"In vitro" 3D models of tumor-immune system interaction

Contributions of 3D Cell Cultures for Cancer Research

Cancer cell lines have contributed immensely in understanding the complex physiology of cancers. They are excellent material for studies as they offer homogenous samples without individual variations and can be utilised with ease and flexibility. Also, the number of assays and end-points one can study is almost limitless; with the advantage of improvising, modifying or altering several variables and methods. Literally, a new dimension to cancer research has been achieved by the advent of 3Dimensional (3D) cell culture techniques. This approach increased many folds the ways in which cancer cell lines can be utilised for understanding complex cancer biology. 3D cell culture techniques are now the preferred way of using cancer cell lines to bridge the gap between the 'absolute in vitro' and 'true in vivo'. The aspects of cancer biology that 3D cell culture systems have contributed include morphology, microenvironment, gene and protein expression, invasion/migration/metastasis, angiogenesis, tumour metabolism and drug discovery, testing chemotherapeutic agents, adaptive responses and cancer stem cells. We present here, a comprehensive review on the applications of 3D cell culture systems for these aspects of cancers. J. Cell. Physiol. 232: 2679-2697, 2017. © 2016 Wiley Periodicals, Inc.

Engineering a Cell Home for Stem Cell Homing and Accommodation

Distilling complexity to advance regenerative medicine from laboratory animals to humans, in situ regeneration will continue to evolve using biomaterial strategies to drive endogenous cells within the human body for therapeutic purposes; this approach avoids the need for delivering ex vivo-expanded cellular materials. Ensuring the recruitment of a significant number of reparative cells from an endogenous source to the site of interest is the first step toward achieving success. Subsequently, making the "cell home" cell-friendly by recapitulating the natural extracellular matrix (ECM) in terms of its chemistry, structure, dynamics, and function, and targeting specific aspects of the native stem cell niche (e.g., cell-ECM and cell-cell interactions) to program and steer the fates of those recruited stem cells play equally crucial roles in yielding a therapeutically regenerative solution. This review addresses the key aspects of material-guided cell homing and the engineering of novel biomaterials with desirable ECM composition, surface topography, biochemistry, and mechanical properties that can present both biochemical and physical cues required for in situ tissue regeneration. This growing body of knowledge will likely become a design basis for the development of regenerative biomaterials for, but not limited to, future in situ tissue engineering and regeneration.

Molecular and Functional Diagnostic Tools in Precision Oncology for Urological Malignancies

Urological malignancies, represented mainly by prostate, bladder, and renal cancers, are some of the leading causes of cancer-related mortalities worldwide. Despite various efforts over decades to develop early detection tests and effective therapeutic paradigms, the response rate to the existing treatments remains low for both primary and late stage/recurrent phases of these cancers. The evolving landscape of molecular diagnostics, aiming to make the diagnosis and treatment more patient-driven, underpins precision oncology and particularly intends to rationally profile individual tumors and highlight the mechanistic insight and complexity of tumor microenvironment in order to develop biomarkers of toxicity risks and response prediction in a clinically oriented dynamical setting. The present review is an effort to capture some of the recent developments in the area of molecular diagnostics and functional testing platforms and their potential application in clinical decision making in the premises of precision oncology of urological malignancies.

Monocarboxylate transporters in the brain and in cancer

Monocarboxylate transporters (MCTs) constitute a family of 14 members among which MCT1-4 facilitate the passive transport of monocarboxylates such as lactate, pyruvate and ketone bodies together with protons across cell membranes. Their anchorage and activity at the plasma membrane requires interaction with chaperon protein such as basigin/CD147 and embigin/gp70. MCT1-4 are expressed in different tissues where they play important roles in physiological and pathological processes. This review focuses on the brain and on cancer. In the brain, MCTs control the delivery of lactate, produced by astrocytes, to neurons, where it is used as an oxidative fuel. Consequently, MCT dysfunctions are associated with pathologies of the central nervous system encompassing neurodegeneration and cognitive defects, epilepsy and metabolic disorders. In tumors, MCTs control the exchange of lactate and other monocarboxylates between glycolytic and oxidative cancer cells, between stromal and cancer cells and between glycolytic cells and endothelial cells. Lactate is not only a metabolic waste for glycolytic cells and a metabolic fuel for oxidative cells, but it also behaves as a signaling agent that promotes angiogenesis and as an immunosuppressive metabolite. Because MCTs gate the activities of lactate, drugs targeting these transporters have been developed that could constitute new anticancer treatments. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

