In-vivo isolation of circulating tumor cells in non-small cell lung cancer patients by CellCollector

In non-small cell lung cancer (NSCLC) circulating tumor cells (CTCs) can provide information on patient prognosis and treatment efficacy. Currently CTCs are mostly isolated in vitro from small volumes of patient blood samples. The aim of the study was to assess a medical device for in vivo isolation of CTCs directly from the blood of NSCLC patients. The device was inserted in a cubital vein through a standard cannula for thirty minutes. The interaction of target CTCs with the CellCollector was mediated by an antibody directed against the epithelial cell adhesion molecule. There were 60 applications of the wire in 48 stage I-IIIB NSCLC patients and 12 non-cancer patients. The device was well tolerated in all applications without side effects. We obtained in vivo isolation of CTCs in 32 of 34 NSCLC patients (94.1%) with a median (range) of 13 (0-300) CTCs. In the non-cancer patients, no CTCs were detected. The safety and efficacy of an in vivo CTC detection method directly from the bloodstream of patients with NSCLC has been demonstrated. This proof of concept study may have important clinical implications, as the implementation of the device into clinical practice may improve early detection, prognosis and therapy monitoring of NSCLC patients.

Sorting by interfacial tension (SIFT): label-free selection of live cells based on single-cell metabolism

Selection of live cells from a population is critical in many biological studies and biotechnologies. We present here a novel droplet microfluidic approach that allows for label-free and passive selection of live cells using the glycolytic activity of individual cells. It was observed that with the use of a specific surfactant utilized to stabilize droplet formation, the interfacial tension of droplets was very sensitive to pH. After incubation, cellular lactate release results in droplets containing a live cell to attain a lower pH than other droplets. This enables the sorting of droplets containing live cells when confined droplets flow over a microfabricated trench oriented diagonally with respect to the direction of flow. The technique is demonstrated with human U87 glioblastoma cells for the selection of only droplets containing a live cell while excluding either empty droplets or droplets containing a dead cell. This label-free sorting method, dubbed sorting by interfacial tension (SIFT) presents a new strategy to sort diverse cell types based on metabolic activity.

Label-free separation of leukocyte subpopulations using high throughput multiplex acoustophoresis

Multiplex separation of mixed cell samples is required in a variety of clinical and research applications. Herein, we present an acoustic microchip with multiple outlets and integrated pre-alignment channel to enable high performance and label-free separation of three different cell or particle fractions simultaneously at high sample throughput. By implementing a new cooling system for rigorous temperature control and minimal acoustic energy losses, we were able to operate the system isothermally and sort suspensions of 3, 5 and 7 μm beads with high efficiencies (>95.4%) and purities (>96.3%) at flow rates up to 500 μL min-1 corresponding to a throughput of ∼2.5 × 106 beads per min. Also, human viable white blood cells were successfully fractionated into lymphocytes, monocytes and granulocytes with high purities of 96.5 ± 1.6%, 71.8 ± 10.1% and 98.8 ± 0.5%, respectively, as well as high efficiencies (96.8 ± 3.3%, 66.7 ± 3.2% and 99.0 ± 0.7%) at flow rates up to 100 μL min-1 (∼100 000 cells per min). By increasing the flow rate up to 300 μL min-1 (∼300 000 cells per min) both lymphocytes and granulocytes were still recovered with high purities (92.8 ± 1.9%, 98.2 ± 1 .0%), whereas the monocyte purity decreased to 20.9 ± 10.3%. The proposed isothermal multiplex acoustophoresis platform offers efficient fractionation of complex samples in a label-free and continuous manner at thus far unreached high sample throughput rates.

Hydrodynamic shuttling for deterministic high-efficiency multiple single-cell capture in a microfluidic chip

Studies on cellular heterogeneity have emerged as a powerful approach for developing new strategies to treat diseases including cancer. However, it is difficult to set up an in vitro co-culture experiment to study the interaction of individual live cells. In this paper, we report a hydrodynamic shuttling chip (HSC) which can deterministically capture single cells into microfluidic chambers to set up multiple single-cell co-culture experiments in which individual live cells can be microscopically observed. Using this chip device, we demonstrated a triple single-cell culture of oral squamous cell carcinoma and lymphatic endothelial cells to observe the effect of cell-cell interaction on the cell motility. Triple, single-cell pairing efficiency by our HSC device was eightfold higher than that of the probabilistic method. Using this HSC device, we were able to perform triple-culture experiments to show the cell type-dependent motility of oral squamous cell carcinoma and lymphatic endothelial cells, which was not observed in co-culture experiments.

