Development of an \u3ci\u3eIn Vitro\u3c/i\u3e Three-dimensional Breast Tissue Model to Decipher the Effects of Stromal Heterogeneity on Normal and Cancerous Mammary Epithelial Cells

A goal of breast cancer research is to develop a detailed understanding of the underlying mechanisms of disease progression and to generate approaches to improve early detection, monitoring, and treatment of breast cancerous lesions. Current breast cancer therapies are not successful for all cases as they were developed as a standard of care for \u27average\u27 breast cancer condition. To further current clinical success, the characteristics of each tumor mass must be considered. Such an individualized or personalized approach is incompatible with current understanding of \u27average\u27 breast cancer tumors and responses to treatments. The long-term objective of the present research is to develop modular breast tissue models to (1) further our understanding of individual breast cancer tumors and (2) monitor and develop customized treatment plans, thus contributing to breast tissue and breast cancer research. The main goal of this project was to develop a three-dimensional (3D) breast tissue in vitro test system using tissue engineering concepts. The model is uniquely different from existing models in that it accounts for extracellular matrix (ECM) heterogeneity through use of an ECM hydrogel embedded with polylactide beads. Furthermore, the 3D model was used to specifically investigate the effect of heterogeneity of the mammary microenvironment on normal human mammary epithelial cells (MCF10A) and human breast cancer cells (MCF7). Specifically, (1) polylactide beads with various physicochemical features were produced and characterized, (2) an ECM hydrogel representing the stromal component was evaluated and selected, and (3) a 3D tissue engineered composite system with and without polylactide beads, containing either MCF10A or MCF7 cells, was used to investigate the effects of microenvironment heterogeneity. Development of a benchmark 3D breast tissue model, where cellular interaction can be studied in an environment that is more representative of the native tissue, helps researchers better understand cell reactions and behaviors in breast cancer. This model allows the rapid assessment of therapies as well as controlled studies of basic breast cancer processes and mechanisms. The outcome of this research was the generation of a 3D in vitro breast tissue model that better mimics specific influences of the ECM in breast tissue and breast cancer progression. While the scientific merit of the proposed work was to advance the understanding of breast tissue development and early breast cancer stages, the goal was to reach outside the breast cancer community to share the work and progress. Further, the second objective of this research was to reach out to young scientists and engineers through an undergraduate introductory research program, highlighting interdisciplinary approaches in scientific endeavors. This initiative broadened the intellectual merit of the project and introduced ideas related to breast cancer research in other related fields of research, thereby generating additional in-depth research opportunities and advancements in the field of breast cancer research