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

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Lowering Entropic Barriers in Triplex DNA Switches Facilitating Biomedical Applications at Physiological pH.

Triplex DNA switches are attractive allosteric tools for engineering smart nanodevices, but their poor triplex-forming capacity at physiological conditions limited the practical applications. To address this challenge, we proposed a low-entropy barrier design to facilitate triplex formation by introducing a hairpin duplex linker into the triplex motif, and the resulting triplex switch was termed as CTNSds. Compared to the conventional clamp-like triplex switch, CTNSds increased the triplex-forming ratio from 30 % to 91 % at pH 7.4 and stabilized the triple-helix structure in FBS and cell lysate. CTNSds was also less sensitive to free-energy disturbances, such as lengthening linkers or mismatches in the triple-helix stem. The CTNSds design was utilized to reversibly isolate CTCs from whole blood, achieving high capture efficiencies (>86 %) at pH 7.4 and release efficiencies (>80 %) at pH 8.0. Our approach broadens the potential applications of DNA switches-based switchable nanodevices, showing great promise in biosensing and biomedicine.

Targeting Mucin Protein Enables Rapid and Efficient Ovarian Cancer Cell Capture: Role of Nanoparticle Properties in Efficient Capture and Culture.

The development of specific and sensitive immunomagnetic cell separation nanotechnologies is central to enhancing the diagnostic relevance of circulating tumor cells (CTCs) and improving cancer patient outcomes. The limited number of specific biomarkers used to enrich a phenotypically diverse set of CTCs from liquid biopsies has limited CTC yields and purity. The ultra-high molecular weight mucin, mucin16 (MUC16) is shown to physically shield key membrane proteins responsible for activating immune responses against ovarian cancer cells and may interfere with the binding of magnetic nanoparticles to popular immunomagnetic cell capture antigens. MUC16 is expressed in ≈90% of ovarian cancers and is almost universal in High Grade Serous Epithelial Ovarian Cancer. This work demonstrates that cell bound MUC16 is an effective target for rapid immunomagnetic extraction of expressor cells with near quantitative yield, high purity and viability from serum. The results provide a mechanistic insight into the effects of nanoparticle physical properties and immunomagnetic labeling on the efficiency of immunomagnetic cell isolation. The growth of these cells has also been studied after separation, demonstrating that nanoparticle size impacts cell-particle behavior and growth rate. These results present the successful isolation of "masked" CTCs enabling new strategies for the detection of cancer recurrence and select and monitor chemotherapy.

Recent advances in aptamer applications for analytical biochemistry.

Aptamers are typically defined as relatively short (20-60 nucleotides) single-stranded DNA or RNA molecules that bind with high affinity and specificity to various types of targets. Aptamers are frequently referred to as "synthetic antibodies" but are easier to obtain, less expensive to produce, and in several ways more versatile than antibodies. The beginnings of aptamers date back to 1990, and since then there has been a continual increase in aptamer publications. The intent of the present account was to focus on recent original research publications, i.e., those appearing in 2019 through April 2020, when this account was written. A Google Scholar search of this recent literature was performed for relevance-ranking of articles. New methods for selection of aptamers were not included. Nine categories of applications were organized and representative examples of each are given. Finally, an outlook is offered focusing on "faster, better, cheaper" application performance factors as key drivers for future innovations in aptamer applications.

Investigation of Interaction between the Spike Protein of SARS-CoV-2 and ACE2-Expressing Cells Using an In Vitro Cell Capturing System.

BACKGROUND: The Interaction between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein with Angiotensin converting enzyme 2 (ACE2) on the host cells is a crucial step for the viral entry and infection. Therefore, investigating the molecular mechanism underlying the interaction is of great importance for the prevention of the infection of SARS-CoV-2. In this study, we aimed to establish a virus-free in vitro system to study the interaction between the spike protein and host cells of SARS-CoV-2. RESULTS: Our results show that ACE2-overexpressing HEK293T cells are captured by immobilized spike S1 protein, and the cell capturing process can be inhibited by the receptor binding domain of the spike protein or antibodies against S protein. Furthermore, spike S1 protein variant with D614G mutant show a higher cell capturing ability than wild type spike S1 protein and stronger binding capacity of its receptor ACE2. In addition, the captured cells can be eluted as living cells for further investigation. CONCLUSIONS: This study provides a new in vitro system for investigating the interaction between SARS-CoV-2 and host cells and purifying ACE2-expressing cells.