A comparison of two protocols for optimal red blood cell depletion using Sepax-2 device for ABO-major incompatible transplantation in adults

PURPOSE OF THE STUDY

In ABO-incompatible bone marrow transplantation, an efficient depletion of red blood cells (RBC) within the graft is mandatory to avoid adverse events in transplanted patients. Using non therapeutic products, we evaluated the substitution of the standard density gradient-based separation (DGBS) over Ficoll-Paque with the use of an automated procedure intended for buffy coat only (SmartRedux software) introducing modifications within the settings to achieve a drastic reduction of the initial volume of the product. Both methods were conducted on the Sepax-2 device.

SAMPLES AND METHODS

RBC depletion rates and CD34+ cells recoveries from eight procedures with SmartRedux software using "in-house" settings (method A) were compared to those obtained from four procedures using NeatCell software, an automated DGBS over Ficoll-Paque (method B).

RESULTS

Median erythrocyte depletion of 95,4% (92,7%-99,0%) and 99,8% (99,0%-99,9%) were observed using methods A and B, respectively. Median residual RBC volumes in the final product were 19 mL (4,4 mL-31,2 mL) and 0,7 mL (0,4 mL-4,7 mL), respectively (p = 0,014). CD34+ cells recoveries of 90,9% (62,7%-102,1%) and 78,4% (64,1%-86,2%) were achieved for methods A and B. Median platelet depletion was 16,6% (10%-42,7%) and 89,8% (88,5%-92,4%) using methods A and B, respectively (p = 0,004). Processing duration was shorter using method A (168 ± 29 min) than method B (295 ± 21 min) (p = 0,004).

CONCLUSION

Both methods achieved satisfactory erythrocyte depletion and CD34+ recovery. The use of Sepax-2 device in association with SmartRedux software could be extended to efficiently deplete RBC from large-volume BM in a raw instead of DGBS.

A temporary indwelling intravascular aphaeretic system for in vivo enrichment of circulating tumor cells

Circulating tumor cells (CTCs) have become an established biomarker for prognosis in patients with various carcinomas. However, current ex vivo CTC isolation technologies rely on small blood volumes from a single venipuncture limiting the number of captured CTCs. This produces statistical variability and inaccurate reflection of tumor cell heterogeneity. Here, we describe an in vivo indwelling intravascular aphaeretic CTC isolation system to continuously collect CTCs directly from a peripheral vein. The system returns the remaining blood products after CTC enrichment, permitting interrogation of larger blood volumes than classic phlebotomy specimens over a prolonged period of time. The system is validated in canine models showing capability to screen 1-2% of the entire blood over 2 h. Our result shows substantial increase in CTC capture, compared with serial blood draws. This technology could potentially be used to analyze large number of CTCs to facilitate translation of analytical information into future clinical decisions.

Miniaturized optical fiber tweezers for cell separation by optical force

In advanced biomedicine and microfluidics, there is a strong desire to sort and manipulate various cells and bacteria based on miniaturized microfluidic chips. Here, by integrating fiber tweezers into a T-type microfluidic channel, we report an optofluidic chip to selectively trap Escherichia coli in human blood solution based on different sizes and shapes. Furthermore, we simulate the trapping and pushing regions of other cells and bacteria, including rod-shaped bacteria, sphere-shaped bacteria, and cancer cells based on finite-difference analysis. With the advantages of controllability, low optical power, and compact construction, the strategy may be possibly applied in the fields of optical separation, cell transportation, and water quality analysis.

Isolation of B-cells using Miltenyi MACS bead isolation kits

This article describes the procedures used to isolate pure B-cell populations from whole blood using various Miltenyi magnetic-activated cell sorting (MACS) bead Isolation kits. Such populations are vital for studies investigating the functional capacity of B-cells, as the presence of other cell types may have indirect effects on B-cell function through cell-cell interactions or by secretion of several soluble molecules. B-cells can be isolated by two main approaches: 1) Negative selection—in which B-cells remain “untouched” in their native state; this is advantageous as it is likely that B-cells remain functionally unaltered by this process. 2) Positive selection–in which B-cells are labelled and actively removed from the sample. We used three Negative B-cell isolation kits as well as the Positive B-cell isolation kit from Miltenyi and compared the purity of each of the resulting B-cells fractions. Contamination of isolated B-cell fractions with platelets was the conclusive finding for all of the isolation techniques tested. These results illustrate the inefficiency of current available MACS B-cell isolation kits to produce pure B-cell populations, from which concrete findings can be made. As such we suggest cell sorting as the preferred method for isolating pure B-cells to be used for downstream functional assays.

