Advances in rare cell isolation: an optimization and evaluation study

Rare Cell Population Analysis in Early-Stage Breast Cancer Patients

Background

Circulating rare cells participate in breast cancer evolution as systemic components of the disease and thus, are a source of theranostic information. Exploration of cancer-associated rare cells is in its infancy.

Objectives

We aimed to investigate and classify abnormalities in the circulating rare cell population among early-stage breast cancer patients using fluorescence marker identification and cytomorphology. In addition, we sought to determine the dependency of these markers on the presence of tumors.

Design

We evaluated the validity of a multi-rare-cell detection platform and demonstrated the utility of a specific rare cell subset as a novel approach to characterize the breast cancer system. Sampling was conducted both before and after tumor resection.

Methods

Linearity of the Rarmax platform was established using a spike-in approach. The platform includes red blood cell lysis, leukocyte depletion and high-resolution fluorescence image recording. Rare cell analysis was conducted on 28 samples (before and after surgery) from 14 patients with breast cancer, 20 healthy volunteers and 9 noncancer control volunteers. In-depth identification of rare cells, including circulating tumor cells, endothelial-like cells, erythroblasts, and inflammation-associated cells, was performed using a phenotype and morphology-based classification system.

Results

The platform performed linearly over a range of 5 to 950 spiked cells, with an average recovery of 84.6%. Circulating epithelial and endothelial-like cell subsets have been demonstrated to be associated with or independent of cancer with tumor presence. Furthermore, certain cell profile patterns may be associated with treatment-related adverse effects. The sensitivity in detecting tumor-presence and cancer-associated abnormality before surgery was 43% and 85.7%, respectively, and the specificity was 100% and 96.6%, respectively.

Conclusion

This study supports the idea of a cancer-associated rare cell abnormality to represent tumor entities as well as systemic cancer. The latter is independent of the apparent clinical cancer.

Rebuilding the microenvironment of primary tumors in humans: a focus on stroma

Conventional tumor models have critical shortcomings in that they lack the complexity of the human stroma. The heterogeneous stroma is a central compartment of the tumor microenvironment (TME) that must be addressed in cancer research and precision medicine. To fully model the human tumor stroma, the deconstruction and reconstruction of tumor tissues have been suggested as new approaches for in vitro tumor modeling. In this review, we summarize the heterogeneity of tumor-associated stromal cells and general deconstruction approaches used to isolate patient-specific stromal cells from tumor tissue; we also address the effect of the deconstruction procedure on the characteristics of primary cells. Finally, perspectives on the future of reconstructed tumor models are discussed, with an emphasis on the essential prerequisites for developing authentic humanized tumor models.

Systemic cytology. A novel diagnostic approach for assessment of early systemic disease

Recognition of low grade or asymptomatic systemic diseases suggests prevention of the worst, yet has been proven challenging ever since. Biomarker-based liquid biopsy has emerged in recent years as a practical platform for the assessment of systemic diseases yet, technical realizations were mainly focused on cancer, faced challenges in accuracy at early stage and are lacking provision of sufficient evidence of disease. In particular in cell-based cancer liquid biopsy, obstacles are rarity and heterogeneity of circulating tumor and tumor-associated rare cells. Evidence is mounting about an entire spectrum of distinct circulating rare cell types that denotes the systemic component of a certain physiological state. Therefore, circulating rare cells in combination may arise from yet, also account for systemic diseases, which we denote as multi-rare cell association and involves foremost bone marrow-derived progenitor and stem cells yet, also matured somatic cell types. One would expect immense diagnostic value in the read-out of the so called rare cell population which represents cytological evidence of abnormality. We hypothesize that comprehensive rare cell population profiling as contrasted to the biomarker screening approach may realize the premise of a biopsy as to confirm, characterize, grade, stage or predict a systemic disease. This novel approach represents the "missing link" in diagnostic care of in particular early or residual systemic disease and presumes a steady gain in knowledge about the clinical interpretation of rare cell population profiles thus, expecting the knowledge-driven transformation of cell-based liquid biopsy from suggestion to confirmation. We support our hypothesis by past findings made by others and us and provide insights how to interpret a certain rare cell population profile.

