Ex vivo cultures and drug testing of primary acute myeloid leukemia samples: Current techniques and implications for experimental design and outcome.

New treatment options of acute myeloid leukemia (AML) are rapidly emerging. Pre-clinical models such as ex vivo cultures are extensively used towards the development of novel drugs and to study synergistic drug combinations, as well as to discover biomarkers for both drug response and anti-cancer drug resistance. Although these approaches empower efficient investigation of multiple drugs in a multitude of primary AML samples, their translational value and reproducibility are hampered by the lack of standardized methodologies and by culture system-specific behavior of AML cells and chemotherapeutic drugs. Moreover, distinct research questions require specific methods which rely on specific technical knowledge and skills. To address these aspects, we herein review commonly used culture techniques in light of diverse research questions. In addition, culture-dependent effects on drug resistance towards commonly used drugs in the treatment of AML are summarized including several pitfalls that may arise because of culture technique artifacts. The primary aim of the current review is to provide practical guidelines for ex vivo primary AML culture experimental design.

Microfluidics-Based Single-Cell Protrusion Analysis for Screening Drugs Targeting Subcellular Mitochondrial Trafficking in Cancer Progression.

Cancer cell migration is often guided by cell protrusions, whose formation and activity involve subcellular localization of mitochondria. However, the role of subcellular mitochondrial trafficking during cell protrusion generation is not well-understood amidst a lack of quantitative data. Here, we present a high-throughput microfluidic platform that enables the quantitative, single-cell precision analysis of cell protrusion formation during cell migration that is regulated by subcellular mitochondrial trafficking. Gene expression profiling of the isolated cell protrusions suggested that mitochondria were found in high numbers within cell protrusions, a finding validated by mitochondrial staining. Quantitative analysis revealed that the formation of cell protrusions could be effectively suppressed by inhibiting subcellular mitochondrial trafficking. We further demonstrated that rapid screening of mitochondria-specific therapeutic drugs to evaluate their effects on cell protrusion formation with single-cell precision could be achieved in the microfluidic platform, which could have clinical utility in the development of new anticancer agents.

Novel N-cadherin antagonist causes glioblastoma cell death in a 3D bioprinted co-culture model.

Glioblastoma multiforme (GBM) is a deadly type of brain cancer. There is a need to identify novel therapies for GBM as current treatments only marginally increase survival. Modelling the complexity of cancerous tissues using 3D bioprinted constructs serves as a novel approach for preclinical testing of anticancer drugs. A novel small molecule antagonist of the cell adhesion molecule, N-cadherin (NCAD), (S)-1-(3,4-Dichlorophenoxy)-3-(4-((S)-2-hydroxy-3-(4-methoxyphenoxy)propylamino)piperidin-1-yl)propan-2-ol has shown promise as an anticancer agent. This study investigated the influence of this antagonist on GBM cells bioprinted with astrocytes into 3D constructs. The NCAD antagonist prevented spheroid formation and induced cell death in the 3D model. This is the first demonstration that an NCAD antagonist can cause GBM cell death.

Microfluidic-enabled self-organized tumor model for in vitro cytotoxicity assessment of doxorubicin.

The advent of microfluidic technologies has enabled a better recapitulation of in vitro tumor model with higher biological relevance over conventional monolayer assays. This work built upon a microfluidic system that supported the spontaneous aggregate formation of tumoral cells under flow-induced dynamic physical forces in a confined microchamber without additional matrix materials. Our findings indicated that fluidic streams significantly modulated the biological and architectural features of human breast adenocarcinoma cell (MCF-7), human hepatocarcinoma cell (HepG2), and human cervix adenocarcinoma cell (HeLa) with cell-type-dependent variation. The microfluidic platform was further integrated with a fluorescence detection and imaging system, allowing for non-invasive monitoring of cellular accumulation and spatial distribution of a chemotherapeutic agent, doxorubicin (DOX). The cytotoxic effects of DOX of various concentrations were determined and compared in MCF-7 cells in conventional two-dimensional (2D) static and microfluidic culture conditions. Dose-dependent response to DOX was noticed in both cultures, whereas tumor micronodules grown in microfluidic devices demonstrated significantly lower sensitivity to DOX at increased concentration. Our platform owns promising potentials as a universal modality for bridging traditional 2D cell cultures and in vivo experimentation for preclinical anticancer drug screening.

