A novel high throughput immunomagnetic cell sorting system for potential clinical scale depletion of T cells for allogeneic stem cell transplantation

Liquid Biopsy in Pancreatic Cancer: Are We Ready to Apply It in the Clinical Practice?

Pancreatic ductal adenocarcinoma (PDAC) exhibits the poorest prognosis of all solid tumors, with a 5-year survival of less than 10%. To improve the prognosis, it is necessary to advance in the development of tools that help us in the early diagnosis, treatment selection, disease monitoring, evaluation of the response and prognosis. Liquid biopsy (LB), in its different modalities, represents a particularly interesting tool for these purposes, since it is a minimally invasive and risk-free procedure that can detect both the presence of genetic material from the tumor and circulating tumor cells (CTCs) in the blood and therefore distantly reflect the global status of the disease. In this work we review the current status of the main LB modalities (ctDNA, exosomes, CTCs and cfRNAs) for detecting and monitoring PDAC.

Detection of Rare Objects by Flow Cytometry: Imaging, Cell Sorting, and Deep Learning Approaches

Flow cytometry nowadays is among the main working instruments in modern biology paving the way for clinics to provide early, quick, and reliable diagnostics of many blood-related diseases. The major problem for clinical applications is the detection of rare pathogenic objects in patient blood. These objects can be circulating tumor cells, very rare during the early stages of cancer development, various microorganisms and parasites in the blood during acute blood infections. All of these rare diagnostic objects can be detected and identified very rapidly to save a patient's life. This review outlines the main techniques of visualization of rare objects in the blood flow, methods for extraction of such objects from the blood flow for further investigations and new approaches to identify the objects automatically with the modern deep learning methods.

Large-scale immuno-magnetic cell sorting of T cells based on a self-designed high-throughput system for potential clinical application

In this contribution, we designed four types of immuno-magnetic nanoparticles for separation of different T cells (CD3⁺, CD4⁺, CD8⁺ and CD14⁺ T cells), and we established a new large-scale immuno-magnetic cell sorting procedure to achieve an enrichment of particular T cells using our designed auto-IMACS device. This device could achieve recyclable large-scale cell sorting, for which the throughput of the system reached ∼4000 mL and the maximum cell capacity was 4 × 10¹⁰. The collected cells were analyzed by flow cytometry and visual cytology data, and the effective selection rates of CD3⁺, CD4⁺, CD8⁺ and CD14⁺ T cells were 79.3%, 74.1%, 57.1% and 67.9%, respectively. The sorted CD8⁺ T cells still retained good cytotoxic activity against specific cells. In addition, the sorted T cells can also be further incubated in vitro and proliferated, and even could be infused back into patients for immunotherapy in the near future.

Optofluidic device for the quantification of circulating tumor cells in breast cancer

Metastatic cancer patients require a continuous monitoring during the sequential treatment cycles to carefully evaluate their disease evolution. Repetition of biopsies is very invasive and not always feasible. Herein, we design and demonstrate a 3D-flow focusing microfluidic device, where all optics are integrated into the chip, for the fluorescence quantification of CTCs in real samples. To test the chip performance, two cell membrane targets, the epithelial cell adhesion molecule, EpCAM, and the receptor tyrosine-protein kinase, HER2, are selected. The efficiency of the platform is demonstrated on cell lines and in a variety of healthy donors and metastatic-breast cancer patients.

Skeletal stem cell isolation: A review on the state-of-the-art microfluidic label-free sorting techniques

Skeletal stem cells (SSC) are a sub-population of bone marrow stromal cells that reside in postnatal bone marrow with osteogenic, chondrogenic and adipogenic differentiation potential. SSCs reside only in the bone marrow and have organisational and regulatory functions in the bone marrow microenvironment and give rise to the haematopoiesis-supportive stroma. Their differentiation capacity is restricted to skeletal lineages and therefore the term SSC should be clearly distinguished from mesenchymal stem cells which are reported to exist in extra-skeletal tissues and, critically, do not contribute to skeletal development. SSCs are responsible for the unique regeneration capacity of bone and offer unlimited potential for application in bone regenerative therapies. A current unmet challenge is the isolation of homogeneous populations of SSCs, in vitro, with homogeneous regeneration and differentiation capacities. Challenges that limit SSC isolation include a) the scarcity of SSCs in bone marrow aspirates, estimated at between 1 in 10-100,000 mononuclear cells; b) the absence of specific markers and thus the phenotypic ambiguity of the SSC and c) the complexity of bone marrow tissue. Microfluidics provides innovative approaches for cell separation based on bio-physical features of single cells. Here we review the physical principles underlying label-free microfluidic sorting techniques and review their capacity for stem cell selection/sorting from complex (heterogeneous) samples.

