Fabrication of three-dimensional vascular network with geometrical regulation of angiogenesis by using 3D bioprinting

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. The vascular channels were formed by direct printing of hydrogels containing endothelial cells and fibroblasts were placed at a distance to induce the formation of micro-vessels from the vascular channels. To control the angiogenesis pattern, different concentrations of fibrin gel were patterned to differentiate the diffusion rate of angiogenic factors and matrix stiffness within the structure. Using this method, it was possible to induce the desired structure of vascular network