Three-dimensional culture models to study drug resistance in breast cancer.

Despite recent advances in breast cancer treatment, drug resistance frequently presents as a challenge, contributing to a higher risk of relapse and decreased overall survival rate. It is now generally recognized that the extracellular matrix and cellular heterogeneity of the tumor microenvironment influences the cancer cells' ultimate fate. Therefore, strategies employed to examine mechanisms of drug resistance must take microenvironmental influences, as well as genetic mutations, into account. This review discusses three-dimensional (3D) in vitro model systems which incorporate microenvironmental influences to study mechanisms of drug resistance in breast cancer. These bioengineered models include spheroid-based models, biomaterial-based models such as polymeric scaffolds and hydrogels, and microfluidic chip-based models. The advantages of these model systems over traditionally studied two-dimensional tissue culture polystyrene are examined. Additionally, the applicability of such 3D models for studying the impact of tumor microenvironment signals on drug response and/or resistance is discussed. Finally, the potential of such models for use in the development of strategies to combat drug resistance and determine the most promising treatment regimen is explored.

Development and verification of a three-dimensional (3D) breast cancer tumor model composed of circulating tumor cell (CTC) subsets.

Breast cancer is one of the most common cancer types among women in which early tumor invasion leads to metastases and death. EpCAM (epithelial cellular adhesion molecule) and HER2 (human epidermal growth factor receptor 2) are two main circulating tumor cell (CTC) subsets in HER2+ breast cancer patients. In this regard, the main aim of this study is to develop and characterize a three-dimensional (3D) breast cancer tumor model composed of CTC subsets to evaluate new therapeutic strategies and drugs. For this reason, EpCAM(+) and HER2(+) sub-populations were isolated from different cell lines to establish 3D tumor model that mimics in situ (in vivo) more closely than two-dimensional (2D) models. EpCAM(+)/HER2(+) cells had a high proliferation rate and low tendency to attach to the surface in comparison with parental MDA-MB-453 cells as CTC subsets. Aggressive breast cancer subpopulations cultured in 3D porous chitosan scaffold had enhanced cell-cell and cell-matrix interactions compared to 2D cultured cells and these 3D models showed more aggressive morphology and behavior, expressed higher levels of pluripotency marker genes, Nanog, Sox2 and Oct4. For the verification of the 3D model, the effects of doxorubicin which is a chemotherapeutic agent used in breast cancer treatment were examined and increased drug resistance was determined in 3D cultures. The 3D tumor model comprising EpCAM(+)/HER2(+) CTC subsets developed in this study has a promising potential to be used for investigation of an aggressive CTC microenvironment in vitro that mimics in vivo characteristics to test new drug candidates against CTCs.

In vitro humanized 3D microfluidic chip for testing personalized immunotherapeutics for head and neck cancer patients.

OBJECTIVES: Immunotherapy and personalized medicine therapeutics are emerging as promising approaches in the management of head and neck squamous cell carcinoma (HNSCC). In spite of that, there is yet no assay that could predict individual response to immunotherapy. METHODS: We manufactured an in vitro 3D microfluidic chip to test the efficacy of immunotherapy. The assay was first tested using a tongue cancer cell line (HSC-3) embedded in a human tumour-derived matrix "Myogel/fibrin" and immune cells from three healthy donors. Next, the chips were used with freshly isolated cancer cells, patients' serum and immune cells. Chips were loaded with different immune checkpoint inhibitors, PD-L1 antibody and IDO 1 inhibitor. Migration of immune cells towards cancer cells and the cancer cell proliferation rate were evaluated. RESULTS: Immune cell migration towards HSC-3 cells was cancer cell density dependent. IDO 1 inhibitor induced immune cells to migrate towards cancer cells both in HSC-3 and in two HNSCC patient samples. Efficacy of PD-L1 antibody and IDO 1 inhibitor was patient dependent. CONCLUSION: We introduced the first humanized in vitro microfluidic chip assay to test immunotherapeutic drugs against HNSCC patient samples. This assay could be used to predict the efficacy of immunotherapeutic drugs for individual patients.

