Engineering mammary tissue microenvironments in vitro

Breast cancer is the most common cancer in women worldwide, and while screening, diagnostic tools and treatments have improved over the decades, many women still succumb to the disease. The heterogeneity of breast cancer and the many subtypes and sites of origin mean that it is remains a difficult disease to fully elucidate. Additionally, the extracellular matrix plays a major role in the development, progression and metastasis of the disease and these cell-ECM interactions are still poorly understood. Animal and two-dimensional models have been the gold standard for understanding the disease and developing novel treatments. However, these models possess undesirable characteristics and do not fully represent the complexity of the mammary tumor microenvironment. This has created a need for mammary biomimetic tools, which in recent years have been developed. These tools are known as three-dimensional (3D) models and they all aim to replicate the physiological complexity of breast cancer by facilitating 3D cell-cell interactions, providing scaffolds or by encapsulating cells and tissues in a extracellular matrix. These bioengineered tools have already shown to be a promising field of research for breast cancer, and have already facilitated deeper researcher into hallmarks such as angiogenesis and the relationship with metastasis, local invasion and also has allowed complex co- and tri-cultures consisting of many cell types. We postulate that 3D models will be the next large step needed to study breast cancer at a more deeper and complex level and will provide chemotherapeutics and pharmaceutical companies platforms for more reliable drug development.