AO Research Institute Davos, Davos Platz, Switzerland. Department of Biomaterials Science and Technology, University of Twente, Enschede, The Netherlands.
Biofabrication. 2018 Sep 25;10(4):044104. doi: 10.1088/1758-5090/aadf58.
Extrusion-based three-dimensional bioprinting relies on bioinks engineered to combine viscoelastic properties for extrusion and shape retention, and biological properties for cytocompatibility and tissue regeneration. To satisfy these conflicting requirements, bioinks often utilize either complex mixtures or complex modifications of biopolymers. In this paper we introduce and characterize a bioink exploiting a dual crosslinking mechanism, where an enzymatic reaction forms a soft gel suitable for cell encapsulation and extrusion, while a visible light photo-crosslinking allows shape retention of the printed construct. The influence of cell density and cell type on the rheological and printability properties was assessed correlating the printing outcomes with the damping factor, a rheological characteristic independent of the printing system. Stem cells, chondrocytes and fibroblasts were encapsulated, and their viability was assessed up to 14 days with live/dead, alamar blue and trypan blue assays. Additionally, the impact of the printing parameters on cell viability was investigated. Owing to its straightforward preparation, low modification, presence of two independent crosslinking mechanisms for tuning shear-thinning independently of the final shape fixation, the use of visible green instead of UV light, the possibility of encapsulating and sustaining the viability of different cell types, the hyaluronan bioink here presented is a valid biofabrication tool for producing 3D printed tissue-engineered constructs.
基于挤出的三维生物打印依赖于生物墨水，这些墨水经过工程设计，结合了挤出和形状保持所需的粘弹性，以及细胞相容性和组织再生所需的生物特性。为了满足这些相互冲突的要求，生物墨水通常使用复杂的混合物或生物聚合物的复杂修饰。在本文中，我们介绍并表征了一种利用双重交联机制的生物墨水，其中酶反应形成一种柔软的凝胶，适合细胞包封和挤出，而可见光光交联允许打印结构的形状保持。通过将打印结果与阻尼因子相关联，评估了细胞密度和细胞类型对流变和可打印性的影响，阻尼因子是一个与打印系统无关的流变特性。将干细胞、软骨细胞和成纤维细胞包封，并通过活/死、alamar blue 和台盼蓝测定法评估其在 14 天内的活力。此外，还研究了打印参数对细胞活力的影响。由于其制备简单、低修饰、具有两种独立的交联机制，可独立于最终形状固定来调节剪切稀化、使用可见绿光而不是紫外线、能够包封和维持不同细胞类型的活力，因此本文提出的透明质酸生物墨水是一种有效的生物制造工具，可用于生产 3D 打印的组织工程构建体。
