Microfluidic Tumor Model Research Articles

Development and validation of a controlled heating apparatus for long‐term MRI of 3D microfluidic tumor models

AbstractConventional testing of novel contrast agents for magnetic resonance imaging (MRI) involves cell and animal studies. However, 2D cultures lack dynamic flow and in vivo MRI is limited by regulatory approval of long‐term anesthesia use. Microfluidic tumor models (MTMs) offer a cost‐effective, reproducible, and high throughput platform for bridging cell and animal models. Yet, MRI of microfluidic devices is challenging, due to small fluid volumes generating low sensitivity. For the first time, an MRI of MTMs was performed at low field strength (1 T) using conventional imaging equipment without microcoils. To enable longitudinal MRI, we developed (1) CHAMP‐3 (controlled heating apparatus for microfluidics and portability) which heats MTMs during MRI scans and (2) an MRI‐compatible temperature monitoring system. CHAMP‐3 maintained chip surface temperature at ~37°C and the media inside at ~35.5°C. Enhanced T1‐weighted MRI contrast was achieved in 3D MTMs with free manganese (Mn2+) solutions and Mn2+ labeled tumor cells.

Relatively Rare Populations of Invasive Cells Drive Progression of Heterogeneous Tumors.

Breast tumors often display an astonishing degree of spatial and temporal heterogeneity, which are associated with cancer progression, drug resistance, and relapse. Triple-negative breast cancer (TNBC) is a particularly aggressive and heterogeneous subtype for which targeted therapies are scarce. Consequently, patients with TNBC have a poorer overall prognosis compared to other breast cancer patients. Within heterogeneous tumors, individual clonal subpopulations may exhibit differences in their rates of growth and degrees of invasiveness. We hypothesized that such phenotypic heterogeneity at the single-cell level may accelerate tumor progression by enhancing the overall growth and invasion of the entire tumor. To test this hypothesis, we isolated and characterized clonal subpopulations with distinct morphologies and biomarker expression from the inherently heterogeneous 4T1 mouse mammary carcinoma cell line. We then leveraged a 3D microfluidic tumor model to reverse-engineer intratumoral heterogeneity and thus investigate how interactions between phenotypically distinct subpopulations affect tumor growth and invasion. We found that the growth and invasion of multiclonal tumors were largely dictated by the presence of cells with epithelial and mesenchymal traits, respectively. The latter accelerated overall tumor invasion, even when these cells comprised less than 1% of the initial population. Consistently, tumor progression was delayed by selectively targeting the mesenchymal subpopulation. This work reveals that highly invasive cells can dominate tumor phenotype and that specifically targeting these cells can slow the progression of heterogeneous tumors, which may help inform therapeutic approaches. The online version contains supplementary material available at 10.1007/s12195-023-00792-w.

Selective Targeting of Tumor Cells in a Microfluidic Tumor Model with Multiple Cell Types.

Organ-on-a-chip technology allows researchers to precisely monitor drug efficacy in 3D tissue culture systems that are physiologically more relevant to humans compared to 2D cultures and that allow better control over experimental conditions as compared to animal models. Specifically, the high control over microenvironmental conditions combined with the broad range of direct measurements that can be performed in these systems makes organ-on-a-chip devices a versatile tool to investigate tumor targeting and drug delivery. Here, we describe a detailed protocol for studying the cell-selective targeting of protein drugs to tumor cells on an organ-on-a-chip system using a co-culture consisting of BT-474 cancer cells and C5120 human fibroblasts as an example.

Biofilm Potentiates Cancer‐Promoting Effects of Tumor‐Associated Macrophages in a 3D Multi‐Faceted Tumor Model (Small 19/2023)

3D Multi-Faceted Tumor Models In article number 2205904, Bee Luan Khoo and co-workers present a novel microfluidic tumor model, TAMPIEB, which integrates tumor-associated macrophages (TAMs) and bladder cancer cells to investigate the influence of bacterial distribution on immunomodulation in the tumor microenvironment in vivo. This research represents the first successful demonstration that biofilm-induced inflammatory conditions can trigger the transformation of TAMs from a pro-inflammatory to a pro-tumor state.