Separation and Detection of Escherichia coli and Saccharomyces cerevisiae Using a Microfluidic Device Integrated with an Optical Fibre

This paper describes the development of an integrated system using a dry film resistant (DFR) microfluidic channel consisting of pulsed field dielectrophoretic field-flow-fractionation (DEP-FFF) separation and optical detection. The prototype chip employs the pulse DEP-FFF concept to separate the cells (Escherichia coli and Saccharomyces cerevisiae) from a continuous flow, and the rate of release of the cells was measured. The separation experiments were conducted by changing the pulsing time over a pulsing time range of 2⁻24 s and a flow rate range of 1.2⁻9.6 μ L min - 1 . The frequency and voltage were set to a constant value of 1 M Hz and 14 V pk-pk, respectively. After cell sorting, the particles pass the optical fibre, and the incident light is scattered (or absorbed), thus, reducing the intensity of the transmitted light. The change in light level is measured by a spectrophotometer and recorded as an absorbance spectrum. The results revealed that, generally, the flow rate and pulsing time influenced the separation of E. coli and S. cerevisiae. It was found that E. coli had the highest rate of release, followed by S. cerevisiae. In this investigation, the developed integrated chip-in-a lab has enabled two microorganisms of different cell dielectric properties and particle size to be separated and subsequently detected using unique optical properties. Optimum separation between these two microorganisms could be obtained using a longer pulsing time of 12 s and a faster flow rate of 9.6 μ L min - 1 at a constant frequency, voltage, and a low conductivity.

Step-by-step protocols for rice gamete isolation

A detailed, step-by-step protocol for isolation of rice gametes for transcriptional profiling, with a general workflow that includes controls for RNA contamination from surrounding cells and tissues is presented. Characterization of the transcriptome and other -omics studies of flowering plant gametes are challenging as a consequence of the small sizes and relative inaccessibility of these cells. Collecting such poorly represented cells is also complicated by potential contamination from surrounding sporophytic, adjacent gametophytic tissues and difficulties in extracting high-quality intact cells. Here we present detailed, step-by-step procedures for collecting intact, unfixed rice (Oryza sativa) egg cells and sperm cells without enzymatic treatments. In addition, we also present a general workflow for assessing sample purity by RT-PCR, using primers specific for marker genes preferentially expressed in surrounding cells and tissues. These protocols should facilitate future studies of genome-scale characterization of gametes in this important model crop.

Detection of circulating tumor cells in drainage venous blood from colorectal cancer patients using a new filtration and cytology-based automated platform

Numerous technologies exist to detect circulating tumor cells (CTCs), although reports on cytological detection of CTCs remain limited. We recently developed a cytology-based CTC detection device using glass slides and light microscopy. In this study, we automated this previously manual device to improve its efficiency and cost effectiveness for clinical applications. We conducted a pilot study using this device to compare CTCs in peripheral blood (PB) and draining venous blood (DVB) from patients with colorectal cancer (CRC). The cytology-based automated CTC detection platform consisted of a disposable filtration device with a three-dimensional (3D) metal filter and multichannel automated CTC enrichment device. This platform allowed rapid and gentle filtration of CTCs and their efficient transfer from the filter to glass slides for subsequent Papanicolaou (Pap) and immunocytochemical (ICC) staining. Cytological diagnosis of CTCs was performed by observing permanent glass slide specimens by light microscopy. The current pilot clinical study enrolled CRC patients (n = 26) with stage I–IV tumors, who underwent surgery. PB was collected before surgery, and DVB was obtained from the mesenteric vein immediately after resection. Based on the CTC morphology obtained from PB and DVB samples, we proposed the following cytological criteria for the diagnosis of CTCs: pan-cytokeratin-positive, atypical cells with malignant morphological features identified by Pap staining. The numbers of CTCs defined by these criteria were significantly higher in DVB than PB from CRC patients (p<0.01), and the number of CTCs in DVB was increased significantly with stage progression (p<0.05). These results suggest that DVB may be another potential source of CTCs other than PB for liquid biopsies including downstream analysis. This automated cytology-based CTC detection device therefore provides a unique and powerful tool to investigate the significance of CTCs in CRC patients in a clinical setting.

