The transition from 2D to 3D cell culture techniques is an important step in a trend towards better biomimetic tissue models. Microfluidics allows spatial control over fluids in micrometer-sized channels has become a valuable tool to further increase the physiological relevance of 3D cell culture by enabling spatially controlled co-cultures, perfusion flow and spatial control over of signaling gradients. This paper reviews most important developments in microfluidic 3D culture since 2012. Most efforts were exerted in the field of vasculature, both as a tissue on its own and as part of cancer models. We observe that the focus is shifting from tool building to implementation of specific tissue models. The next big challenge for the field is the full validation of these models and subsequently the implementation of these models in drug development pipelines of the pharmaceutical industry and ultimately in personalized medicine applications.

A common bottleneck in any drug development process is finding sufficiently accurate models that capture key aspects of disease development and progression. Conventional drug screening models often rely on simple 2D culture systems that fail to recapitulate the complexity of the organ situation. In this study, we show the application of a robust high throughput 3D gut-on-a-chip model for investigating hallmarks of inflammatory bowel disease (IBD). Using the OrganoPlate platform, we subjected enterocyte-like cells to an immune-relevant inflammatory trigger in order to recapitulate key events of IBD and to further investigate the suitability of this model for compound discovery and target validation activities. The induction of inflammatory conditions caused a loss of barrier function of the intestinal epithelium and its activation by increased cytokine production, two events observed in IBD physiopathology. More importantly, anti-inflammatory compound exposure prevented the loss of barrier function and the increased cytokine release. Furthermore, knockdown of key inflammatory regulators RELA and MYD88 through on-chip adenoviral shRNA transduction alleviated IBD phenotype by decreasing cytokine production. In summary, we demonstrate the routine use of a gut-on-a-chip platform for disease-specific aspects modeling. The approach can be used for larger scale disease modeling, target validation and drug discovery purposes.

Human tissues and organs are inherently heterogeneous. Their functionality is determined by the interplay between different cell types, their secondary architecture, vascular system and gradients of signaling molecules and metabolites. Here we propose a stratified 3D cell culture platform, in which adjacent lanes of gels and liquids are patterned by phaseguides to capture this tissue heterogeneity. We demonstrate 3D cell culture of HepG2 hepatocytes under continuous perfusion, a rifampicin toxicity assay and co-culture with fibroblasts. 4T1 breast cancer cells are used to demonstrate invasion and aggregation models. The platform is incorporated in a microtiter plate format that renders it fully compatible with automation and high-content screening equipment. The extended functionality, ease of handling and full compatibility to standard equipment is an important step towards adoption of Organ-on-a-Chip technology for screening in an industrial setting.

With great advances in the field of in vitro brain modelling, the challenge is now to implement these technologies for development and evaluation of new drug candidates. Here we demonstrate a method for culturing three-dimensional networks of spontaneously active neurons and supporting glial cells in a microfluidic platform. The high-throughput nature of the platform in combination with its compatibility with all standard laboratory equipment allows for parallel evaluation of compound effects.

Breast cancer is the most common invasive cancer among women. Currently, there are only a few models used for therapy selection, and they are often poor predictors of therapeutic response or take months to set up and assay. In this report, we introduce a microfluidic OrganoPlate® platform for extracellular matrix (ECM) embedded tumor culture under perfusion as an initial study designed to investigate the feasibility of adapting this technology for therapy selection. The triple negative breast cancer cell lines MDA-MB-453, MDA-MB-231 and HCC1937 were selected based on their different BRCA1 and P53 status, and were seeded in the platform. We evaluate seeding densities, ECM composition (Matrigel®, BME2rgf, collagen I) and biomechanical (perfusion vs static) conditions. We then exposed the cells to a series of anti-cancer drugs (paclitaxel, olaparib, cisplatin) and compared their responses to those in 2D cultures. Finally, we generated cisplatin dose responses in 3D cultures of breast cancer cells derived from 2 PDX models. The microfluidic platform allows the simultaneous culture of 96 perfused micro tissues, using limited amounts of material, enabling drug screening of patient-derived material. 3D cell culture viability is improved by constant perfusion of the medium. Furthermore, the drug response of these triple negative breast cancer cells was attenuated by culture in 3D and differed from that observed in 2D substrates. We have investigated the use of a high-throughput organ-on-a-chip platform to select therapies. Our results have raised the possibility to use this technology in personalized medicine to support selection of appropriate drugs and to predict response to therapy in a real time fashion.