Dynamic Fibrous Scaffolds for Repairing Dense Connective Tissues

摘要 肌肉骨骼系统的纤维组织（例如，膝关节半月板）受到其差的内在 治愈能力。在之前的融资周期中，我们开发了包括多光纤 支架，以引入各种时间和结构信号，从而修复关节组织。我们使用 这些支架用于工程化具有与天然组织相似的性质和组织的构建体（第一循环）， 然后开发了支架，通过输送因子来招募局部组织， 细胞（第二周期）。此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因子递送，将工程化支架首先（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） 募集并稳定修复支架内这些细胞的表型。我们假设， 这些因素将允许从半月板向支架募集活的内源性细胞 对这些因子的空间控制将改善支架定殖，即使是厚支架。我们会委聘 复合支架（在以前的资助周期中开发），提供稳定的纤维部分 （聚己内酯（PCL），以提供指导图案和机械稳定性），牺牲纤维部分 （聚环氧乙烷（PEO）），以确定初始支架孔隙率，并提供早期释放的因子进入 环境）和工程透明质酸（HA）纤维部分（在数周内降解并释放 以持续的方式）。为了解决我们的假设，第一个目标将利用体外微流体- 平台，以研究核软化（曲古抑菌素A），趋化性（血小板- 衍生生长因子）和纤维软骨形成因子（转化生长因子-β3）， 力学，细胞募集，并促进细胞表型的细胞迁移到纤维组织中的恢复。 从尿道组织中提取支架在第二个目标中，我们将控制整个支架的释放（如 之前）或从内层（新提出的）跨越各种支架厚度和释放速率， 促进厚支架的形成。这项目标将使用我们最近开发的皮下 半月板组织修复模型。在第三个目标中，支架将被植入尤卡坦半岛的乳房缺陷中。 小型猪以评价它们在临床相关缺陷模型中的功效。如果成功，这些研究和 技术将促进我们对使用工程支架治疗内源性半月板的理解， 修复并向临床翻译迈出一步。

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.