Microrobotic assembly of shape-controllable microstructures to perfusable 3D cell-laden microtissues

Tissue engineered cellular microtissues by three-dimensional assembly to clearly model human organs in vitro is increasingly needed. In this paper, cell-encapsulated 3D microstructures with micro vessel-like lumen were fabricated using PEGDA (poly (ethylene) glycol diacrylate) hydrogels. The available DMD-based (Digital Mirror Device) photolithography system was utilized to fabricate 2D cellular micromodules in a microfluidic channel with no need of mask. The heterogeneous micromodules were assembled by a modified rail-guided microrobotic system with a straight forward strategy and high efficiency. The adjustment to align assembled micromodules to be a regular geometry relied on liquid surface tension. With rapid 2D fabrication and 3D assembly, NIH/3T3 cells encapsulated in hydrogels can be survived for over 14 days in 2D micromodules and 2days in 3D microstructures with incubation. Long-term culture of cells were performed with different concentration of PEGDA, and shown that cells viability increased by decreasing PEGDA concentration. Cell adhesion was improved by adding RGDS (Arg-Gly-Asp-Ser) peptide sequence with observation under optical microscope. The assembled 3D cellular microtissues have a significant potential to be used in regenerative medicine in the future.