Capture Of Rare Cells Research Articles

Spatially Controlled DNA Frameworks for Sensitive Detection and Specific Isolation of Tumor Cells.

High-affinity, specific, and sensitive probes are crucial for the specific recognition and identification of tumor cells from complex matrices. Multivalent binding is a powerful strategy, but the irrational spatial distribution of the functional moieties may reduce the probe performance. Here, we constructed a Janus DNA triangular prism nanostructure (3Zy1-JTP-3) for sensitive detection and specific isolation of tumor cells. Benefiting from spatial features of the triangular prism, the fluorescence intensity induced by 3Zy1-JTP-3 was almost 4 times that of the monovalent structure. Moreover, the DNA triangular prisms were connected to form hand-in-hand multivalent DNA triangular prism structures (Zy1-MTP), in which the fluorescence intensity and affinity were increased to 9-fold and 10-fold of 3Zy1-JTP-3, respectively. Furthermore, 3Zy1-JTP-3 and Zy1-MTP were combined with magnetic beads, and the latter showed higher capture efficiency (> 90%) in whole blood. This work provides a new strategy for the efficient capture of rare cells in complex biological samples.

Spatially Controlled DNA Frameworks for Sensitive Detection and Specific Isolation of Tumor Cells

High‐affinity, specific, and sensitive probes are crucial for the specific recognition and identification of tumor cells from complex matrices. Multivalent binding is a powerful strategy, but the irrational spatial distribution of the functional moieties may reduce the probe performance. Here, we constructed a Janus DNA triangular prism nanostructure (3Zy1‐JTP‐3) for sensitive detection and specific isolation of tumor cells. Benefiting from spatial features of the triangular prism, the fluorescence intensity induced by 3Zy1‐JTP‐3 was almost 4 times that of the monovalent structure. Moreover, the DNA triangular prisms were connected to form hand‐in‐hand multivalent DNA triangular prism structures (Zy1‐MTP), in which the fluorescence intensity and affinity were increased to 9‐fold and 10‐fold of 3Zy1‐JTP‐3, respectively. Furthermore, 3Zy1‐JTP‐3 and Zy1‐MTP were combined with magnetic beads, and the latter showed higher capture efficiency (> 90%) in whole blood. This work provides a new strategy for the efficient capture of rare cells in complex biological samples.

Prognostic value of cerebrospinal fluid tumor cell count in leptomeningeal disease from solid tumors.

Treatment decisions for leptomeningeal disease (LMD) rely on patient risk stratification, since clinicians lack objective prognostic tools. The introduction of rare cell capture technology for identification of cerebrospinal fluid tumor cells (CSF-TCs), such as CNSide assay, improved the sensitivity of LMD diagnosis, but prognostic value is unknown. This study assesses the prognostic value of CSF-TC density in patients with LMD from solid tumors. We conducted a retrospective cohort study of patients with newly diagnosed or previously treated LMD from a single institution who had CNSide assay testing for CSF-TCs from 2020 to 2023. Univariable and multivariable survival analyses were conducted with Cox proportional-hazards modeling. Maximally-selected rank statistics were used to determine an optimal cutpoint for CSF-TC density and survival. Of 31 patients, 29 had CSF-TCs detected on CNSide. Median (interquartile range [IQR]) CSF-TC density was 67.8 (4.7-639) TCs/mL. CSF cytology was positive in 16 of 29 patients with positive CNSide (CNSide diagnostic sensitivity = 93.5%, negative predictive value = 85.7%). Median (IQR) survival from time of CSF-TC detection was 176 (89-481) days. On univariable and multivariable analysis, CSF-TC density was significantly associated with survival. An optimal cutpoint for dichotomizing survival by CSF-TC density was 19.34 TCs/mL. The time-dependent sensitivity and specificity for survival using this stratification were 76% and 67% at 6 months and 65% and 67% at 1 year, respectively. CSF-TC density may carry prognostic value in patients with LMD from solid tumors. Integrating CSF-TC density into LMD patient risk-stratification may help guide treatment decisions.

Numerical Studies on the Motions of Magnetically Tagged Cells Driven by a Micromagnetic Matrix.

