the wall-induced lift force generated by the channel wall gave cells a push away from the wall. As the wall-induced lift force is proportional to the third power of the cell diameter, TCs with larger diameter will have a larger lateral migration under the wall-induced lift force, realizing the separation of TCs from blood sample. Fluorescent particles with diameters of 19.3 μm and 4.5 μm were used to simulate TCs and red blood cells, respectively, to verify the separation capacity of the proposed CEA microchannel for particles with different diameter. And a separation efficiency 98.7% for 19.3 μm particles and a removal rate 96.2% for 4.5 μm particles was observed at sample flow rate of 10 μL min-1 and sheath flow rate of 190 μL min-1. In addition, a separation efficiency about 96.1% for MCF-7 cells (stained with DiI) and removal rates of 96.2% for red blood cells (RBCs) and 98.7% for white blood cells (WBCs) were also obtained under the same condition. However, on account of the large number of blood cells in the blood, there will be a large number of blood cells remained in the isolated TCs, so a purification unit based on hydrodynamic filtration (HDF) was added after the separation microchannel. The purification channel is a size-dictated cell filter that can remove residual blood cells but retain TCs, thus achieving the purification of TCs. Combined the CEA microchannel and the purifier, the microchip facilitates sorting of MCF-7 cells from whole blood with a separation rate about 95.3% and a removal rate over 99.99% for blood cells at a sample flow rate of 10 μL min-1, sheath flow rate of 190 μL min-1 and washing flow rate of 63 μL min-1.

Genetic and phenotypic profiling of single living circulating tumor cells from patients with microfluidics

Accurate prediction of the efficacy of immunotherapy for cancer patients through the characterization of both genetic and phenotypic heterogeneity in individual patient cells holds great promise in informing targeted treatments, and ultimately in improving care pathways and clinical outcomes. Here, we describe the nanoplatform for interrogating living cell host-gene and (micro-)environment (NICHE) relationships, that integrates micro- and nanofluidics to enable highly efficient capture of circulating tumor cells (CTCs) from blood samples. The platform uses a unique nanopore-enhanced electrodelivery system that efficiently and rapidly integrates stable multichannel fluorescence probes into living CTCs for in situ quantification of target gene expression, while on-chip coculturing of CTCs with immune cells allows for the real-time correlative quantification of their phenotypic heterogeneities in response to immune checkpoint inhibitors (ICI). The NICHE microfluidic device provides a unique ability to perform both gene expression and phenotypic analysis on the same single cells in situ, allowing us to generate a predictive index for screening patients who could benefit from ICI. This index, which simultaneously integrates the heterogeneity of single cellular responses for both gene expression and phenotype, was validated by clinically tracing 80 non-small cell lung cancer patients, demonstrating significantly higher AUC (area under the curve) (0.906) than current clinical reference for immunotherapy prediction.

Pre-analytical conditions and implementation of quality control steps in liquid biopsy analysis

Over the last decade, great advancements have been made in the field of liquid biopsy through extensive research and the development of new technologies that facilitate the use of liquid biopsy for cancer patients. This is shown by the numerous liquid biopsy tests that gained clearance by the US Food and Drug Administration (FDA) in recent years. Liquid biopsy has significantly altered cancer treatment by providing clinicians with powerful and immediate information about therapeutic decisions. However, the clinical integration of liquid biopsy is still challenging and there are many critical factors to consider prior to its implementation into routine clinical practice. Lack of standardization due to technical challenges and the definition of the clinical utility of specific assays further complicates the establishment of Standard Operating Procedures (SOPs) in liquid biopsy. Harmonization of laboratories to established guidelines is of major importance to overcome inter-lab variabilities observed. Quality control assessment in diagnostic laboratories that offer liquid biopsy testing will ensure that clinicians can base their therapeutic decisions on robust results. The regular participation of laboratories in external quality assessment schemes for liquid biopsy testing aims to promptly pinpoint deficiencies and efficiently educate laboratories to improve their quality of services. Accreditation of liquid biopsy diagnostic laboratories based on the ISO15189 standard in Europe or by CLIA/CAP accreditation procedures in the US is the best way to achieve the adaptation of liquid biopsy into the clinical setting by assuring reliable results for the clinicians and their cancer patients. Nowadays, various organizations from academia, industry, and regulatory agencies collaborate to set a framework that will include all procedures from the pre-analytical phase and the analytical process to the final interpretation of results. In this review, we underline several challenges in the analysis of circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) concerning standardization of protocols, quality control assessment, harmonization of laboratories, and compliance to specific guidelines that need to be thoroughly considered before liquid biopsy enters the clinic.

Implantable microfluidics: methods and applications

Implantable microfluidics involves integrating microfluidic functionalities into implantable devices, such as medical implants or bioelectronic devices, revolutionizing healthcare by enabling personalized and precise diagnostics, targeted drug delivery, and regeneration of targeted tissues or organs. The impact of implantable microfluidics depends heavily on advancements in both methods and applications. Despite significant progress in the past two decades, continuous advancements are still required in fluidic control and manipulation, device miniaturization and integration, biosafety considerations, as well as the development of various application scenarios to address a wide range of healthcare issues. In this review, we discuss advancements in implantable microfluidics, focusing on methods and applications. Regarding methods, we discuss progress made in fluid manipulation, device fabrication, and biosafety considerations in implantable microfluidics. In terms of applications, we review advancements in using implantable microfluidics for drug delivery, diagnostics, tissue engineering, and energy harvesting. The purpose of this review is to expand research ideas for the development of novel implantable microfluidic devices for various healthcare applications.

Circulating Tumor Cells as a Promising Tool for Early Detection of Hepatocellular Carcinoma

Liver cancer is a significant contributor to the cancer burden, and its incidence rates have recently increased in almost all countries. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and is the second leading cause of cancer-related deaths worldwide. Because of the late diagnosis and lack of efficient therapeutic modality for advanced stages of HCC, the death rate continues to increase by ~2-3% per year. Circulating tumor cells (CTCs) are promising tools for early diagnosis, precise prognosis, and follow-up of therapeutic responses. They can be considered to be an innovative biomarker for the early detection of tumors and targeted molecular therapy. In this review, we briefly discuss the novel materials and technologies applied for the practical isolation and detection of CTCs in HCC. Also, the clinical value of CTC detection in HCC is highlighted.

Detection and Molecular Characterization of Circulating Tumour Cells: Challenges for the Clinical Setting

Over the last decade, liquid biopsy has gained much attention as a powerful tool in personalized medicine since it enables monitoring cancer evolution and follow-up of cancer patients in real time. Through minimally invasive procedures, liquid biopsy provides important information through the analysis of circulating tumour cells (CTCs) and circulating tumour-derived material, such as circulating tumour DNA (ctDNA), circulating miRNAs (cfmiRNAs) and extracellular vehicles (EVs). CTC analysis has already had an important impact on the prognosis, detection of minimal residual disease (MRD), treatment selection and monitoring of cancer patients. Numerous clinical trials nowadays include a liquid biopsy arm. CTC analysis is now an exponentially expanding field in almost all types of solid cancers. Functional studies, mainly based on CTC-derived cell-lines and CTC-derived explants (CDx), provide important insights into the metastatic process. The purpose of this review is to summarize the latest findings on the clinical significance of CTCs for the management of cancer patients, covering the last four years. This review focuses on providing a comprehensive overview of CTC analysis in breast, prostate and non-small-cell lung cancer. The unique potential of CTC single-cell analysis for understanding metastasis biology, and the importance of quality control and standardization of methodologies used in this field, is also discussed.