Abstract 4576: 3D in vitro models uncover malignant cell intrinsic and extrinsic mechanisms of CAR-T cell resistance in high grade serous ovarian cancer

Abstract Chimeric antigen receptor (CAR)-T cell therapies have promising outcomes in hematologic malignancies but limited activity in solid tumors. We used 3-dimentional (3D) in vitro human cell models of increasing complexity to investigate resistance to CAR-T cell therapy in high grade serous ovarian cancer (HGSOC), a disease with poor response to immunotherapy. We identified mucin-1 (MUC1) and TnMUC1 as target antigens in HGSOC omental metastasis and the HGSOC cell lines, OvCAR3 and G164. We then generated CAR-T cells against these targets and tested them in spheroids, collagen gels and microfluidic models. In spheroids, OvCAR3 cells were killed by CAR-T cells whereas, G164 cells were resistant to CAR-T cell cytotoxicity. RNA sequencing suggested that the impaired apoptotic signaling in G164 cells caused malignant cell-intrinsic resistance to CAR-T cell cytotoxicity. Treating G164 spheroids with birinapant, an antagonist of cellular inhibitor of apoptosis protein, induced CAR-T cell cytotoxicity. Moreover, when resistant cells were co-cultured as spheroids with primary omental fibroblasts from ovarian cancer patients, CAR-T cells were activated and cytotoxic. G164 spheroids cultured in fibroblast-conditioned medium also induced CAR-T cell cytotoxicity due to C-C motif chemokine ligand 2 (CCL2) produced by fibroblasts. CCL2 activated CCR2/4+ CAR-T cells to induce cytotoxicity in an antigen-dependent manner. We then investigated CAR-T cell migration and cytotoxicity in malignant cell/fibroblast co-culture collagen gels. CAR-T cell migrated into OvCAR3 gels and were cytotoxic against the malignant cells. However, a dense extracellular matrix (ECM) produced primarily by fibroblasts prevented CAR-T cell migration and cytotoxicity in G164 gels. Treating G164 gels with transforming growth factor beta (TGFβ) receptor inhibitor SB431542 reduced ECM content and altered ECM structure, thus stimulating CAR-T cell penetration and restoring cytotoxicity against G164 cells. We also developed an ovarian cancer-on-a-chip model which involved culturing cell-seeded collagen gels in vascularized tri-channel microfluidic devices. CAR-T cells successfully penetrated and killed malignant cells in co-culture collagen gels when delivered through vascularized microfluidic devices. To our knowledge, this is the first report to use microfluidic tumor models to successfully deliver CAR-T cells. Using these different human 3D in vitro models, we uncovered malignant cell-intrinsic factors and novel mechanisms involving fibroblasts which may influence CAR-T cell activity. Complex human cell models may accelerate preclinical research into CAR-T cell therapies in solid tumors. Citation Format: Joash Dominic Joy, Beatrice Malacrida, Florian Laforêts, Panoraia Kotantaki, Eleni Maniati, Sarah Hopkins, Ianire Garrobo-Calleja, Julien Gautrot, Frances Balkwill. 3D in vitro models uncover malignant cell intrinsic and extrinsic mechanisms of CAR-T cell resistance in high grade serous ovarian cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4576.

Recapitulating Tumor Hypoxia in a Cleanroom-Free, Liquid-Pinning-Based Microfluidic Tumor Model.

In tumors, the metabolic demand of cancer cells often outpaces oxygen supply, resulting in a gradient of tumor hypoxia accompanied with heterogeneous resistance to cancer therapeutics. Models recapitulating tumor hypoxia are therefore essential for developing more effective cancer therapeutics. Existing in vitro models often fail to capture the spatial heterogeneity of tumor hypoxia or involve high-cost, complex fabrication/handling techniques. Here, we designed a highly tunable microfluidic device that induces hypoxia through natural cell metabolism and oxygen diffusion barriers. We adopted a cleanroom-free, micromilling-replica-molding strategy and a microfluidic liquid-pinning approach to streamline the fabrication and tumor model establishment. We also implemented a thin-film oxygen diffusion barrier design, which was optimized through COMSOL simulation, to support both two-dimensional (2-D) and three-dimensional (3-D) hypoxic models. We demonstrated that liquid-pinning enables an easy, injection-based micropatterning of cancer cells of a wide range of parameters, showing the high tunability of our design. Human breast cancer and prostate cancer cells were seeded and stained after 24 h of 2-D and 3-D culture to validate the natural induction of hypoxia. We further demonstrated the feasibility of the parallel microfluidic channel design to evaluate dual therapeutic conditions in the same device. Overall, our new microfluidic tumor model serves as a user-friendly, cost-effective, and highly scalable platform that provides spatiotemporal analysis of the hypoxic tumor microenvironments suitable for high-content biological studies and therapeutic discoveries.

