Hoch Eva, Tovar Günter E M, Borchers Kirsten
Institute for Interfacial Process Engineering and Plasma Technology IGVP, University of Stuttgart, Stuttgart, Germany.
Institute for Interfacial Process Engineering and Plasma Technology IGVP, University of Stuttgart, Stuttgart, Germany Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany
Eur J Cardiothorac Surg. 2014 Nov;46(5):767-78. doi: 10.1093/ejcts/ezu242. Epub 2014 Jun 26.
Free-form fabrication techniques, often referred to as '3D printing', are currently tested with regard to the processing of biological and biocompatible materials in general and for fabrication of vessel-like structures in particular. Such computer-controlled methods assemble 3D objects by layer-wise deposition or layer-wise cross-linking of materials. They use, for example, nozzle-based deposition of hydrogels and cells, drop-on-demand inkjet-printing of cell suspensions with subsequent cross-linking, layer-by-layer cross-linking of synthetic or biological polymers by selective irradiation with light and even laser-induced deposition of single cells. The need of vessel-like structures has become increasingly crucial for the supply of encapsulated cells for 3D tissue engineering, or even with regard to future application such as vascular grafts. The anticipated potential of providing tubes with tailored branching geometries made of biocompatible or biological materials pushes future visions of patient-specific vascularized tissue substitutions, tissue-engineered blood vessels and bio-based vascular grafts. We review here the early attempts of bringing together innovative free-form manufacturing processes with bio-based and biodegradable materials. The presented studies provide many important proofs of concepts such as the possibility to integrate viable cells into computer-controlled processes and the feasibility of supplying cells in a hydrogel matrix by generation of a network of perfused channels. Several impressive results in the generation of complex shapes and high-aspect-ratio tubular structures demonstrate the potential of additive assembly methods. Yet, it also becomes obvious that there remain major challenges to simultaneously match all material requirements in terms of biological functions (cell function supporting properties), physicochemical functions (mechanical properties of the printed material) and process-related (viscosity, cross-linkability) functions, towards the demanding goal of biofabricating artificial blood vessels.
自由成型制造技术，通常被称为“3D打印”，目前正在针对生物及生物相容性材料的加工进行测试，尤其是用于制造血管样结构。这类计算机控制的方法通过材料的逐层沉积或逐层交联来组装三维物体。例如，它们使用基于喷嘴的水凝胶和细胞沉积、按需喷墨打印细胞悬液并随后交联、通过光的选择性照射对合成或生物聚合物进行逐层交联，甚至是激光诱导单细胞沉积。对于三维组织工程中封装细胞的供应，甚至对于诸如血管移植物等未来应用而言，对血管样结构的需求变得越来越关键。由生物相容性或生物材料制成具有定制分支几何形状的管子所预期的潜力推动了针对患者特定的血管化组织替代物、组织工程血管和生物基血管移植物的未来设想。我们在此回顾将创新的自由成型制造工艺与生物基及可生物降解材料相结合的早期尝试。所呈现的研究提供了许多重要的概念验证，例如将活细胞整合到计算机控制过程中的可能性，以及通过生成灌注通道网络在水凝胶基质中供应细胞的可行性。在生成复杂形状和高纵横比管状结构方面的一些令人印象深刻的结果证明了添加剂组装方法的潜力。然而，同样明显的是，要同时满足生物功能（支持细胞功能的特性）、物理化学功能（打印材料的机械性能）和与工艺相关（粘度、可交联性）功能方面的所有材料要求，朝着生物制造人造血管这一苛刻目标仍存在重大挑战。
