Zhao Yu, Li Yang, Mao Shuangshuang, Sun Wei, Yao Rui
Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing, People's Republic of China. Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing, People's Republic of China.
Biofabrication. 2015 Nov 2;7(4):045002. doi: 10.1088/1758-5090/7/4/045002.
Three-dimensional (3D) cell printing technology has provided a versatile methodology to fabricate cell-laden tissue-like constructs and in vitro tissue/pathological models for tissue engineering, drug testing and screening applications. However, it still remains a challenge to print bioinks with high viscoelasticity to achieve long-term stable structure and maintain high cell survival rate after printing at the same time. In this study, we systematically investigated the influence of 3D cell printing parameters, i.e. composition and concentration of bioink, holding temperature and holding time, on the printability and cell survival rate in microextrusion-based 3D cell printing technology. Rheological measurements were utilized to characterize the viscoelasticity of gelatin-based bioinks. Results demonstrated that the bioink viscoelasticity was increased when increasing the bioink concentration, increasing holding time and decreasing holding temperature below gelation temperature. The decline of cell survival rate after 3D cell printing process was observed when increasing the viscoelasticity of the gelatin-based bioinks. However, different process parameter combinations would result in the similar rheological characteristics and thus showed similar cell survival rate after 3D bioprinting process. On the other hand, bioink viscoelasticity should also reach a certain point to ensure good printability and shape fidelity. At last, we proposed a protocol for 3D bioprinting of temperature-sensitive gelatin-based hydrogel bioinks with both high cell survival rate and good printability. This research would be useful for biofabrication researchers to adjust the 3D bioprinting process parameters quickly and as a referable template for designing new bioinks.
三维（3D）细胞打印技术为制造负载细胞的组织样构建体以及用于组织工程、药物测试和筛选应用的体外组织/病理模型提供了一种通用方法。然而，打印具有高粘弹性的生物墨水以实现长期稳定结构并同时在打印后保持高细胞存活率仍然是一个挑战。在本研究中，我们系统地研究了3D细胞打印参数，即生物墨水的组成和浓度、保持温度和保持时间，对基于微挤压的3D细胞打印技术中可打印性和细胞存活率的影响。利用流变学测量来表征基于明胶的生物墨水的粘弹性。结果表明，当增加生物墨水浓度、增加保持时间并将保持温度降低至凝胶化温度以下时，生物墨水的粘弹性会增加。在增加基于明胶的生物墨水的粘弹性时，观察到3D细胞打印过程后细胞存活率下降。然而，不同的工艺参数组合会导致相似的流变学特性，因此在3D生物打印过程后显示出相似的细胞存活率。另一方面，生物墨水的粘弹性也应达到一定程度以确保良好的可打印性和形状保真度。最后，我们提出了一种用于3D生物打印温度敏感型基于明胶的水凝胶生物墨水的方案，该方案具有高细胞存活率和良好的可打印性。这项研究将有助于生物制造研究人员快速调整3D生物打印工艺参数，并作为设计新型生物墨水的参考模板。
