Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA.
Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA.
Biomaterials. 2018 Oct;180:24-35. doi: 10.1016/j.biomaterials.2018.06.042. Epub 2018 Jul 4.
Fibrous proteins found in the natural extracellular matrix (ECM) function as host substrates for migration and growth of endogenous cells during wound healing and tissue repair processes. Although various fibrous scaffolds have been developed to recapitulate the microstructures of the native ECM, facile synthesis of hydrogel microfibers that are mechanically robust and biologically active have been elusive. Described herein is the use of interfacial bioorthogonal polymerization to create hydrogel-based microfibrous scaffolds via tetrazine ligation. Combination of a trifunctional strained trans-cyclooctene monomer and a difunctional s-tetrazine monomer at the oil-water interface led to the formation of microfibers that were stable under cell culture conditions. The bioorthogonal nature of the synthesis allows for direct incorporation of tetrazine-conjugated peptides or proteins with site-selectively, genetically encoded tetrazines. The microfibers provide physical guidance and biochemical signals to promote the attachment, division and migration of fibroblasts. Mechanistic investigations revealed that fiber-guided cell migration was both F-actin and microtubule-dependent, confirming contact guidance by the microfibers. Prolonged culture of fibroblasts in the presence of an isolated microfiber resulted in the formation of a multilayered cell sheet wrapping around the fiber core. A fibrous mesh provided a 3D template to promote cell infiltration and tissue-like growth. Overall, the bioorthogonal approach led to the straightforward synthesis of crosslinked hydrogel microfibers that can potentially be used as instructive materials for tissue repair and regeneration.
天然细胞外基质（ECM）中发现的纤维蛋白作为宿主基质，在伤口愈合和组织修复过程中，促进内源性细胞的迁移和生长。尽管已经开发了各种纤维支架来再现天然 ECM 的微观结构，但仍然难以制备具有机械强度和生物活性的水凝胶微纤维。本文描述了使用界面生物正交聚合通过四嗪键合来创建基于水凝胶的微纤维支架。在油水界面处使用三官能化的扭曲环辛烯单体和二官能化的 s-四嗪单体的组合导致微纤维的形成，该微纤维在细胞培养条件下稳定。该合成的生物正交性质允许直接掺入带有位置选择性的、经基因编码的四嗪的四嗪缀合肽或蛋白质。微纤维为成纤维细胞的附着、分裂和迁移提供物理指导和生化信号。机理研究表明，纤维引导的细胞迁移既依赖于 F-肌动蛋白又依赖于微管，证实了微纤维的接触引导作用。在存在单个微纤维的情况下延长成纤维细胞的培养时间会导致围绕纤维核心形成多层细胞片。纤维网格提供了一个 3D 模板，以促进细胞渗透和组织样生长。总的来说，这种生物正交方法导致了交联水凝胶微纤维的简单合成，这些微纤维有可能被用作组织修复和再生的指导材料。
