Catarina Pinto

Adaptable stirred-tank culture strategies for large scale production of multicellular spheroid-based tumor cell models.

Currently there is an effort toward the development of in vitro cancer models more predictive of clinical efficacy. The onset of advanced analytical tools and imaging technologies has increased the utilization of spheroids in the implementation of high throughput approaches in drug discovery. Agitation-based culture systems are commonly proposed as an alternative method for the production of tumor spheroids, despite the scarce experimental evidence found in the literature. In this study, we demonstrate the robustness and reliability of stirred-tank cultures for the scalable generation of 3D cancer models. We developed standardized protocols to a panel of tumor cell lines from different pathologies and attained efficient tumor cell aggregation by tuning hydrodynamic parameters. Large numbers of spheroids were obtained (typically 1000-1500 spheroids/mL) presenting features of native tumors, namely morphology, proliferation and hypoxia gradients, in a cell line-dependent mode. Heterotypic 3D cancer models, based on co-cultures of tumor cells and fibroblasts, were also established in the absence or presence of additional physical support from an alginate matrix, with maintenance of high cell viability. Altogether, we demonstrate that 3D tumor cell model production in stirred-tank culture systems is a robust and versatile approach, providing reproducible tools for drug screening and target verification in pre-clinical oncology research.

Modeling human neural functionality in vitro: three-dimensional culture for dopaminergic differentiation.

Advances in mechanistic knowledge of human neurological disorders have been hindered by the lack of adequate human in vitro models. Three-dimensional (3D) cellular models displaying higher biological relevance are gaining momentum; however, their lack of robustness and scarcity of analytical tools adapted to three dimensions hampers their widespread implementation. Herein we show that human midbrain-derived neural progenitor cells, cultured as 3D neurospheres in stirred culture systems, reproducibly differentiate into complex tissue-like structures containing functional dopaminergic neurons, as well as astrocytes and oligodendrocytes. Moreover, an extensive toolbox of analytical methodologies has been adapted to 3D neural cell models, allowing molecular and phenotypic profiling and interrogation. The generated neurons underwent synaptogenesis and elicit spontaneous Ca(2+) transients. Synaptic vesicle trafficking and release of dopamine in response to depolarizing stimuli was also observed. Under whole-cell current-and-voltage clamp, recordings showed polarized neurons (Vm=-70 mV) and voltage-dependent potassium currents, which included A-type-like currents. Glutamate-induced currents sensitive to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate antagonists revealed the existence of functional glutamate receptors. Molecular and phenotypic profiling showed recapitulation of midbrain patterning events, and remodeling toward increased similarity to human brain features, such as extracellular matrix composition and metabolic signature. We have developed a robust and reproducible human 3D neural cell model, which may be extended to patient-derived induced pluripotent stem cells, broadening the applicability of this model.

Imaging of human differentiated 3D neural aggregates using light sheet fluorescence microscopy

The development of three dimensional (3D) cell cultures represents a big step for the better understanding of cell behavior and disease in a more natural like environment, providing not only single but multiple cell type interactions in a complex 3D matrix, highly resembling physiological conditions. Light sheet fluorescence microscopy (LSFM) is becoming an excellent tool for fast imaging of such 3D biological structures. We demonstrate the potential of this technique for the imaging of human differentiated 3D neural aggregates in fixed and live samples, namely calcium imaging and cell death processes, showing the power of imaging modality compared with traditional microscopy. The combination of light sheet microscopy and 3D neural cultures will open the door to more challenging experiments involving drug testing at large scale as well as a better understanding of relevant biological processes in a more realistic environment.

Evaluation of helper-dependent canine adenovirus vectors in a 3D human CNS model.

Gene therapy is a promising approach with enormous potential for treatment of neurodegenerative disorders. Viral vectors derived from canine adenovirus type 2 (CAV-2) present attractive features for gene delivery strategies in the human brain, by preferentially transducing neurons, are capable of efficient axonal transport to afferent brain structures, have a 30-kb cloning capacity and have low innate and induced immunogenicity in preclinical tests. For clinical translation, in-depth preclinical evaluation of efficacy and safety in a human setting is primordial. Stem cell-derived human neural cells have a great potential as complementary tools by bridging the gap between animal models, which often diverge considerably from human phenotype, and clinical trials. Herein, we explore helper-dependent CAV-2 (hd-CAV-2) efficacy and safety for gene delivery in a human stem cell-derived 3D neural in vitro model. Assessment of hd-CAV-2 vector efficacy was performed at different multiplicities of infection, by evaluating transgene expression and impact on cell viability, ultrastructural cellular organization and neuronal gene expression. Under optimized conditions, hd-CAV-2 transduction led to stable long-term transgene expression with minimal toxicity. hd-CAV-2 preferentially transduced neurons, whereas human adenovirus type 5 (HAdV5) showed increased tropism toward glial cells. This work demonstrates, in a physiologically relevant 3D model, that hd-CAV-2 vectors are efficient tools for gene delivery to human neurons, with stable long-term transgene expression and minimal cytotoxicity.