Single cell capture, isolation, and long-term in-situ imaging using quantitative self-interference spectroscopy.

Single cell research with microfluidic chip is of vital importance in biomedical studies and clinical medicine. Simultaneous microfluidic cell manipulations and long-term cell monitoring needs further investigations due to the lack of label-free quantitative imaging techniques and systems. In this work, single cell capture, isolation and long-term in-situ monitoring was realized with a microfluidic cell chip, compact cell incubator and quantitative self-interference spectroscopy. The proposed imaging method could obtain quantitative and dynamic refractive index distribution in living cells. And the designed microfluidic chip could capture and isolate single cells. The customized incubator could support cell growth conditions when single cell was captured in microfluidic chip. According to the results, single cells could be trapped, transferred and pushed into the culture chamber with the microfluidic chip. The incubator could culture single cells in the chip for 120 h. The refractive index sensitivity of the proposed quantitative imaging method was 0.0282 and the relative error was merely 0.04%.

Sex differences in 1-year clinical outcomes after percutaneous coronary intervention with COMBO stents: From the COMBO collaboration.

BACKGROUND: The COMBO drug eluting stent is a novel device with luminal endothelial progenitor cell capture technology for rapid homogeneous endothelialization. METHODS AND RESULTS: We examined for sex differences in 1-year outcomes after COMBO stenting from the COMBO collaboration, a pooled patient-level dataset from the MASCOT and REMEDEE multicenter registries. The primary endpoint was 1-year target lesion failure (TLF), composite of cardiac death, target vessel-myocardial infarction (TV-MI), or clinically driven target lesion revascularization (CD-TLR). Secondary outcomes included stent thrombosis (ST). Adjusted outcomes were assessed using Cox regression methods. The study included 861 (23.8%) women and 2,753 (76.2%) men. Women were older with higher prevalence of several comorbidities including diabetes mellitus. Risk of 1-year TLF was similar in both sexes (3.8% vs. 3.9%, HR 0.92, 95% CI 0.59-1.42, p = .70), without sex differences in the incidence of cardiac death (1.6% vs. 1.5%, p = .78), TV-MI (1.5% vs. 1.1%, p = .32), or CD-TLR (2.0% vs. 2.2%, p = .67). Definite or probable ST occurred in 0.4% women and 1.0% men (HR 0.26, 95% CI 0.06-1.11, p = .069). CONCLUSIONS: Despite greater clinical risks at baseline, women treated with COMBO stents had similarly low 1-year TLF and other ischemic outcomes compared to men.

One-Year COMBO Stent Outcomes in Acute Coronary Syndrome: from the COMBO Collaboration.