Three-Dimensional Cell Cultures as an In Vitro Tool for Prostate Cancer Modeling and Drug Discovery.

In the last decade, three-dimensional (3D) cell culture technology has gained a lot of interest due to its ability to better recapitulate the in vivo organization and microenvironment of in vitro cultured cancer cells. In particular, 3D tumor models have demonstrated several different characteristics compared with traditional two-dimensional (2D) cultures and have provided an interesting link between the latter and animal experiments. Indeed, 3D cell cultures represent a useful platform for the identification of the biological features of cancer cells as well as for the screening of novel antitumor agents. The present review is aimed at summarizing the most common 3D cell culture methods and applications, with a focus on prostate cancer modeling and drug discovery.

THz Spectroscopy for a Rapid and Label-Free Cell Viability Assay in a Microfluidic Chip Based on an Optical Clearing Agent.

Simple, rapid, and efficient cell viability assays play a fundamental role in much of biomedical research, including cell toxicology investigations and antitumor drug screening. Here, we demonstrate for the first time a rapid and label-free cell viability assay using THz spectroscopy in combination with a new optical clearing agent (OCA) and microfluidic technology. This strategy uses a considerably less absorptive OCA to replace the highly absorptive water molecules around the living cells and thus to decrease the background signal interference. Three low-viscosity oils were screened as potential OCA candidates, among which fluorinated oil was selected because of its lower absorption and lowest cytotoxicity. After the liquid medium was replaced with fluorinated oil in a microfluidic chip, an obvious THz spectral difference was observed between the fluorinated oils with and without living cells. This change in THz response was preliminarily attributed to the distinguishable signals between the cells and the fluorinated oil. In addition, we applied this method to cell viability assays of human breast cancer cells (MDA-MB-231) after treatment with different antitumor drugs. The results indicated that THz spectroscopy with the aid of the proposed water-replacement strategy presented excellent quantification of cell viability with the advantages of a rapid, label-free, nondestructive microassay, which offers significant potential to developing a convenient and practical cell analysis platform.

A novel microfluidic device capable of maintaining functional thyroid carcinoma specimens ex vivo provides a new drug screening platform.

BACKGROUND: Though the management of malignancies has improved vastly in recent years, many treatment options lack the desired efficacy and fail to adequately augment patient morbidity and mortality. It is increasingly clear that patient response to therapy is unique to each individual, necessitating personalised, or 'precision' medical care. This demand extends to thyroid cancer; ~ 10% patients fail to respond to radioiodine treatment due to loss of phenotypic differentiation, exposing the patient to unnecessary ionising radiation, as well as delaying treatment with alternative therapies. METHODS: Human thyroid tissue (n = 23, malignant and benign) was live-sliced (5 mm diameter × 350-500 µm thickness) then analysed or incorporated into a microfluidic culture device for 96 h (37 °C). Successful maintenance of tissue was verified by histological (H&E), flow cytometric propidium iodide or trypan blue uptake, immunohistochemical (Ki67 detection/ BrdU incorporation) and functional analysis (thyroxine [T4] output) in addition to analysis of culture effluent for the cell death markers lactate dehydrogenase (LDH) and dead-cell protease (DCP). Apoptosis was investigated by Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL). Differentiation was assessed by evaluation of thyroid transcription factor (TTF1) and sodium iodide symporter (NIS) expression (western blotting). RESULTS: Maintenance of gross tissue architecture was observed. Analysis of dissociated primary thyroid cells using flow cytometry both prior to and post culture demonstrated no significant change in the proportion of viable cells. LDH and DCP release from on-chip thyroid tissue indicated that after an initial raised level of release, signifying cellular damage, detectable levels dropped markedly. A significant increase in apoptosis (p < 0.01) was observed after tissue was perfused with etoposide and JNK inhibitor, but not in control tissue incubated for the same time period. No significant difference in Ki-67 positivity or TTF1/NIS expression was detected between fresh and post-culture thyroid tissue samples, moreover BrdU positive nuclei indicated on-chip cellular proliferation. Cultured thyroid explants were functionally viable as determined by production of T4 throughout the culture period. CONCLUSIONS: The described microfluidic platform can maintain the viability of thyroid tissue slices ex vivo for a minimum of four days, providing a platform for the assessment of thyroid tissue radioiodine sensitivity/adjuvant therapies in real time.

