Biofabrication of Modular Spheroids as Tumour-Scale Microenvironments for Drug Screening.

To streamline the drug discovery pipeline, there is a pressing need for preclinical models which replicate the complexity and scale of native tumours. While there have been advancements in the formation of microscale tumour units, these models are cell-line dependent, time-consuming and have not improved clinical trial success rates. In this study, two methods for generating 3D tumour microenvironments were compared, rapidly-fabricated hydrogel microspheres and traditional cell-dense spheroids. These modules were then bioassembled into 3D printed thermoplastic scaffolds, using an automated biofabrication process, to form tumour-scale models. Modules were formed with SKOV3 and HFF cells as monocultures and cocultures, and the fabrication efficiency, cell architecture and drug response profiles were characterised, both as single modules and as multi-modular constructs. Cell-encapsulated Gel-MA microspheres were fabricated with high-reproducibility and dimensions necessary for automated tumour-scale bioassembly regardless of cell type, however, only cocultured spheroids formed compact modules suitable for bioassembly. Chemosensitivity assays demonstrated the reduced potency of doxorubicin in coculture bioassembled constructs and a ∼5-fold increase in drug resistance of cocultured cells in 3D modules compared with 2D monolayers. This bioassembly system is efficient and tailorable so that a variety of relevant-sized tumour constructs could be developed to study tumorigenesis and modernise drug discovery. This article is protected by copyright. All rights reserved.