Stevens, K.R. et al. Nat. Commun. 4, 1847 (2013).

Tissue engineering of complex organs such as liver, kidney and heart remains challenging owing to the hierarchical arrangement of tissue compartments. To construct complex engineered tissues in the dish, and particularly for potential clinical applications, one needs technologies that enable multicellular patterning and that are scalable. Stevens et al. report a method called Intaglio-Void/Embed-Relief Topographic (InVERT) molding that is compatible with several hydrogel systems and can be used to pattern different types of cells into specific compartments and build large, complex engineered tissues. They used InVERT to organize primary hepatocytes (including human induced pluripotent stem cell–derived hepatocytes), fibroblasts and endothelial cells and to reproduce the microstructure and multicellular composition of liver tissue. The engineered hepatic structures displayed native function in vitro and good viability after in vivo transplantation in rodents.