Technological Advances in Tumor-On-Chip Technology: From Bench to Bedside.

Simple SummaryVarious 3D in vitro tumor models are rapidly advancing cancer research. Unlike animal models, they can be produced quickly and are amenable to high-throughput studies. Growing tumor spheroids in microfluidic tumor-on-chip platforms has particularly elevated the capabilities of such models. Tumor-on-chip devices can mimic multiple aspects of the dynamic in vivo tumor microenvironment in a precisely controlled manner. Moreover, new technologies for the on- and off-chip analysis of these tumor mimics are continuously emerging. There is thus an urgent need to review the latest developments in this rapidly progressing field. Here, we present an overview of the technological advances in tumor-on-chip technology by reviewing state-of-the-art tools for on-chip analysis. In particular, we evaluate the potential for tumor-on-chip technology to guide personalized cancer therapies. We strive to appeal to cancer researchers and biomedical engineers alike, informing on current progress, while provoking thought on the outstanding developments needed to achieve clinical-stage research.Tumor-on-chip technology has cemented its importance as an in vitro tumor model for cancer research. Its ability to recapitulate different elements of the in vivo tumor microenvironment makes it promising for translational medicine, with potential application in enabling personalized anti-cancer therapies. Here, we provide an overview of the current technological advances for tumor-on-chip generation. To further elevate the functionalities of the technology, these approaches need to be coupled with effective analysis tools. This aspect of tumor-on-chip technology is often neglected in the current literature. We address this shortcoming by reviewing state-of-the-art on-chip analysis tools for microfluidic tumor models. Lastly, we focus on the current progress in tumor-on-chip devices using patient-derived samples and evaluate their potential for clinical research and personalized medicine applications.

3D microfluidic tumor models for biomimetic engineering of glioma niche and detection of cell morphology, migration and phenotype change

In this work, an integrated 3-dimensional microfluidic device was developed for simulation of the immune microenvironment of glioma niche through the co-culture of three kinds of related cells. Glioma cells, endothelial cells and macrophages were co-cultured together in the microfluidic device, spatially separated by the design of a coffer structure and the use of hydrogel. This platform enabled separate monitoring of the morphology change and migration of cells, as well as molecular interactions between different kinds of cells. Tumor cells were found to exhibit EMT like shape change to become thinner, and sensitive perception and taxis toward macrophages. The influence of tumor cells and the microenvironment, macrophages would be re-educated and the phenotype could be changed from M1 (tumor-suppressive) to M2 (tumor-supportive), which could be validated through cytokines analysis. This 3D microfluidic tumor model provides a powerful tool for studying the biological properties of glioma niche.

Indirect co-culture of lung carcinoma cells with hyperthermia-treated mesenchymal stem cells influences tumor spheroid growth in a collagen-based 3-dimensional microfluidic model

BackgroundMesenchymal stem cells (MSCs) have paradoxically been reported to exert either pro- or anti-tumor effects in vitro. Hyperthermia, in combination with chemotherapy, has tumor-inhibiting effects; however, its role, together with MSCs, so far is not well understood. Furthermore, a lot of research is conducted using conventional 2-dimensional in vitro models that do not mimic the actual tumor microenvironment. AimIn light of this fact, an indirect method of co-culturing human amniotic membrane-derived MSCs (AMMSCs) with collagen-encapsulated human lung carcinoma cells (A549) was performed using a 3-dimensional (3D) tumor-on-chip device. MethodsThe conditioned medium of AMMSCs (AMMSC-CM) or heat-treated AMMSCs (heat-AMMSC-CM) was utilized to create indirect co-culture conditions. Tumor spheroid growth characterization, immunocytochemistry and cytotoxicity assays, and anti-cancer peptide (P1) screening were performed to determine the effects of the conditioned medium. ResultsThe A549 cells cultured inside the 3D microfluidic chip developed into multicellular tumor spheroids over five days of culture. The AMMSC-CM, contrary to previous reports claiming its tumor-inhibiting potential, led to significant proliferation of tumor spheroids. Heat-AMMSC-CM led to reductions in both spheroid diameter and cell proliferation. The medium containing the P1 peptide was found to be the least cytotoxic to tumor spheroids in co-culture compared with the monoculture and heat-co-culture groups. ConclusionsHyperthermia, in combination with the anticancer peptide, exhibited highest cytotoxic effects. This study highlights the growing importance of 3D microfluidic tumor models for testing stem-cell-based and other anti-cancer therapies.