Concise review: humanized models of tumor immunology in the 21st century: convergence of cancer research and tissue engineering

Despite positive testing in animal studies, more than 80% of novel drug candidates fail to proof their efficacy when tested in humans. This is primarily due to the use of preclinical models that are not able to recapitulate the physiological or pathological processes in humans. Hence, one of the key challenges in the field of translational medicine is to "make the model organism mouse more human." To get answers to questions that would be prognostic of outcomes in human medicine, the mouse's genome can be altered in order to create a more permissive host that allows the engraftment of human cell systems. It has been shown in the past that these strategies can improve our understanding of tumor immunology. However, the translational benefits of these platforms have still to be proven. In the 21st century, several research groups and consortia around the world take up the challenge to improve our understanding of how to humanize the animal's genetic code, its cells and, based on tissue engineering principles, its extracellular microenvironment, its tissues, or entire organs with the ultimate goal to foster the translation of new therapeutic strategies from bench to bedside. This article provides an overview of the state of the art of humanized models of tumor immunology and highlights future developments in the field such as the application of tissue engineering and regenerative medicine strategies to further enhance humanized murine model systems.

Microfluidics: A new tool for modeling cancer-immune interactions

In recognition of the enormous potential of immunotherapies against cancer, research into the interactions between tumor and immune cells has accelerated, leading to the recent FDA approval of several drugs that reduce cancer progression. Numerous cellular and molecular interactions have been identified by which immune cells can intervene in the metastatic cascade, leading to the development of several in vivo and in vitro model systems that can recapitulate these processes. Among these, microfluidic technologies hold many advantages in terms of their unique ability to capture the essential features of multiple cell type interactions in three-dimensions while allowing tight control of the microenvironment and real-time monitoring. Here, we review current assays and discuss the development of new microfluidic technologies for immunotherapy.

Biomaterials and emerging anticancer therapeutics: engineering the microenvironment

The microenvironment is increasingly recognized to have key roles in cancer, and biomaterials provide a means to engineer microenvironments both in vitro and in vivo to study and manipulate cancer. In vitro cancer models using 3D matrices recapitulate key elements of the tumour microenvironment and have revealed new aspects of cancer biology. Cancer vaccines based on some of the same biomaterials have, in parallel, allowed for the engineering of durable prophylactic and therapeutic anticancer activity in preclinical studies, and some of these vaccines have moved to clinical trials. The impact of biomaterials engineering on cancer treatment is expected to further increase in importance in the years to come.

Patterning hypoxic multicellular spheroids in a 3D matrix - a promising method for anti-tumor drug screening

3D multicellular spheroid models are of great value in the investigation of tumor biology and tumor responses to chemotherapy and radiation. To establish a mimicking tumor microenvironment in vitro, we developed a straightforward method by patterning hypoxic multicellular spheroids in a 3D matrix. The efficacy of this approach was evaluated by characterizing spheroid formation, invasive capability and phenotypic transition in aggressive human glioma cells. We observed enhanced cell proliferation, spheroid formation and invasive capability in U87 glioma cells transfected with hypoxia-inducible factors (HIFs) compared with non-treated cells. We also demonstrated that the overexpression of HIFs in hypoxic glioma cells may promote cell migration by epithelial-mesenchymal transition within the 3D matrix. Compared with conventional 3D culturing techniques, the simple operation, rapid prototyping, low cost and high throughput format of the micro-patterning method facilitates the characterization of cell proliferation, migration, phenotypic function and drug evaluation in physiologically relevant 3D microenvironments. This in vitro 3D system can recapitulate the physiologically relevant tumor microenvironment and is a promising method for 3D anti-tumor drug screening and the identification of novel targets for tumor invasion and angiogenesis.

