Reconstruction of biological three-dimensional tissues: Bioprinting and biofabrication using inkjet technology

We have developed three-dimensional (3D) fabrication technology using direct cell printing to overcome several intrinsic problems of tissue engineering and regenerative medicine. Initial experiments using inkjet technology showed good feasibility of direct printing of living cells, however, problems such as drying and ink bleeding persisted. Using gel precursor and gel reactant such as sodium alginate solution and calcium chloride solution, we succeeded in developing a gelation technique capable of printing living cells by inkjet safely and effectively. This technique prevents cells from drying and maintaining printed position even in wet conditions. In addition, semi-solid hydrogel enables us to fabricate 3D structures using the individual inkjet droplet as the base unit of fabrication. Our '3D Bioprinter' is capable of fabricating 3D hydrogel structures such as fibers, sheets, lattices and tube structures with only hydrogel and with hydrogel and living cells together. Using multi-nozzles, 3D hydrogel structures with different types of living cells were successfully fabricated. In this chapter, we present the development of 3D biofabrication by direct cell printing using an inkjet and hydrogel. We will also discuss the present state of 3D tissue engineering and potential issues for future developments using our approach in the context of development of artificial organs.