An engineered pancreatic cancer model with intra-tumoral heterogeneity of driver mutations.

Pancreatic ductal adenocarcinoma (PDAC) is a complex disease with significant intra-tumoral heterogeneity (ITH). Currently, no reliable PDAC tumor model is available that can present ITH profiles in a controlled manner. We develop an in vitro microfluidic tumor model mimicking the heterogeneous accumulation of key driver mutations of human PDAC using cancer cells derived from genetically engineered mouse models. These murine pancreatic cancer cell lines have KPC (Kras and Trp53 mutations) and KIC genotypes (Kras mutation and Cdkn2a deletion). Also, the KIC genotypes have two distinct phenotypes - mesenchymal or epithelial. The tumor model mimics the ITH of human PDAC to study the effects of ITH on the gemcitabine response. The results show gemcitabine resistance induced by ITH. Remarkably, it shows that cancer cell-cell interactions induce the gemcitabine resistance potentially through epithelial-mesenchymal-transition. The tumor model can provide a useful testbed to study interaction mechanisms between heterogeneous cancer cell subpopulations.

A Human Organotypic Microfluidic Tumor Model Permits Investigation of the Interplay between Patient-Derived Fibroblasts and Breast Cancer Cells.

Tumor-stroma interactions significantly influence cancer cell metastasis and disease progression. These interactions are partly comprised of the cross-talk between tumor and stromal fibroblasts, but the key molecular mechanisms within the cross-talk that govern cancer invasion are still unclear. Here, we adapted our previously developed microfluidic device as a 3D in vitro organotypic model to mechanistically study tumor-stroma interactions by mimicking the spatial organization of the tumor microenvironment on a chip. We cocultured breast cancer and patient-derived fibroblast cells in 3D tumor and stroma regions, respectively, and combined functional assessments, including cancer cell migration, with transcriptome profiling to unveil the molecular influence of tumor-stroma cross-talk on invasion. This led to the observation that cancer-associated fibroblasts (CAF) enhanced invasion in 3D by inducing expression of a novel gene of interest, glycoprotein nonmetastatic B (GPNMB), in breast cancer cells, resulting in increased migration speed. Importantly, knockdown of GPNMB blunted the influence of CAF on enhanced cancer invasion. Overall, these results demonstrate the ability of our model to recapitulate patient-specific tumor microenvironments to investigate the cellular and molecular consequences of tumor-stroma interactions. SIGNIFICANCE: An organotypic model of tumor-stroma interactions on a microfluidic chip reveals that CAFs promote invasion by enhancing expression of GPNMB in breast cancer cells.

Rapid Assessment of Nanoparticle Extravasation in a Microfluidic Tumor Model

The development of nanoparticle-based targeted therapeutics for the treatment of cancer requires a well-defined understanding of the tumor microenvironment, which is challenging due to tumor complexity and heterogeneity. Recent advancements in three-dimensional (3D) cell models such as tumor-on-a-chip devices can overcome some of these challenges by providing coculture in vitro systems (tumor surrounded by tubular endothelial cells) that mimic native cellular environments to accurately study the enhanced permeability and retention (EPR) potential of drug delivery systems under flow conditions. However, inducing “leaky” vasculature in endothelial cells surrounding solid tumors in microfluidic devices is not readily controllable and highly dependent on tumor cell identity. Utilizing a microfluidic tumor model (MTM) consisting of a tumor region surrounded by a 3D microvascular network, we have simulated the EPR effect by activating a known regulator of endothelial junction formation and edema: the transient ...

