Stratified and mechanically-tough biomaterial implant to improve tendon-to-bone enthesis regeneration

摘要 肩袖撕裂是常见的，主要起源于分层的纤维软骨界面(末端)连接。 从肌腱到骨骼。肌腱与骨的手术再接合形成了狭窄的纤维血管疤痕，而不是 再生一个连续的纤维软骨端部。由此产生的机械上的尖锐边界 肌腱和骨骼的不匹配会导致末端应变集中和高再失败率。这个 这项建议的目的是指导功能再生和修复的结构，成分和 使用一种创新的层状生物材料对损伤的肌腱-骨连接的力学性能进行研究。 在手术修复过程中，在损伤部位植入MSCs是一个有吸引力的加速选择 宿根再生。然而，开发一种生物材料载体以提高保留率和 损伤部位间充质干细胞的再生活性。我们将评估一款创新的设计 分层生物材料提供机械和营养刺激以促进MSC的固位和套接 再生。我们已经为含有骨的胶原蛋白生物材料生成了严格的原理证明数据- 和模拟肌腱的支架隔间，通过连续的水凝胶界面连接。我们将向您展示 水凝胶界面抑制了通常在失配生物材料之间形成的应变浓度 载荷下的力学性能。此外，水凝胶界面提供了加速纤维软骨形成的场所- 就像分化和重塑一样，是对邻近肌腱和骨骼中产生的营养因子的反应- 模拟的脚手架隔间。综上所述，我们假设包含了一个连续的水凝胶带 连接肌腱和骨骼特定的支架隔间提供了机械和营养方面的优势 与整体式和传统的层状生物材料相比，加快再生能力。向我们的 假设我们将首先确定机械优化的水凝胶植入是否以及如何增加 力学性能和支持纤维软骨的体外分化(目标1)。我们随后将 证明在层状生物材料中产生的营养因子加速了末端特异的MSC 体外分化和基质重塑(目标2)。我们将最终评估功能修复和 利用生物材料--间充质干细胞体内构建再生大鼠肩袖吻合部(目标3)。我们 将使用体外循环应变生物反应器研究来优化MSC-生物材料的相互作用，然后在 活体大鼠肩袖损伤模型，以基准通过细胞再生的质量和动力学， 组织形态和机械测量。该项目将为临床翻译提供必要的见解 一种促进肌肉骨骼末端再生的生物材料疗法。

ABSTRACT Rotator cuff tears are common and primarily initiate at the stratified fibrocartilage interface (enthesis) linking tendon to bone. Surgical reattachment of tendon to bone forms a narrow fibrovascular scar rather than regenerates a continuous fibrocartilage enthesis. The resultant sharp boundary between mechanically mismatched tendon and bone leads to strain concentrations and high rates of re-failure at the enthesis. The objective of this proposal is to guide functional regeneration and repair of the structure, composition, and mechanical performance of the injured tendon-to-bone enthesis using an innovative stratified biomaterial. Intraoperative implantation of MSCs at the injury site during surgical repair is an attractive option to accelerate enthesis regeneration. However it is essential to develop a biomaterial carrier to improve retention and regenerative activity of bioactive MSCs across the injury site. We will evaluate the design of an innovative stratified biomaterial to provide mechanical and trophic stimuli to promote MSC retention and enthesis regeneration. We have generated rigorous proof-of-principle data for a collagen biomaterial that contains bone- and tendon-mimetic scaffold compartments linked with a continuous hydrogel interface. We will show the hydrogel interface inhibits strain concentrations that typically form between biomaterials with mismatched mechanical properties under load. Further, the hydrogel interface provides a site to accelerate fibrocartilage- like differentiation and remodeling in response to trophic factors produced in adjacent tendon- and bone- mimetic scaffold compartments. Taken together, we hypothesize inclusion of a continuous hydrogel zone linking tendon- and bone-specific scaffold compartments provides mechanical and trophic advantages to accelerate regenerative potency versus monolithic and conventional stratified biomaterials. To address our hypothesis we will first determine if and how a mechanically-optimized hydrogel insertion both increases mechanical performance and supports fibrocartilage differentiation in vitro (Aim 1). We will subsequently demonstrate trophic factors produced across the stratified biomaterial accelerate enthesis-specific MSC differentiation and matrix remodeling in vitro (Aim 2). We will ultimately evaluate functional repair and regeneration of the rat rotator cuff enthesis using an enthesis biomaterial-MSC construct in vivo (Aim 3). We will use in vitro cyclic strain bioreactor studies to optimize MSC-biomaterial interactions, then a tiered set of in vivo rat rotator cuff injury models to benchmark the quality and kinetics of enthesis regeneration via cellular, tissue morphology, and mechanical metrics. This project will provide essential insight to aid clinical translation of a biomaterial therapy to improve musculoskeletal enthesis regeneration.