Development of a Liver-specific immune 3D microenvironment for the study of primary and metastatic liver tumour

Two dimensional (2D) in vitro models have been insufficient in replicating the complex interplay that occurs in the in vivo microenvironment between cancer and immune cells. The main reason for this discrepancy is due to the lack of cell-cell interactions and the cell-tumour microenvironment in conventional 2D plastic models. Indeed, cancer is a product of the complex interaction between cancer cells and tumour microenvironment, which comprises a three-dimensional (3D) extracellular matrix (ECM) together with tissue-resident cells as well as immune cells. The aim of this project was to evaluate immune and cancer cells interaction, cell infiltration and the ability of immune cells to target cancer cells, within tissue-specific and disease-specific human ECM scaffolds. Additionally, we aimed to test a 3D liver model of primary and metastatic liver cancer for therapy and immunotherapy. The results revealed that 3D cultures induced a mesenchymal-like phenotypes depending on disease-specific biochemical and biomechanical composition of the scaffold (Healthy or Cirrhotic). In fact, 3D, unlike 2D cultures of hepatocellular carcinoma (HCC) cell line, induced E-cadherin downregulation in healthy and cirrhotic scaffolds, suggesting the activation of the epithelial to mesenchymal transition (EMT). Current models for testing new immunotherapeutic drugs in solid tumours are not satisfactory. One of the potential limitations affecting the translation of therapies towards effective treatments for solid tumours is due to the lack of reliable in vitro and in vivo models. Therefore, another aim of my thesis is to investigate the impact of tissue-specific and disease-specific ECM scaffolds in modulating tumour and immune cells behaviours as well as response to immunotherapy. Our results demonstrated that the disease-specific 3D environment promoted a protective microenvironment for cancer cells as well as an immune cells exclusion phenotype, accounting for the low therapeutic efficacy found in clinical practice. Based on the finding that 3D healthy and cirrhotic scaffolds recreate molecular features of immunological “hot” and “cold” tumour, respectively, we propose 3D ECM cultures as a novel and powerful platform for drug screening. Finally, the observation that the efficacy of sorafenib and immunotherapy (anti-PD1 and anti-PDL1) 13 is strongly reduced in 3D (especially cirrhotic ECM) compared to 2D models suggests that 3D scaffolds can represent also a useful tool for the study of the mechanisms underlying cancer cell resistance.