3D Bioprinting of Strong Living Scaffolds

项目摘要 再生，再生：具有生物力学功能的受损或患病组织的再生，如肌肉骨骼 组织中的蛋白质，一直是临床实践和研究中的长期挑战。再生工程提供 一种有前途的替代自体或同种异体移植物的组织再生结合生物材料支架，可行的 细胞和生物活性因子。提供机械支撑和生物活性的工程支架 对于再生具有生物力学功能的组织至关重要。然而，现有的脚手架， 其包括具有有限生物活性的坚韧聚合物或具有差机械性能的软水凝胶， 不能满足机械和生物学的需要。为了解决这个问题，我们建议发展 一种新型的乳液生物墨水家族，能够3D生物打印具有内置 机械坚固性和组织再生所需的生物学功能。的封装 支架内的生物制剂（细胞和生物活性因子）提供了一种有吸引力的策略， 所需的生物功能。将生物制剂封装在坚韧聚合物中的主要障碍包括它们的 缺乏生物活性和经常使用有害化学品，如有机溶剂和/或有毒反应物。 在本研究中，通过分散水凝胶的水性内相，设计了油包水乳液生物墨水 微滴（微凝胶）与包封的生物制剂在坚韧聚合物溶液的外相中。是 假设微凝胶将通过以下方式保护封装的生物制剂的功能免受有害化学物质的影响： 限制了它们从外相向内相的扩散。坚韧的聚合物在每个 在3D生物打印期间分散的微凝胶将主要有助于最终支架的机械坚固性。 初步数据表明：1）在乳液生物墨水中实现了>95%的成纤维细胞活力; 和2）所得的乳液支架提供机械坚固性（弹性模量5-40 MPa） 和>90%的细胞活力。该项目将开始与细胞相容性和生物打印细胞的发展， 装载的乳液生物墨水，随后是3D生物打印的乳液支架的表征，并得出结论： 验证用于半月板再生的支架内包封的生物活性因子和细胞的功能 作为测试模型。该模型将包括体外增殖、纤维软骨形成分化， 和体内新半月板形成。总的来说，我们的方法提出了一种新的方法， 通过整合乳化化学和3D生物打印， 技术.我们预计这项工作将对再生工程产生广泛而重大的影响 通过有利于具有生物力学功能的广谱组织的修复或再生。

Project Summary The regeneration of damaged or diseased tissues that serve biomechanical functions, such as musculoskeletal tissues, has been a long-standing challenge in clinical practice and research. Regenerative engineering offers a promising alternative to auto- or allografts for tissue regeneration by combining biomaterial scaffolds, viable cells, and bioactive factors. Engineering scaffolds that provide both mechanical support and biological activities is critical for regenerating such tissues with biomechanical functions. However, currently existing scaffolds, which include either tough polymers with limited bioactivities or soft hydrogels with poor mechanical properties, fall short of meeting both mechanical and biological needs. To address this issue, we propose the development of a novel family of emulsion bioinks to enable the 3D bioprinting of strong living scaffolds with built-in mechanical robustness and desirable biological functions for tissue regeneration. The encapsulation of biologics (cells and bioactive factors) within scaffolds presents an attractive strategy to equip the scaffolds with desired biological functions. The major roadblocks to encapsulate biologics within tough polymers include their lack of bioactivity and the frequent usage of harmful chemicals, such as organic solvents and/or toxic reactants. In this study, a water-in-oil emulsion bioink is designed by dispersing an aqueous internal phase of hydrogel droplets (microgels) with encapsulated biologics in an external phase of tough polymer solution. It is hypothesized that microgels will protect the functions of encapsulated biologics from harmful chemicals by limiting their diffusion from the external to internal phases. The solidification of tough polymer around each dispersed microgel during 3D-bioprinting will mainly contribute to mechanical robustness of the final scaffold. The preliminary data demonstrates that: 1) >95% viability of fibroblast cells is achieved in an emulsion bioink; and 2) the resulting emulsion scaffolds afford both the mechanical robustness (elastic moduli 5-40 MPa) and >90% cell viability. This project will initiate with the development of cytocompatible and bioprintable cell- laden emulsion bioinks, followed by characterization of 3D-bioprinted emulsion scaffolds, and conclude with validating the functions of encapsulated bioactive factors and cells within scaffolds for meniscus regeneration as a test model. This model will include assessments of proliferation, fibrochondrogenic differentiation in vitro, and neo-menisci formation in vivo. Overall, our approach presents a new method to produce mechanically strong and biologically functional living scaffolds by integrating emulsion chemistry and 3D bioprinting technology. We anticipate that this work will have a broad and significant impact on regenerative engineering by benefiting repair or regeneration of broad-spectrum tissues with biomechanical functions.