Mitochondrial Function in Modulating Human Granulosa Cell Steroidogenesis and Female Fertility

Ovarian follicle steroidogenesis associated with embryo quality results in a successful pregnancy. Each follicle consists of an oocyte surrounded by granulosa cells, which secrete several steroid and peptide hormones. Follicles harvested from women who conceived after assisted reproductive therapy (ART) had significantly higher estradiol levels in follicular fluids than the follicles from women who failed to conceive after ART. The higher follicular estradiol levels correlate well with successful fertilization following ART. Mitochondria are the central sites for steroid hormone biosynthesis. The first and rate-limiting step in the biosynthesis of steroid hormones occurs in the mitochondria of granulosa cells. In the present study, we hypothesized that the mitochondria in granulosa cells are critical for maintaining oocyte quality and fertility capacity. This study aims to clarify the relationship between mitochondrial function and granulosa cell steroidogenesis, and the relationship between hormone levels and fertility capacity. Sera, follicular fluids and granulosa cells were obtained from individuals undergoing IVF-ET treatment. The oocyte numbers, oocyte quality, fertilization rate, and pregnancy rate were also recorded. The patients who provided the granulosa cells were further classified into four groups: endometriosis, ovarian endometrioma, endometriosis without ovarian endometrioma, and polycystic ovary syndrome (PCOS); patients with other female factor infertility and male factor infertility were used as controls. We measured the levels of estradiol (E2) by radioimmunoassay. Concurrently, we analyzed the mitochondrial mass and membrane potential, and apoptosis by flow cytometry using nonyl acridine orange, TMRE, Annexin V-FITC and PI. Mitochondrial morphology was visualized by transfection with pLV-mitoDsRed. In addition, we assessed the protein levels of steroidogenic enzymes, steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD) by Western blot. The results showed significantly decreased serum E2 and follicular E2 levels, and decreased IVF outcomes, in the patients with endometriosis. Reduced mitochondrial mass and decreased mitochondrial membrane potential were correlated with lower E2. Furthermore, a significant decrease in StAR and 3β-HSD was found in patients with ovarian endometrioma. The enzyme levels of StAR and 3β-HSD were highly correlated with E2 levels. Finally, elevated cumulus cell apoptosis was found in the patient group with ovarian endometrioma and PCOS. In conclusion, mitochondrial dysfunction of human granulosa cells may contribute to the decline of steroidogenesis, decreased fertilization rate, oocyte maturation rate, and oocyte quality, and it can ultimately jeopardize fertility.

The Blood Circulating Rare Cell Population. What is it and What is it Good For?

Blood contains a diverse cell population of low concentration hematopoietic as well as non-hematopoietic cells. The majority of such rare cells may be bone marrow-derived progenitor and stem cells. This paucity of circulating rare cells, in particular in the peripheral circulation, has led many to believe that bone marrow as well as other organ-related cell egress into the circulation is a response to pathological conditions. Little is known about this, though an increasing body of literature can be found suggesting commonness of certain rare cell types in the peripheral blood under physiological conditions. Thus, the isolation and detection of circulating rare cells appears to be merely a technological problem. Knowledge about rare cell types that may circulate the blood stream will help to advance the field of cell-based liquid biopsy by supporting inter-platform comparability, making use of biological correct cutoffs and “mining” new biomarkers and combinations thereof in clinical diagnosis and therapy. Therefore, this review intends to lay ground for a comprehensive analysis of the peripheral blood rare cell population given the necessity to target a broader range of cell types for improved biomarker performance in cell-based liquid biopsy.

Neuroendocrine Neoplasms of the Small Bowel and Pancreas

The traditionally promulgated perspectives of neuroendocrine neoplasms (NEN) as rare, indolent tumours are blunt and have been outdated for the last 2 decades. Clear increments in their incidence over the past decades render them increasingly clinically relevant, and at initial diagnosis many present with nodal and/or distant metastases (notably hepatic). The molecular pathogenesis of these tumours is increasingly yet incompletely understood. Those arising from the small bowel (SB) or pancreas typically occur sporadically; the latter may occur within the context of hereditary tumour predisposition syndromes. NENs can also be associated with endocrinopathy of hormonal hypersecretion. Tangible advances in the development of novel biomarkers, functional imaging modalities and therapy are especially applicable to this sub-set of tumours. The management of SB and pancreatic neuroendocrine tumours (NET) may be challenging, and often comprises a multidisciplinary approach wherein surgical, medical, interventional radiological and radiotherapeutic modalities are implemented. This review provides a comprehensive overview of the epidemiology, pathophysiology, diagnosis and treatment of SB and pancreatic NETs. Moreover, we provide an outlook of the future in these tumour types which will include the development of precision oncology frameworks for individualised therapy, multi-analyte predictive biomarkers, artificial intelligence-derived clinical decision support tools and elucidation of the role of the microbiome in NEN development and clinical behaviour.