PURPOSE: The COMBO biodegradable polymer sirolimus-eluting stent includes endothelial progenitor cell capture (EPC) technology for rapid endothelialization, which may offer advantage in acute coronary syndromes (ACS). We sought to analyze the performance of the COMBO stent by ACS status and ACS subtype. METHODS: The COMBO collaboration (n = 3614) is a patient-level pooled dataset from the MASCOT and REMEDEE registries. We evaluated outcomes by ACS status, and ACS subtype in patients with ST segment elevation myocardial infarction (STEMI) or non-STEMI (NSTEMI) versus unstable angina (UA). The primary endpoint was 1-year target lesion failure (TLF), composite of cardiac death, target vessel myocardial infarction, or clinically driven target lesion revascularization. Secondary outcomes included stent thrombosis (ST). RESULTS: We compared 1965 (54%) ACS and 1649 (46.0%) non-ACS patients. ACS presentations included 40% (n = 789) STEMI, 31% (n = 600) NSTEMI, and 29% (n = 576) UA patients. Risk of 1-year TLF was greater in ACS patients (4.5% vs. 3.3%, HR 1.51 95% CI 1.01-2.25, p = 0.045) without significant differences in definite/probable ST (1.1% vs 0.5%, HR 2.40, 95% CI 0.91-6.31, p = 0.08). One-year TLF was similar in STEMI, NSTEMI, and UA (4.8% vs 4.8% vs. 3.7%, p = 0.60), but definite/probable ST was higher in STEMI patients (1.9% vs 0.5% vs 0.7%, p = 0.03). Adjusted outcomes were not different in MI versus UA patients. CONCLUSIONS: Despite the novel EPC capture technology, COMBO stent PCI was associated with somewhat greater risk of 1-year TLF in ACS than in non-ACS patients, without significant differences in stent thrombosis. No differences were observed in 1-year TLF among ACS subtypes.

Electrospun Nanofibers for Cancer Therapy.

Lately, a remarkable progress has been recorded in the field of electrospinning for the preparation of numerous types of nanofiber scaffolds. These scaffolds present some remarkable features including high loading capacity and encapsulation efficiency, superficial area and porosity, potential for modification, structure for the co-delivery of various therapies, and cost-effectiveness. Their present and future applications for cancer diagnosis and treatment are promising and pioneering. In this chapter we provide a comprehensive overview of electrospun nanofibers (ESNFs) applications in cancer diagnosis and treatment, covering diverse types of drug-loaded electrospun nanofibers.

Asymmetrically coating Pt nanoparticles on magnetic silica nanospheres for target cell capture and therapy.

A Janus cargo has been developed via the combination of magnetic mesoporous silica (MMS) with asymmetric decoration of Pt nanoparticles (PtNPs). Mesoporous morphology of MMS provides plenty of space for loading photosensitizers and targeting agents; the magnetic feature endows the as-formed nanospheres with satisfactory isolation function in removal of low abundant target cells. The excellent catalytic ability of PtNPs can effectively alleviate the hypoxia condition of tumor microenvironment via the decomposition of hydrogen peroxide (H2O2), as well as an O2-drived nanomotor for highly efficient drug release. Using CCRF-CEM as the model target cell, the Janus cargo is demonstrated to possess significantly improved performance in cell capture and photodynamic therapy. Specially, owing to the patchy Pt decoration, the loaded photosensitizers exhibit a more efficient release behavior. More importantly, asymmetric O2-emission from one side of the nanocargo acts as a driving force, which could effectively accelerate the motion ability of cargo in cell media, thus leading to an enhanced therapeutic effect compared with the traditionally symmetric nanocargo. This Janus cargo would offer a new paradigm to design highly efficient drug carrier for gaining an improved photodynamic therapy in hypoxic cancer cells.

Tumor growth suppression by implantation of an anti-CD25 antibody-immobilized material near the tumor via regulatory T cell capture.

In this study, we designed and synthesized an implantable anti-CD25 antibody-immobilized polyethylene (CD25-PE) mesh to suppress tumor growth by removing regulatory T cells (Tregs). The PE mesh was graft-polymerized with poly(acrylic acid), and the anti-mouse CD25 antibody was then immobilized using the 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide reaction. Immobilization of the antibody on the PE mesh was confirmed by immunostaining. The CD25-PE mesh could effectively and selectively capture CD25-positive cells through antigen-antibody interactions when the CD25-PE mesh was incubated with a suspension of mouse spleen cells, including CD25-positive cells. In addition, implantation of the CD25-PE mesh into mice subcutaneously demonstrated the Treg-capturing ability of the CD25-PE mesh with only a weak inflammatory reaction. In tumor-bearing mice, tumor growth was suppressed by subcutaneous implantation of the CD25-PE mesh near the tumor for 1 week. These results suggested that the anti-CD25 antibody-immobilized material could capture Tregs in vivo and inhibit tumor proliferation in a limited tumor-bearing mouse model. Further research is needed to facilitate cancer immunotherapy using implantable anti-CD25 antibody-immobilized material as a Treg-capturing device.

