Mechanobiological challenges related to hydrogel-based bioprinting technology for manufacturing novel 3D cell culture models
Lead supervisor: H. Fischer, Co-supervisor: W. Wagner Uniklinik RWTH Aachen, Department of Dental Materials and Biomaterials Research (ZWBF)
Hypothesis: 3D bioprinting techniques affect cellular proliferation and differentiation potential.
Key aspects of project D2. (A) Schematic representation of the occurrence of shear stress in the nozzle of a bioprinter14. (B) 3D printed vessel bifurcation made of tailored cell-laden hydrogels using custom-made drop-on-demand bioprinter demonstrating the potential of 3D bioprinting technology (ZWBF).
Background: Hydrogel-based bioprinting technology has gained increasing attention in the field of tissue engineering as it enables the manufacturing of 3D tissue constructs with a defined arrangement of different cell types and materials97,98. This spatial control of distinct regions in the microenvironment has the potential to better mimic the native heterogeneities of native tissues thereby enhancing the functionality, size, and longlevity of artificial tissues. Besides the use of bioprinted constructs as tissue replacements they are of particular interest for producing advanced 3D in vitro tissue models for analyzing of context-dependent pathophysiology99. We have already successfully bioprinted vascularized tissue substitutes and established a novel in vitro model to analyze tumor angiogenesis100. Despite the encouraging results of the new technology, little is known about cellular responses to the printing process itself. The hydrogel-embedded cells are dispensed through a nozzle, which exerts considerable shear stress. A pilot study by our group showed that these shear stresses can have a decisive influence on cell viability, proliferation and differentiation potential14. Aims: We intend to systematically study the mechanobiological effects of different dispensing techniques in bioprinting on the proliferation and differentiation of epithelial cells used to prepare the 3D culture models of MEƎT. The role of the dispensing technique and the hydrogel properties, such as viscosity and relaxation behavior, are investigated. Considering the expected insights, the improved potential of 3D bioprinting to realize biomimetic 3D in vitro models are explored. Approach: We use our custom-made 3D bioprinting platform to investigate cellular responses to the printing-related shear stress (mechanical signal). We compare different nozzle types, apply pressure at different levels, use a variety of natural and synthetic hydrogels and hydrogel blends, and test the effects of cell density. The shear stresses that occur in the nozzle are modeled on the basis of fundamental fluid dynamic equations. The shear stress under different conditions are then be correlated with the observed cellular responses.