Spatiotemporal control of tendon healing through modular, injectable hydrogel composites

项目总结 基于生物材料的方法有治疗肌腱损伤的潜力，其慢性后遗症包括 疼痛，功能减退，以及由于异常疤痕形成而再次受伤的风险增加。不幸的是， 许多参与肌腱损伤反应的细胞球员的起源和功能不明使它 很难确定这些不良结果的生物学机制。因此，治疗的目标是 生物材料介导的肌腱修复方法尚未建立。最近，有证据表明， 新生小鼠完全再生完全横断的肌腱。比较了他们在伤害反应方面的关键差异 表明祖细胞的募集及其随后的伸展分化可以 导致再生愈合。因此，拟议工作的长期目标是开发一种生物材料疗法。 能够协调肌腱愈合的多个不同阶段。为此，我们的目标是设计一种合成的， 水凝胶基复合支架，集成了物理(机械和地形)和可溶线索以 1)将特定的祖细胞群体招募到损伤部位，以及2)引导伸肌祖细胞分化 以及肌腱损伤后适当成分和组织的从头合成基质。我们的中央 假说是，组合微环境线索的时空呈现可以控制 修复细胞进入损伤部位并促进其分化和基质的丰度和一致性 重塑活动，两者都会改善成人肌腱的愈合反应。我们的初步数据 建立一种允许肌腱祖细胞(TPC)迁移和肌腱分化的材料； 此外，我们还建立了一种可调节的可溶性因子释放系统，使趋化因子能够逐渐释放 提示和细胞触发的分化因子的释放。我们已经发现了物理和微凝胶- 提供的可溶性线索协同增强了TPC在这些复合水凝胶中的招募。因此，在 目的1，我们将优化微环境线索，以驱动强大的体外伸展分化。在《目标2》中，这个 葡聚糖-乙烯基砜材料体系将在小鼠跟腱损伤模型上进行测试，以研究 这些线索对TPC在伤口部位的募集、随后的腱形成和基质的影响 证词/组织。伸展分化的程度将通过表达一种 伸展因子的组合，支持伸展的有组织的从头形成基质的沉积，以及功能 再生肌腱的分析。这项工作将建立一种新型的、可注射的、模块化的水凝胶支架 在成年小鼠身上驱动强健的肌腱愈合反应。此外，这项工作还将提供更深层次的 理解调控肌腱发生的微环境线索，这些信息对肌腱发生的进展至关重要 以结缔组织再生为目标的生物材料疗法。

PROJECT SUMMARY Biomaterials-based approaches have potential for treating tendon injury, the chronic sequelae of which include pain, diminished function, and heightened risk of reinjury due to aberrant scar formation. Unfortunately, the undefined origin and function of numerous cellular players involved in the tendon injury response have made it difficult to identify biological mechanisms of these poor outcomes. As a result, therapeutic targets for biomaterials-mediated tendon repair approaches have not been established. Recently, it has been shown that neonatal mice fully regenerate completely transected tendons. Key differences in their injury response compared to that of adults suggest that recruitment of progenitor cells and their subsequent tenogenic differentiation can lead to regenerative healing. Thus, the long-term goal of the proposed work is to develop a biomaterial therapy capable of coordinating multiple, distinct phases of tendon healing. Toward this end, we aim to design a synthetic, hydrogel-based composite scaffold that integrates physical (mechanical and topographical) and soluble cues to 1) recruit specific progenitor cell populations to the injury site and 2) direct tenogenic progenitor cell differentiation and de novo matrix synthesis of the appropriate composition and organization following tendon injury. Our central hypothesis is that spatiotemporal presentation of combinatorial microenvironmental cues can control the abundance and identity of reparative cells entering the injury site and promote their differentiation and matrix remodeling activity, both of which will improve the adult tendon healing response. Our preliminary data establishes a material that is permissive to tendon progenitor cell (TPC) migration and tenogenic differentiation; moreover, we have established a tunable soluble factor release system enabling gradual release of chemotactic cues and cell-triggered release of differentiation factors. We have already found that physical and microgel- delivered soluble cues synergistically enhance TPC recruitment into these composite hydrogels. Therefore, in Aim 1, we will optimize microenvironmental cues for driving robust tenogenic differentiation in vitro. In Aim 2, this dextran vinyl sulfone-based material system will be tested in a murine Achilles tendon injury model to study the effects of these cues on recruitment of TPCs to the wound site, subsequent tenogenesis, and matrix deposition/organization. The extent of tenogenic differentiation will be quantified through the expression of a panel of tenogenic factors, deposition of organized de novo matrix supporting tenogenesis, and functional analysis of regenerated tendons. This work will establish a novel, injectable, modular hydrogel scaffold capable of driving a robust tendon healing response in adult mice. Moreover, this work will provide a deeper understanding of the microenvironmental cues regulating tenogenesis, information critical to the advancement of biomaterial therapeutics geared toward connective tissue regeneration.