Engineering large-scale perfused tissues via synthetic 3D soft microfluidics

The vascularization of engineered tissues and organoids has remained a major unresolved challenge in regenerative medicine. While multiple approaches have been developed to vascularize in vitro tissues, it has thus far not been possible to generate perfusable vessels in sufficiently close proximity and at sufficient small scale to perfuse large de novo tissues. Here, we achieve the perfusion of multi-mm3 tissue constructs by generating perfusable synthetic capillary-scale 3D channels. Our 3D soft microfluidic strategy is uniquely enabled by a 3D-printable 2-photon-polymerizable hydrogel formulation, which allows for precise microvessel printing at scales below the diffusion limit. We demonstrate that these large-scale engineered tissues are viable, proliferative and exhibit complex morphogenesis during long-term in-vitro culture, while avoiding hypoxia and necrosis. We show by scRNAseq and immunohistochemistry that neural differentiation is significantly accelerated in perfused neural constructs. Additionally, we illustrate the versatility of this platform by demonstrating long-term perfusion of developing liver tissue. This fully synthetic vascularization platform opens the door to the generation of human tissue models at unprecedented scale and complexity. Overall design: 3 samples are analyzed to compare the effect of perfusion on human brain tissue. 1x day 8 brain organoids in suspentions (chip control), 1x day 8 brain tissue in non-perfused chip (perfusion control), and 1x day 8 brain tissue in a perfused chip.