Size- and density-dependent acoustic differential bioassembly of spatially-defined heterocellular architecture.

Emerging acoustic bioassembly represents an attractive strategy to build cellular closely-packed organotypic constructs in a tunable manner for biofabrication. However, simultaneously assemble heterogeneous cell types into heterocellular functional units with spatially-defined cell arrangements, such as complementary and sandwich cytoarchitectures, remains a long-lasting challenge. To overcome this challenge, herein we present an acoustic differential bioassembly technique to assemble different cell types at the distinct positions of the acoustic field based on their inherent physical characteristics including cellular size and buoyant density. Specifically, different cell types can be differentially assembled beneath the nodal or the antinode regions of the Faraday wave to form complementary cytoarchitectures, or be selectively positioned at the center or edge area beneath either the nodal or the antinode regions to form sandwich cytoarchitectures. Using this technique, we assemble human induced pluripotent stem cell-derived liver spheroids and endothelial cells into hexagonal cytoarchitectures in vitro to mimic the cord and sinusoid structures in the hepatic lobules. This hepatic lobule model reconstitutes liver metabolic and synthetic functions, such as albumin secretion and urea production. Overall, the acoustic differential bioassembly technique facilitates the construction of human relevant in vitro organotypic models with spatially-defined heterocellular architectures, and can potentially find wide applications in tissue engineering and regenerative medicine.