Uniaxial and Coaxial Vertical Embedded Extrusion Bioprinting.

The three-dimensional bioprinting technologies have attracted increasing attention due to their flexibility in producing architecturally relevant tissue constructs. Here, we present an enabling vertical embedded extrusion bioprinting strategy using uniaxial or coaxial nozzles, which allows formation of vertical structures of homogeneous or heterogeneous properties in nature. By adjusting the bioprinting parameters, the characteristics of the bioprinted vertical patterns could be precisely controlled. Using this strategy, we demonstrated two proof-of-concept applications in tissue biofabrication. Specifically, intestinal villi and hair follicles, two liner-shaped tissue types in the human body, were successfully generated with the vertical embedded bioprinting method, reconstructing some of their key structures as well as restoring partial functions in vitro. Caco-2 cells in the bioprinted intestinal villus constructs proliferated and aggregated properly, also showing functional biomarker expressions such as ZO-1 and villin. Moreover, preliminary hair follicle structures featuring keratinized human keratinocytes and spheroid-shaped human dermal papilla cells were formed after vertical bioprinting and culturing. In summary, this vertical embedded extrusion bioprinting technique harnessing a uniaxial or coaxial format will likely bring further improvements in the reconstruction of certain human tissues and organs, especially those with a linear structure in nature, potentially leading to wide utilities in tissue engineering, tissue model engineering, and drug discovery. This article is protected by copyright. All rights reserved.