Precisely controlling magnetically tagged cells in a complex environment is crucial to constructing a magneto-microfluidic platform. We propose a two-dimensional model for capturing magnetic beads from non-magnetic fluids under a micromagnetic matrix. A qualitative description of the relationship between the capture trajectory and the micromagnetic matrix with an alternating polarity configuration was obtained by computing the force curve of the magnetic particles. Three stages comprise the capture process: the first, where motion is a parabolic fall in weak fields; the second, where the motion becomes unpredictable due to the competition between gravity and magnetic force; and the third, where the micromagnetic matrix finally captures cells. Since it is not always obvious how many particles are adhered to the surface, attachment density is utilized to illustrate how the quantity of particles influences the capture path. The longitudinal magnetic load is calculated to measure the acquisition efficiency. The optimal adhesion density is 13%, and the maximum adhesion density is 18%. It has been demonstrated that a magnetic ring model with 100% adhesion density can impede the capture process. The results offer a theoretical foundation for enhancing the effectiveness of rare cell capture in practical applications.

High-porosity thin membrane for high-efficiency capture of rare cells

High efficiency capture of rare cells such as circulating tumor cells (CTCs) in the blood of cancer-patient is challenging for size-based separation methods, because of the heterogeneity of the cells, the presence of a huge number of background cells (red and white blood cells), and the overlap in size of the rare cells and some of the background cells. In this work, we developed a systematic study to evaluate the parametric dependence of rare cell capture efficiency by using model cells. High-porosity and thin membranes with supporting honeycomb microframe are fabricated by using a two-level lithography technique. They are then integrated into a microfluidic device for real-time monitoring of flow-induced transmembrane pressure with a solution with or without cells. Our results show both experimentally and theoretically a great importance of the pore number of the membrane and the flow rate. When more than 80% of pores are clogged by large background cells, the rare cell capture efficiency decreases significantly. Otherwise, a lossless capture is theoretically achievable with a high-porosity and large-area membrane under optimal flow conditions.

Bioinspired nano-plate-coral platform enabled efficient detection of circulating tumor cells via the synergistic capture of multivalent aptamer and tumor cell membrane

Circulating tumor cells (CTCs) offer rich information for early disease diagnosis and therapy evaluation. However, the limited sensitivity, binding affinity, and stability of current monovalent recognition-based CTCs detection techniques remain a challenge for extending their applications. Inspired by the highly efficient predation manner of plate corals, we firstly introduce an efficient and sensitive biomimetic CTCs recognition platform based on the conjugation of multivalent aptamer onto tumor cell membrane-coated magnetic graphene oxide to form a plate coral-like CTCs capture nanoprobe (MNPA-TCMMGO). In this method, the tumor cell membrane was employed to provide a biomimetic homologous fluidic interface for targeting homologous tumor cells. At the same time, multivalent aptamers were used as capture probes, which greatly enhanced the binding affinity and association probability between aptamer and target cells via cooperative multivalent effect. The unique features (robustness, high binding affinity and specificity, and biocompatibility) of MNPA-TCMMGO allow efficient, sensitive, and specific capture of rare tumor cells from biological samples. More importantly, the captured cells could maintain good viability, which is crucial for downstream analysis. Therefore, our developed biomimetic approach offers a new way to address the limitations of current CTCs detection methods and presents considerable potential for clinical cancer diagnostics.

Integration of Single-Cell Transcriptomics With a High Throughput Functional Screening Assay to Resolve Cell Type, Growth Kinetics, and Stemness Heterogeneity Within the Comma-1D Cell Line.

Cell lines are one of the most frequently implemented model systems in life sciences research as they provide reproducible high throughput testing. Differentiation of cell cultures varies by line and, in some cases, can result in functional modifications within a population. Although research is increasingly dependent on these in vitro model systems, the heterogeneity within cell lines has not been thoroughly investigated. Here, we have leveraged high throughput single-cell assays to investigate the Comma-1D mouse cell line that is known to differentiate in culture. Using scRNASeq and custom single-cell phenotype assays, we resolve the clonal heterogeneity within the referenced cell line on the genomic and functional level. We performed a cohesive analysis of the transcriptome of 5,195 sequenced cells, of which 85.3% of the total reads successfully mapped to the mm10-3.0.0 reference genome. Across multiple gene expression analysis pipelines, both luminal and myoepithelial lineages were observed. Deep differential gene expression analysis revealed eight subclusters identified as luminal progenitor, luminal differentiated, myoepithelial differentiated, and fibroblast subpopulations—suggesting functional clustering within each lineage. Gene expression of published mammary stem cell (MaSC) markers Epcam, Cd49f, and Sca-1 was detected across the population, with 116 (2.23%) sequenced cells expressing all three markers. To gain insight into functional heterogeneity, cells with patterned MaSC marker expression were isolated and phenotypically investigated through a custom single-cell high throughput assay. The comparison of growth kinetics demonstrates functional heterogeneity within each cell cluster while also illustrating significant limitations in current cell isolation methods. We outlined the upstream use of our novel automated cell identification platform—to be used prior to single-cell culture—for reduced cell stress and improved rare cell identification and capture. Through compounding single-cell pipelines, we better reveal the heterogeneity within Comma-1D to identify subpopulations with specific functional characteristics.