Perfusion Stirred-Tank Bioreactors for 3D Differentiation of Human Neural Stem Cells

Therapeutic breakthroughs in neurological disorders have been hampered by the lack of accurate central nervous system (CNS) models. The development of these models allows the study of the disease onset/progression mechanisms and the preclinical evaluation of new therapeutics. This has traditionally relied on genetically engineered animal models that often diverge considerably from the human phenotype (developmental, anatomic, and physiological) and 2D in vitro cell models, which fail to recapitulate the characteristics of the target tissue (cell-cell and cell-matrix interactions, cell polarity, etc.). Recapitulation of CNS phenotypic and functional features in vitro requires the implementation of advanced culture strategies, such as 3D culture systems, which enable to mimic the in vivo structural and molecular complexity. Models based on differentiation of human neural stem cells (hNSC) in 3D cultures have great potential as complementary tools in preclinical research, bridging the gap between human clinical studies and animal models. The development of robust and scalable processes for the 3D differentiation of hNSC can improve the accuracy of early stage development in preclinical research. In this context, the use of software-controlled stirred-tank bioreactors (STB) provides an efficient technological platform for hNSC aggregation and differentiation. This system enables to monitor and control important physicochemical parameters for hNSC culture, such as dissolved oxygen. Importantly, the adoption of a perfusion operation mode allows a stable flow of nutrients and differentiation/neurotrophic factors, while clearing the toxic by-products. This contributes to a setting closer to the physiological, by mimicking the in vivo microenvironment. In this chapter, we address the technical requirements and procedures for the implementation of 3D differentiation strategies of hNSC, by operating STB under perfusion mode for long-term cultures. This strategy is suitable for the generation of human 3D neural in vitro models, which can be used to feed high-throughput screening platforms, contributing to expand the available in vitro tools for drug screening and toxicological studies.

3D-3-culture: A tool to unveil macrophage plasticity in the tumour microenvironment

The tumour microenvironment (TME) shapes disease progression and influences therapeutic response. Most aggressive solid tumours have high levels of myeloid cell infiltration, namely tumour associated macrophages (TAM). Recapitulation of the interaction between the different cellular players of the TME, along with the extracellular matrix (ECM), is critical for understanding the mechanisms underlying disease progression. This particularly holds true for prediction of therapeutic response(s) to standard therapies and interrogation of efficacy of TME-targeting agents. In this work, we explored a culture platform based on alginate microencapsulation and stirred culture systems to develop the 3D-3-culture, which entails the co-culture of tumour cell spheroids of non-small cell lung carcinoma (NSCLC), cancer associated fibroblasts (CAF) and monocytes. We demonstrate that the 3D-3-culture recreates an invasive and immunosuppressive TME, with accumulation of cytokines/chemokines (IL4, IL10, IL13, CCL22, CCL24, CXCL1), ECM elements (collagen type I, IV and fibronectin) and matrix metalloproteinases (MMP1/9), supporting cell migration and promoting cell-cell interactions within the alginate microcapsules. Importantly, we show that both the monocytic cell line THP-1 and peripheral blood-derived monocytes infiltrate the tumour tissue and transpolarize into an M2-like macrophage phenotype expressing CD68, CD163 and CD206, resembling the TAM phenotype in NSCLC. The 3D-3-culture was challenged with chemo- and immunotherapeutic agents and the response to therapy was assessed in each cellular component. Specifically, the macrophage phenotype was modulated upon treatment with the CSF1R inhibitor BLZ945, resulting in a decrease of the M2-like macrophages. In conclusion, the crosstalk between the ECM and tumour, stromal and immune cells in microencapsulated 3D-3-culture promotes the activation of monocytes into TAM, mimicking aggressive tumour stages. The 3D-3-culture constitutes a novel tool to study tumour-immune interaction and macrophage plasticity in response to external stimuli, such as chemotherapeutic and immunomodulatory drugs.

1H-NMR spectroscopy for human 3D neural stem cell cultures metabolic profiling

Background The current lack of predictable central nervous system (CNS) models in pharmaceutical industry early stage development strongly contributes for the high attrition rates registered for new therapeutics [1]. Thus, there is an increasing need for a paradigm shift towards more human relevant cell models, which can closely recapitulate the in vivo cell-cell interactions, presenting higher physiological relevance by bridging the gap between animal models and human clinical trials. In this context, human 3D in vitro models are promising tools with great potential for preclinical research, as they can mimic some of the main features of tissues, such as cell-cell and cell-extracellular matrix (ECM) interactions [2,3]. Moreover these complex cell models are suitable for high-throughput screening (HTS) platforms, essential in drug discovery pipelines by reducing both costs and time in clinical trials [2,4]. However, despite important advances in the last years and the increasing clinical and biological relevance, the full establishment of human 3D in vitro models in pre-clinical research requires a significant increase in the power of the available analytical methodologies towards more robust and comprehensive readouts [4]. With the emergence of systems biology field and several “-omics” technologies, such as metabolomics, it became possible to have a more mechanistic approach in the understanding of cellular programs. H-nuclear magnetic resonance (H-NMR) spectroscopy is a powerful and widely accepted high resolution methodology for a number of applications, including metabolic profiling [5]. Despite the low sensitivity when compared with mass spectrometry (MS), H-NMR profiling presents several advantages, enabling a non-invasive and non-destructive quantitative analysis requiring only minimal sample preparation [5]. In this work we present the development of a robust and optimized workflow for the exometabolome profiling of 3D in vitro cultures of human midbrain-derived neural progenitor cells (hmNPC).