Engineering cancer microenvironments for in vitro 3-D tumor models

The natural microenvironment of tumors is composed of extracellular matrix (ECM), blood vasculature, and supporting stromal cells. The physical characteristics of ECM as well as the cellular components play a vital role in controlling cancer cell proliferation, apoptosis, metabolism, and differentiation. To mimic the tumor microenvironment outside the human body for drug testing, two-dimensional (2-D) and murine tumor models are routinely used. Although these conventional approaches are employed in preclinical studies, they still present challenges. For example, murine tumor models are expensive and difficult to adopt for routine drug screening. On the other hand, 2-D in vitro models are simple to perform, but they do not recapitulate natural tumor microenvironment, because they do not capture important three-dimensional (3-D) cell-cell, cell-matrix signaling pathways, and multi-cellular heterogeneous components of the tumor microenvironment such as stromal and immune cells. The three-dimensional (3-D) in vitro tumor models aim to closely mimic cancer microenvironments and have emerged as an alternative to routinely used methods for drug screening. Herein, we review recent advances in 3-D tumor model generation and highlight directions for future applications in drug testing.

Precision medicine for cancer with next-generation functional diagnostics

Precision medicine is about matching the right drugs to the right patients. Although this approach is technology agnostic, in cancer there is a tendency to make precision medicine synonymous with genomics. However, genome-based cancer therapeutic matching is limited by incomplete biological understanding of the relationship between phenotype and cancer genotype. This limitation can be addressed by functional testing of live patient tumour cells exposed to potential therapies. Recently, several 'next-generation' functional diagnostic technologies have been reported, including novel methods for tumour manipulation, molecularly precise assays of tumour responses and device-based in situ approaches; these address the limitations of the older generation of chemosensitivity tests. The promise of these new technologies suggests a future diagnostic strategy that integrates functional testing with next-generation sequencing and immunoprofiling to precisely match combination therapies to individual cancer patients.

Engineering opportunities in cancer immunotherapy

Immunotherapy has great potential to treat cancer and prevent future relapse by activating the immune system to recognize and kill cancer cells. A variety of strategies are continuing to evolve in the laboratory and in the clinic, including therapeutic noncellular (vector-based or subunit) cancer vaccines, dendritic cell vaccines, engineered T cells, and immune checkpoint blockade. Despite their promise, much more research is needed to understand how and why certain cancers fail to respond to immunotherapy and to predict which therapeutic strategies, or combinations thereof, are most appropriate for each patient. Underlying these challenges are technological needs, including methods to rapidly and thoroughly characterize the immune microenvironment of tumors, predictive tools to screen potential therapies in patient-specific ways, and sensitive, information-rich assays that allow patient monitoring of immune responses, tumor regression, and tumor dissemination during and after therapy. The newly emerging field of immunoengineering is addressing some of these challenges, and there is ample opportunity for engineers to contribute their approaches and tools to further facilitate the clinical translation of immunotherapy. Here we highlight recent technological advances in the diagnosis, therapy, and monitoring of cancer in the context of immunotherapy, as well as ongoing challenges.

Into the depths: Techniques for in vitro three-dimensional microtissue visualization

Three-dimensional (3-D) in vitro platforms have been shown to closely recapitulate human physiology when compared with conventional two-dimensional (2-D) in vitro or in vivo animal model systems. This confers a substantial advantage in evaluating disease mechanisms, pharmaceutical drug discovery, and toxicity testing. Despite the benefits of 3-D cell culture, limitations in visualization and imaging of 3-D microtissues present significant challenges. Here we optimized histology and microscopy techniques to overcome the constraints of 3-D imaging. For morphological assessment of 3-D microtissues of several cell types, different time points, and different sizes, a two-step glycol methacrylate embedding protocol for evaluating 3-D microtissues produced using agarose hydrogels improved resolution of nuclear and cellular histopathology characteristic of cell death and proliferation. Additional immunohistochemistry, immunofluorescence, and in situ immunostaining techniques were successfully adapted to these microtissues and enhanced by optical clearing. Utilizing the Clear(T2) protocol greatly increased fluorescence signal intensity, imaging depth, and clarity, allowing for more complete confocal fluorescence microscopy imaging of these 3-D microtissues compared with uncleared samples. The refined techniques presented here address the key challenges associated with 3-D imaging, providing new and alternative methods in evaluating disease pathogenesis, delineating toxicity pathways, and enhancing the versatility of 3-D in vitro testing systems in pharmacological and toxicological applications.

