Trends in Photopolymerizable Bioinks for 3D Bioprinting of Tumor Models

Three-dimensional (3D) bioprinting technologies involvingphotopolymerizablebioinks (PBs) have attracted enormous attention in recent times owingto their ability to recreate complex structures with high resolution,mechanical stability, and favorable printing conditions that are suitedfor encapsulating cells. 3D bioprinted tissue constructs involvingPBs can offer better insights into the tumor microenvironment andoffer platforms for drug screening to advance cancer research. Thesebioinks enable the incorporation of physiologically relevant celldensities, tissue-mimetic stiffness, and vascularized channels andbiochemical gradients in the 3D tumor models, unlike conventionaltwo-dimensional (2D) cultures or other 3D scaffold fabrication technologies.In this perspective, we present the emerging techniques of 3D bioprintingusing PBs in the context of cancer research, with a specific focuson the efforts to recapitulate the complexity of the tumor microenvironment.We describe printing approaches and various PB formulations compatiblewith these techniques along with recent attempts to bioprint 3D tumormodels for studying migration and metastasis, cell-cell interactions,cell-extracellular matrix interactions, and drug screeningrelevant to cancer. We discuss the limitations and identify unexploredopportunities in this field for clinical and commercial translationof these emerging technologies.