Engineering Multi-scale Structure of the Knee Meniscus using Advanced 3D Nonwovens Fabrication

摘要 半月板撕裂是最常见的膝关节损伤，大约有100万例手术， 在美国每年进行半月板手术。组织工程和再生医学方法 作为克服当前临床治疗的局限性的潜在替代方案正在被积极地追求。然而， 这些方法向临床应用的转化受到其有限能力的阻碍， 有效地和可重复地创建生理尺寸的、患者特异性的支架， 并且机械性能与天然半月板相当。3D打印可以创建复制的支架 生理尺寸和患者特定几何形状，具有高度可重复性和良好的操作性 然而，这些纤维尺寸通常在数百微米的量级上， 比天然组织高几个数量级。另一方面，非织造纺织品接近 允许在天然胶原原纤维的规模上制造纤维，但不可能产生复杂的胶原纤维。 解剖学3D几何形状，例如膝关节半月板的几何形状。本提案的总体目标是 研究一种新的3D非织造支架制造方法的能力， 传统的非织造熔喷和3D打印的属性，以克服这些限制，并概括 在多个尺度下的弯月面的复杂各向异性结构特性作为提供 体外和体内上级结局。我们假设这种3D熔喷（3DMB）方法可以允许 生理纤维形态（类似于其他非织造物，如静电纺丝），同时也使 通过定制的旋转心轴（类似于3D打印）创建患者特定的半月板3D几何形状。 我们进一步假设所得到的支架特征将允许上级体内结果，特别是， 细胞浸润、新基质的产生以及通过控制多孔性和 纤维尺寸目的1是确定3DMB工艺变量对聚己内酯支架纤维的影响 形态和所得ECM组织和生物力学功能，使用体外，离体和亚- 皮肤体内模型。此外，在这一目标范围内，将开发响应面函数， 经验证可将细胞浸润、胶原蛋白含量、基质排列和力学作为以下因素的函数进行关联： 纤维直径和支架孔隙率。目的2是评估细胞浸润和活力的分布， 患者特异性3D的绵羊模型中26周内对齐的ECM形成和生物力学功能 根据目标1结果确定的领先组的熔喷弯月面支架。这一目标还将 提供了3DMB非织造布和传统3D非织造布特性之间的首次一对一比较 打印支架，其中纤维形态存在数量级差异。完成后， 本项目将提供有关微观和宏观层次的过程-结构-功能的基本知识 使用我们新的3DMB非织造布方法制造的支架相关的关系， 作为一项具有重要意义的基础技术，可促进骨科纤维性软组织的治疗， 组织损伤

Abstract Meniscal tears are the most commonly reported knee injuries, and approximately 1 million surgeries involving the meniscus are performed annually in the US. Tissue engineering and regenerative medicine approaches are being actively pursued as potential alternatives to overcome limitations of current clinical treatments. Yet, the translation of these approaches to clinical application has been hampered by their limited ability to efficiently and reproducibly create physiologic-sized, patient-specific scaffolds featuring anisotropic structural and mechanical properties on the order of native meniscus. 3D printing can create scaffolds that replicate physiologic size and patient-specific geometry in a highly repeatable manner and with good handling characteristics for surgical implantation, yet, these fiber sizes are typically on the order of hundreds of microns, several orders of magnitude higher than the native tissue. On the other hand, nonwoven textiles approaches allow the fabrication of fibers on the scale of native collagen fibrils, but it is infeasible to create complex anatomical 3D geometries, such as that of the knee meniscus. The overall goal of this proposal is to investigate the ability of a new 3D nonwoven scaffold fabrication approach that synergistically integrates attributes of traditional nonwoven melt blowing and 3D printing to overcome these limitations and recapitulate complex anisotropic structural characteristics of the meniscus at multiple scales as a means to provide superior outcomes, in-vitro and in-vivo. We hypothesize that this 3D Melt Blowing (3DMB) approach can allow physiological fiber morphology (similar to other nonwovens such as electrospinning), while also enabling the creation of patient-specific meniscus 3D geometry via the customized rotating mandrel (similar to 3D printing). We further hypothesize that the resulting scaffold features will permit superior in-vivo outcomes, particularly, cell infiltration, new matrix production, and the prevention of cartilage degeneration via control of porosity and fiber size. Aim 1 is to determine the effect of the 3DMB process variables on polycaprolactone scaffold fibrous morphology and resulting ECM organization and biomechanical function using in-vitro, ex-vivo and sub- cutaneous in-vivo models. Additionally within this aim, a response surface function will be developed and validated to correlate cellular infiltration, collagen content, matrix alignment, and mechanics as a function of fiber diameter and scaffold porosity. Aim 2 is to assess the distribution of cellular infiltration and viability, aligned ECM formation and biomechanical function over 26 weeks in a sheep model for patient-specific 3D melt blown meniscus scaffolds of the leading-group determined from Aim 1 outcomes. This Aim will also provide the first one-on-one comparison between the characteristics of the 3DMB nonwoven and traditional 3D printed scaffolds, wherein there is an order of magnitude difference in the fiber morphologies. On completion, this project will provide fundamental knowledge about the micro- and macro-level process-structure-function relationships in meniscus-relevant scaffolds fabricated using our new 3DMB nonwovens approach, and will serve as a base technology of great significance allowing advances in the treatment of orthopaedic fibrous soft tissue injuries.