Suspended particles for omnidirectional template sacrifice for rapid vascular patterning within engineered tissues.

Engineered tissues offer great promise for therapeutic organ repair. Yet, biofabrication of organ-scale tissues can take hours or days for large constructs with geometric complexity, during which living cells in the construct lack vascular support. To address this, we developed an approach to accelerate biofabrication by embedding microreservoirs of evacuation reagents throughout geometrically patterned sacrificial agents. We call this approach Suspended Particles for Omnidirectional Template Sacrifice (SPOTS). We show that microparticles can serve as both structural impurities as well as depots for dissolution agents within sacrificial materials, both of which facilitate accelerated degradation of sacrificial materials and vascular templates. We used SPOTS to produce branched vascular networks in engineered tissue constructs. These networks support perfusion and endothelialization, improve the viability of human cells embedded in the construct, and support phenotype and function of human hepatocytes in the surrounding matrix. By accelerating biofabrication processes, SPOTS thus addresses a critical remaining challenge hindering translation of engineered tissues.