Abstract A049: Three-dimensional microfluidic platform mimicking the tumor microenvironment

Abstract Immunotherapy is currently a main breakthrough in cancer treatment, but therapeutic approaches for solid tumors still present limitations in the clinical scenario due to the challenges posed by the immunosuppressive tumor microenvironment (TME). Specifically, among immune cells recruited to the TME, monocytes/macrophages are especially abundant. Macrophages in vitro have been classified as classically activated M1 macrophages and alternatively activated M2 macrophages. However, macrophages are highly plastic cells and they often present mixed phenotypes in the in vivo TME. Monocytes/macrophages are involved in cancer cell proliferation, cell invasion, cell killing, vascular angiogenesis, T-cell immunosuppression, and are often correlated with a poor outcome in an extended range of cancers. However, disrupting the protumor activity of monocytes/macrophages and their interactions with the complex cellular system in the TME remains a challenge. Thus, a better understanding of the mechanisms that modulate monocyte/macrophage phenotype and their interactions with tumors may lead to make them a relevant therapeutic strategy. To study the immunosuppressive TME, we developed microfluidic-based integrated platforms with a 3-dimensional (3D) co-culture of tumor cells and immune cells to investigate how physical and molecular cues in the TME regulate the cellular interplay. Our 3D multicellular platforms offer considerable benefits and have already demonstrated in previous studies a clear advantage over classical 2D platforms to model the TME and to screen for different therapeutic approaches. Our previous studies demonstrated the crucial role of immune system interactions with cancer cells in metastasis either at a primary tumor site or at a secondary metastatic site. Further, we investigated the impact of monocytes and Programmed Death Ligand 1 (PD-L1) immune checkpoint on T-cell receptor (TCR)-engineered T-cells. We have now developed a new 3D microfluidic platform to study the effects of interstitial flow (IF), the flow of fluid through tumor stroma, which is an important component of the TME that may contribute to the polarization of macrophages toward a protumor phenotype. The microfluidic model allows the co-culture of tumor cells and monocytes/macrophages, to stimulate them with IF and to quantify cell migration in 3D. To the best of our knowledge, this study represents the first microfluidic tumor model that incorporates IF and both tumor and immune cells. Our preliminary results confirmed that the presence of tumor cells and hence tumor-cell secreted factors (TSF) increased the migration speed and directedness of macrophages toward cancer cells, potentially contributing to cancer cell dissemination. Interestingly, the presence of the IF-based mechanical cue (without tumor cells in culture) resulted in a similar increase in macrophage migration. Further, by combining both TSF and IF we observed no synergistic or additive effect on macrophage migration. A mixed population of macrophage phenotypes (M1 and M2) was observed with either the stimulus of TSF and/or IF while lower expression levels of M1 and M2 markers were observed without TSF or IF. Importantly, the understanding gained from this investigation can help in the design and functional testing of immunotherapeutic strategies to modulate macrophage polarization in the TME towards an antitumor phenotype. Citation Format: Andrea Pavesi, Siew Cheng Wong, Roger Kamm, Sharon Wei Ling Lee, Giulia Adriani. Three-dimensional microfluidic platform mimicking the tumor microenvironment [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A049.

Microfluidic modelling of the tumor microenvironment for anti-cancer drug development.

Cancer is the leading cause of death worldwide. The complex and disorganized tumor microenvironment makes it very difficult to treat this disease. The most common in vitro drug screening method now is based on 2D culture models which poorly represent actual tumors. Therefore, many 3D tumor models which are more physiologically relevant have been developed to conduct in vitro drug screening and alleviate this situation. Among all these models, the microfluidic tumor model has the unique advantage of recapitulating the tumor microenvironment in a comparatively easier and representative fashion. While there are many review papers available on the related topic of microfluidic tumor models, in this review we aim to focus more on the possibility of generating "clinically actionable information" from these microfluidic systems, besides scientific insight. Our topics cover the tumor microenvironment, conventional 2D and 3D cultures, animal models, and microfluidic tumor models, emphasizing their link to anti-cancer drug discovery and personalized medicine.

