Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143, USA.
Spine (Phila Pa 1976). 2011 Apr 1;36(7):512-20. doi: 10.1097/BRS.0b013e3181f72b94.
Experimental quantification of relationships between vertebral endplate morphology, permeability, disc cell density, glycosaminoglycan (GAG) content, and degeneration in samples harvested from human cadaveric spines.
To test the hypothesis that variation in endplate permeability and porosity contributes to changes in intervertebral disc cell density and overall degeneration.
Cells within the intervertebral disc are dependent on diffusive exchange with capillaries in the adjacent vertebral bone. Previous findings suggest that blocked routes of transport negatively affect disc quality, yet there are no quantitative relationships between human vertebral endplate permeability, porosity, cell density, and disc degeneration. Such relationships would be valuable for clarifying degeneration risk factors and patient features that may impede efforts at disc tissue engineering.
Fifty-one motion segments were harvested from 13 frozen cadaveric human lumbar spines (32-85 years) and classified for degeneration using the magnetic resonance imaging-based Pfirrmann scale. A cylindrical core was harvested from the center of each motion segment that included vertebral bony and cartilage endplates along with adjacent nucleus tissue. The endplate mobility, a type of permeability, was measured directly using a custom-made permeameter before and after the cartilage endplate was removed. Cell density within the nucleus tissue was estimated using the picogreen method, while the nuclear GAG content was quantified using the dimethylmethylene blue technique. Specimens were imaged at 8 μm resolution using microCT; bony porosity was calculated. Analysis of variance, linear regression, and multiple comparison tests were used to analyze the data. RESULTS.: Nucleus cell density increased as the disc height decreased (R² = 0.13; P = 0.01) but was not related to subchondral bone porosity (P > 0.5), total mobility (P > 0.4), or age (P > 0.2). When controlling for disc height, however, a significant, negative effect of age on cell density was observed (P = 0.03). In addition to this, GAG content decreased with age nonlinearly (R² = 0.83, P < 0.0001) and a cell function measurement, GAGs/cell, decreased with degeneration (R² = 0.24; P < 0.0001). Total mobility (R² = 0.14; P < 0.01) and porosity (R² = 0.1, P < 0.01) had a positive correlation with age.
Although cell density increased with degeneration, cell function indicated that GAGs/cell decreased. Because permeability and porosity increase with age and degeneration, this implies that cell dysfunction, rather than physical barriers to transport, accelerates disc disease.
从人体尸体脊柱中采集样本，对椎体终板形态、通透性、椎间盘细胞密度、糖胺聚糖（GAG）含量和退变之间的关系进行实验量化。
验证这样一个假设，即终板通透性和孔隙率的变化导致椎间盘细胞密度和整体退变的变化。
椎间盘内的细胞依赖于与相邻椎骨毛细血管的扩散交换。先前的研究结果表明，运输途径受阻会对椎间盘质量产生负面影响，但目前尚没有人类椎体终板通透性、孔隙率、细胞密度和椎间盘退变之间的定量关系。这些关系对于阐明退变的危险因素和可能阻碍椎间盘组织工程努力的患者特征将是有价值的。
从 13 个冷冻人体腰椎尸体（32-85 岁）中采集了 51 个运动节段，并使用基于磁共振成像的 Pfirrmann 量表对其进行退变分类。从每个运动节段的中心采集一个圆柱形核心，该核心包括椎体骨和软骨终板以及相邻的核组织。在去除软骨终板之前和之后，使用定制的渗透计直接测量终板的移动性，这是一种渗透性类型。使用 picogreen 方法估计核组织内的细胞密度，使用二甲亚甲基蓝技术定量核 GAG 含量。使用 8μm 分辨率的 microCT 对标本进行成像；计算骨孔隙率。使用方差分析、线性回归和多重比较检验来分析数据。结果：核细胞密度随椎间盘高度的降低而增加（R²=0.13；P=0.01），但与软骨下骨孔隙率（P>0.5）、总移动性（P>0.4）或年龄（P>0.2）无关。然而，当控制椎间盘高度时，年龄对细胞密度的显著负影响是观察到的（P=0.03）。此外，GAG 含量随年龄呈非线性下降（R²=0.83，P<0.0001），细胞功能测量，GAGs/细胞，随退变而下降（R²=0.24；P<0.0001）。总移动性（R²=0.14；P<0.01）和孔隙率（R²=0.1，P<0.01）与年龄呈正相关。
尽管细胞密度随退变而增加，但细胞功能表明 GAGs/细胞减少。由于通透性和孔隙率随年龄和退变而增加，这意味着细胞功能障碍，而不是运输的物理障碍，加速了椎间盘疾病。