T-Probe: An Integrated Microscale Device for Online In Situ Single Cell Analysis and Metabolic Profiling Using Mass Spectrometry.

The exploration of single cells reveals cell heterogeneity and biological principle of cellular metabolism. Although a number of mass spectrometry (MS) based single cell MS (SCMS) techniques have been dedicatedly developed with high efficiency and sensitivity, limitations still exist. In this work, we introduced a microscale multifunctional device, the T-probe, which integrates cellular contents extraction and immediate ionization, to implement online in situ SCMS analysis at ambient conditions with minimal sample preparation. With high sensitivity and reproducibility, the T-probe was employed for MS analysis of single HeLa cells under control and anticancer drug treatment conditions. Intracellular species and xenobiotic metabolites were detected, and changes of cellular metabolic profiles induced by drug treatment were measured. Combining SCMS experiments with statistical data analyses, including Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) and two-sample t-test, we provided biological insights into cellular metabolic response to drug treatment. Online MS/MS analysis was conducted at single cell level to identify species of interest, including endogenous metabolites and the drug compound. Using the T-probe SCMS technique combined with comprehensive data analyses, we provide an approach to understanding cellular metabolism and evaluate chemotherapies at the single cell level.

iTRAQ Quantitative Proteomic Profiling and MALDI-MSI of Colon Cancer Spheroids Treated with Combination Chemotherapies in a 3D Printed Fluidic Device.

For a patient with metastatic colorectal cancer there are limited clinical options aside from chemotherapy. Unfortunately, the development of new chemotherapeutics is a long and costly process. New methods are needed to identify promising drug candidates earlier in the drug development process. Most chemotherapies are administered to patients in combinations. Here, an in vitro platform is used to assess the penetration and metabolism of combination chemotherapies in three-dimensional colon cancer cell cultures, or spheroids. Colon carcinoma HCT 116 cells were cultured and grown into three-dimensional cell culture spheroids. These spheroids were then dosed with a common combination chemotherapy, FOLFIRI (folinic acid, 5-fluorouracil, and irinotecan) in a 3D printed fluidic device. This fluidic device allows for the dynamic treatment of spheroids across a semipermeable membrane. Following dosing, the spheroids were harvested for quantitative proteomic profiling to examine the effects of the combination chemotherapy on the colon cancer cells. Spheroids were also imaged to assess the spatial distribution of administered chemotherapeutics and metabolites with MALDI-imaging mass spectrometry. Following treatment, we observed penetration of folinic acid to the core of spheroids and metabolism of the drug in the outer proliferating region of the spheroid. Proteomic changes identified included an enrichment of several cancer-associated pathways. This innovative dosing device, along with the proteomic evaluation with iTRAQ-MS/MS, provides a robust platform that could have a transformative impact on the preclinical evaluation of drug candidates. This system is a high-throughput and cost-effective approach to examine novel drugs and drug combinations prior to animal testing.

Bionic 3D spheroids biosensor chips for high-throughput and dynamic drug screening.

