One of the most problems to fabricate three-dimensional thick tissue is how to supply oxygen and nutrients to the parenchymal cells. To solve this problem, we have to fabricate the vascular network system which is strong enough to endure the perfusion culture.
In this study, we reported technologies for electrochemical cell detachment from culture surface and photo-crosslinkable scaffold and demonstrated that it is beneficial for the fabrication of vascular structures to combine these technologies.

　Uniform and nozzle shape vascular-like structures were successfully fabricated. In nozzle shape configuration, pressure and shear stress changes continuously. Furthermore, HUVECs adhering vasculatures start to migrate and connect with encapsulated HUVECs each other during the perfusion culture and these endothelial cells formed lumen structures that can supply oxygen and nutrient to inner part of the thick tissues. Additionally when we mixed HepG2 to this tissue, survival rate and the liver functions increased during the perfusion culture by means of the pressure difference. Further examination were needed, however, when we make a pressure gradient by changing the shape of the needle to taper, the medium flow will be encouraged in a positive manner and angiogenesis, and vascular networks formation can be accelerated dramatically.