A Transient Mystery: Nucleolar Channel Systems.

The nucleus is a complex organelle with functions beyond being a simple repository for genomic material. For example, its actions in biomechanical sensing, protein synthesis, and epigenomic regulation showcase how the nucleus integrates multiple signaling modalities to intricately regulate gene expression. This innate dynamism is underscored by subnuclear components that facilitate these roles, with elementsof the nucleoskeleton, phase-separated nuclear bodies, and chromatin safeguarding by nuclear envelope proteins providingexamplesof this functional diversity. Among these, one of the lesser characterized nuclear organelles is the nucleolar channel system (NCS), first reported several decades ago inhuman endometrial biopsies. This tubular structure, believed to be derived from the inner nuclear membrane of the nuclear envelope, was first observed in secretory endometrial cells during a specific phase of the menstrual cycle. Reported as a consistent, yet transient, nuclear organelle, current interpretations of existing data suggest that it serves as a marker of a window for optimal implantation. In spite of this available data, the NCS remains incompletely characterized structurally and functionally, due in part to its transient spatial and temporal expression. As a further complication, evidence exists showing NCS expression in fetal tissue, suggesting that it may not act exclusively as a marker of uterine receptivity, but rather as a hormone sensor sensitive to estrogen and progesterone ratios. To gain a better understanding of the NCS, current technologies can be applied to profile rare cell populations or capture transient structural dynamics, for example, at a level of sensitivity and resolution not previously possible. Moving forward, advanced characterization of the NCS will shed light on an uncharacterized aspect of reproductive physiology, with the potential to refine assisted reproductive techniques.

A microfluidic device for differential capture of heterogeneous rare tumor cells with epithelial and mesenchymal phenotypes

Accumulating evidence suggests that the features associated with epithelial to mesenchymal transition (EMT) in circulating tumor cells (CTCs) reflect intrinsic metastatic potential and associate with therapy resistance. Thus, profiling the EMT phenotypes of CTCs is increasingly important for cancer diagnosis and prediction of therapeutic responses. However, rapid assessment of the EMT status of a global CTC population is still a challenge due to the difficulty in enriching and phenotyping CTCs simultaneously. Here, we report a microfluidic device consisting of an enrichment section and a capture section for differential capture of rare tumor cells from blood according to their EMT phenotypes. A row of micropillars was constructed in the enrichment section to provide cross-flows for the size-dependent filtration of cells. Thus, MCF-7 and MDA-MB-231 tumor cells mimicking CTCs were first separated from white blood cells through the micropillars and continually flowed into the capture section at a reduced velocity under a differential hydrodynamic pressure. In the capture section, the heterogeneous tumor cells were then phenotypically sorted and captured in two cascaded compartments functionalized with either an anti-EpCAM antibody or a cocktail of antibodies against mesenchymal markers including Axl, PD-L1, and EGFR. Direct counting of the captured cells in each compartment resulted in the enumeration of epithelial and mesenchymal subpopulations of the tumor cells without additional labeling. Furthermore, the captured tumor cells were successfully maintained for up to six days in the device with high viability and marked proliferation for downstream analysis. Thus, this integrated microfluidic device may have great potential in phenotyping EMT status of CTCs for precision cancer therapy.

Abstract B26: A new way of fabricating high-porosity parylene membranes for high-throughput capturing of viable circulating and exfoliated tumor cells from large-volume bodily fluids