Two-level submicron high porosity membranes (2LHPM) for the capture and release of white blood cells (WBCs)

A method modifying a vacuum-assisted UV micro-molding (VAUM) process is proposed for the fabrication of polymer two-level submicron high porosity membranes (2LHPM). The modified process allows for the fabrication of robust, large-area membranes over 5 × 5 cm2 with a hierarchical architecture made from a 200 nm-thick layer having submicron level pores (as small as 500 nm) supported by a 20 μm-thick layer forming a microporous structure with 10-15 μm diameter pores. The fabricated freestanding membranes are flexible and mechanically robust enough for post manipulation and filtration of cell samples. Very high white blood cell (WBC) capture efficiencies (≈97%) from healthy blood samples after red blood cell (RBC) lysis are demonstrated using a 3D-printed filter cartridge incorporated within these 2LHPM. A high release efficiency of ≈95% is also proved using the same setup. Finally, on-filter multistep immunostaining of captured cells is also shown.

Optical tweezers as an effective tool for spermatozoa isolation from mixed forensic samples

A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and transferred to a tube for DNA analysis workflow. The objective of this research was to optimize sperm cell collection for maximum DNA yield, and to determine the number of trapped sperm cells necessary to produce a full STR profile. A varying number of sperm cells from both a single-source semen sample and a mock sexual assault sample were isolated utilizing optical tweezers and processed using conventional STR analysis methods. Results demonstrated that approximately 50 trapped spermatozoa were required to obtain a consistently full DNA profile. A complete, single-source DNA profile was also achieved by isolating sperm cells via optical trapping from a mixture of sperm and vaginal epithelial cells. Based on these results, optical tweezers are a viable option for forensic applications such as separation of mixed populations of cells in forensic evidence.

Biophysical Insights on the Enrichment of Cancer Cells from Whole Blood by (Affinity) Filtration

Circulating tumor cells (CTCs) play a key role during the metastatic process of human cancers and their reliable detection and characterization could enable new and effective ways of cancer diagnosis, monitoring and treatment. However, due to their ultralow concentration in patient blood, the CTCs must first be enriched before such analysis can be performed. Classical microfiltration is an important and widely used method for the mechanical enrichment of CTCs. This method exploits that CTCs are generally larger than the accompanying blood cells, however, does not differentiate the cells in other ways. In an affinity filtration, selectivity is added by functionalizing the membrane with specific antibodies against a CTC-characteristic surface protein such as the epithelial cell adhesion molecule (EpCAM). A common shortcoming of both filtration approaches is that there is still a poor understanding of the enrichment process and the systems developed so far are frequently operated under non-optimized conditions. To address this, systematic filtration experiments are performed in this work using the EpCAM+ cell line MCF-7 as CTC-model and standard track-etched membranes modified with or without antibodies against EpCAM. The influences of the key filtration parameters time and applied pressure are studied and it is found that in all cases the extent of cell recovery is limited by a lysis process which occurs on the membrane surface. Counterintuitively, it is found that filtration at rather high pressures is advantageous to ensure high recovery rates. To describe the pressure-induced lysis process a biophysical model is developed. This model allows the determination of optimum filtration conditions to achieve both high cancer cell recovery and large blood sample throughput. It is demonstrated that this way practically 100% of spiked cancer cells can be recovered from milliliters of undiluted whole blood within seconds.

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.

Plastic-based acoustofluidic devices for high-throughput, biocompatible platelet separation

Platelet separation is a crucial step for both blood donation and treatment of essential thrombocytosis. Here we present an acoustofluidic device that is capable of performing high-throughput, biocompatible platelet separation using sound waves. The device is entirely made of plastic material, which renders the device disposable and more suitable for clinical use. We used this device to process undiluted human whole blood, and we demonstrate a sample throughput of 20 mL min-1, a platelet recovery rate of 87.3%, and a red/white blood cell removal rate of 88.9%. We preserved better platelet function and integrity for isolated platelets than those which are isolated using established methods. Our device features advantages such as rapid fabrication, high throughput, and biocompatibility, so it is a promising alternative to existing platelet separation approaches.

