Development of engineered three-dimensional microenvironments for in vitro cancer model

Abstract

The tumor microenvironment is characterized by intra-tumoral spatial heterogeneity of tumor cells and complex signalling networks that influence their growth, invasion, and metastasis. Given the limitations of conventional two-dimensional culture platforms to replicate the dynamic and complex nature of the tumor microenvironment, there is a need for more complex culture platforms capable of mimicking tissue-like structures. On the other hand, three-dimensional in vitro models offer an alternative to over-simplified 2D systems and animal models that are time-consuming and expensive. 3D platforms can be modified by incorporating of patient-derived tissues or cells and enable spatio-temporal measurements, thus providing a deeper understanding of cell- cell or cell-stromal interactions. In this project, 3D breast cancer models that preserve complex cell-cell interactions and microenvironmental diversity were designed as an alternative to animal models.

In the first part of this work, a breast cancer model was engineered by rolling a single biocomposite strip to form multiple layers around a 3D printed core. This model can be rapidly unrolled, enabling the analysis of the spatiotemporal distribution of cells. To present the suitability of the rolled biocomposite sheets as a 3D breast cancer model, capability of biocomposite layers to generate a hypoxic gradient, hypoxia-induced ROS production and anticancer drug resistance are tested. Additionally, in Chapter 3, the feasibility of a 3D breast cancer model to evaluate the ECM remodelling capacity of cells was investigated. The study revealed that the designed 3D breast cancer model is a valuable tool for studying cell migration from the outer layer to the inner layers over long culture times. In Chapter 4, the study highlighted that breast cancer cell types have distinct optimal requirements when designing user-defined three-dimensional models for in vitro applications. Understanding the critical role of tissue ECM structure in the metastatic selection mechanism of cancer cells was the objective of Chapter 5. In light of recent advances in decellularisation techniques, perfusion systems containing scaffolds from different tissues were designed to mimic the in vitro tumor microenvironment.

Overall, this study demonstrated the need for state-of-the-art 3D models to study tumor-stroma interactions. It also showed that these models are an excellent tool to bridge the gap between oversimplified 2D systems and animal models that are not representative of humans.