Advances in 3D bioprinting for the biofabrication of tumor models

Abstract Cancer research depends on the challenging task of producing representative and reliable models of human disease; these have largely been limited to mouse models or human cancer cell lines cultured in monolayers. Three-dimensional (3D) cell culture offers more realistic options, but conventional 3D models still fail to recreate the human tumor microenvironment. One biofabrication technique that has emerged as a powerful tool is 3D bioprinting, which can generate tumor constructs with increasing complexity. By incorporating factors like stromal cells, vasculature, hydrogels, and functional molecules into the bioprinting process, researchers are now able to create human tumor models that quite realistically represent human glioblastoma, breast, cervical, ovarian, hepatoma, lung, colon, and oral cancers. The obtained structures range from coaxially extruded fibers and monolayered grids to cylinders, cubes, discs, beads, and even mini-organs. Here, we discuss recent advances in cancer research based on 3D bioprinting. Our aim is to provide a broad perspective of the possibilities provided by this biofabrication technique for the generation of complex tumor models. We also review the different structures and characterization techniques used with these models. The use of 3D bioprinted tumors is increasing in areas like tumor biology, migration, invasion, and metastasis, as well as in pharmaceutical testing and even personalized medicine. Future work will involve improvement of the mechanical properties and chemical cues provided to the cells within the 3D constructs. The inclusion of several cell types within a single construct will upgrade current recapitulations of real tumor tissues. Bioprinting of cells cultured from patients’ own biopsies will generate personalized models of the tumor niche.