A Silicon-based Coral-like Nanostructured Microfluidics to Isolate Rare Cells in Human Circulation: Validation by SK-BR-3 Cancer Cell Line and Its Utility in Circulating Fetal Nucleated Red Blood Cells

Circulating fetal cells (CFCs) in maternal blood are rare but have a strong potential to be the target for noninvasive prenatal diagnosis (NIPD). "Cell Reveal^TM system" is a silicon-based microfluidic platform capable to capture rare cell populations in human circulation. The platform is recently optimized to enhance the capture efficiency and system automation. In this study, spiking tests of SK-BR-3 breast cancer cells were used for the evaluation of capture efficiency. Then, peripheral bloods from 14 pregnant women whose fetuses have evidenced non-maternal genomic markers (e.g., de novo pathogenic copy number changes) were tested for the capture of circulating fetal nucleated red blood cells (fnRBCs). Captured cells were subjected to fluorescent in situ hybridization (FISH) on chip or recovered by an automated cell picker for molecular genetic analyses. The capture rate for the spiking tests is estimated as 88.1%. For the prenatal study, 2⁻71 fnRBCs were successfully captured from 2 mL of maternal blood in all pregnant women. The captured fnRBCs were verified to be from fetal origin. Our results demonstrated that the Cell Reveal^TM system has a high capture efficiency and can be used for fnRBC capture that is feasible for the genetic diagnosis of fetuses without invasive procedures.

An update of circulating rare cell types in healthy adult peripheral blood: findings of immature erythroid precursors

Background

Circulating rare cells (CRCs) are benign or malignant minuscule events in the peripheral blood or other bodily fluids. The detection and quantification of certain CRC types is an invaluable or proposed candidate biomarker for diagnosis, prognosis and prediction of various pathological conditions. The list of CRC types and biomarker applicability thereof continues to expand along with improvements in cell selection technology. Past findings may suggest commonness of healthy donor peripheral blood circulating mature erythroblasts. This work suggests the occurrence of morphologically distinct bone marrow native circulating early erythroid precursors that we intend to add to the list of CRCs.

Methods

We tested 15 healthy individuals that varied in age and gender employing a negative cell selection assay based on magnetic bead technology to characterize healthy adult circulating CD45 negative cell events using cell surface markers CD71 and glycophorin-A.

Results

Positive events were detected and varied in cell and nuclear size ranging between 7.5 µm till 15 µm and 4.5 till 9.2 µm, respectively with distinct appearance under bright field microscope. Cell rarity increased with cell and nuclear size. Largest cells exceeded 13.5 µm in cell diameter and were found in 7 out of 15 donors.

Conclusions

Circulating erythroid precursors occur at different stages of maturation and may be part of the benign CRC spectrum.

Novel method for DNA methylation analysis using high-performance liquid chromatography and its clinical application

The aim of this study was to develop a new methodology that is suitable for DNA methylation diagnostics and to demonstrate its clinical applicability. We developed a new anion-exchange column for high-performance liquid chromatography (HPLC) with electrostatic and hydrophobic properties. Both cytosine and thymine, corresponding to methylated and unmethylated cytosine after bisulfite modification, respectively, are captured by electrostatic interaction and then discriminated from each other by their hydrophobic interactions. The DNA methylation levels of synthetic DNA were quantified accurately and reproducibly within 10 minutes without time-consuming pretreatment of PCR products, and the measured values were unaffected by the distribution of methylated CpG within the synthetic DNA fragments. When the DNA methylation status of the FAM150A gene, a marker of the CpG island methylator phenotype specific to clear cell renal cell carcinoma (ccRCC), was examined in 98 patients with ccRCC, bulk specimens of tumorous tissue including cancer cells showing DNA methylation of the FAM150A gene were easily identifiable by simply viewing the differentiated chromatograms, even when the cancer cell content was low. Sixteen ccRCC showing DNA methylation more frequently exhibited clinicopathological parameters reflecting tumor aggressiveness (ie, a larger diameter, higher histological grade, vascular involvement, renal vein tumor thrombi, infiltrating growth, tumor necrosis, renal pelvis invasion and higher pathological TNM stage), and had significantly lower recurrence-free and overall survival rates. These data indicate that HPLC analysis using this newly developed anion-exchange column could be a powerful tool for DNA methylation diagnostics, including prognostication of patients with cancers, in a clinical setting.

Gold nanoparticle-based rapid detection and isolation of cells using ligand-receptor chemistry

Identification and isolation of low-frequency cells of interest from a heterogeneous cell mixture is an important aspect of many diagnostic applications (including enumeration of circulating tumor cells) and is integral to various assays in (cancer) biology. Current techniques typically require expensive instrumentation and are not amenable to high throughput. Here, we demonstrate a simple and effective platform for cell detection and isolation using gold nanoparticles (Au NPs) conjugated with hyaluronic acid (HA) i.e. Au-PEG-HA NPs. The proposed platform exploits ligand-receptor chemistry to detect/isolate cells with high specificity and efficiency. When the Au-PEG-HA NPs come in contact with cells that express CD44 (the receptor for HA), a clear colorimetric change occurs (along with an accompanying SPR peak shift from 521 nm to 559 nm) in the solution due to NPs-cell interaction. This clearly discernible, colorimetric change can be leveraged by point-of-care devices employed in diagnostic applications. Finally, we show that we can successfully isolate viable cells from a heterogeneous cell population (including from human blood samples) with high specificity, which can be used in further downstream applications. The developed NPs-based platform can be a convenient and cost-efficient alternative for diagnostic applications and for cell isolation or sorting in research laboratories.