Study on polyethylene glycol cross-linker in peptide-conjugated antibody on efficiency of cell capture and release.

Cell separation is important in cell therapy and disease diagnosis. Therefore, various cell separation methods have been studied, but cellular damage and the need for pretreatment remain substantial problems. Recently, in the diagnostic field, the detachment and recovery of antibody-captured cells was actively studied to obtain more detailed information on cancer cells. Previously, we have developed a highly efficient cell separation method using microfibers. In the present study, the efficiency of cell capture and release was examined by controlling the molecular mobility of an immobilized antibody to efficiently detect cells with low expression of a marker molecule. We found that improvement in molecular mobility of antibodies enhances cell capture efficiency but decreases the detachment effectiveness of the captured cells. Therefore, the molecular mobility of antibodies can be utilized to control cell capture and release according to the level of expression of the marker molecule.

One-year clinical outcomes in patients with chronic kidney disease treated with COMBO stents: From the COMBO collaboration.

BACKGROUND: Chronic kidney disease (CKD) patients undergoing percutaneous coronary intervention (PCI) experience greater ischemic events including clinically driven target lesion revascularization (CD-TLR). Whether the COMBO biodegradable-polymer sirolimus-eluting stent promotes better outcomes in these patients by virtue of endothelial progenitor cell capture technology is unknown. OBJECTIVE: We examined one-year outcomes by CKD status from the COMBO collaboration. METHODS: The COMBO collaboration was a patient-level pooled dataset from the REMEDEE and MASCOT registries (3,614 patients) of all-comers undergoing attempted COMBO stent PCI. The primary endpoint was one-year target lesion failure (TLF), composite of cardiac death, target-vessel myocardial infarction (TV-MI) or CD-TLR. Secondary endpoints included stent thrombosis (ST). RESULTS: The study included 6.4% (n = 231) CKD and 93.6% (n = 3,361) non-CKD patients. CKD patients were older and included more women with greater prevalence of several comorbidities but similar rate of acute coronary syndrome (50.6% vs. 54.5%, p = .26). CKD patients underwent radial PCI less often (56.1% vs. 70.3%, p < .001) and received clopidogrel (78.6% vs. 68.3%) more often (p = .004). One-year TLF occurred in 7.9% CKD vs. 3.7% non-CKD patients, p = .001. CKD patients also demonstrated greater incidence of cardiac death (6.2% vs. 1.2%, p < .0001), TV-MI (2.7% vs. 1.1%, p = .04) but similar CD-TLR (2.7% vs 2.2%, p = .61) and definite/probable ST (1.4% vs. 0.8%, p = .42), compared to non-CKD patients. CONCLUSIONS: CKD patients treated with COMBO stents had significantly greater incidence of one-year TLF compared to non-CKD patients driven by cardiac death and to a lesser extent TV-MI but not CD-TLR. They had similar rates of definite/probable ST.

A single-cell identification and capture chip for automatically and rapidly determining hydraulic permeability of cells.

The hydraulic permeability of the lipid bilayer membrane of a single cell, a very important parameter in biological and medical fields, has been attracting increasing attention. To date, methods developed to determine this permeability are either operation-complicated or time-consuming. Therefore, we developed a chip for automatically and rapidly determining the permeability of cells that integrates microfluidics and cell impedance analysis. The chip is designed to automatically identify a single cell, capture the cell, and record the volume change in that cell. We confirmed the abilities of single-cell identification and capture with the upper and lower voltage thresholds determined, validated the performance of the differential electrode design for accurate cell volume measurements, deduced the extracellular osmotic pressure change in the presence of a hypertonic solution according to fluorescence intensity, and demonstrated the single-cell volume change recorded by the chip. Then, the accuracy of the permeability determined with the chip was verified using HeLa cells. Finally, the permeability of human-induced pluripotent stem cells (hiPSCs) was determined to be 0.47 ± 0.03 µm/atm/min. Using the chip, the permeability can be determined within 5 min. This study provides insights for the new design of an automatic single-cell identification and capture chip for single cell-related studies. Graphical abstract.

