Directed Assembly and Development of Material-Free Tissues with Complex Architectures

An accessible and versatile microfabrication platform was demonstrated to build scaffold-free 3D tissues with complex architectures. As a platform for the controlled and uniform formation of multicellular building blocks and tissues, a microwell array system was fabricated using soft lithography methods. Microstructures were copied from a SU-8/silicon wafer via a negative replica of the same in the form of an elastomeric stamp cast from poly(dimethylsiloxane) (PDMS) into an agarose hydrogel The resulting hydrogel chips including the microstructures were transferred into standard 12-well culture plates (12wp) to maximize compatibility with existing laboratory equipment. A single PDMS stamp was able to imprint arrays of several hundreds to thousands of cylindrical microwells per well of a 12wp and with high precision and reproducibility. As a second step, these aggregates were used as multicellular building blocks within cavities of millimeter length-scale hydrogel templates with defined geometry. The formation of stapes-like tissues demonstrates the dimensional flexibility of the bottom-up approach in building larger tissues with precisely defined shape.