ESTRO 2023 - Abstract Book

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ESTRO 2023

PO-2215 3D bioprinting of breast cancer and its stroma: tool to decrypt cell interactions upon radiotherapy

T. DESIGAUX 1 , L. Comperat 1 , N. Dusserre 1 , M. Stachowicz 1 , H. Oliveira 1 , J. Fricain 1 , F. Paris 2

1 INSERM, U1026, Bordeaux, France; 2 INSERM, UMR1232, Nantes, France

Purpose or Objective Despite recent progress in breast cancer (BC) treatment, this tumor remains a public health challenge due to its preeminent frequency[1]. Following resection, radiotherapy (RT) is used in routine for BC patient’s care, therefore improving its efficacy could improve patient outcome by preventing relapse and metastasis of the primary tumor. Interestingly, radiotherapy does not only affect breast cancer, but also its microenvironment. Notably, endothelial cells (EC) have been shown to secrete paracrine factors, that can modulate cancer cells response to RT[2]. On the other side, cancer associated fibroblasts (CAF) can affect radiosensitivity[3], and endothelial cell phenotype[4]. As such, to gain new insights on the cell communication for these 3 cell types will enable to characterize new mechanisms for the prospection of new targets for treatment improvement. 2D models lack complexity for this kind of study, while in vivo experiments are lacking tunability, thus refraining us to clarify the role of each microenvironment actor. Here, we propose 3D bioprinting of a tunable breast cancer model, that can recapitulate the tumor extracellular matrix, microvasculature and response to treatment, as a tool to decrypt the impact of cell communication in tumor resistance to RT.

Materials and Methods Culture – MCF7, CAF and Normal Mammary Fibroblasts (NMF) HUVECs were bioprinted and maintained in EGM2-MV (Lonza) for maturation. MCF7-GFP and HUVEC-mKate were obtained using lentiviral vector. Single dose γ -irradiation at 3Gy/min were performed 4 days post-printing. Gel formulation - Based on previous work[5] we used a gel composed by: collagen (2mg/mL), hyaluronic acid (10mg/mL), both methacrylated, IKVAV laminin-derived peptide (1mg/mL) and LAP photoinitiator (1mg/mL). Cells were diluted at 5M/mL in the gel to obtain the bioink. Bioprinting – RegenHU 3D Discovery bioprinter (2-head 0.41mm extrusion nozzles) was used to create two concentric circles geometry, cancer core surrounded by stroma (5mm total diameter). Results We first quantified cells viability in our model and observed a >70% post-printing viability. Interestingly, a viability gradient appeared after 7 days of culture, mimicking the necrotic core observed in tumors. We then quantified the maturation of HUVEC into microvascular-like network and could show that the presence of CAF favored a more complex network compared to HUVEC alone or with NMF. We could observe significant response at 72h post-irradiation above 10 Gy. Conclusion Here, we present a new 3D bioprinted BC-stroma model to study intercellular communication during RT. We demonstrate the capacity to attain such model with high reproducibility, in high troughput, its tunability, its consistency with current literature and ability to respond to RT. We currently use this model to further characterize paracrine interactions, during treatment-induced oxidative stress. We evaluate potential targets, such as CXCL-1 and ceramide for CAF-EC communication that would affect BC response to RT.