To perform the drug screening, planar cultured cell models are commonly applied to test efficacy and toxicity of drugs. However, planar cultured cells are different from the human 3D organs or tissues in vivo. To simulate the human 3D organs or tissues, 3D spheroids are developed by culturing a small aggregate of cells which reside around the extracellular matrix and interact with other cells in liquid media. Here we apply lung carcinoma cell lines to engineer the 3D lung cancer spheroid-based biosensor using the interdigitated electrodes for drug efficacy evaluation. The results show 3D spheroid had higher drug resistance than the planar cell model. The anticarcinogen inhibition on different 3D lung cancer spheroid models (A549, H1299, H460) can be quantitatively evaluated by electric impedance sensing. Besides, we delivered combination of anticarcinogens treatments to A549 spheroids which is commonly used in clinic treatment, and found the synergistic effect of cisplatin plus etoposide had higher drug response. To simultaneously test the drug efficacy and side effects on multi-organ model with circulatory system, a connected multiwell interdigitated electrode arraywas applied to culture different organoid spheroids. Overall, the organization of 3D cancer spheroids-based biosensor, which has higher predictive value for drug discovery and personalized medicine screening, is expected to be well applied in the area of pharmacy and clinical medicine.

Biomimetic brain tumor niche regulates glioblastoma cells towards a cancer stem cell phenotype.

Glioblastoma (GBM) is the most malignant primary brain tumor and contains tumorigenic cancer stem cells (CSCs), which support the progression of tumor growth. The selection of CSCs and facilitation of the brain tumor niches may assist the development of novel therapeutics for GBM. Herein, hydrogel materials composed of agarose and hydroxypropyl methyl cellulose (HMC) in different concentrations were established and compared to emulate brain tumor niches and CSC microenvironments within a label-free system. Human GBM cell line, U-87 MG, was cultured on a series of HMC-agarose based culture system. Cell aggregation and spheroids formation were investigated after 4 days of culture, and 2.5% HMC-agarose based culture system demonstrated the largest spheroids number and size. Moreover, CD133 marker expression of GBM cells after 6 days of culture in 2.5% HMC-agarose based culture system was 60%, relatively higher than the control group at only 15%. Additionally, cells on 2.5% HMC-agarose based culture system show the highest chemoresistance, even at the high dose of 500 µM temozolomide for 72 h, the live cell ratio was still > 80%. Furthermore, the results also indicate that the expression of ABCG2 gene was up-regulated after culture in 2.5% HMC-agarose based culture system. Therefore, our results demonstrated that biomimetic brain tumor microenvironment may regulate GBM cells towards the CSC phenotype and expression of CSC characteristics. The microenvironment selection and spheroids formation in HMC-agarose based culture system may provide a label-free CSC selection strategy and drug testing model for future biomedical applications.

Formation of size-controllable tumour spheroids using a microfluidic pillar array (µFPA) device.

Spheroids are recognized for replicating the physiological microenvironment of tumours. However, because of the lack of controllability of the spheroid size, the response to anticancer drugs is variable in conventional spheroid culture methods. In this paper, we describe a method to generate several hundreds of spheroids of various types of cancer cells including patient derived cancer cells (PDCs) using a microfluidic device with pillars (diameter: 40 µm, height: 70 µm, center-to-center distance: 140 µm), called a microfluidic pillar array (µFPA) device. About three hundred glioma (U87) spheroids were obtained in the µFPA device within 3 days, and about 90% of them ranged from 175 to 225 µm. These spheroids were more resistant to doxorubicin at 10 µM than U87 cells in a monolayer. The former showed higher expression of CD133, a cancer stem cell marker, than the latter. Hypoxia inducible factor-1α (HIF-1α), another cancer stem cell marker, was found in the nucleus of the former, but found in the cytoplasm of the cells in a monolayer. Drug responses of spheroids of another glioma cell line (U251) and triple negative breast cancer (TNBC) primary cells were also easily quantified by measuring changes in spheroid size at different concentrations of their respective drug on the µFPA device. The µFPA device can be a powerful platform for obtaining uniform spheroids and monitoring the drug response of cancer cells including PDCs.

Mimicking Tumors: Toward More Predictive In Vitro Models for Peptide- and Protein-Conjugated Drugs.

