MRI-Based Method to Evaluate Engineered Cartilage

描述（由申请人提供）：关节软骨对人类关节的正常功能至关重要。腕关节具有独特的机械和摩擦学性能，通过提供几乎无摩擦和耐磨的承载关节表面来实现运动。骨关节炎是最常见的风湿性疾病，并且与不同程度的软骨退化和改变的关节力学（即，响应于施加的载荷而变形）相关。修复和再生受骨关节炎和其他退行性过程影响的软骨组织的努力已经成为最近新兴的组织工程领域的焦点，组织工程是设计和制造用于受损或患病器官的功能恢复的新组织的科学。组织工程的基础科学研究旨在成功恢复软骨的功能，最终取决于诱导信号，响应干细胞和细胞外基质支架。 本文提出的研究将（1）开发一种新的非侵入性方法来测量整个正常和组织工程化软骨结构体积的异质三维（3D）变形，（2）评估牛关节软骨外植体中缺损修复的有效性。在过去的十年中，磁共振成像（MRI）技术或脉冲序列的重大进展已被证明在通过跟踪3D空间中特定组织区域的运动来测量变形方面非常有效。此外，申请人开发了基于MRI的方法来确定软骨中的3D变形，以完成其研究生研究。该方法使用自定义MRI脉冲序列、加载装置和图像处理算法量化了整个牛关节软骨外植体体积中的不均匀机械变形。在拟议的研究中，将使用MRI脉冲序列DANTE（延迟与章动交替用于定制激励）和FS-FSE（脂肪抑制快速自旋回波）跟踪软骨组织区域的变形。变形测量将用于近似整个正常和组织工程软骨的3D有限应变张量场。

DESCRIPTION (provided by applicant): Articular cartilage is critical to the normal function of human diarthrodial joints. Cartilage has unique mechanical and tribological properties that allows for locomotion by providing a nearly frictionless and wear-resistant load bearing joint surface. Osteoarthritis is the most common rheumatic disease and is associated with various degrees of cartilage degradation and altered joint mechanics (i.e. deformation in response to applied loads). Efforts to repair and regenerate cartilage tissue effected by osteoarthritis and other degenerative processes has been the focus of the recently emerging field of tissue engineering, which is the science of design and manufacture of new tissues for the functional restoration of impaired or diseased organs. Basic science studies in tissue engineering aimed at the successful functional restoration of cartilage ultimately depend on inductive signals, responding stem cells, and extracellular matrix scaffolding. The research proposed here will (1) develop a novel noninvasive method to measure heterogeneous three dimensional (3D) deformations throughout the volume of normal and tissue-engineered cartilage constructs and (2) to evaluate the efficacy of defect repairs in bovine articular cartilage explants. Within the past decade, significant advances in magnetic resonance imaging (MRI) techniques, or pulse sequences, have proven highly effective at measuring deformation by tracking the motion of specific tissue regions in 3D space. Further, the initial development of an MRI-based method to determine 3D deformations in cartilage was developed by the applicant to complete his graduate research. This method quantified heterogeneous mechanical deformations throughout the volume of bovine articular cartilage explants using a custom MRI pulse sequence, loading apparatus, and image processing algorithm. In the proposed research, cartilage tissue regions will be tracked as they deform with the use of the MRI pulse sequences DANTE (delays alternating with nutations for tailored excitation) and FS-FSE (fat-suppressed fast spin echo). The deformation measurements will be used to approximate the 3D finite strain tensor field throughout normal and tissue engineered cartilage.