One of the challenging issues in tissue engineering is a building of functional vascular network systems inside an artificial
tissue. Without proper vascular networks, enough oxygen and nutrients cannot be provided to the cells in the artificial
tissue. Therefore, the cells cannot maintain their viability and functionality during tissue growth and maturation without
proper vascular networks. Also, the structure of vascular networks has a significant role in living tissues to improve the
functionality of the cells. To fabricate a functional and well-organized vascular structure, researches using 3D bioprinting
are actively studied due to its superior ability to produce complex structures with variable materials in desired patterns.
Here, we propose the novel method for the fabrication of complex vascular networks using 3D bioprinting technology.
Within fibrin hydrogel, vascular channels with a diameter of several hundred micrometers were produced by direct-writing
an endothelial cells-laden bio-ink. And, a micro-scale angiogenic sprouting from the endothelial cells was self-induced by
gradient of angiogenic factors by co-printing fibroblasts. This result demonstrated that the desired vascular structure pattern
can be precisely constructed by our approach. The proposed bioprinting method has a great potential to construct biomimetic
vascular networks within 3D artificial tissues