Endothelial cell scaffolds generated by 3D direct writing of biodegradable polymer microfibers.

The engineering of large (thickness > 100 μm) tissues requires a microvascular network to supply nutrients and remove waste. To produce microvasculature in vitro, a scaffold is required to mechanically support and stimulate endothelial cell (EC) adhesion and growth. Scaffolds for ECs are currently produced by patterning polymers or other biomaterials into configurations which often possess isotropic morphologies such as porous films and fibrous mats. We propose a new "direct-write" process for fabricating scaffolds composed of suspended polymer microfibers that are precisely oriented in 3D, providing directional architecture for selectively guiding cell growth along a desired pathway. The diameters of the fibers produced with this process were predictably and repeatably controlled through modulation of the system parameters, enabling production of fibers with microvascular-scale diameters (5-20 μm) from a variety of biodegradable polymers. These scaffolds were successfully seeded with ECs, which conformed to the geometry of the fibers and proliferated over the course of one week.