Optimizing Ultrasound Regimens for Achieving Cartilage Repair

摘要 由于软骨具有较差的先天修复和再生能力， 并防止骨关节炎进一步恶化将具有很大的临床影响。由于容易隔离 和间充质基质细胞（MSC）的多谱系分化潜能，依赖于 基质辅助间充质基质细胞植入术（MSCI）或微骨折术（MF）吸引了临床 关注目前，MSCI或MF的功能性成果，包括提供增长因子的方法， 在体内，其特征在于生物力学较差的纤维软骨和较差的整合评分。关节炎症 已被鉴定为抑制MSC的软骨形成，从而导致软骨修复的低功效 结果。重要的是，通过减轻促软骨素的分解代谢作用来提供软骨保护的方法， 同时促进原位软骨形成。为了解决关键问题， 改善功能性软骨修复结果的挑战，一种非侵入性的辅助手段;持续低 最近发表的具有软骨诱导和软骨保护特性的高强度超声（cLIUS） 以证明对于MACI和MF手术的增强的软骨修复。的能力 cLIUS改善软骨修复结局的能力将通过三个具体目标得到证明：目的1：证明 cLIUS诱导的MSC在促炎环境中的软骨形成。RNA测序将是 用于收集驱动MSC软骨形成的深入转录组学分析和潜在途径 在促炎环境下进行cLIUS。目标2：开发经过计算验证和优化的 cLIUS治疗方案。计算网格将建立从磁共振图像（MRI）耦合 使用关节中波传播的双相有限元模型，以确定特定的cLIUS方案 羊关节模型将在羊尸膝关节中进行声传播实验进行验证。 目的3：证明cLIUS下肱骨修复的功能结局改善。证明 应用MF和MSCI对绵羊关节软骨严重软骨缺损的上级修复 优化cLIUS的经皮递送，并在六个月时进行评估。再生软骨的分析将是 通过组织学、生物力学和生物化学的方法。这项工作的顺利完成预计将 导致基于cLIUS的方案和递送系统的开发， 软骨表型，同时推进MSC的基本理解， cLIUS下预处理。这将反过来直接解决4600万美国人的待遇问题， 估计每年造成1，280亿美元的损失。

ABSTRACT As cartilage has poor innate repair and regeneration capacity, therapies that can address early cartilage injury and prevent further osteoarthritic deterioration would have a large clinical impact. Due to the ease of isolation and multi-lineage differentiation potential of mesenchymal stromal cells (MSCs), methods that rely either on matrix assisted mesenchymal-stromal-cell-implantation (MSCI) or microfracture (MF) have attracted clinical attention. Currently, the functional outcomes of MSCI or MF, including approaches that deliver growth factors in vivo, are characterized by biomechanically inferior fibrocartilage, and poor integration scores. Joint inflammation has been identified to inhibit chondrogenesis of MSCs, thus contributing to the low efficacy of cartilage repair outcomes. Critically, approaches that offer chondroprotection by the mitigating the catabolic effects of the pro- inflammatory joint environment while promoting in situ chondrogenesis are required. To address the critical challenge of improving functional-cartilage-repair outcomes, a non-invasive adjunct; continuous low- intensity ultrasound (cLIUS) with recently published chondroinductive and chondroprotective properties to demonstrate enhanced chondral repair for both MACI and MF procedures will be employed. The ability of cLIUS to improve cartilage repair outcomes will be demonstrated via three specific aims: AIM 1: Demonstrate cLIUS-induced chondrogenesis of MSCs in a pro-inflammatory environment. RNA-sequencing will be employed to gather an in-depth transcriptomic profiling and underlying pathways that drive MSC chondrogenesis under cLIUS in a pro-inflammatory environment. AIM 2: Develop a computationally validated and optimized regimen of cLIUS therapy. Computational grids will be built from magnetic resonance images (MRIs) coupled with a biphasic finite element model for wave propagation in the joints to determine the specific cLIUS regimen for sheep joints. Models will be validated with acoustic propagation experiments in sheep-cadaver knee joints. AIM 3: Demonstrate Improved Functional Outcomes of Cartilage Repair Under cLIUS. Demonstrate the superior repair of critically sized chondral defects via MF and MSCI in the articular cartilage of sheep using an optimized transdermal delivery of cLIUS and evaluate at six months. Analysis of regenerated cartilage will be through histological, biomechanical and biochemical methods. Successful completion of this work is expected to lead to the development of a cLIUS-based regimen and delivery system capable of generating a stable hyaline cartilage phenotype via minimally invasive procedures, while advancing the fundamental understanding of MSC preconditioning under cLIUS. This would, in turn, directly address the treatment of 46 million Americans who suffer from OA at an estimated cost of $128 billion annually.