5 Conclusion
We proposed a new approach to making small diameter vessels with complicated patterns and special cell distribution. The two-step crosslinking method created a continuous connection between different printed parts and resulted an intact tubular structure with biological advantages, as well proper sealing and mechanical properties. We accomplished this method by the investigation of GelMA properties varied by crosslinking time and optimized by crosslinking process. We fabricated a small vessel that possesses printed outer layer of SMCs and perfused inner layer of HUVECs by GelMA bioink printing and two-step crosslinking process. We also observed that the SMCs and HUVECs were expanded, proliferated, and functionalized during post printing culture. Our study might provide a new fabrication method for the construction of small diameter vessel with clinically relevant size and characteristics.