Abstract

Organoids and Complex Cell-based Architectures in Biofabrication and Volumetric Bioprinting

Riccardo Levato, Assistant Professor of Biofabrication and Regenerative Medicine, University Medical Center Utrecht and Regenerative Medicine Center Utrecht

The function of living tissues is intimately linked to their complex architectures. Advances in biofabrication technologies offer unprecedented opportunities to capture salient features of tissue composition and thus guide the maturation of engineered constructs into mimicking functionalities of native organs. In this lecture, the design of novel biofabrication strategies and printable biomaterials to enable the reconstitution of complex 3D structures with precise heterocellular, multi-material and hierarchical composition is discussed. Architectures designed to stimulate the native interaction between multiple (stem) cell types and self-assembled organoids are introduced, with a particular focus on applications in musculoskeletal regeneration and liver tissue engineering. Layerwise hydrogel extrusion and bioprinting, different additive manufacturing technologies, such as melt electrowriting of polymeric microfibers, ceramic plotting and digital light processing lithographic printing, can be combined to create composite, cell-laden constructs that enable integration between engineered hydrogels and hard tissue scaffolds to generate osteochondral grafts. Albeit powerful and versatile, this approach poses relevant limitations on the scalability and production of constructs having clinically relevant size, as well as on the generation of free-form and support free overhanging, porous structures, typically of native anatomy. To overcome these challenges, custom-designed light responsive hydrogels can be sculpted into cell-laden convoluted 3D structures within tens of second, via the development of layerless, volumetric bioprinting  approaches inspired by visible light computed tomography. With such nozzle and shear stress-free, highly rapid cell processing approach a variety of hydrogel-based constructs can be assembled into hydrogel-based actuators for potential applications in soft robotics, or as platforms to enhance cell viability and maturation post-printing, including the shaping of large networks of hepatic epithelial organoids into defined 3D perfusable structures  which exhibit biosynthetic and metabolic functions. Altogether, the combination of the different strengths of advanced bioprinting technologies offers new opportunities for the biofabrication of large, clinically-relevant multi-tissue constructs for regenerative medicine and tissue engineering.