Abstract A21: 3D tumor models in bioreactors recapitulate microenvironment and disease progression

The high attrition rates observed in cancer drug discovery (up to 95% of failure of drugs tested in phase I trials) have raised the awareness of the scientific and industrial communities towards the need for more predictive pre-clinical models. These models should be more representative of the disease and consequently help to eliminate at pre-clinical stages drug candidates that lack efficacy or safety. Tumor microenvironment is composed by a network of fibroblasts, endothelial cells, immune-competent cells within the extracellular matrix (ECM). Interactions between these components are critical for tumor initiation, proliferation, migration and metastasis. The design of in vitro cancer cell models that recapitulate the tumor microenvironment and 3D architecture provides higher physiological relevance as they more closely resemble the in vivo cellular context. We have established methodologies for scalable generation of 3D cancer cell models in stirred-tank culture systems, and applied these to a large panel of tumor cell lines from different pathologies, including breast, colon, hepatic and lung tumor cell lines. Large numbers of spheroids were obtained per culture (typically 1000-1500 spheroids/mL) with representative characteristics of native tumors, such as morphology, proliferation and hypoxia gradients, in a cell-line dependent mode. With the aim of increasing the relevance of spheroids as tumor cell models, several aspects of tumor microenvironment were incorporated, such as the presence of stromal cells (fibroblasts and monocytes) and specific physical parameters, namely by embedding cells in a polymeric matrix. Heterotypic 3D breast and Non-Small Cell Lung Carcinoma (NSCLC) cancer models, based on co-cultures of tumor cells with stromal cells were established by using an alginate matrix to provide physical support to cells. Tumor spheroids were microencapsulated alone or with fibroblasts and monocytes, thus allowing the establishment of an epithelial tumor compartment and a stromal compartment of increasing complexity. Cultures were performed in stirred-tank vessels for 15 days with continuous monitoring. In both breast and lung tumor models, the presence of fibroblasts was associated with secretion of pro-inflammatory cytokines and accumulation of collagen in the microcapsules. Long-term culture (up to 15 days) resulted in phenotypic alterations in co-cultured breast tumor spheroids, such as loss of cell polarity, reduced cell-cell adhesions, collective cell migration and increased angiogenic potential. In contrast, the effects of fibroblasts were not as significant in NSCLC co-cultures using H1650, H1437 and H157 cell lines suggesting that the effect of tumor-stroma cross-talk is cell line dependent. Moreover, these models have also been shown as feasible tools for drug screening by assessing the effect of chemotherapeutic and specific inhibitors compounds on mono- and co-cultures. In conclusion, we have developed scalable, robust and versatile methodologies for the generation and culture of 3D cancer models, enabling long-term in vitro recapitulation of tumor-stroma crosstalk, via reconstruction of key aspects of the tumor microenvironment, allowing continuous monitoring of disease progression events in vitro. In addition, it is easily transferable to industry for feeding high-throughput systems or miniaturized bioreactors used in drug development, target validation and target identification. Acknowledgments: We acknowledge support from the Innovative Medicines Initiative Joint Undertaking (IMI grant agreement n° 115188), resources composed of financial contribution from EU - FP7 and EFPIA companies in kind contribution. iNOVA4Health Research Unit (LISBOA-01-0145-FEDER-007344), which is cofunded by Fundacao para a Ciencia e Tecnologia / Ministerio da Ciencia e do Ensino Superior, through national funds, and by FEDER under the PT2020 Partnership Agreement, is acknowledged. This research has also received support from Fundacao para a Ciencia e Tecnologia, Portugal—PTDC/BBB-BIO/1240/2012. MFE, SA and CP are the recipients of PhD fellowships from FCT (SFRH/BD/52208/2013, PD/BD/105768/2014 and SFRH/BD/52202/2013, respectively). Citation Format: Vitor E Santo, Marta F Estrada, Sofia P Rebelo, Sofia Abreu, Catarina Pinto, Elizabeth Anderson, Wolfgang Sommergruber, Paula Alves, Erwin Boghaert, Catarina Brito. 3D tumor models in bioreactors recapitulate microenvironment and disease progression. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A21.