Han Sang K, Chen Chao-Wei, Labus Kevin M, Puttlitz Christian M, Chen Yu, Hsieh Adam H
Fischell Department of Bioengineering, University of Maryland, College Park, MD.
Advanced Biomedical and Smart Welfare Technology R&BD Group, Korea Institute of Industrial Technology, Cheonan, Chungnam, South Korea.
Spine (Phila Pa 1976). 2016 Jul 1;41(13):E770-E777. doi: 10.1097/BRS.0000000000001463.
Basic science study using in vitro tissue testing and imaging to characterize local strains in annulus fibrosus (AF) tissue.
To characterize mesoscale strain inhomogeneities between lamellar and inter-/translamellar (ITL) matrix compartments during tissue shear loading.
The intervertebral disc is characterized by significant heterogeneities in tissue structure and plays a critical role in load distribution and force transmission in the spine. In particular, the AF possesses a lamellar architecture interdigitated by a complex network of extracellular matrix components that form a distinct ITL compartment. Currently, there is not a firm understanding of how the lamellar and ITL matrix coordinately support tissue loading.
AF tissue samples were prepared from frozen porcine lumbar spines and mounted onto custom fixtures of a materials testing system that incorporates optical coherence tomography (OCT) imaging to perform tissue elastography. Tissues were subjected to 20 and 40% nominal shear strain, and OCT images were captured and segmented to identify regions of interest corresponding to lamellar and ITL compartments. Images were analyzed using an optical flow algorithm to quantify local shear strains within each compartment.
Using histology and OCT, we first verified our ability to visualize and discriminate the ITL matrix from the lamellar matrix in porcine AF tissues. Local AF strains in the ITL compartment (22.0 ± 13.8, 31.1 ± 16.9 at 20% and 40% applied shear, respectively) were significantly higher than corresponding strains in the surrounding lamellar compartment (12.1 ± 5.6, 15.3 ± 5.2) for all tissue samples (P < 0.05).
Results from this study demonstrate that the lamellar and ITL compartments of the AF distribute strain unevenly during tissue loading. Specifically, shear strain is significantly higher in the ITL matrix, suggesting that these regions may be more susceptible to tissue damage and more mechanobiologically active.
N/A.
采用体外组织测试和成像的基础科学研究，以表征纤维环（AF）组织中的局部应变。
表征组织剪切加载过程中层状和层间/跨层（ITL）基质隔室之间的中尺度应变不均匀性。
椎间盘的组织结构具有显著的异质性，在脊柱的负荷分布和力传递中起关键作用。特别是，AF具有层状结构，由复杂的细胞外基质成分网络相互交错，形成一个独特的ITL隔室。目前，对于层状和ITL基质如何协同支持组织负荷尚无确切的认识。
从冷冻的猪腰椎制备AF组织样本，并安装到材料测试系统的定制夹具上，该系统结合光学相干断层扫描（OCT）成像以进行组织弹性成像。对组织施加20%和40%的名义剪切应变，并采集和分割OCT图像，以识别对应于层状和ITL隔室的感兴趣区域。使用光流算法分析图像，以量化每个隔室内的局部剪切应变。
通过组织学和OCT，我们首先验证了在猪AF组织中可视化和区分ITL基质与层状基质的能力。对于所有组织样本，ITL隔室中的局部AF应变（在施加20%和40%剪切时分别为22.0±13.8、31.1±16.9）显著高于周围层状隔室中的相应应变（12.1±5.6、15.3±5.2）（P<0.05）。
本研究结果表明，AF的层状和ITL隔室在组织负荷期间应变分布不均匀。具体而言，ITL基质中的剪切应变显著更高，表明这些区域可能更容易受到组织损伤且具有更高的机械生物学活性。
无。
