3D extrusion bioprinting

Three-dimensional (3D) bioprinting strategies use computer-aided processes to enable automated simultaneous spatial patterning of cells and/or biomaterials. These technologies are suitable for a broad range of biomedical applications owing to their capability to produce structurally sophisticated and functionally relevant tissue constructs. Extrusion-based 3D bioprinting strategies were among the first modalities developed and are now arguably the most widely used for producing 3D tissue constructs. These technologies have rapidly evolved over the past two decades, providing a powerful tool set for the biofabrication of tissues that can facilitate translational efforts in the field. In this Primer, we describe the methodology of 3D extrusion bioprinting, focusing on the selection of hardware, software and bioinks. We expand upon recent advances in 3D extrusion bioprinting by illustrating the key variations that promote its biofabrication abilities. Finally, we provide an outlook on possible future refinements of the technology.3D extrusion bioprinting methods can be used to produce tissue constructs in vitro and in situ and are arguably the most commonly used bioprinting strategies. In this Primer, Zhang and colleagues describe the variants of 3D extrusion bioprinting methods and their specific applications, considerations for the formulation of bioinks and strategies for assessing print quality. The authors conclude by looking to recent and upcoming developments in 4D printing and artificial intelligence-assisted dynamic printing strategies