3D Bioprinting of Continuous Nanofibrous Yarn-Reinforced Cell-Laden Constructs

Despite notable progress, 3D-bioprinted constructs exhibit limited mechanical robustness and lack the essential ECM-mimicking features crucial for promoting bioactivity, cell growth, and tissue formation. To address these shortcomings, we devised an innovative technique that reinforces bioprinted constructs with polymeric nanofibrous yarns composed of thousands of nanofibers. Utilizing an <i>in situ</i> printing process, a continuous strand of nanofibrous yarn was embedded within the core of the extruded bioink to fabricate a 3D-printed construct. We optimized the key design parameters of the nanofibrous yarn, bioink, and the printing process, which are necessary for direct bioprinting of a nanofibrous yarn-reinforced 3D construct, which has never been demonstrated before. The hydrophilicity of the nanofibrous yarns promoted interfacial interaction with the bioink, while the shear stress developed at the nozzle during extrusion allowed the nanofibrous yarns to be spooled out as a single continuous strand integrated with the bioink. The micron-sized channels within the bundled nanofibrous yarn facilitated cell wicking into the nanifibrous yarn. This approach has enhanced the ability to manufacture cell-laden structures, whereby live cells are freely incorporated into a highly organized nanofibrous architecture. The resulting construct offers the high bioactivity needed for cell regeneration and the superior structural integrity required for diverse biomedical and regenerative medicine applications.