Abstract LB-035: 3D microfluidic tumor model for investigating metastatic tumor migration and colonization of secondary sites

Abstract Introduction: The ability to model the microenvironment of primary and secondary tumor sites is critical for advancing treatment options for metastatic breast cancer. There are currently no 3D tumor models that mimic the in vivo vascular geometry and tumor microenvironment for monitoring extravasation, tissue invasion, and colonization of secondary sites by metastatic tumors. In this study, we report on the development of a 3D tumor model with primary and secondary tumor sites, where metastatic breast cancer cells can escape the primary site, circulate in circulation, adhere to the vascular endothelium and subsequently invade distant tissues. Materials and Methods: Multiple synthetic tumor networks comprising primary and secondary tumor sites were developed using in vivo images and fabricated using soft lithography. Fluorescent dyes (FITC-dextran) was used to test the fluidic integrity while nano and micro-particles were used to test the porosity of the developed devices. Primary vascular endothelial cells were cultured in the vascular channels while GFP-labeled metastatic human breast cancer cell line (MDA-MB-231/GFP) or non-metastatic (MCF-7/GFP) was cultured in the primary tumor site in a 3D environment using Matrigel™. The vascular networks were perfused with endothelial cell media under physiological fluid flow conditions. Real-time monitoring of cellular growth, extravasation and invasion was performed using fluorescence microscopy over a four week period. Results and Discussion: Metastatic MDA-MB-231 breast cancer cells proliferated rapidly in the primary tumor site in contrast to non-metastatic MCF-7. Tumor cells were found to initiate a metastatic cascade as early as 7-10 days following growth in the primary site comprising of intravasation into the vascular channels, rolling and adhesion on the endothelium and extravasation into the secondary site. Significant differences were observed on the tumor behavior based on the flow profiles and morphology of the vascular networks. These results provide a unique perspective of the in vivo realism in an in vitro system for monitoring metastasis Conclusions: We have developed a 3D vascularized model for monitoring the invasive growth and the metastatic potential of tumors thereby mimicking the in vivo microenvironment of solid tumors. This model can be used to investigate tumor-endothelial cell interactions using a combination of real-time imaging techniques and screening of targeted therapeutics that may reduce the metastatic potential of tumors. Citation Format: Deborah Ramsey, Dustin Haithcock, Charles Garson, Ashley Gilbert, Ketan Bhatt, Balabhaskar Prabhakarpandian, Kapil Pant. 3D microfluidic tumor model for investigating metastatic tumor migration and colonization of secondary sites [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-035.

Differential response to doxorubicin in breast cancer subtypes simulated by a microfluidic tumor model

Successful drug delivery and overcoming drug resistance are the primary clinical challenges for management and treatment of cancer. The ability to rapidly screen drugs and delivery systems within physiologically relevant environments is critically important; yet is currently limited due to lack of appropriate tumor models. To address this problem, we developed the Tumor-microenvironment-on-chip (T-MOC), a new microfluidic tumor model simulating the interstitial flow, plasma clearance, and transport of the drug within the tumor. We demonstrated T-MOC's capabilities by assessing the delivery and efficacy of doxorubicin in small molecular form versus hyaluronic acid nanoparticle (NP) formulation in MCF-7 and MDA-MB-231, two cell lines representative of different molecular subtypes of breast cancer. Doxorubicin accumulated and penetrated similarly in both cell lines while the NP accumulated more in MDA-MB-231 than MCF-7 potentially due to binding of hyaluronic acid to CD44 expressed by MDA-MB-231. However, the penetration of the NP was less than the molecular drug due to its larger size. In addition, both cell lines cultured on the T-MOC showed increased resistance to the drug compared to 2D culture where MDA-MB-231 attained a drug-resistant tumor-initiating phenotype indicated by increased CD44 expression. When grown in immunocompromised mice, both cell lines exhibited cell-type-dependent resistance and phenotypic changes similar to T-MOC, confirming its predictive ability for in vivo drug response. This initial characterization of T-MOC indicates its transformative potential for in vitro testing of drug efficacy towards prediction of in vivo outcomes and investigation of drug resistance mechanisms for advancement of personalized medicine.

In vitro microfluidic models of tumor microenvironment to screen transport of drugs and nanoparticles.

