3D Bioprinting of Strong Living Scaffolds

项目摘要 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，一直是临床实践和研究中的一个长期挑战。再生工程提供 通过结合生物材料支架来替代自体或同种异体组织移植的一种有前途的替代方案， 细胞和生物活性因子。既提供机械支持又具有生物活性的工程支架 对于再生具有生物力学功能的此类组织至关重要。然而，目前已有的脚手架， 包括生物活性有限的坚韧聚合物或机械性能较差的软水凝胶， 不能同时满足机械和生物需求。为了解决这一问题，我们提出了开发 一种新型的乳胶生物墨水家族，能够实现具有内置的坚固生物支架的3D生物打印 机械坚固性和组织再生所需的生物功能。数据包的封装 支架内的生物制品(细胞和生物活性因子)提供了一种有吸引力的策略来装备支架 所需的生物功能。在坚韧的聚合物中封装生物制剂的主要障碍包括 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，通过分散水凝胶的内水相来设计油包水乳状生物油墨。 在坚韧的聚合物溶液的外相中，含有封装的生物制剂的液滴(微凝胶)。它是 假设微凝胶将保护被包裹的生物制品的功能不受有害化学物质的影响 限制了它们从外部相向内部相的扩散。每一种坚韧的聚合物的固化 在3D生物打印过程中分散的微凝胶将主要有助于最终支架的机械稳定性。 初步数据表明：1)成纤维细胞在乳状生物墨水中的存活率为95%； 2)所制得的乳胶支架具有机械稳定性(弹性模数为5-40兆帕) 细胞存活率为90%。该项目将以细胞兼容和生物可染细胞的开发为起点。 加载乳胶生物油墨，然后表征3D生物打印的乳胶支架，并结束 包埋生物活性因子和细胞支架对半月板再生作用的验证 作为测试模型。该模型将包括体外增殖、纤维软骨分化、 体内新半月板的形成。总体而言，我们的方法提供了一种机械生产的新方法 集乳液化学和3D生物打印于一体的强大的生物功能生物支架 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.