Fig. 1

Liver microsystems in vitro for drug responses. Cell micropatterning techniques use soft lithography and dielectrophoresis to arrange precisely the various cells on a micrometer scale. Hydrogel biofabrication techniques apply photolithography, micromolding and 3D bioprinting to reconstruct a 3D heterogeneous extracellular matrix. Microfluidic perfusion culture systems offer endothelial-like structures to mimic flow conditions and gradient generators to reconstruct gradients of oxygen, nutrients and metabolites