Advances in nanotechnology have enabled numerous types of nanoparticles (NPs) to improve drug delivery to tumors. While many NP systems have been proposed, their clinical translation has been less than anticipated primarily due to failure of current preclinical evaluation techniques to adequately model the complex interactions between the NP and physiological barriers of tumor microenvironment. This review focuses on microfluidic tumor models for characterization of delivery efficacy and toxicity of cancer nanomedicine. Microfluidics offer significant advantages over traditional macroscale cell cultures by enabling recapitulation of tumor microenvironment through precise control of physiological cues such as hydrostatic pressure, shear stress, oxygen, and nutrient gradients. Microfluidic systems have recently started to be adapted for screening of drugs and NPs under physiologically relevant settings. So far the two primary application areas of microfluidics in this area have been high-throughput screening using traditional culture settings such as single cells or multicellular tumor spheroids, and mimicry of tumor microenvironment for study of cancer-related cell-cell and cell-matrix interactions. These microfluidic technologies are also useful in modeling specific steps in NP delivery to tumor and characterize NP transport properties and outcomes by systematic variation of physiological conditions. Ultimately, it will be possible to design drug-screening platforms uniquely tailored for individual patient physiology using microfluidics. These in vitro models can contribute to development of precision medicine by enabling rapid and patient-specific evaluation of cancer nanomedicine. WIREs Nanomed Nanobiotechnol 2017, 9:e1460. doi: 10.1002/wnan.1460 For further resources related to this article, please visit the WIREs website.

M2a macrophages induce contact-dependent dispersion of carcinoma cell aggregates

Monocytes and macrophages accumulate at the site of tumors driven by chemokines such as CCL2, monocyte chemotactic protein 1 (MCP1), vascular endothelial growth factor (VEGF), and macrophage colony stimulating factor (M-CSF). Convincing evidence suggests that tumor-associated macrophages (TAMs) promote tumor growth, epithelial-mesenchymal transition (EMT) and intravasation of blood and lymph vessels. Recently, we reported experimental findings in a microfluidic tumor model demonstrating that M2a macrophages induce contact-dependent EMT of carcinoma cell aggregates via ICAM-1 and integrin β2 interactions. These findings support the pro-metastatic activities of M2a macrophages and may help in designing novel immunotherapies for cancer patients.

Phosphorescent nanoparticles for quantitative measurements of oxygen profiles in vitro and in vivo

We present the development and characterization of nanoparticles loaded with a custom phosphor; we exploit these nanoparticles to perform quantitative measurements of the concentration of oxygen within three-dimensional (3-D) tissue cultures in vitro and blood vessels in vivo. We synthesized a customized ruthenium (Ru)-phosphor and incorporated it into polymeric nanoparticles via self-assembly. We demonstrate that the encapsulated phosphor is non-toxic with and without illumination. We evaluated two distinct modes of employing the phosphorescent nanoparticles for the measurement of concentrations of oxygen: 1) in vitro, in a 3-D microfluidic tumor model via ratiometric measurements of intensity with an oxygen-insensitive fluorophore as a reference, and 2) in vivo, in mouse vasculature using measurements of phosphorescence lifetime. With both methods, we demonstrated micrometer-scale resolution and absolute calibration to the dissolved oxygen concentration. Based on the ease and customizability of the synthesis of the nanoparticles and the flexibility of their application, these oxygen-sensing polymeric nanoparticles will find a natural home in a range of biological applications, benefiting studies of physiological as well as pathological processes in which oxygen availability and concentration play a critical role.

Microfluidic Culture Models of Tumor Angiogenesis

Blood vessels control all stages of tumor development and therapy by defining the physicochemical and cellular state of the tumor microenvironment. However, no pathologically relevant culture systems currently exist that recapitulate the associated cellular and convective mass transfer processes that are implicated in tumor angiogenesis. By integrating tissue engineering and microfluidic technologies, it will be possible to develop tumor-mimetic culture environments with embedded microvascular structures. Utilization of these microfluidic tumor models will help reveal the importance of the transport of chemical and cellular factors in tumor angiogenesis, and provide a test bed that may ultimately improve current strategies to antiangiogenic therapy.