Projection-Based 3D Printing of Cell Patterning Scaffolds with Multiscale Channels

To fully actualize artificial, cell-laden biological models in tissue engineering, such as 3D organoids and organs-on-a-chip systems, cells need to be patterned such that they can precisely mimic natural microenvironments in vitro. Despite increasing interest in this area, patterning cells at multiscale (similar to 10 mu m 10 mm) remains a significant challenge in bioengineering. Here, we report a projection-based 3D printing system that achieves rapid and high-resolution fabrication of hydrogel scaffolds featuring intricate channels for multiscale cell patterning. Using this system, we were able to use biocompatible poly(ethylene glycol)diacrylate in fabricating a variety of scaffold architectures, ranging from regular geometries such as serpentine, spiral, and fractal-like to more irregular/intricate geometries, such as biomimetic arborescent and capillary networks. A red food dye solution was able to freely fill all channels in the scaffolds, from the trunk (>1100 mu m in width) to the small branch (similar to 17 mu m in width) without an external pump. The dimensions of the printed scaffolds remained stable over 3 days while being immersed in Dulbecco's phosphate-buffered saline at 37 degrees C, and a penetration analysis revealed that these scaffolds are suitable for metabolic and nutrient transport. Cell patterning experiments showed that red fluorescent protein-transfected A549 human nonsmall lung cancer cells adhered well in the scaffolds' channels, and showed further attachment and penetration during cell culture proliferation.