Three-dimensional bioprinting using self-assembling scalable scaffold-free “tissue strands” as a new bioink

TLDR

Bioprinting advances enable assembly of biomaterials, cells, and signaling molecules into functional tissues, yet scalable, scaffold‑free fabrication that recapitulates tissue biology at clinically relevant dimensions remains a major roadblock. The study aims to fabricate and engineer scaffold‑free scalable tissue strands as a novel bioink for robotic‑assisted bioprinting. The approach uses cartilage strands as building units to bioprint articular cartilage tissue, demonstrating the feasibility of scaffold‑free, scalable tissue strands as a bioink. Compared to 400 µm‑thick spheroids printed in liquid media and molds, the authors successfully bioprinted ~8 cm‑long tissue strands in solid form without scaffolds, molds, or liquid delivery, achieving native‑like scale‑up tissues.

Abstract

Recent advances in bioprinting have granted tissue engineers the ability to assemble biomaterials, cells, and signaling molecules into anatomically relevant functional tissues or organ parts. Scaffold-free fabrication has recently attracted a great deal of interest due to the ability to recapitulate tissue biology by using self-assembly, which mimics the embryonic development process. Despite several attempts, bioprinting of scale-up tissues at clinically-relevant dimensions with closely recapitulated tissue biology and functionality is still a major roadblock. Here, we fabricate and engineer scaffold-free scalable tissue strands as a novel bioink material for robotic-assisted bioprinting technologies. Compare to 400 μm-thick tissue spheroids bioprinted in a liquid delivery medium into confining molds, near 8 cm-long tissue strands with rapid fusion and self-assemble capabilities are bioprinted in solid form for the first time without any need for a scaffold or a mold support or a liquid delivery medium, and facilitated native-like scale-up tissues. The prominent approach has been verified using cartilage strands as building units to bioprint articular cartilage tissue.