Dynamic Fibrous Scaffolds for Engineering Dense Connective Tissues

描述（由申请人提供）： 当内源性修复失败时，通常是致密纤维肌肉骨骼组织（如膝关节半月板）的情况，必须开发新的策略和技术来增强组织再生。虽然已经开发了许多组织工程疗法用于纤维增强组织的工程化，但一个持续的限制是制造保持结构完整性和指导适当组织结构的支架的能力，同时在整个再生期间促进细胞浸润。在这个建议中，我们解决了这些限制与生产一种新的多聚合物复合纳米纤维支架，提供了一个新组织形成的三维微观图案。这些支架的纤维直径与天然细胞外基质的纤维直径相当，可以产生具有限定的纤维各向异性的支架，这些纤维各向异性模仿纤维增强组织的结构排列。此外，通过引入聚合物特性的灵活性，通过一个图书馆的光交联大分子单体，表现出一系列的机械和降解性能时，聚合，我们建议定制的时间孔形成内的支架通过控制降解的个别聚合物组分。我们假设，这些纳米纤维多聚物光交联补片将具有反映最硬和降解最慢的组件的受控机械性能，并显示空隙空间随时间增加，同时保持其整体机械性能。此外，我们假设，通过牺牲元件的侵蚀，这些支架内空隙空间的受控增加将促进细胞浸润到多聚合物网中，并将导致更均匀的功能组织结构。此外，由于半月板的机械环境在其成熟和体内平衡中至关重要，我们假设定制的机械预处理方案同样会促进浸润的半月板结构的功能成熟。为此，开发了一种新型的动态加载生物反应器，该生物反应器施加压缩和拉伸以促进组织成熟。该提案的第一个目的是开发电纺多组分纳米纤维支架的技术，并使用预测性纤维增强复合材料模型将其特性与天然组织进行比较。在第二个目标中，将在单聚合物和三聚合物细胞负载纳米纤维支架中探索细胞的相互作用和渗透以及最终的机械性能。第三个目标涉及开发用于预处理支架的生物反应器，并评估机械刺激对组织形成的短期和长期影响。如果成功，这种创新方法将为受损纤维增强肌肉骨骼组织的功能再生提供几种新的技术。 公共卫生相关性声明（由申请人提供）：该项目开发了一种新型多聚合物支架制造系统，以控制聚合物化学和整体支架力学以及随时间的降解，从而改善纤维组织工程化结构中的细胞浸润和均匀组织沉积。如果成功，这种方法将克服肌肉骨骼系统致密结构的组织工程中的主要障碍，并提供一种机械 功能性的、结构各向异性的3D微图案，用于定向新组织形成，同时促进完全细胞定殖和完全溶解后聚合物结构的最终替换。这种创新的方法，耦合支架制造，机械载荷和体内评估，将有助于开发纤维增强的肌肉骨骼组织，如膝关节半月板，否则无法愈合，几乎没有临床可行的修复策略的组织工程治疗。

DESCRIPTION (provided by applicant): When endogenous repair fails, as is often the case with dense fibrous musculoskeletal tissues (like the knee meniscus), novel strategies and enabling technologies must be developed to enhance tissue regeneration. While numerous tissue engineering therapies have been developed for the engineering of fiber-reinforced tissues, one persistent limitation is the ability to fabricate scaffolds that maintain structural integrity and direct appropriate tissue architecture, while simultaneously promoting cellular infiltration throughout the regeneration period. In this proposal, we address these limitations with the production of a novel multi-polymer composite nanofibrous scaffold that provides a 3-dimensional micropattern for neo-tissue formation. These scaffolds, with fiber diameters on the order of the native extracellular matrix, can be produced with defined fiber anisotropies that mimic the structural arrangement of fiber-reinforced tissues. Further, by introducing flexibility in polymer properties via a library of photocrosslinkable macromers that exhibit a range of mechanical and degradation properties when polymerized, we propose to tailor temporal pore formation within the scaffold through the controlled degradation of individual polymer components. We hypothesize that these nanofibrous multipolymer photocrosslinked meshes will have controlled mechanical properties reflective of the stiffest and slowest degrading component and show a time dependent increase in void space while maintaining their overall mechanical properties. Further, we hypothesize that the controlled increase in void space within these scaffolds, via the erosion of sacrificial elements, will promote cellular infiltration into the multi-polymer mesh and will result in a more uniform functional tissue structure. Additionally, as the mechanical environment of the meniscus is paramount in its maturation and homeostasis, we hypothesize that tailored mechanical preconditioning regimens will likewise promote functional maturation of infiltrated meniscus constructs. To this end, a novel dynamic loading bioreactor that applies compression and tension is developed to promote tissue maturation. The first Aim of this proposal is to develop technology to electrospin multi-component nanofibrous scaffolds and compare properties to the native tissue using a predictive fiber-reinforced composite model. In the second Aim, the interaction and infiltration of cells and ultimate mechanical properties will be explored in single- and tri-polymer cell-laden nanofibrous scaffolds. The third Aim involves the development of a bioreactor for pre-conditioning scaffolds and evaluating the impact of mechanical stimulation on tissue formation in the short and long term. If successful, this innovative approach will provide several new enabling technologies for the functional regeneration of damaged fiber-reinforced musculoskeletal tissues. Public Health Relevance Statement (provided by applicant): This project develops a novel multi-polymer nanofiber fabrication system to exert control over polymer chemistry and overall scaffold mechanics and degradation with time to improve cellular infiltration and uniform tissue deposition in fibrous tissue-engineered constructs. If successful, this approach would surmount a major hurdle in the tissue engineering of dense structures of the musculoskeletal system and provide a mechanically functional, structurally anisotropic 3D micro-pattern for directed neo-tissue formation while promoting full cellular colonization and eventual replacement of the polymer structure after complete dissolution. This innovative approach, coupling scaffold fabrication, mechanical loading, and in vivo assessments, will aid in the development of tissue engineered therapies for fiber-reinforced musculoskeletal tissues such as the knee meniscus that otherwise fail to heal and have few clinically viable repair strategies.