Scaffold-free inkjet printing of three-dimensional zigzag cellular tubes.

The capability to print three-dimensional (3D) cellular tubes is not only a logical first step towards successful organ printing but also a critical indicator of the feasibility of the envisioned organ printing technology. A platform-assisted 3D inkjet bioprinting system has been proposed to fabricate 3D complex constructs such as zigzag tubes. Fibroblast (3T3 cell)-based tubes with an overhang structure have been successfully fabricated using the proposed bioprinting system. The post-printing 3T3 cell viability of printed cellular tubes has been found above 82% (or 93% with the control effect considered) even after a 72-h incubation period using the identified printing conditions for good droplet formation, indicating the promising application of the proposed bioprinting system. Particularly, it is proved that the tubular overhang structure can be scaffold-free fabricated using inkjetting, and the maximum achievable height depends on the inclination angle of the overhang structure. As a proof-of-concept study, the resulting fabrication knowledge helps print tissue-engineered blood vessels with complex geometry.