Associations of chemo- and radio-resistant phenotypes with the gap junction, adhesion and extracellular matrix in a three-dimensional culture model of soft sarcoma

Background

Three-dimensional (3D) culture models are considered to recapitulate the cell microenvironment in solid tumors, including the extracellular matrix (ECM), cell-cell interactions, and signal transduction. These functions are highly correlated with cellular behaviors and contribute to resistances against chemo- and radio-therapies. However, the biochemical effects and mechanisms remain unknown in soft sarcoma. Therefore, we developed an in vitro 3D model of sarcoma to analyze the reasons of the chemo- and radio-resistance in therapies.

Methods

Four soft sarcoma cell lines, HT1080, RD, SW872, and human osteosarcoma cell line 1 (HOSS1), a cell line established from a patient-derived xenograft, were applied to 3D culture and treated with growth factors in methylcellulose-containing medium. Spheroids were examined morphologically and by western blotting, RT-qPCR, and immunofluorescence staining to analyze cell adhesion, gap junctions, ECM genes, and related factors. Proliferation and colony formation assays were performed to assess chemo- and radio-resistances between 3D and two-dimensional (2D) cell cultures. Annexin V and Propidium Iodide staining was used to detect early apoptotic sarcoma cells treated with Doxorubicin, Gemcitabine, and Docetaxel in the 3D model.

Results

The four soft sarcoma cell lines formed spheres in vitro by culture in modified condition medium. Compared with 2D cell culture, expression of ECM genes and proteins, including COL1A1, LOX, SED1, FN1, and LAMA4, was significantly increased in 3D culture. Analysis of cadherin and gap junction molecules showed significant changes in the gene and protein expression profiles under 3D conditions. These changes affected cell–cell communication and were mainly associated with biological processes such as cell proliferation and apoptosis related to chemo- and radio-resistances.

Conclusions

Our findings revealed significant differences between 3D and 2D cell culture systems, and indicated that cellular responsiveness to external stress such as radiation and chemotherapeutics is influenced by differential expression of genes and proteins involved in regulation of the ECM, cell adhesion, and gap junction signaling.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0175-0) contains supplementary material, which is available to authorized users.

Predicting clinical response to anticancer drugs using an ex vivo platform that captures tumour heterogeneity

Predicting clinical response to anticancer drugs remains a major challenge in cancer treatment. Emerging reports indicate that the tumour microenvironment and heterogeneity can limit the predictive power of current biomarker-guided strategies for chemotherapy. Here we report the engineering of personalized tumour ecosystems that contextually conserve the tumour heterogeneity, and phenocopy the tumour microenvironment using tumour explants maintained in defined tumour grade-matched matrix support and autologous patient serum. The functional response of tumour ecosystems, engineered from 109 patients, to anticancer drugs, together with the corresponding clinical outcomes, is used to train a machine learning algorithm; the learned model is then applied to predict the clinical response in an independent validation group of 55 patients, where we achieve 100% sensitivity in predictions while keeping specificity in a desired high range. The tumour ecosystem and algorithm, together termed the CANScript technology, can emerge as a powerful platform for enabling personalized medicine.

Mathematical model of brain tumour with glia-neuron interactions and chemotherapy treatment

In recent years, it became clear that a better understanding of the interactions among the main elements involved in the cancer network is necessary for the treatment of cancer and the suppression of cancer growth. In this work we propose a system of coupled differential equations that model brain tumour under treatment by chemotherapy, which considers interactions among the glial cells, the glioma, the neurons, and the chemotherapeutic agents. We study the conditions for the glioma growth to be eliminated, and identify values of the parameters for which the inhibition of the glioma growth is obtained with a minimal loss of healthy cells.

Lessons from patient-derived xenografts for better in vitro modeling of human cancer

The development of novel cancer therapeutics is often plagued by discrepancies between drug efficacies obtained in preclinical studies and outcomes of clinical trials. The inconsistencies can be attributed to a lack of clinical relevance of the cancer models used for drug testing. While commonly used in vitro culture systems are advantageous for addressing specific experimental questions, they are often gross, fidelity-lacking simplifications that largely ignore the heterogeneity of cancers as well as the complexity of the tumor microenvironment. Factors such as tumor architecture, interactions among cancer cells and between cancer and stromal cells, and an acidic tumor microenvironment are critical characteristics observed in patient-derived cancer xenograft models and in the clinic. By mimicking these crucial in vivo characteristics through use of 3D cultures, co-culture systems and acidic culture conditions, an in vitro cancer model/microenvironment that is more physiologically relevant may be engineered to produce results more readily applicable to the clinic.