Label-free enrichment of primary human skeletal progenitor cells using deterministic lateral displacement

Skeletal stem cells (SSCs) are present in bone marrow (BM) and offer great potential for bone regenerative therapies. However, in the absence of a unique marker, current sorting approaches remain challenging in the quest for simple strategies to deliver SSCs with consistent regeneration and differentiation capacities. Microfluidics offers the possibility to sort cells marker-free, based on intrinsic biophysical properties. Recent studies indicate that SSCs are stiffer than leukocytes and are contained within the larger cell fraction in BM. This paper describes the use of deterministic lateral displacement (DLD) to sort SSCs based on cell size and stiffness. DLD is a technology that uses arrays of micropillars to sort cells based on their diameter. Cell deformation within the device can change the cell size and affect sorting - here evidenced using human cell lines and by fractionation of expanded SSCs. Following sorting, SSCs remained viable and retained their capacity to form clonogenic cultures (CFU-F), indicative of stem cell potential. Additionally, larger BM cells showed enhanced capacity to form CFU-F. These findings support the theory that SSCs are more abundant within the larger BM cell fraction and that DLD, or other size-based approaches, could be used to provide enriched SSC populations with significant implications for stem cell research and translation to the clinic.

A scalable filtration method for high throughput screening based on cell deformability

Cell deformability is a label-free biomarker of cell state in physiological and disease contexts ranging from stem cell differentiation to cancer progression. Harnessing deformability as a phenotype for screening applications requires a method that can simultaneously measure the deformability of hundreds of cell samples and can interface with existing high throughput facilities. Here we present a scalable cell filtration device, which relies on the pressure-driven deformation of cells through a series of pillars that are separated by micron-scale gaps on the timescale of seconds: less deformable cells occlude the gaps more readily than more deformable cells, resulting in decreased filtrate volume which is measured using a plate reader. The key innovation in this method is that we design customized arrays of individual filtration devices in a standard 96-well format using soft lithography, which enables multiwell input samples and filtrate outputs to be processed with higher throughput using automated pipette arrays and plate readers. To validate high throughput filtration to detect changes in cell deformability, we show the differential filtration of human ovarian cancer cells that have acquired cisplatin-resistance, which is corroborated with cell stiffness measurements using quantitative deformability cytometry. We also demonstrate differences in the filtration of human cancer cell lines, including ovarian cancer cells that overexpress transcription factors (Snail, Slug), which are implicated in epithelial-to-mesenchymal transition; breast cancer cells (malignant versus benign); and prostate cancer cells (highly versus weekly metastatic). We additionally show how the filtration of ovarian cancer cells is affected by treatment with drugs known to perturb the cytoskeleton and the nucleus. Our results across multiple cancer cell types with both genetic and pharmacologic manipulations demonstrate the potential of this scalable filtration device to screen cells based on their deformability.

Applications of Acoustofluidics in Bioanalytical Chemistry

Acoustics has a broad spectrum of applications, ranging from noise cancelation to ultrasonic imaging. In the past decade, there has been increasing interest in developing acoustic-based methods for biological and biomedical applications. This Perspective summarizes the recent progress in applying acoustofluidic methods (i.e., the fusion of acoustics and microfluidics) to bioanalytical chemistry. We describe the concepts of acoustofluidics and how it can be tailored to different types of bioanalytical applications, including sample concentration, fluorescence-activated cell sorting, label-free cell/particle separation, and fluid manipulation. Examples of each application are given, and the benefits and limitations of these methods are discussed. Finally, our perspectives on the directions that developing solutions should take to address the bottlenecks in the acoustofluidic applications in bioanalytical chemistry are presented.

