High cell density and high-resolution 3D bioprinting for fabricating vascularized tissues

This study introduces a novel digital light processing (DLP)-based 3D bioprinting strategy to overcome the ‘density-viability-resolution trilemma’ in high-cell-density (HCD) tissue fabrication. By incorporating iodixanol (IDX) into bioinks, the refractive index was precisely matched to the cytoplasm, reducing light scattering by 10-fold and achieving a 50 µm printing resolution at 0.1 billion cells/mL density. The method enabled fabrication of thick, perfusable vascularized tissues containing 40 million cells/mL, which maintained 66% cell viability after 14 days of perfusion culture. This refractive-index–tuned printing technique allowed generation of complex microvasculature, demonstrating endothelialization and angiogenesis without post-seeding steps.