Sacrificial strategy towards the formation of vascular-like networks in volumetric tissue constructs

The fields of tissue engineering and regenerative medicine have made astounding progress in recent years, evidenced by cutting-edge 4D printing technologies, precise gene editing tools, and sustained long-term functionality of engineered tissue grafts. Despite these fantastic feats, the clinical success of tissue-engineered constructs so far remains limited to only those relatively simple types of tissues such as thin bilayer skin equivalents or avascular cartilage. On the other hand, volumetric tissues (larger than a few millimeters in all dimensions), which are highly desirable for clinical utility, suffer from poor oxygen supply due to limited dimensional diffusion. Notably, large, complex tissues typically require a vascular network to supply the growing cells with nutrients for metabolic demands to prolong viability and support tissue formation. In recognition, extensive efforts have been made to create vascular-like networks in order to facilitate mass exchange through volumetric scaffolds. This review underlines the urgent need for continued research to create more complex and functional vascular networks, which is crucial for generating viable volumetric tissues, and highlights the recent advances in sacrificial template-enabled formation of vascular-like networks.