LAUSR

Engineered three-dimensional (3D) microtissues that recapitulate in vivo tissue morphology and microvessel lumens have shown significant potential in drug screening and regenerative medicine. Although microfluidic-based techniques have been developed for bottom-up assembly of 3D tissue models, the spatial organization of heterogeneous micromodules into tissue-specific 3D constructs with embedded microvessels remains challenging. Inspired by a hydrodynamic-based classic game which stacks rings in water through the flow, a facile strategy is proposed for effective assembly of heterogeneous hierarchical micromodules with a central hole, into permeable hollow 3D tissue-like constructs through hydrodynamic interaction in a versatile microfluidic chip. The micromodules are fabricated by in situ multi-step photo-crosslinking of cell-laden hydrogels with different mechanical properties to give the high fidelity. With the hydrodynamic interaction derived from the discontinuous circulating flow, the micromodules are spatially organized layer-by-layer to form a 3D construct with a microvessel-like lumen. As an example, a ten-layered liver lobule-like construct containing inner radial-like poly(ethylene glycol) diacrylate (PEGDA) structure with hepatocytes and outer hexagonal gelatin methacrylate (GelMA) structure with endothelial cells are assembled in 2 min. During 10 days of co-culture, cells maintain high viability and proliferated along with the composite lobule-like morphology. The 3D construct owns a central lumen, which allows perfusion culture to promote albumin secretion. We anticipate that this microassembly strategy can be used to fabricate vascularized 3D tissues with various physiological morphologies as alternatives for biomedical research applications.