3D printed hydrogel scaffolds with macro pores and interconnected microchannel networks for tissue engineering vascularization

The macro pores and interconnected microchannels in three-dimensional (3D) scaffolds are important archi-tecture cures to support new tissues growth and vascularization. To date, the fabrication of hydrogel scaffold possessing both designed macro pores and fully interconnected microchannel (FIM) networks is still a challenge. Herein, we reported a facile method to effectively fabricate hydrogel scaffold containing designed macro pores and FIM networks by 3D printing and surface crosslinking. The surface of the printed scaffold is crosslinked, while the inner parts of the filaments are still in uncrosslinked state, after soaking the scaffold in crosslinking solution for a certain time. Then, the FIM networks are generated by removing the uncrosslinked gels from the printed filaments. The created FIM scaffold shows improved mechanical properties and structural integrity after post treatment. The channel wall with barrier function endows the scaffold with the ability of fast perfusion of liquid in the microchannels. Human umbilical vein endothelial cells are well adhered on the inner surface of the microchannels with high cell viability. In vivo study shows the excellent performance to facilitate vessels for-mation not only in the interface zone between scaffolds and host tissue, but also in the center of the FIM scaffolds. It also demonstrate that FIM scaffolds hold the potential capability to promote wound healing. In conclusion, the present study proposes a facile method to fabricate hydrogel scaffolds with both macro pores and FIM networks, and demonstrates their strong potential for tissue engineering application.