Abstract

3D Laser Printing of Biomaterials and Living Cells

Lothar Koch, Head of Biofabrication Group, Laser Zentrum Hannover e.V.

Common ex vivo cell studies are not appropriate to simulate the complex interactions in three-dimensional (3D) tissue and cell–microenvironments in vivo. Therefore, 3D cell systems are necessary. For 3D cell culture, usually cells are seeded on scaffolds. These scaffolds typically do not have a defined structure, but porosity with varying pore size, shape and density. However, besides the material, also the scaffolds micro-structure strongly affects the cell behavior. Therefore, defined scaffolds with reproducible pore size and shape are required. Furthermore, seeding cells on scaffolds with a pipette generally does not allow a homogenous cell distribution or even a defined arrangement of different cell types in the scaffold. Printing cells into 3D patterns can advance 3D cell culture towards engineering pre-defined complex tissue samples. We present laser-based techniques to precisely generate scaffolds with sub-micron resolution and for printing living cells into 3D patterns. Two-photon polymerization allows high resolution writing of CAD structures directly into the volume of polymer solutions, including biomaterials like ceramic composites, biodegradable polymers, and hydrogels. The effect of the micro-structure on cell behavior will be discussed. For arranging different cell types in 3D patterns, laser-assisted bioprinting is used. Thereby, 3D stem cell grafts, skin tissue, and cell patterns for studying cell-cell interactions have been generated. Both techniques are capable of advancing 3D cell culture towards CAD defined and precisely arranged 3D cell models. Such innovative 3D cell models could provide new insights in understanding of cell behavior, tissue functions and regeneration.