Abstract Liquid biopsy is a critical component in cancer precision medicine. The ability to capture rare cancer cells from liquid samples, such as circulating tumor cells (CTCs) from peripheral blood as well as exfoliated tumor cells (ETCs) from other body fluids, has shown great promises in cancer detection and prognosis, as well as understanding of cancer biology at different stages. Different ways have been developed for rare cancer cell capture, including biomarker-based immunocapture and capture through other physical processes, such as size, mechanical or dielectric properties, hydrodynamic fluids, etc. However, the throughputs of these techniques are limited to 0.2-2 mL/min. Recently, a high-porosity parylene membrane has been shown to be able to process sample at a fluid rate of > 100 mL/min, which would greatly extend the capability of CTC and ETC-based liquid biopsy. The high porosity of the membrane can also dramatically reduce the shear stress the tumor cells encountered during capture, which has been shown to be critical to maintain cell viability. However, the current parylene membrane fabrication involves deep Si reactive ion etching, which is an expensive process and not widely available. The release of the parylene membrane can also be challenging. We report here a new method to fabricate the parylene membrane using simple photolithography and reactive ion etching techniques. The fabricated parylene membranes and their capability of processing large volume sample for viable cell capture will be presented. Citation Format: Jian Gu, Inad Rabadi, Frederic Zenhausern, David Carpentieri, Jue Wang. A new way of fabricating high-porosity parylene membranes for high-throughput capturing of viable circulating and exfoliated tumor cells from large-volume bodily fluids [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B26.

Capture and detection of rare cancer cells in blood by intrinsic fluorescence of a novel functionalized diatom.

The ability to identify and enrich target cells can play a significant role in biosensing in general. For the separation of rare cells; a biosilica structure was extracted from "Chaetoceros sp." diatoms as a novel natural source of mesoporous materials. These diatoms had special optical capabilities, especially in fluorescence emission. Biosilica surfaces of Chaetoceros sp. were chemically modified by iron oxide nanoparticles resulting in diatom silica magnetic particles functionalized with Trastuzumab antibody to separate the breast cancer cells from normal cells. The fully characterization of magnetic biosilica structure were studied by various spectroscopic techniques. The magnetic diatom conjugated with antibody displays strong absorption and two main types of fluorescence emission with peaks centered at 493 and 650 nm (photo-excited at 405 nm). As in vitro study, SKBR3 cells (HER2 positive cells) were selectively targeted and separated with this magnetic diatom structure from the mix of HER2 negative cells using a magnetic field. These results show that Chaetoceros silica shells are promising eco-friendly biomaterials suitable for biosensing chip and the targeted delivery of drugs to the specific sites.

An automated microfluidic system for efficient capture of rare cells and rapid flow-free stimulation.

Cell fates are controlled by environmental stimuli that rapidly change the activity of intracellular signaling. Studying these processes requires rapid manipulations of micro-environmental conditions while continuously observing single cells over long periods of time. Current microfluidic devices are unable to simultaneously i) efficiently capture and concentrate rare cells, ii) conduct automated rapid media exchanges via diffusion without displacing non-adherent cells, and iii) allow sensitive high-throughput long-term time-lapse microscopy. Hematopoietic stem and progenitor cells pose a particular challenge for these types of experiments as they are impossible to obtain in very large numbers and are displaced by the fluid flow usually used to change culture media, thus preventing cell tracking. Here, we developed a programmable automated system composed of a novel microfluidic device for efficient capture of rare cells in independently addressable culture chambers, a custom incubation system, and user-friendly control software. The chip's culture chambers are optimized for efficient and sensitive fluorescence microscopy and their media can be individually and quickly changed by diffusion without non-adherent cell displacement. The chip allows efficient capture, stimulation, and sensitive high-frequency time-lapse observation of rare and sensitive murine and human primary hematopoietic stem cells. Our 3D-printed humidification and incubation system minimizes gas consumption, facilitates chip setup, and maintains stable humidity and gas composition during long-term cell culture. This approach now enables the required continuous long-term single-cell quantification of rare non-adherent cells with rapid environmental manipulations, e.g. of rapid signaling dynamics and the later stem cell fate choices they control.

Dimensional analysis and parametric studies of the microwell for particle trapping

Recently, the microwell has been widely used for cell trapping due to its simple design and enclosed microenvironment for on-chip cell culture and stimulation. In this paper, we investigated the effect of various geometrical factors on microwells for efficient particle analysis. We used the Arbitrary Lagrangian–Eulerian method to calculate the trajectory of particles entering circular and triangular microwells under various geometrical factors, particle size, and flow conditions. Our simulation results show that the W/L = 2 triangular microwell provides the best trapping efficiency due to a stronger recirculation vortex. A smaller particle size or slower flow rate also enhances particle trapping efficiency. To validate simulation results, we flowed 4.5, 6, and 10 µm diameter polystyrene beads into W/L = 1 circular, W/L = 1 and W/L = 2 triangular microwells under various flow rates. The experimental results agreed well with simulation results, showing that the occupancy of W/L = 2 triangular microwell was sevenfold and twofold higher than W/L = 1 circular and W/L = 1 triangular microwells, respectively. Overall, the above results can provide a useful guideline to design the microwell device for efficient hydrodynamic particle trapping, which can be applied to single cell analysis or rare cell capture.

