Mittelstaedt Daniel, Xia Yang
Department of Physics and Center for Biomedical Research, Oakland University, Rochester, MI, USA.
Cartilage. 2015 Oct;6(4):216-25. doi: 10.1177/1947603515596418.
A quantitative contrast-enhanced micro-computed tomography (qCECT) method was developed to investigate the depth dependency and heterogeneity of the glycosaminoglycan (GAG) concentration of ex vivo cartilage equilibrated with an anionic radiographic contrast agent, Hexabrix.
Full-thickness fresh native (n = 19 in 3 subgroups) and trypsin-degraded (n = 6) articular cartilage blocks were imaged using micro-computed tomography (μCT) at high resolution (13.4 μm(3)) before and after equilibration with various Hexabrix bathing concentrations. The GAG concentration was calculated depth-dependently based on Gibbs-Donnan equilibrium theory. Analysis of variance with Tukey's post hoc was used to test for statistical significance (P < 0.05) for effect of Hexabrix bathing concentration, and for differences in bulk and zonal GAG concentrations individually and compared between native and trypsin-degraded cartilage.
The bulk GAG concentration was calculated to be 74.44 ± 6.09 and 11.99 ± 4.24 mg/mL for native and degraded cartilage, respectively. A statistical difference was demonstrated for bulk and zonal GAG between native and degraded cartilage (P < 0.032). A statistical difference was not demonstrated for bulk GAG when comparing Hexabrix bathing concentrations (P > 0.3214) for neither native nor degraded cartilage. Depth-dependent GAG analysis of native cartilage revealed a statistical difference only in the radial zone between 30% and 50% Hexabrix bathing concentrations.
This nondestructive qCECT methodology calculated the depth-dependent GAG concentration for both native and trypsin-degraded cartilage at high spatial resolution. qCECT allows for more detailed understanding of the topography and depth dependency, which could help diagnose health, degradation, and repair of native and contrived cartilage.
开发一种定量对比增强微型计算机断层扫描（qCECT）方法，以研究用阴离子放射造影剂Hexabrix平衡后的离体软骨中糖胺聚糖（GAG）浓度的深度依赖性和异质性。
对全层新鲜天然软骨（3个亚组，共19个）和胰蛋白酶降解的软骨（6个）块，在与不同Hexabrix浴液浓度平衡前后，使用微型计算机断层扫描（μCT）以高分辨率（13.4μm³）进行成像。基于吉布斯-唐南平衡理论，深度依赖性地计算GAG浓度。采用方差分析及Tukey事后检验，以检验Hexabrix浴液浓度的效应、天然软骨和胰蛋白酶降解软骨整体及分层GAG浓度的差异是否具有统计学意义（P<0.05）。
天然软骨和降解软骨的整体GAG浓度分别计算为74.44±6.09和11.99±4.24mg/mL。天然软骨和降解软骨在整体及分层GAG方面存在统计学差异（P<0.032）。比较Hexabrix浴液浓度时，天然软骨和降解软骨的整体GAG均未显示出统计学差异（P>0.3214）。天然软骨的深度依赖性GAG分析显示，仅在Hexabrix浴液浓度为30%至50%时，径向区域存在统计学差异。
这种非破坏性的qCECT方法在高空间分辨率下计算了天然软骨和胰蛋白酶降解软骨的深度依赖性GAG浓度。qCECT有助于更详细地了解其形貌和深度依赖性，这有助于诊断天然软骨和人工软骨的健康状况、降解情况及修复情况。
