3D Bioprinted Artificial Breast Cancer Tumor Disks: A New Tool for Understanding Intra‐tumor Heterogeneity?

Abstract

Recently the UWRF Tissue and Cellular Innovation Center and the Century College Biofabrication Program have engaged in a series of new collaborative research projects using bioprinting technology and methods to model and study in‐vitro 3D artificial tumor and stromal tissues. In this presentation, we report on results obtained from efforts to bioprint cancer disks using the human breast adenocarcinoma cell line MCF‐7. This breast cancer cell line is considered to be one of the “gold standard” cultures to study this type tumor. In extensive previous studies in our lab using other 3D modeling methods, we have established a robust library of experience and data with these cells and artificial tissue constructs. In these new studies, bioprinting methods were applied to establish tumor structures which initially contained specific cell numbers per unit volume as well as relatively mono‐cellular distribution patterns. Both of these characteristics had been very difficult to predictably generate and control in earlier studies using precast or molded hydrogels made of chitosan and hyaluronic acid or decellularized natural marine sponge ECM. In this project, two distinct bioinks were tested including one called GelMa, a gelatin/methacrylate hydrogel and another called GelMa‐C which is basically the same, but with nanocellulose added to enhance the structural stability of constructs during printing. While both bioinks generated structures and tissues, the GelMa bioink specifically generated relatively transparent tumor structures that provided a unique window into the cell interactions and eventual early development of these artificial tumor tissues. Using a Cellink “Inkcredible” model printer loaned to the TCIC by Century College for the duration of this project, we printed tumor disks with a diameter of 5 mm and thickness of 2.5 mm and then cultured these in 6 well plates for up to 3 months. These breast cancer disks displayed features and tissue progression similar to that seen with the other methods used in our earlier work, while also providing new and unique insights into the interior artificial tumor tissue development in real‐time. These new observations also demonstrated a unique cell/tissue behavior in the resulting constructs that we hypothesize may directly address the origins of intra‐tumor heterogeneity of various cell subpopulations and their relative contributions to the overall tumor development. Future studies are planned to further evaluate and qualify these observations and to apply this new 3D artificial tissue tool to further elucidate cancer biology as a whole.