Fundamentals and application of magnetic particles in cell isolation and enrichment: a review

Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions. Due to the inherent ability of magnets to provide forces at a distance, magnetic cell manipulation is now a standardized process step in numerous processes in tissue engineering, medicine, and in fundamental biological research. Herein we review the current status of magnetic particles to enable isolation and separation of cells, with a strong focus on the fundamental governing physical phenomena, properties and syntheses of magnetic particles and on current applications of magnet-based cell separation in laboratory and clinical settings. We highlight the contribution of cell separation to biomedical research and medicine and detail modern cell-separation methods (both magnetic and non-magnetic). In addition to a review of the current state-of-the-art in magnet-based cell sorting, we discuss current challenges and available opportunities for further research, development and commercialization of magnetic particle-based cell-separation systems.

Multi-shell structured fluorescent-magnetic nanoprobe for target cell imaging and on-chip sorting

In this paper, we have developed a core-triple-shell structured multi-functional nanoprobe Fe3O4/SiO2/CdSeTe@ZnS-SiO2/polydopamine with strong fluorescence and a fast magnetic response for specifically recognizing, fluorescently labeling, and magnetically sorting target tumor cells on a microfluidic chip. The outer polydopamine layer not only effectively alleviated the quenching effect of the interlayer quantum dots but also provided a convenient and versatile functional interface to readily conjugate with the recognizing model molecules of aptamer KH1C12 with amine, thiol, or carboxyl groups. Moreover, the polydopamine isolation and PEG decoration equipped the as-fabricated nanoprobes with little cytotoxicity and nonspecific affinity, leading to the effective and specific profiling of the protein epitopes expressed on the target tumor cells. Taking advantage of the magnetic property and specific recognition, the modified nanoprobe was utilized to label and isolate HL-60 cells from a homogeneous cell mixture of HL-60 and K562 cells on a microfluidic chip. Combining with the high throughput of the microfluidic chip, 1.0 × 10(4) HL-60 cells were readily separated from 2.0 × 10(4) cells in only 10 min with 98% separation efficiency, markedly improved in comparison with conventional strategies. This study presents an innovative strategy for developing highly integrated nanoprobes of strong fluorescence and magnetic controllability, opening up a promising probe-based avenue for biological imaging and separation.

Circulating tumor cells: a review of present methods and the need to identify heterogeneous phenotypes

The measurement and characterization of circulating tumor cells (CTCs) hold promise for advancing personalized therapeutics. CTCs are the precursor to metastatic cancer and thus have the potential to radically alter patient treatment and outcome. Currently, clinical information provided by the enumeration of CTCs is limited to predicting clinical outcome. Other areas of interest in advancing the practice of pathology include: using CTCs for early detection of potential metastasis, determining and monitoring the efficacy of individualized treatment regimens, and predicting site-specific metastasis. Important hurdles to overcome in obtaining this type of clinical information involve present limitations in defining, detecting, and isolating CTCs. Currently, CTCs are detected using epithelial markers. The definition of what distinguishes a CTC should be expanded to include CTCs with heterogeneous phenotypes, and markers should be identified to enable a more comprehensive capture. Additionally, most methods available for detecting CTCs do not capture functionally viable CTCs. Retaining functional viability would provide a significant advantage in characterizing CTC-subtypes that may predict the site of metastatic invasion and thus assist in selecting effective treatment regimens. In this review we describe areas of clinical interest followed by a summary of current circulating cell-separation technologies and present limitations. Lastly, we provide insight into what is required to overcome these limitations as they relate to applications in advancing the practice of pathology and laboratory medicine.

