(161h) Therapeutic Screening on a Novel Hybrid Scaffold Assisted Multicellular Model of Pancreatic Cancer

Introduction: With a 5-year survival rate of only 9%, Pancreatic Ductal Adenocarcinoma (PDAC) is the 7^th leading cause of cancer related death worldwide¹. The aggressive nature and high mortality rate of PDAC are attributed to its late diagnosis, heterogeneity in the tumour and the tumour microenvironment and its resistance to currently available treatment methods². An in-depth study of the PDAC’s resistance to current therapeutic methods requires the development of biomimetic, niche mimicking in vitro tumour models. Current research focuses on the development of 3D in vitro tumour models to replace 2D culture systems and animal models in order to tide over limitations associated with such systems. More specifically, 3D in vitro models can recapitulate more accurately the structural and biochemical complexity of the tumour microenvironment (TME) in comparison to 2D cultures while mitigating the cost and reproducibility problems associated with animal models. Additionally, as in all tissues, the PDAC TME is heterogeneous in cellular nature consisting, additionally to cancer cells, different cell types , e.g., stellate cells and endothelial cells, all contributing to the tumour formation, metastasis as well as its response and resistance to treatment. Thus, recent studies have focused on generating multicellular pancreatic cancer models, which are primarily spheroid based^3,4. Spheroids are useful 3D models due to their ease of development and their ability to allow for fast analysis and high throughput treatment screening. However, it is difficult to maintain spheroid cultures for long time without requiring resuspension, the latter inevitably affecting the formed cell-cell and cell-extracellular matrix (ECM) interactions. Building on our previously developed monocellular polyurethane (PU) based PDAC model ^5,6,7,9, we have recently developed a 3D hybrid multicellular model of pancreatic cancer model using pancreatic cancer cells, endothelial cells and pancreatic stellate cells, with zonal ECM mimicry (via protein coating in the PU scaffolds) to maximise the cell proliferation, cell density/aggregation and ECM secretion for different cell compartments of the TME. Our multicellular model allows the maintenance of long term in vitro culture (4 weeks), without the need of cell re-suspension along with a recapitulation of desmoplasia/fibrosis, which is a hallmark of PDAC⁸.

The current work focusses on the feasibility of using this multicellular model for the purposes of therapeutic assessments (chemotherapy & radiotherapy). We also look at the effects of a zonal/hybrid scaffold vs a single scaffold based multicellular model.

METHODS: PU scaffolds were prepared using the Thermal Induced Phase Separation (TIPS) method. Absorption based surface modification of the scaffolds enabled coating with ECM proteins (collagen and fibronectin) for enhancement of ECM mimicry⁴. A zonal structure with (i) endothelial and stellate cells on the outer side of the scaffold coated with collagen I and (ii) pancreatic cancer cells in the inner scaffold coated with fibronectin was designed, along with a single scaffold based simplistic multicellular model⁸. Chemotherapy treatment of 50 µM Gemcitabine and Radiotherapy of 6 Gy was applied to the model after 4 weeks of culture, followed by 7 days post-treatment monitoring. Various in situ imaging assays for monitoring the cell viability, spatial organisation, ECM production were carried out at specific time points throughout the culture period.

RESULTS: We report here therapeutic assessment (chemotherapy & radiotherapy) on our novel multicellular PDAC model. Effects of therapeutic agents on cell viability, apoptosis and ECM spatial secretion was observed. A comparative study between a single scaffold model and a complex zonal model was carried out.

CONCLUSION: Our data show, that our multicellular model is an appropriate in vitro model for therapeutic assessment of PDAC. Our developed model is a low cost high throughput tool that can be used for personalized studies and treatment screening of pancreatic cancer.

ACKNOWLEDGMENT: Financial support was received from the Department of Chemical and Process Engineering of the University of Surrey, an Impact Acceleration Grant (IAA-KN9149C) from the University of Surrey, an IAA–EPSRC Grant (RN0281J) and the Royal Society. P.G has received financial support from a Commonwealth Rutherford Post-Doctoral Fellowship (2018 – 2020) and the 3D BioNet (UKRI) (current). E.V. is thankful to the Royal Academy of Engineering for an Industrial Fellowship.

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