Macromolecular drug candidates and nanoparticles are typically tested in 2D cancer cell culture models, which are often directly followed by in vivo animal studies. The majority of these drug candidates, however, fail in vivo. In contrast to classical small-molecule drugs, multiple barriers exist for these larger molecules that two-dimensional approaches do not recapitulate. In order to provide better mechanistic insights into the parameters controlling success and failure and due to changing ethical perspectives on animal studies, there is a growing need for in vitro models with higher physiological relevance. This need is reflected by an increased interest in 3D tumor models, which during the past decade have evolved from relatively simple tumor cell aggregates to more complex models that incorporate additional tumor characteristics as well as patient-derived material. This review will address tissue culture models that implement critical features of the physiological tumor context such as 3D structure, extracellular matrix, interstitial flow, vascular extravasation, and the use of patient material. We will focus on specific examples, relating to peptide-and protein-conjugated drugs and other nanoparticles, and discuss the added value and limitations of the respective approaches.

A general method to regenerate arrayed gold microelectrodes for label-free cell assay.

We developed a method to regenerate arrayed gold microelectrodes equipped for a commercial label-free cell analyzer. The regeneration process includes efficient treatment of the gold surface with trypsin (0.25%, v/v) digestion, rinsing with ethanol and deionized water and spinning steps. The proposed method ensured complete regeneration and repeated usage of gold microchips up to 4 times for the real-time electric impedance measurement of anti-cancer drug cytotoxicity.

Do Multiwell Plate High Throughput Assays Measure Loss of Cell Viability Following Exposure to Genotoxic Agents?

Cell-based assays in multiwell plates are widely used for radiosensitivity and chemosensitivity assessment with different mammalian cell types. Despite their relative ease of performance, such assays lack specificity as they do not distinguish between the cytostatic (reversible/sustained growth arrest) and cytotoxic (loss of viability) effects of genotoxic agents. We recently reported studies with solid tumor-derived cell lines demonstrating that radiosensitivity as measured by multiwell plate colorimetric (e.g., XTT) and fluorimetric (e.g., CellTiter-Blue) assays reflects growth arrest but not loss of viability. Herein we report similar observations with cancer cell lines expressing wild-type p53 (A549 lung carcinoma) or mutant p53 (MDA-MB-231 breast carcinoma) after treatment with the chemotherapeutic drug cisplatin. Importantly, we show that treatment of cancer cells with concentrations of cisplatin that result in 50% effect (i.e., IC50) in multiwell plate assays trigger the emergence of growth arrested cells that exhibit highly enlarged morphology, remain viable and adherent to the culture dish, and metabolize the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) to its formazan derivative. The emergence of markedly enlarged viable cells complicates the interpretation of chemosensitivity data obtained with multiwell plate high throughput assays. Relying solely on IC50 values could be misleading.

Building a Personalized Cancer Treatment System.

This paper reports the process by which a personalized cancer treatment system was built, following a user-centered approach. We give some background on personalized cancer treatment, the particular tumor chemosensitivity assay supported by the system, as well as some quality and legal issues related to such health systems. We describe how Contextual Design was applied when building the system. Contextual design is a user-centered design technique involving seven steps. We also provide some details about the system implementation. Finally, we explain how the Think-Aloud protocol and Heuristic Evaluation methods were used to evaluate the system and report its results. A qualitative assessment from the users perspective is also provided. Results from the heuristic evaluation indicate that only one of ten heuristics was missing from the system, while five were partially covered and four were fully covered.

Fast Single-Cell Patterning for Study of Drug-Induced Phenotypic Alterations of HeLa Cells Using Time-of-Flight Secondary Ion Mass Spectrometry.

A facile single-cell patterning (ScP) method was developed and integrated with time-of-flight secondary ion mass spectrometry (TOF-SIMS) for the study of drug-induced cellular phenotypic alterations. Micropatterned poly(dimethylsiloxane) (PDMS) stencil film and centrifugation-assisted cell trapping were combined for the preparation of on-surface single-cell microarrays, which exhibited both high site occupancy (>90%) and single-cell resolution (>97%). TOF-SIMS is a surface-sensitive mass spectrometry and is increasingly utilized in biological studies. Here we demonstrated, for the first time, its successful application in high-throughput single-cell analysis. Drug-induced phenotypic alterations of HeLa cells in the early stage of apoptosis were investigated using TOF-SIMS. The major molecular sources of variations were analyzed by principle component analysis (PCA).