Simultaneous, single particle, magnetization and size measurements of micron sized, magnetic particles

Single particle magnetization and size measurements of micron and nano sized, magnetic particles were made using a previously described device referred to as Cell Tracking Velocimetry, CTV. Three types of commercially available, and commonly used, magnetic particles were studied in this report. While the CTV instrument provides individual particles measurements, the average magnetization and size measurements were found to have reasonable agreements with reported values from instruments which measure bulk values. In addition, the CTV instrument, using electromagnets, can also determine magnetization curves, which also proved to have reasonable agreement with other published studies. Given that magnetic separation and analysis technology is dependent on the quality of the magnetic particles used, studies such as this one using CTV provide not only average data, but also provides information with respect to the distribution of the properties such as magnetization and size. For example, the spread of the data in magnetic and settling velocities were found to be predominately due to the size distribution of the analyzed particles.

Emerging technologies for CTC detection based on depletion of normal cells

Properly conducted, an enrichment step can improve selectivity, sensitivity, yield, and most importantly, significantly reduce the time needed to isolate rare circulating tumor cells (CTCs). The enrichment process can be broadly categorized as positive selection versus negative depletion, or in some cases, a combination of both. We have developed a negative depletion CTC enrichment strategy that relies on the removal of normal cells using immunomagnetic separation in the blood of cancer patients. This method is based on the combination of magnetic and fluid forces in an axial, laminar flow in long cylinders placed in quadrupole magnets. Using this technology, we have successfully isolated CTCs from patients with breast carcinoma and squamous cell carcinoma of the head and neck. In contrast to a positive selection methodology, this approach provides an unbiased characterization of these cells, including markers associated with epithelial mesenchymal transition.

Computational Fluid Dynamics Simulation of a Quadrupole Magnetic Sorter Flow Channel: Effect of Splitter Position on Nonspecific Crossover

In the Quadrupole Magnetic Sorter (QMS) magnetic particles enter a vertical flow annulus and are separated from non-magnetic particles by radial deflection into an outer annulus where the purified magnetic particles are collected via a flow splitter. The purity of magnetically isolated particles in QMS is affected by the migration of nonmagnetic particles across transport lamina in the annular flow channel. Computational Fluid Dynamics (CFD) simulations were used to predict the flow patterns, pressure drop and nonspecific crossover in QMS flow channel for the isolation of pancreatic islets of Langerhans. Simulation results were compared with the experimental results to validate the CFD model. Results of the simulations were used to show that one design gives up to 10% less nonspecific crossover than another and this model can be used to optimise the flow channel design to achieve maximum purity of magnetic particles.

Separation and detection of rare cells in a microfluidic disk via negative selection

Cyto-analysis of rare cells often requires separation and detection with each procedure posing substantial challenges. This paper presents a disk-based microfluidic platform for both procedures via an immunomagnetic negative selection process. The microfluidic platform's unique features include a multistage magnetic gradient to trap labeled cells in double trapping areas, drainage of fluid to substantially shorten detection time, and a bin-like regions to capture target cells to facilitate a seamless enumeration process. Proof-of-concept was conducted using MCF7 as target rare cells (stained with anti-cytokeratin-FITC antibodies) spiked into Jurkat Clone E6-1 non-target cells (labeled with anti-CD45-PE and anti-PE BD magnetic beads). Then, mononuclear cells (MNC) from healthy blood donors were mixed with MCF7s, modeling rare cells, and tested in the disk. Results show a non-linear magnetic coupling effect of the multistage magnet substantially increased the trapping efficacy over that of a single magnet, contributing to the depletion rate of Jurkats, which reaches 99.96%. Detection time is extensively shortened by depletion of 95% of non-cell-containing fluid in the collection area. The average yield of detected MCF7 cells is near-constant 60 ± 10% over a wide range of rarity from 10(-3) to 10(-6) and this yield also holds for the MCF7/MNC complex mixture. Comparison with autoMACS and BD IMagnet separators revealed the average yield from the disk (60%) is superior to that of autoMACS (37.3%) and BD IMagnet (48.3%). The advantages of near-constant yield, roughly 30 min of operation, an acceptable level of cell loss, and potentially low cost system should aid in cyto-analysis of rare cells.

Manipulation of magnetically labeled and unlabeled cells with mobile magnetic traps

A platform of discrete microscopic magnetic elements patterned on a surface offers dynamic control over the motion of fluid-borne cells by reprogramming the magnetization within the magnetic bits. T-lymphocyte cells tethered to magnetic microspheres and untethered leukemia cells are remotely manipulated and guided along desired trajectories on a silicon surface by directed forces with average speeds up to 20 microm/s. In addition to navigating cells, the microspheres can be operated from a distance to push biological and inert entities and act as local probes in fluidic environments.

