Effects of formalin fixation and collagen cross-linking on T2 and magnetization transfer in bovine nasal cartilage
Effects of formalin fixation and collagen cross-linking on T2 and magnetization transfer in bovine nasal cartilage
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DOI：
10.1002/mrm.21216
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发表时间：
2007-06-01
影响因子：
3.3
通讯作者：
Spencer, Richard G.
中科院分区：
文献类型：
--
作者：
Fishbein, Kenneth W.;Gluzband, Yehezkiel A.;Spencer, Richard G.
内源性胶原交联影响软骨的生物力学性能和抗降解能力。福尔马林固定改变胶原残基并以剂量依赖的方式形成新的交联。我们测试了假设磁化转移（MT）效应和T-2依赖于软骨中的胶原交联。这些参数分别在固定前、在浓度为0%至10%的福尔马林溶液中浸泡9周、NaBH3CN还原和洗涤后在牛鼻软骨（BNC）中测量。10%福尔马林固定后T2降低59.4% +/- 1.1%，洗涤后T2较初始值缩短32.2% +/- 5.2%。在这些条件下，表观MT率比基线增加了25.9% +/- 3.7%和52.8% +/- 7.1%。生化分析显示，0%和10%福尔马林处理过的样品在水、蛋白聚糖、天然交联或胶原蛋白含量方面没有显著差异，而氨基酸分析显示（羟基）赖氨酸和酪氨酸的损失，只有在固定样品中才出现与亚甲基交联一致的新峰。我们得出结论，软骨的福尔马林固定导致T2显著降低，MT参数增加，在去除未反应的甲醛后持续存在。由此产生的胶原交联与MT和T2的巨大变化有关，这表明根据软骨大分子含量来解释T2和MT值必须谨慎。
Endogenous collagen cross-links influence cartilage biomechanical properties and resistance to degradation. Formalin fixation modifies collagen residues and forms new cross-links in a dose-dependent manner. We tested the hypothesis that magnetization transfer (MT) effects and T-2 depend on collagen cross-linking in cartilage. These parameters were measured in bovine nasal cartilage (BNC) prior to fixation, after 9 weeks of immersion in formalin solutions ranging in concentration from 0% to 10%, and after NaBH3CN reduction and washing. T2 decreased by 59.4% +/- 1.1% upon fixation in 10% formalin, and was 32.2% +/- 5.2% shorter than initial values after washing. The apparent MT rate increased 25.9% +/- 3.7% and 52.8% +/- 7.1% over baseline under these conditions. Biochemical assays showed no significant differences in water, proteoglycan, natural cross-link, or collagen content between the 0% and 10% formalin-treated samples, while amino acid analysis demonstrated losses in (hydroxy)lysine and tyrosine, and new peaks consistent with methylene cross-links in fixed samples only. We conclude that formalin fixation of cartilage results in significant decreases in T2 and increases in MT parameters that persist after removal of unreacted formaldehyde. The collagen crosslinks thus created are associated with large changes in MT and T2, indicating that interpretation of T2 and MT values in terms of cartilage macromolecular content must be made with caution.