The rapid and tailored biofabrication of natural materials is of high interest for the field of tissue engineering and regenerative medicine. Scaffolds require both high biocompatibility and tissue-dependent mechanical strength to function as basis for tissue-engineered implants. Thus, natural hydrogels such as fibrin are promising but their rapid biofabrication remains challenging. Printing of low viscosity and slow polymerizing solutions with good spatial resolution can be achieved by freeform reversible embedding of suspended hydrogels (FRESH) bioprinting of cell-laden natural hydrogels. In this study, fibrin and hyaluronic acid were used as single components as well as blended ink mixtures for the FRESH bioprinting. Rheometry revealed that single materials were less viscous than the blended bioink showing higher values for viscosity over a shear rate of 10–1000 s⁻¹. While fibrin showed viscosities between 0.1624 and 0.0017 Pa·s, the blended ink containing fibrin and hyaluronic acid were found to be in a range of 0.1–1 Pa·s. In 3D vascularization assays, formation of vascular structures within the printed constructs was investigated indicating that the printing process did not harm cells and allowed formation of vasculature comparable to moulded control samples. Best values for vascularization were achieved in bioinks consisting of 1.0% fibrin-0.5% hyaluronic acid. The vascular structure area and length were three times higher compared to other tested bioinks, and structure volume as well as number of branches revealed almost four times higher values. In this study, we combined the benefits of the FRESH printing technique with in vitro vascularization, showing that it is possible to achieve a mechanically stable small-scale hydrogel construct incorporating vascular network formation.

天然材料的快速定制生物制造对组织工程和再生医学领域具有重要意义。支架需要高生物相容性和依赖于组织的机械强度才能作为组织工程植入物的基础。因此，纤维蛋白等天然水凝胶很有前景，但它们的快速生物制造仍然具有挑战性。通过悬浮水凝胶 (FRESH) 生物打印的悬浮水凝胶 (FRESH) 的自由形式可逆嵌入，可以实现具有良好空间分辨率的低粘度和慢聚合溶液的打印。在这项研究中，纤维蛋白和透明质酸被用作 FRESH 生物打印的单一成分以及混合墨水混合物。⁻¹. 虽然纤维蛋白的粘度在 0.1624 到 0.0017 Pa·s 之间，但发现含有纤维蛋白和透明质酸的混合油墨的粘度在 0.1-1 Pa·s 之间。在 3D 血管化分析中，研究了打印结构内血管结构的形成，表明打印过程不会伤害细胞并允许形成与模制对照样品相当的脉管系统。在由 1.0% 纤维蛋白-0.5% 透明质酸组成的生物墨水中实现了血管化的最佳值。与其他测试的生物墨水相比，血管结构面积和长度高出三倍，结构体积和分支数量显示出几乎高出四倍的值。在这项研究中，我们将 FRESH 打印技术的优点与体外血管化相结合，