Abstract

The application of 3 D printing technology in tissue engineering has become increasingly important. However, due to the limitations of bio-ink, there are still some remaining problems. For example, the major challenge for ideal bio-ink is to maintain stable 3 D structure and good biocompatibility in the meantime while conventional gels are week and nearly unprintable. So, the development of new bio-ink material with improved rheological and mechanical properties is highly demanded to avoid compromising biocompatibility for tissue engineering. Silk fibroin (SF), a natural degradable polymer, is considered to be a proper material for the preparation of bio-inks. We used SF, gelatin, and polyols as raw materials to fabricate bio-inks and scaffolds. We evaluated the rheological properties and printability of bio-inks with a rotational rheometer and a 3 D printer. The scaffolds were prepared by crosslinking and freeze-drying technologies. The biocompatibility and osteoinductive functions of scaffolds were investigated by evaluating proliferation, osteogenic differentiation and related cell signaling of cultured MC3T3-E1 cells. The results showed that the scaffolds using SF, Gel and propanediol (PG) not only had good rheological properties and storage modulus, but also could better enhance osteogenic specific genes expression mediated by Smad1/5/8 and Runx2 pathways. What is more, morphological characterization showed that α-mem incubation could help scaffold form porous structure on its surface, which could shed a light on a new 3 D bio-printed bone repair scaffold with both naturally emerged and CAD-designed porous structure. Our findings provide a potential biomaterial for the treatment of bone tissue regeneration.

摘要

3D打印技术在组织工程中的应用变得越来越重要。但是，由于生物墨水的局限性，仍然存在一些问题。例如，理想的生物墨水的主要挑战是同时保持稳定的 3D 结构和良好的生物相容性，而传统凝胶则是周而复始且几乎无法打印。因此，迫切需要开发具有改进流变学和机械性能的新型生物墨水材料，以避免损害组织工程的生物相容性。丝素蛋白（SF）是一种天然可降解聚合物，被认为是制备生物墨水的合适材料。我们使用SF、明胶和多元醇作为原材料来制造生物墨水和支架。我们使用旋转流变仪和 3D 打印机评估了生物墨水的流变特性和可印刷性。支架通过交联和冷冻干燥技术制备。通过评估培养的 MC3T3-E1 细胞的增殖、成骨分化和相关细胞信号传导来研究支架的生物相容性和骨诱导功能。结果表明，使用SF、Gel和丙二醇(PG)的支架不仅具有良好的流变学特性和储能模量，而且可以更好地增强Smad1/5/8和Runx2通路介导的成骨特异性基因表达。更重要的是，形态学表征表明，α-mem 孵化可以帮助支架在其表面形成多孔结构，这可以为具有自然出现和 CAD 设计的多孔结构的新型 3D 生物打印骨修复支架提供启示。我们的发现为治疗骨组织再生提供了一种潜在的生物材料。