Magnetic ionic liquids: interactions with bacterial cells, behavior in aqueous suspension, and broader applications.

Previously, we demonstrated capture and concentration of Salmonella enterica subspecies enterica ser. Typhimurium using magnetic ionic liquids (MILs), followed by rapid isothermal detection of captured cells via recombinase polymerase amplification (RPA). Here, we report work intended to explore the broader potential of MILs as novel pre-analytical capture reagents in food safety and related applications. Specifically, we evaluated the capacity of the ([P66614+][Ni(hfacac)3-]) ("Ni(II)") MIL to bind a wider range of human pathogens using a panel of Salmonella and Escherichia coli O157:H7 isolates, including a "deep rough" strain of S. Minnesota. We extended this exploration further to include other members of the family Enterobacteriaceae of food safety and clinical or agricultural significance. Both the Ni(II) MIL and the ([P66614+][Dy(hfacac)4-]) ("Dy(III)") MIL were evaluated for their effects on cell viability and structure-function relationships behind observed antimicrobial activities of the Dy(III) MIL were determined. Next, we used flow imaging microscopy (FIM) of Ni(II) MIL dispersions made in model liquid media to examine the impact of increasing ionic complexity on MIL droplet properties as a first step towards understanding the impact of suspension medium properties on MIL dispersion behavior. Finally, we used FIM to examine interactions between the Ni(II) MIL and Serratia marcescens, providing insights into how the MIL may act to capture and concentrate Gram-negative bacteria in aqueous samples, including food suspensions. Together, our results provide further characterization of bacteria-MIL interactions and support the broader utility of the Ni(II) MIL as a cell-friendly capture reagent for sample preparation prior to cultural or molecular analyses. Graphical abstract.

Design of Hierarchical Beads for Efficient Label-Free Cell Capture.

Defined hierarchical materials promise cell analysis and call for application-driven design in practical use. The further issue is to develop advanced materials and devices for efficient label-free cell capture with minimum instrumentation. Herein, the design of hierarchical beads is reported for efficient label-free cell capture. Silica nanoparticles (size of ≈15 nm) are coated onto silica spheres (size of ≈200 nm) to achieve nanoscale surface roughness, and then the rough silica spheres are combined with microbeads (≈150-1000 µm in diameter) to assemble hierarchical structures. These hierarchical beads are built via electrostatic interaction, covalent bonding, and nanoparticle adherence. Further, after functionalization by hyaluronic acid (HA), the hierarchical beads display desirable surface hydrophilicity, biocompatibility, and chemical/structural stability. Due to the controlled surface topology and chemistry, HA-functionalized hierarchical beads afford high cell capture efficiency up to 98.7% in a facile label-free manner. This work guides the development of label-free cell capture techniques and contributes to the construction of smart interfaces in bio-systems.

Graphene- and Graphene Oxide-Based Nanocomposite Platforms for Electrochemical Biosensing Applications.

Graphene and its derivatives such as graphene oxide (GO) and reduced GO (rGO) offer excellent electrical, mechanical and electrochemical properties. Further, due to the presence of high surface area, and a rich oxygen and defect framework, they are able to form nanocomposites with metal/semiconductor nanoparticles, metal oxides, quantum dots and polymers. Such nanocomposites are becoming increasingly useful as electrochemical biosensing platforms. In this review, we present a brief introduction on the aforementioned graphene derivatives, and discuss their synthetic strategies and structure-property relationships important for biosensing. We then highlight different nanocomposite platforms that have been developed for electrochemical biosensing, introducing enzymatic biosensors, followed by non-enzymatic biosensors and immunosensors. Additionally, we briefly discuss their role in the emerging field of biomedical cell capture. Finally, a brief outlook on these topics is presented.