Assessing the value of autologous and allogeneic cells for regenerative medicine

The advantages and disadvantages of autologous and allogeneic human cells for regenerative medicine are summarized. The comparison of relative advantages includes: ease and cost of treating large numbers of patients, the speed of availability of therapy and the differing complexity of the development pathways. The comparison of relative disadvantages deals with issues such as variability of source material, the risks of cell abnormality and of viral and prion contamination, and the sensitive issues surrounding use of embryo-derived cells. From the comparisons, several potentially decisive issues are drawn out, such as possible immune response and teratoma formation, the impact of patents and the virtues of hospital versus industry-centered development.

Quadrupole magnetic sorting of porcine islets of Langerhans

Islet transplantation is emerging as a treatment option for selected patients with type 1 diabetes. Inconsistent isolation, purification, and recovery of large numbers of high-quality islets remain substantial impediments to progress in the field. Removing islets as soon as they are liberated from the pancreas during digestion and circumventing the need for density gradient purification is likely to result in substantially increased viable islet yields by minimizing exposure to proteolytic enzymes, reactive oxygen intermediates, and mechanical stress associated with centrifugation. This study capitalized on the hypervascularity of islets compared with acinar tissue to explore their preferential enrichment with magnetic beads to enable immediate separation in a magnetic field utilizing a quadrupole magnetic sorting. The results demonstrate that (1) preferential enrichment of porcine islets is achievable, but homogeneous bead distribution within the pancreas is difficult to achieve with current protocols; (2) greater than 70% of islets in the dissociated pancreatic tissue were recovered by quadrupole magnetic sorting, but their purity was low; and (3) infused islets purified by density gradients and subsequently passed through quadrupole magnetic sorting had similar potency as uninfused islets. These results demonstrate proof of concept and define the steps for implementation of this technology in pig and human islet isolation.

Magnetic wire traps and programmable manipulation of biological cells

We present a multiplex method, based on microscopic programmable magnetic traps in zigzag wires patterned on a platform, to simultaneously apply directed forces on multiple fluid-borne cells or biologically inert magnetic microparticles or nanoparticles. The gentle tunable forces do not produce damage and retain cell viability. The technique is demonstrated with T-lymphocyte cells remotely manipulated (by a joystick) along desired trajectories on a silicon surface with average speeds up to 20 microm/s.

Optimization of an enrichment process for circulating tumor cells from the blood of head and neck cancer patients through depletion of normal cells

The optimization of a purely negative depletion, enrichment process for circulating tumor cells (CTCs) in the peripheral blood of head and neck cancer patients is presented. The enrichment process uses a red cell lysis step followed by immunomagnetic labeling, and subsequent depletion, of CD45 positive cells. A number of relevant variables are quantified, or attempted to be quantified, which control the performance of the enrichment process. Six different immunomagnetic labeling combinations were evaluated as well as the significant difference in performance with respect to the blood source: buffy coats purchased from the Red Cross, fresh, peripheral blood from normal donors, and fresh peripheral blood from human cancer patients. After optimization, the process is able to reduce the number of normal blood cells in a cancer patient's blood from 4.05 x 10(9) to 8.04 x 10(3) cells/mL and still recover, on average, 2.32 CTC per mL of blood. For all of the cancer patient blood samples tested in which CTC were detected (20 out of 26 patients) the average recovery of CTCs was 21.7 per mL of blood, with a range of 282 to 0.53 CTC. Since the initial number of CTC in a patient's blood is unknown, and most probably varies from patient to patient, the recovery of the CTC is unknown. However, spiking studies of a cancer cell line into normal blood, and subsequent enrichment using the optimized protocol indicated an average recovery of approximately 83%. Unlike a majority of other published studies, this study focused on quantifying as many factors as possible to facilitate both the optimization of the process as well as provide information for current and future performance comparisons. The authors are not aware any other reported study which has achieved the performance reported here (a 5.66 log(10)) in a purely negative enrichment mode of operation. Such a mode of operation of an enrichment process provides significant flexibility in that it has no bias with respect to what attributes define a CTC; thereby allowing the researcher or clinician to use any maker they choose to define whether the final, enrich product contains CTCs or other cell type relevant to the specific question (i.e., does the CTC have predominantly epithelial or mesenchymal characteristics?).