Open source 3D-printing approach for economic and fast engineering of perfusable vessel-like channels within cell-laden hydrogels

The size of engineered tissue constructs is mainly constrained by diffusion limitations in the bulk materials. It has been proposed that engineering of constructs with embedded perfusable vascular networks might advance the engineering of larger tissue constructs and allow novel applications for biomedical studies. However, the progress in this field so far is relatively slow. A possible reason could be that the equipment and software needed to design and produce such constructs were so far out of reach for most laboratories. In this study, we present an economic and fast technique for the fabrication of such cell-laden hydrogels with an integrated perfusable vessel-like channel, based on open source approaches. We designed the molds and devices using free open source software and fabricated them using widely available low-cost thermoplast 3D printing using polylactic acid. With a soft lithographic technique, channels in cell-laden agarose hydrogels were fabricated within the printed device. Medium perfusion was performed for 1 and 3 days. We could show that the formed channels within the agarose hydrogels sustained perfusion without deformation. Cell viability was closely associated with flow conditions and distance from the channels, suggesting channel-dependent transport of nutrients and oxygen to the cells. In the flow group, cell viability in the first 300 μm around the channels stayed at 90% over 3 days, while it dropped to ∼50% in all the no-flow conditions, as well as at distances of >1200 μm from the channels in the flow condition. The vessel-like channels in the hydrogels fabricated in this approach provided nutrient supply to the surrounding cells. The described technique allows the construction and maintenance of bigger tissue engineered constructs with widely available hardware at a relatively low price and may therefore become a platform for the study of larger tissue constructs and embedded vascular structures.