Patterned Optoelectronic Tweezers: A New Scheme for Selecting, Moving, and Storing Dielectric Particles and Cells.

Optical micromanipulation has become popular for a wide range of applications. In this work, a new type of optical micromanipulation platform, patterned optoelectronic tweezers (p-OET), is introduced. In p-OET devices, the photoconductive layer (that is continuous in a conventional OET device) is patterned, forming regions in which the electrode layer is locally exposed. It is demonstrated that micropatterns in the photoconductive layer are useful for repelling unwanted particles/cells, and also for keeping selected particles/cells in place after turning off the light source, minimizing light-induced heating. To clarify the physical mechanism behind these effects, systematic simulations are carried out, which indicate the existence of strong nonuniform electric fields at the boundary of micropatterns. The simulations are consistent with experimental observations, which are explored for a wide variety of geometries and conditions. It is proposed that the new technique may be useful for myriad applications in the rapidly growing area of optical micromanipulation.

Wedge-shaped microfluidic chip for circulating tumor cells isolation and its clinical significance in gastric cancer.

BACKGROUND: Circulating tumor cells (CTCs) have great potential in both basic research and clinical application for the managements of cancer. However, the complicated fabrication processes and expensive materials of the existing CTCs isolation devices, to a large extent, limit their clinical translation and CTCs' clinical value. Therefore, it remains to be urgently needed to develop a new platform for achieving CTCs detection with low-cost, mass-producible but high performance. METHODS: In the present study, we introduced a novel wedge-shaped microfluidic chip (named CTC-ΔChip) fabricated by two pieces of glass through wet etching and thermal bonding technique for CTCs isolation, which achieved CTCs enrichment by different size without cell surface expression markers and CTCs identification with three-color immunocytochemistry method (CK+/CD45-/Nucleus+). We validated the feasibility of CTC-ΔChip for detecting CTCs from different types of solid tumor. Furthermore, we applied the newly-developed platform to investigate the clinical significance of CTCs in gastric cancer (GC). RESULTS: Based on "label-free" characteristic, the capture efficiency of CTC-ΔChip can be as high as 93.7 ± 3.2% in DMEM and 91.0 ± 3.0% in whole blood sample under optimized conditions. Clinically, CTC-ΔChip exhibited the feasibility of detecting CTCs from different types of solid tumor, and it identified 7.30 ± 7.29 CTCs from 2 mL peripheral blood with a positive rate of 75% (30/40) in GC patients. Interestingly, we found that GC CTCs count was significantly correlated with multiple systemic inflammation indexes, including the lymphocyte count, platelet count, the level of neutrophil to lymphocyte ratio and platelet to lymphocyte ratio. In addition, we also found that both the positivity rate and CTCs count were significantly associated with multiple clinicopathology parameters. CONCLUSIONS: Our novel CTC-ΔChip shows high performance for detecting CTCs from less volume of blood samples of cancer patients and important clinical significance in GC. Owing to the advantages of low-cost and mass-producible, CTC-ΔChip holds great potential of clinical application for cancer therapeutic guidance and prognostic monitoring in the future.

Tilted pillar array fabrication by the combination of proton beam writing and soft lithography for microfluidic cell capture Part 2: Image sequence analysis based evaluation and biological application.

As a continuation of our previously published work, this paper presents a detailed evaluation of a microfabricated cell capture device utilizing a doubly tilted micropillar array. The device was fabricated using a novel hybrid technology based on the combination of proton beam writing and conventional lithography techniques. Tilted pillars offer unique flow characteristics and support enhanced fluidic interaction for improved immunoaffinity based cell capture. The performance of the microdevice was evaluated by an image sequence analysis based in-house developed single-cell tracking system. Individual cell tracking allowed in-depth analysis of the cell-chip surface interaction mechanism from hydrodynamic point of view. Simulation results were validated by using the hybrid device and the optimized surface functionalization procedure. Finally, the cell capture capability of this new generation microdevice was demonstrated by efficiently arresting cells from a HT29 cell-line suspension.