885P - Spatial-temporal change in quantitative total bone imaging (QTBI) and circulating tumour cells (CTCs) in metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide (ENZA)

885P - Spatial-temporal change in quantitative total bone imaging (QTBI) and circulating tumour cells (CTCs) in metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide (ENZA)

Interfacial Nanoinjection-Based Nanoliter Single-Cell Analysis.

Single-cell analysis offers unprecedented resolution for the investigation of cellular heterogeneity and the capture of rare cells from large populations. Here, described is a simple method named interfacial nanoinjection (INJ), which can miniaturize various single-cell assays to be performed in nanoliter water-in-oil droplets on standard microwell plates. The INJ droplet handler can adjust droplet volumes for multistep reactions on demand with high precision and excellent monodispersity, and consequently enables a wide range of single-cell assays. Importantly, INJ can be coupled with fluorescence-activated cell sorting (FACS), which is currently the most effective and accurate single-cell sorting and isolation method. FACS-INJ pipelines for high-throughput plate well-based single-cell analyses, including single-cell proliferation, drug-resistance testing, polymerase chain reaction (PCR), reverse-transcription PCR, and whole-genome sequencing are introduced. This FACS-INJ pipeline is compatible with a wide range of samples and can be extended to various single-cell analysis applications in microbiology, cell biology, and biomedical diagnostics.

Integration of rare cell capture technology into cytologic evaluation of cerebrospinal fluid specimens from patients with solid tumors and suspected leptomeningeal metastasis

Dissemination of tumor to the leptomeninges, subarachnoid space, and cerebrospinal fluid (CSF) is termed leptomeningeal metastasis (LM) and occurs in approximately 5% of patients with solid tumors. LM is associated with dismal clinical prognosis, and routine cytologic and radiologic methods for diagnosing LM have limited sensitivity. The CellSearch immunomagnetic rare cell capture assay is FDA-approved to detect circulating tumor cells (CTCs) in peripheral blood, but whether it may have a role in identifying CSF CTCs is still unclear. CSF specimens from 20 patients with clinically suspected solid tumor LM collected from 2 institutions between October 2016 and January 2019 were evaluated with routine CSF cytology and underwent concurrent CTC testing with the CellSearch assay (Menarini-Silicon Biosystems, Huntingdon Valley, PA). The results of CTC testing were compared to routine CSF cytology and radiologic studies for detecting LM. The CellSearch assay achieved a sensitivity of 88.9% and specificity of 100% for detecting LM (using a threshold of 1 CTC/mL of CSF as the definition of a positive CTC result). One patient with negative CSF cytology but positive CTCs developed positive cytology 37 days later. In this proof-of-principle pilot study, we demonstrate that the CellSearch assay can be successfully integrated with the routine CSF cytologic workflow to aid in the diagnosis of solid tumor LM. Importantly, CTCs detected by this rare cell capture assay are found in a subset of patients with non-positive routine CSF cytology, which may have significant implications for patient management.

Abstract 2223: High-purity isolation method of rare cells for molecular analyses using microfluidic chip type cell sorter

