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

摘要 腰椎间盘(IVD)退变和伴随的背痛给人们带来了巨大的负担。 作为一个多相组织复合体，下腔静脉各亚组分之间的界面是其组成部分。 正常功能。尽管如此，研究界几乎没有关注全面的 退变和再生过程中IVD界面的评价。这样做的第一个目标是 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)在健康和退行性变的多个长度尺度上 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IVDS界面区域(EP-AF、AF-NP)的关系界面 人和兔IVD的区域将通过生化含量分析在微观尺度上进行评估， 组织学、扫描电子显微镜、原子力显微镜和二次谐波 生成(SHG)成像。宏观属性将通过MRI(T2映射、UTE T2、T1r)进行表征 生物力学测试(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。为了这个 目的：从微观和微观两个方面评价退变兔和人腰椎间盘的界面性质。 使用目标1概述的技术，以阐明结构和功能如何随 IVD变性。最后，在目标3中，同样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盘置换术(终板改良的盘状角度层 结构，eDAPS)，用于治疗晚期变性。这些eDAP的转换将需要 这些工程化盘的界面区域，在EP-AF和AF-NP之间，与天然组织匹配 以确保长期体内功能的基准。这个目标将评估的界面区域 以多种长度尺度再生盘，并确定这些特性如何在工程组织中成熟 在兔全椎间置换术模型中进行体外和随时间的植入。由此产生的结果是 研究将加深我们对正常和退化的结构-功能关系的理解 在IVD和工程组织中的界面。总体而言，这项工作有可能显著提高 腰椎间盘退变伴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.!