The Isolation and Analysis of Circulating Tumor Cells

Circulating tumor cells (CTCs), with their close association with cancer metastasis, the most aggressive feature of solid tumors, represent an important aspect of "liquid biopsy," which provides minimally- or noninvasive approaches for cancer detection and disease status monitoring. CTC analysis has shown the potential clinical applications in several cancer types and has been approved by FDA for clinical use in advanced breast, prostate, and colorectal cancer prognosis. In this chapter, we describe a CTC isolation method using a cell size and deformability-based system, Parsortix, and the immunofluorescence staining method to detect CTCs with both epithelial and mesenchymal features. We also describe a repeated fluorescence in situ hybridization (FISH) approach to detect alterations of multiple genomic regions on the same CTCs after immunofluorescence analysis. This approach allows the study of CTCs as a biomarker for cancer detection, prognosis, and therapeutic response monitoring, as well as the study of the heterogeneity of CTCs and cancers.

In Vitro Differentiation of T Cells: From Nonhuman Primate-Induced Pluripotent Stem Cells

In this chapter, we describe a protocol for hematopoietic differentiation of nonhuman primate (NHP)-induced pluripotent stem cells (iPSCs) derived from T cells and generation of T cells. Derivation of T cells from PSCs involves three steps: induction of PSCs to hematopoietic progenitor cells (HPCs), differentiation of HPCs into progenitor T cells, and maturation of progenitor T cells into mature T cells, in particular CD8 single-positive (SP) T cells.

Spheroid Culture of Human Pancreatic Ductal Cells to Reconstitute Development of Pancreatic Intraepithelial Neoplasia

Pancreatic ductal adenocarcinoma (PDA) presents poor 5-year survival rate, mainly attributable to late diagnosis due to its asymptomatic nature. Therefore, building human cell-based systems that reconstitute hallmark features of the PDA precursors, pancreatic intraepithelial neoplasia (PanINs), will accelerate development of new strategies for early diagnostics and intervention. We previously demonstrated that systematic introduction of genetic modification (KRAS, CDKN2A, SMAD4, and TP53) leads to immortalization of primary human pancreatic cells and, upon orthotopic transplantation, their development to human PanIN-like lesions. Here, we describe detailed methods for fluorescence-activated cell sorting, lentiviral transduction, and three-dimensional spheroid culture of primary adult human pancreatic ductal cells, as well as a method for clonal selection of human pancreatic ductal spheres.

Analysis of Tissue-Resident Immune Cells from Mouse Skin and Lungs by Flow Cytometry

The heterogeneity and complexity of nonlymphoid tissues has become a major obstacle for the study of immune populations. For this reason, the generation of highly reproducible protocols that allow the analysis of immune cells in these tissues has become crucial for clinical and preclinical research. Here we describe an optimized method that allows the obtention of single-cell suspensions from the skin and lungs to analyze and quantify populations of tissue-resident memory CD8⁺ T cells by multi-parametric flow cytometry.

CD107a Degranulation Assay to Evaluate Immune Cell Antitumor Activity

Cancer development is under surveillance by the immune system of the host. Tumor cells can be recognized and killed by cytotoxic lymphocytes- such as CD8+ T lymphocytes and natural killer (NK) cells-mainly through the immune secretion of lytic granules that kill target cells. This process involves the fusion of the granule membrane with the cytoplasmic membrane of the immune effector cell, resulting in surface exposure of lysosomal-associated proteins that are typically present on the lipid bilayer surrounding lytic granules, such as CD107a. Therefore, membrane expression of CD107a constitutes a marker of immune cell activation and cytotoxic degranulation. In this chapter, we detail the steps required to isolate peripheral blood mononuclear cells (PBMCs), coculture them with target tumor cell lines, and evaluate the cytotoxic immune function by means of flow cytometry evaluation of CD107a expression on the surface of NK cells.

Minimal Residual Disease Quantification in Chronic Lymphocytic Leukemia: Clinical Significance and Flow Cytometric Methods

The very sensitive quantification of leukemia cells that persist in chronic lymphocytic leukemia patients after successful therapy is steadily gaining interest with clinical scientists. Minimal residual disease (MRD) has demonstrated prognostic significance in the context of different treatment modalities leading to its approval as an intermediate endpoint for licensure in randomized trials by the European Medicine Agency. Data supporting the clinical impact of MRD as well as a highly standardized and broadly available method for MRD assessments by flow cytometry are described herein. Examples of gating strategies are provided with comprehensive explanations to allow the reader the application of the technology to blood and bone samples with high and very low level MRD, respectively. This chapter has a particular focus on samples acquired shortly after anti-CD20 treatment. The standardization developed by the EuroFlow consortium is additionally described as technical basis for reproducible and standardized flow cytometric MRD assessments.