Crosslinkable cell scale fibers for large meniscus defect repair

摘要 半月板对健康的膝关节功能起着至关重要的作用。然而，考虑到这一组织在负荷中的中心性 转移和苛刻的物理环境，伤害是常见的，成年人的愈合是有限的。这个 目前缺乏半月板损伤的再生解决方案，部分原因是 可用于修复半月板致密而复杂的组织结构的技术。尤其是 挑战是再生不同的组织内部和外部区域，这些区域具有不同的组成和 机械性能，使轴承能够有效承载。而模仿大块几何形状的支架 半月板在临床上被引入以促进半月板的修复/再生，但这些支架并不 提供模拟细胞以形成与这些区域相匹配的组织所需的微观、细胞尺度的线索- 特定属性。这种限制导致未成熟的半月板样组织，缺乏承载能力。它是 越来越多的人认识到，细胞尺度结构的结构属性(例如，形状和刚度)可以 影响细胞活性和直接基质形成。为了利用这些洞察力，我们的团队开发了 FiberGel系统用于产生基于生物聚合物的细胞尺度的微纤维，其中单个纤维具有可调的 直径和硬度。这些超细纤维可以模塑和交联成各种形状，以填充半月板 缺陷，内部微纤维可以形成随机或排列的配置，以模拟 自然半月板的不同区域。半月板细胞可以直接混合到FiberGel糊状物中 交联化以产生均匀的纤维素化结构。在这份提案中，我们优化了这种有希望的材料 确定促进内、外区表型和结构形成的条件。我们会 确定FiberGel系统的可调参数-直径、硬度和排列-如何影响 通过一系列旨在提炼和优化基质的研究获得半月板细胞的生物合成活性 队形。确定基于FiberGel的植入物如何响应关节产生的机械力 运动，我们还将使用定制的机械生物反应器在构建过程中对其施加生理负载 成熟。我们的中心假设是存在一组最佳的微纤维参数(直径， 刚性和对齐)，用于再生我们的半月板的内部和外部区域。成功完成 这项工作将产生可用于临床修复膝关节半月板的FiberGel配方。

Abstract The meniscus plays a vital role in healthy knee function. However, given the centrality of this tissue in load transfer and the demanding physical environment, injury is common and healing in adults is limited. The current lack of regenerative solutions for knee meniscus injury arises, in part, from the significant gap in technology that can be used to repair the dense and complex tissue structure of the meniscus. Particularly challenging is regenerating the distinct inner and outer zones of tissue, which have distinct composition and mechanical properties to enable effective load bearing. While scaffolds that mimic the bulk geometry of meniscus are being introduced clinically to promote the repair/regeneration of meniscus, these scaffolds do not provide the microscopic, cell-scale cues that are needed to simulate cells to form tissue matching these region- specific attributes. This limitation leads to immature meniscus-like tissue, lacking in load-bearing capacity. It is increasingly well understood that structural properties (e.g., shape and stiffness) of cell-scale structures can influence the cell activity and direct matrix formation. To harness these insights, our team developed the FiberGel system to generate biopolymer-based, cell-scale microfibers, in which individual fibers have a tunable diameter and stiffness. These microfibers can be molded and crosslinked into various shapes to fill meniscus defects, and the internal microfibers can be formed into a random or aligned configuration to mimic the different regions of the native meniscus. Meniscus cells can be directly mixed into the FiberGel paste before crosslinking to produce uniformly cellularized constructs. In this proposal, we optimize this promising material to define conditions that promote formation of inner and outer zone phenotypes and structures. We will determine how the tunable parameters of FiberGel system — diameter, stiffness and alignment — impact the biosynthetic activities of meniscus cells through a series of studies designed to refine and optimize matrix formation. To determine how FiberGel-based implants respond to mechanical forces that arise with joint motion, we will also use a custom mechanical bioreactor to apply physiologic load to constructs during their maturation. Our central hypothesis is that there exists an optimal set of microfibers parameters (diameter, stiffness and alignment) for regenerating the inner and outer regions of our meniscus. Successful completion of this work will generate FiberGel formulations that may be used for the clinical repair of the knee meniscus.