Abstract Background: Liquid biopsy using noninvasive sampling of blood is rapidly advancing in cancer diagnostics. Circulating tumor cells (CTCs) are intact tumor-derived cells and are potentially utilized for further molecular analyses. Capturing rare CTCs with high purity, however, remains technically challenging. Here we report the results of preclinical evaluation of the multistep sorting method using On-chip Sort system (On-Chip Biotechnologies) for high-purity capture and isolation of rare cells in the blood for further molecular analyses. Materials and Methods: Non-small-cell lung cancer cell lines PC-9, NCI-H1975 and A549 were used for this preclinical study. Cells were spiked into 4 mL of peripheral blood form healthy donors. After hemolysis and fixation, the samples were labeled with PE/Cy7-CD45 and FITC-cytokeratin (CK) antibodies and Hoechst for nuclei staining followed by three multiple sorting steps based on positive staining for CK and negative staining for CD45. For evaluating the potential of recovered tumor cells for genome sequencing, recovered NCI-H1975 cells, known to harbor EGFR L858R and T790M mutations, from spike-in samples were subjected to next-generation sequencing after whole genome amplification. To further establish the rare cells detection using the preserved blood samples, PC-9 cells were spiked the peripheral blood from healthy donors and transferred to the preservative tubes (Streck, Omaha, NE) and processed and sorted between 24 and 48 hours after the sample preparation. Results: Up to 50 PC-9 and A549 cells were spiked into 4 mL of peripheral blood and recovery rate of both cells were as high as 70% and recovered white blood cells were as low as 20% after three cycles of sorting steps, suggesting the sufficient recovery and purity of tumor cells for further analyses. One NCI-H1975 cells were also spiked into 4 mL of peripheral blood and recovered cells were subjected to next-generation sequencing after whole genome amplification. Both EGFR L858R and T790M mutations were successfully called and mutant allele frequencies of these gene mutations were as high as those called from the control DNA which were extracted from 1000 NCI-H1975 cells. PC-9 cells (0, 10, 100, 500 cells) were spiked into 20 mL of peripheral blood and split into two preservative tubes and the recovery rate ranged from 55.0 to 61.3%, suggesting the robustness of the multistep sorting method when preservative tubes were used. Good correlation was also observed between the observed number and the expected number of cancer cells demonstrating the linearity with a correlation coefficient (R2) of 0.99. Conclusions: We confirmed that rare cancer cells in the blood can be captured and isolated by the multistep sorting method using On-chip Sort system and can be utilized for further molecular analyses Results also suggest that this method allows us to deal with the preserved Citation Format: Yasuhiro Koh, Mio Ikeda, Shunsuke Teraoka, Masayuki Ishige, Yuu Fujimura, Kazuo Takeda, Nahomi Tokudome, Yuichi Ozawa, Hiroki Ueda, Nobuyuki Yamamoto. High-purity isolation method of rare cells for molecular analyses using microfluidic chip type cell sorter [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2223.

Immunofunctional photodegradable poly(ethylene glycol) hydrogel surfaces for the capture and release of rare cells.

Circulating tumor cells (CTCs) play a central role in cancer metastasis and represent a rich source of data for cancer prognostics and therapeutic guidance. Reliable CTC recovery from whole blood therefore promises a less invasive and more sensitive approach to cancer diagnosis and progression tracking. CTCs, however, are exceedingly rare in whole blood, making their quantitative recovery challenging. Several techniques capable of isolating these rare cells have been introduced and validated, yet most suffer from low CTC purity or viability, both of which are essential to develop a clinically viable CTC isolation platform. To address these limitations, we introduce a patterned, immunofunctional, photodegradable poly(ethylene glycol) (PEG) hydrogel capture surface for the isolation and selective release of rare cell populations. Flat and herringbone capture surfaces were successfully patterned via PDMS micromolding and photopolymerization of photolabile PEG hydrogels. Patterned herringbone surfaces, designed to convectively transport cells to the capture surface, exhibited improved capture density relative to flat surfaces for target cell capture from buffer, buffy coat, and whole blood. Uniquely, captured cells were released for collection by degrading the hydrogel capture surface with either bulk or targeted irradiation with cytocompatible doses of long wavelength UV light. Recovered cells remained viable following capture and release and exhibited similar growth rates as untreated control cells. The implementation of molded photodegradable PEG hydrogels as a CTC capture surface provides a micropatternable, cytocompatible platform that imparts the unique ability to recover pure, viable CTC samples by selectively releasing target cells.

A photoelectrochemical platform for the capture and release of rare single cells

For many normal and aberrant cell behaviours, it is important to understand the origin of cellular heterogeneity. Although powerful methods for studying cell heterogeneity have emerged, they are more suitable for common rather than rare cells. Exploring the heterogeneity of rare single cells is challenging because these rare cells must be first pre-concentrated and undergo analysis prior to classification and expansion. Here, a versatile capture & release platform consisting of an antibody-modified and electrochemically cleavable semiconducting silicon surface for release of individual cells of interest is presented. The captured cells can be interrogated microscopically and tested for drug responsiveness prior to release and recovery. The capture & release strategy was applied to identify rare tumour cells from whole blood, monitor the uptake of, and response to, doxorubicin and subsequently select cells for single-cell gene expression based on their response to the doxorubicin.

Low-autofluorescence fluoropolymer membrane filters for cell filtration

A fluoropolymer membrane filter with through-holes was fabricated by photolithographic patterning and the dry etching method. 380,000 highly packed through-holes, each with a diameter of 7 µm were able to cover a whole area with a diameter of 13 mm. Ethylene tetrafluoroethylene (ETFE) was used as the membrane, which was suitable for the fluorescence detection of rare cells such as circulating tumor cells (CTCs) in human blood. The device fabrication for the size based capture of rare cells in blood such as CTCs is realized in this study.