Zwitterionic in situ-gelling hydrogel-based bioinks for tissue regeneration applications

尽管3D生物打印在彻底改变我们再生病变组织和/或创造基于细胞的治疗慢性疾病的能力方面有着巨大的前景，但3D生物打印技术的快速发展已经大大超过了利用这些技术的新型功能性商业生物链接的发展。特别是，生物链接的可用性可以使用多种类型的3D打印机实现自由形式的生物打印，并满足功能性组织支架的关键物理和生物学要求（即靶向力学、可调节降解、定义良好的孔隙度、细胞粘附性和抗纤维化特性），这对于解决组织工程和细胞治疗中的关键转化挑战至关重要。为了应对这一挑战，我们开发了一种原位凝胶两性离子水凝胶，该凝胶基于混合肼、醛和/或酮功能化预聚物，形成可逆的腙交联凝胶网络。这些水凝胶可以在混合时促进超快速凝胶化（<1秒），高度可调的降解时间（从几天到几个月不等），极高的润滑性（有利于3D打印软骨关节再生），非常低的细胞/蛋白质吸附，抗纤维化组织反应，以及支持被封装细胞的活力和扩张的能力，一系列与3D生物链接高度相关的特性。虽然这些材料已经引起了3D生物打印行业潜在公司合作伙伴的兴趣，但在商业3D打印机上实际实施我们的原位凝胶交联化学的概念验证演示，以实现所需的形状保真度和力学，打印临床相关的原代人类细胞或干细胞。在投资可行之前，需要确保化学纯度和生物惰性的生物墨水组件的可扩展制造。在I2I项目中提出的工作旨在回答这些关键的概念验证问题，旨在生产至少一个3D生物墨水“工具包”，可以在I2I项目结束时在一个或多个领先的3D打印公司获得分销和/或内部开发使用的许可。

Despite the tremendous promise of 3D bioprinting for revolutionizing our ability to regenerate diseased tissues and/or create cell-based therapeutics for managing chronic diseases, the rapid development of 3D bioprinting technologies has greatly outpaced the development of new functional commercially-available bioinks to leverage those technologies. In particular, the availability of a bioink that can enable free-form bioprinting using multiple types of 3D printers and meet the key physical and biological requirements of a functional tissue scaffold (i.e. targeted mechanics, tunable degradation, well-defined porosity, cell adhesivity, and anti-fibrotic properties) is essential to address key translational challenges in tissue engineering and cell therapy. Toward meeting this challenge, we have developed an in situ-gelling zwitterionic hydrogel based on mixing hydrazide and aldehyde and/or ketone functionalized pre-polymers to form a reversible hydrazone-crosslinked gel network. These hydrogels can facilitate ultra-fast gelation upon mixing (<1 s), highly tunable degradation times (ranging from a few days to several months), extremely high lubricity (beneficial for 3D printing cartilage for joint regeneration), very low cell/protein adsorption, anti-fibrotic tissue responses, and a capacity to support both the viability and expansion of encapsulated cells, a suite of properties highly relevant to a 3D bioink. While these materials have already attracted interest from potential company partners in the 3D bioprinting industry, proof-of-concept demonstrations around practically implementing our in situ gelation crosslinking chemistry on commercial 3D printers to achieve required shape fidelities and mechanics, printing clinically-relevant primary human cells or stem cells, and ensuring the scalable manufacturing of chemically pure and biologically inert bioink components are required prior to investment being feasible. The work proposed in this I2I grant is designed to answer these key proof-of-concept questions, aiming to produce at least one 3D bioink "kit" that could be licensed for distribution and/or internal development use at one or more leading 3D printing companies by the end of the I2I project period.