Dynamic Fibrous Scaffolds for Repairing Dense Connective Tissues

摘要 肌肉骨骼系统的纤维组织(如膝关节半月板)因其不良的内在特性而受到困扰。 治疗能力。在之前的融资周期中，我们开发了包括多光纤在内的使能技术 支架向半月板组织的修复引入各种时间和结构信号。我们用了 这些支架用于设计具有与天然组织相似的性质和组织的构建物(第一周期)和 然后开发支架，通过传递因子来增强内源性组织修复，局部招募 细胞(第2周期)。这次更新的总体目标是进一步改善内源性半月板修复 通过适当的时间和空间协调要素交付的工程化脚手架，到第一个(I) 软化损伤部位附近的细胞核(通过暂时减少异染色质含量)，然后(Ii) 在修复支架内招募和稳定这些细胞的表型。我们假设这批货物 这些因素将允许有活力的内源性细胞从半月板招募到支架上，并且 对这些因素的空间控制将改善支架的定植，即使是厚厚的支架。我们将聘用 复合支架(在之前的资金周期中开发)，提供稳定的纤维成分 (聚己内酯(PCL)，提供指导性图案和机械稳定性)，牺牲纤维部分 (聚氧乙烷(PEO)，以定义支架的初始孔隙率，并提供早期释放的因素到 环境)，以及经过改造的透明质酸(HA)纤维部分(可在数周内降解并释放 持续的因素)。为了解决我们的假设，第一个目标将利用体外微流控- 研究核软化(曲古抑素A)、趋化(血小板-A)的时间和剂量的平台 衍生生长因子)和纤维软骨生成因子(转化生长因子-β3)改变细胞核 力学，细胞募集，并促进细胞表型的恢复向纤维细胞迁移 半月板组织制成的支架。在第二个目标中，我们将控制从整个脚手架(如 之前)或从内层(新提议的)跨越各种支架厚度和释放率 促进厚重脚手架的普及。这一目标将使用我们最近开发的皮下 半月板组织修复模型。第三个目标是将支架植入尤卡坦半岛的半月板缺损处。 在临床相关的缺陷模型中评估小型猪的疗效。如果成功，这些研究和 技术将促进我们对工程支架用于内源性半月板的理解 修复并向临床翻译迈进一步。

Abstract Fibrous tissues of the musculoskeletal system (e.g., the knee meniscus) are plagued by their poor intrinsic healing capacity. In the previous funding cycles, we developed enabling technologies including multi-fiber scaffolds to introduce various temporal and structural signals towards the repair of meniscal tissue. We used these scaffolds to engineer constructs with properties and organization similar to native tissues (1st cycle) and then developed scaffolds to enhance endogenous tissue repair through the delivery of factors to recruit local cells (2nd cycle). The overall objective of this renewal is to further improve endogenous meniscus repair with engineered scaffolds through the appropriate temporal and spatial orchestration of factor delivery, to first (i) soften nuclei in cells (via a temporary reduction in heterochromatin content) near the injury site and then (ii) recruit and stabilize the phenotype of these cells within the repair scaffolds. We hypothesize that the delivery of these factors will permit recruitment of viable endogenous cells from the meniscus to the scaffolds and that the spatial control of these factors will improve scaffold colonization, even with thick scaffolds. We will employ composite scaffolds (developed during the previous funding cycles) that provide a stable fiber fraction (polycaprolactone (PCL), to provide an instructional pattern and mechanical stability), a sacrificial fiber fraction (polyethylene oxide (PEO), to define initial scaffold porosity and provide early release of factors into the environment), and an engineered hyaluronic acid (HA) fiber fraction (that degrades over weeks and releases factors in a sustained fashion). To address our hypotheses, the first Aim will utilize in vitro microfluidic- platforms to investigate the timing and dosing of nuclear-softening (Trichostatin A), chemotactic (platelet- derived growth factor), and fibro-chondrogenic factors (transforming growth factor-β3) to alter nuclear mechanics, cell recruitment, and promote resumption of the cellular phenotype of cells migrating into fibrous scaffolds from meniscal tissue. In the second Aim, we will control release from either the entire scaffold (as before) or from an internal layer (newly proposed) across a variety of scaffold thicknesses and release rates to promote population of thick scaffolds. This Aim will be conducted using our recently developed subcutaneous model of meniscus tissue repair. In the third Aim, scaffolds will be implanted into meniscal defects in Yucatan minipigs to evaluate their efficacy in a clinically relevant defect model. If successful, these studies and technologies will advance our understanding of the use of engineered scaffolds for endogenous meniscus repair and provide a step towards clinical translation.