Multiscale and Multimodal Structure-Function Analysis of Intervertebral Interfaces During Degeneration and Regeneration

摘要 椎间盘（IVD）退变和相关的背痛给人群带来了沉重的负担。 作为一种多相组织复合体，IVD的子组件之间的界面与其功能不可分割。 正常功能。尽管如此，研究界很少关注全面的 在退化和再生过程中评价IVD的界面。第一个目标是 建议定量评估软骨终板-纤维环（EP-AF）之间的界面 和纤维环-髓核（AF-NP）在健康和退行性病变中的多个长度尺度 光盘。这将通过两个具体目标来实现。目标1将探索多尺度结构力学 健康人和兔IVD的界面区域（EP-AF，AF-NP）的关系。界面 将通过分析生物化学含量在微尺度上评价人和兔IVD的区域， 组织学、扫描电子显微镜（SEM）、原子力显微镜（AFM）和二次谐波 二次谐波（SHG）成像。将通过MRI（T2标测、UTE T2、T1 r）表征宏观特性 和生物力学测试（在压缩和拉伸）。在目标2中，椎间盘退变对 将评估不同长度尺度下EP-AF和AF-NP界面的结构和力学。为此 目的是在显微镜下评估退变兔和人椎间盘的界面特性， 宏观尺度使用目标1概述的技术，以阐明结构和功能如何随着 IVD变性。最后，在目标3中，这些相同的微观到宏观尺度的分析将应用于再生 光盘。我们组有先进的生物全椎间盘置换术（终板改良的椎间盘样角层 结构，eDAPS）用于治疗晚期变性。这些eDAPS的翻译将需要 EP-AF和AF-NP之间的这些工程化椎间盘的界面区域与天然组织匹配 基准，以确保长期的体内功能。本目标将评估以下界面区域： 以多种长度尺度再生椎间盘，并确定这些特性如何在工程组织中成熟 无论是在体外还是在兔全椎间盘置换模型中植入后的时间。结果是 这项研究将进一步加深我们对正常和变性的结构-功能关系的理解， IVD和工程组织中的界面。总的来说，这项工作有可能大大改善 椎间盘退变相关性背痛的诊断和临床治疗。

Abstract Intervertebral disc (IVD) degeneration and associated back pain place a significant burden on the population. As a multiphasic tissue-complex, the interfaces between the subcomponents of the IVD are integral to its normal function. Despite this, there has been little focus in the research community on a comprehensive evaluation of the interfaces of the IVD during degeneration and regeneration. The first objective of this proposal is to quantitatively evaluate the interfaces between the cartilage endplate-annulus fibrosus (EP-AF) and annulus fibrosus-nucleus pulposus (AF-NP) across multiple length scales in healthy and degenerative discs. This will be accomplished via two Specific Aims. Aim 1 will probe the multi-scale structure-mechanics relationships of the interfacial regions (EP-AF, AF-NP) of healthy human and rabbit IVDs. The interfacial regions of human and rabbit IVDs will be evaluated at the microscale via analysis of biochemical content, histology, scanning electron microscopy (SEM), atomic force microscopy (AFM) and second harmonic generation (SHG) imaging. Macroscale properties will be characterized by MRI (T2 mapping, UTE T2, T1r) and biomechanical testing (in compression and tension). In Aim 2, the impact of disc degeneration on the structure and mechanics of EP-AF and AF-NP interfaces at different length scales will be evaluated. For this Aim, interfacial properties of degenerated rabbit and human discs will be assessed at the micro and macroscale using the techniques outlined Aim 1 in order to elucidate how structure and function change with IVD degeneration. Finally, in Aim 3, these same micro- to macro-scale analyses will be applied to regenerating discs. Our group has advanced biologic total disc replacements (endplate-modified disc-like angle-ply structures, eDAPS) for the treatment of advanced stage degeneration. Translation of these eDAPS will require that the interfacial regions of these engineered discs, between the EP-AF and AF-NP match native tissue benchmarks in order to ensure long-term in vivo function. This Aim will assess the interfacial regions of regenerating discs at multiple length scales and determine how these properties mature in engineered tissues both in vitro and with time post-implantation in a rabbit model of total disc replacement. The results from this study will further our understanding of the structure-function relationships of normal and degenerated interfaces in the IVD, and in engineered tissues. Overall, this work has the potential to significantly improve the diagnosis and clinical treatment of back pain associated with disc degeneration.!