Noninvasive prenatal diagnosis of fetal aneuploidy by circulating fetal nucleated red blood cells and extravillous trophoblasts using silicon-based nanostructured microfluidics

BACKGROUND

Noninvasive prenatal testing (NIPT) based on cell-free DNA in maternal circulation has been accepted worldwide by the clinical community since 2011 but limitations, such as maternal malignancy and fetoplacental mosaicism, preclude its full replacement of invasive prenatal diagnosis. We present a novel silicon-based nanostructured microfluidics platform named as "Cell Reveal™" to demonstrate the feasibility of capturing circulating fetal nucleated red blood cells (fnRBC) and extravillous cytotrophoblasts (EVT) for cell-based noninvasive prenatal diagnosis (cbNIPD).

METHODS

The "Cell Reveal™" system is a silicon-based, nanostructured microfluidics using immunoaffinity to capture the trophoblasts and the nucleated RBC (nRBC) with specific antibodies. The automated computer analysis software was used to identify the targeted cells through additional immunostaining of the corresponding antigens. The identified cells were retrieved for whole genome amplification for subsequent investigations by micromanipulation in one microchip, and left in situ for subsequent fluorescence in situ hybridization (FISH) in another microchip. When validation, bloods from pregnant women (n = 24) at gestational age 11-13+6 weeks were enrolled. When verification, bloods from pregnant women (n = 5) receiving chorionic villus sampling or amniocentesis at gestation age 11+4-21 weeks with an aneuploid or euploid fetus were enrolled, followed by genetic analyses using FISH, short tandem repeat (STR) analyses, array comparative genomic hybridization, and next generation sequencing, in which the laboratory is blind to the fetal genetic complement.

RESULTS

The numbers of captured targeted cells were 1-44 nRBC/2 ml and 1-32 EVT/2 ml in the validation group. The genetic investigations performed in the verification group confirmed the captured cells to be fetal origin. In every 8 ml of the maternal blood being blindly tested, both fnRBC and EVT were always captured. The numbers of captured fetal cells were 14-22 fnRBC/4 ml and 1-44 EVT/4 ml of maternal blood.

CONCLUSIONS

This report is one of the first few to verify the capture of fnRBC in addition to EVT. The scalability of our automated system made us one step closer toward the goal of in vitro diagnostics.

Management and potentialities of primary cancer cultures in preclinical and translational studies

The use of patient-derived primary cell cultures in cancer preclinical assays has increased in recent years. The management of resected tumor tissue remains complex and a number of parameters must be respected to obtain complete sample digestion and optimal vitality yield. We provide an overview of the benefits of correct primary cell culture management using different preclinical methodologies, and describe the pros and cons of this model with respect to other kinds of samples. One important advantage is that the heterogeneity of the cell populations composing a primary culture partially reproduces the tumor microenvironment and crosstalk between malignant and healthy cells, neither of which is possible with cell lines. Moreover, the use of patient-derived specimens in innovative preclinical technologies, such as 3D systems or bioreactors, represents an important opportunity to improve the translational value of the results obtained. In vivo models could further our understanding of the crosstalk between tumor and other tissues as they enable us to observe the systemic and biological interactions of a complete organism. Although engineered mice are the most common model used in this setting, the zebrafish (Danio rerio) species has recently been recognized as an innovative experimental system. In fact, the transparent body and incomplete immune system of zebrafish embryos are especially useful for evaluating patient-derived tumor tissue interactions in healthy hosts. In conclusion, ex vivo systems represent an important tool for cancer research, but samples require correct manipulation to maximize their translational value.

Fundamentals of affinity cell separations

Cell separations using affinity methods continue to be an enabling science for a wide variety of applications. In this review, we discuss the fundamental aspects of affinity separation, including the competing forces for cell capture and elution, cell-surface interactions, and models for cell adhesion. Factors affecting separation performance such as bond affinity, contact area, and temperature are presented. We also discuss and demonstrate the effects of nonspecific binding on separation performance. Metrics for evaluating cell separations are presented, along with methods of comparing separation techniques for cell isolation using affinity capture.