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

Three-dimensional (3D) bioprinting techniques have emerged as the most popular methods to fabricate 3D -engineered tissues; however, there are challenges in simultaneously satisfying the requirements of high cell density (HCD), high cell viability, and fine fabrication resolution. In particular, bioprinting resolution of digital light processing-based 3D bioprinting suffers with increasing bioink cell density due to light scattering. We developed a novel approach to mitigate this scattering-induced deterioration of bioprinting resolution. The inclusion of iodixanol in the bioink enables a 10-fold reduction in light scattering and a substantial improvement in fabrication resolution for bioinks with an HCD. Fifty-micrometer fabrication resolution was achieved for a bioink with 0.1 billion per milliliter cell density. To showcase the potential application in tissue/organ 3D bio-printing, HCD thick tissues with fine vascular networks were fabricated. The tissues were viable in a perfusion culture system, with endothelialization and angiogenesis observed after 14 days of culture.

Automated summary

Three-dimensional bioprinting techniques are widely used for fabricating 3D-engineered tissues, but face challenges in maintaining high cell density, cell viability, and fabrication resolution simultaneously. A novel approach using iodixanol in bioink was developed to reduce light scattering and improve fabrication resolution. Tissues with high cell density and fine vascular networks were successfully fabricated, and showed viability and endothelialization after 14 days of culture in a perfusion system.