Abstract：
Non-union of large bone defects has been an existing clinical problem. 3D extrusion-based bioprinting provides an efficient approach to tackle such problems. This approach enables the use of various biomaterials, cell types and growth factors in developing a superior bone graft that is specific to the defect. In this article, we have designed and printed an ECM mimicking, self-assembled polyelectrolyte complex (PEC) based fibrous bioink using natural polymers like chitosan-polygalacturonic acid (PGA) and other biomaterials - gelatin, laponite and nanohydroxyapatite with a modified 3D printer. The developed bioink possesses a thermo-reversible sol-gel transition at physiological pH and temperature. Here, we demonstrated that post-printing, our fiber-reinforced bioink had significant cell proliferation with cell viability of >80% and negligible cell morbidity. The practicability of developing this self-assembled PEC-based bioink was assessed. Bioink with 4% gelatin (PECHLG4) had optimal printability with a minimal swelling ratio of approximately 3%. The printed scaffold had integrity for a period of 8 days under 0.5 mg/mL lysozyme concentration. We also evaluated the mechanical property of the bioink using compression analysis which gave an elastic modulus of 16 KPa. This combination of natural polymers and nanocomposite, along with a fibrous network of PECs, is itself a novel approach for 3D bioprinting and can be a preliminary proposition for the treatment of large bone defects.
摘要：
大骨缺损的不愈合一直是临床上存在的问题。基于3D挤出的生物打印提供了解决此类问题的有效方法。这种方法可以使用各种生物材料，细胞类型，和生长因子在开发针对缺损的优质骨移植物中。在本文中,我们设计并打印了一个ECM模仿，自组装聚电解质复合物（PEC）基纤维生物墨水使用天然聚合物，如壳聚糖-聚半乳糖醛酸（PGA）和其他生物材料-明胶，Laponite和纳米羟基磷灰石与改进的3D打印机。开发的生物墨水在生理pH和温度下具有热可逆的溶胶-凝胶转变。这里,我们证明了印刷后，我们的纤维增强生物墨水具有显著的细胞增殖,细胞活力>80%,细胞发病率可忽略不计.评估了开发这种基于自组装PEC的生物墨水的实用性。具有4%明胶的生物墨水(PECHLG4)具有最佳的可印刷性,具有约3%的最小溶胀率。打印的支架在0.5mg/mL溶菌酶浓度下具有8天的完整性。我们还使用压缩分析评估了生物墨水的机械性能，其弹性模量为16KPa。这种天然聚合物和纳米复合材料的组合，以及PEC的纤维网络，本身是一种新颖的3D生物打印方法，可以成为治疗大型骨缺损的初步命题。
