3D bioprinting complex models of cancer.

Cancer is characterized by the uncontrolled division of cells, resulting in the formation of tumors. The tumor microenvironment (TME) consists of a variety of cell types present within a heterogeneous extracellular matrix (ECM). Current 2D culture methods for mimicking this microenvironment remain limited due to spatial constraints. Many different types of 3D cancer models have been developed in recent years using spheroids/organoids, biomaterial scaffolds, and cancer-on-chip systems. However, these models cannot precisely control the organization of multiple cell types inside of complex architectures. Bioprinted cancer models can incorporate both stromal and cancer cells inside of 3D constructs to generate custom models of this complex disease. 3D bioprinting can generate complex, multicellular, and reproducible constructs where the matrix composition and rigidity are tailored locally to the tumor. These capabilities make 3D bioprinting an attractive method for reproducing the tumor TME found in vivo . Recent advancements in biomaterial-based bioinks enable the generation of 3D bioprinted cancer models that accurately mimic the TM. Here we discuss recent examples of such 3D-bioprinted cancer models, including those of the lungs, prostate, skin, brain, and colon. We then highlight the advantages of using 3D bioprinting compared to other in vitro modeling techniques and detail its limitations.