Yang Fan, Leung Victor Y L, Luk Keith D K, Chan Danny, Cheung Kenneth M C
Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong SAR, China.
J Pathol. 2009 May;218(1):113-21. doi: 10.1002/path.2519.
Intervertebral disc degeneration has been widely studied in different animal models. To test the hypothesis that needle puncture could induce progressive biochemical and molecular changes in murine discs, we established a mouse tail model to investigate the pathogenesis and molecular mechanism of puncture-induced disc degeneration. Caudal discs in mouse tails were punctured using a 31G gauge needle at controlled depth under microscopic guidance. The progress of the disc degeneration was evaluated by radiographic analysis of disc height, histological grading and glycosaminoglycan (GAG) quantification pre-operation and 1, 2, 6 and 12 weeks post-puncture. Gene and protein expression of the extracellular matrix (ECM) was analysed by RT-PCR, in situ hybridization and immunohistochemistry. Histological study and disc height analysis revealed progressive degenerative changes in the punctured discs. Compared with the pre-operation control group, total GAG content decreased 40% (p < 0.05) and aggrecan (Acan), decorin (Dcn) and versican (Vcan; Cspg2) expression was down-regulated at 12 weeks post-puncture. A transient increase of Col2a1-expressing cells and elevation of collagen II protein in the nucleus pulposus (NP) was detected. Fibronectin (Fn1) expression was up-regulated 50% and deposition of collagen I in NP was observed at 12 weeks post-puncture. This study is the first to use an injury-induced model to study disc degeneration in mouse. The disc degeneration involves a transient transformation of NP from notochordal to chondrogenic and eventually into fibrocartilaginous phenotype. The degenerative changes have some similarity to human disc degeneration, suggesting that this model may potentially be used in future to study the molecular mechanism and dissect the pathways of disc degeneration.
椎间盘退变已在不同动物模型中得到广泛研究。为验证针刺可诱导小鼠椎间盘发生渐进性生化和分子变化这一假说，我们建立了小鼠尾部模型来研究针刺诱导椎间盘退变的发病机制和分子机制。在显微镜引导下，使用31G规格的针头在可控深度穿刺小鼠尾部的尾椎间盘。通过术前及穿刺后1、2、6和12周对椎间盘高度进行影像学分析、组织学分级和糖胺聚糖（GAG）定量来评估椎间盘退变的进展。通过逆转录聚合酶链反应（RT-PCR）、原位杂交和免疫组织化学分析细胞外基质（ECM）的基因和蛋白表达。组织学研究和椎间盘高度分析显示穿刺后的椎间盘出现渐进性退变变化。与术前对照组相比，穿刺后12周时，总GAG含量降低了40%（p<0.05），聚集蛋白聚糖（Acan）、核心蛋白聚糖（Dcn）和多功能蛋白聚糖（Vcan；Cspg2）的表达下调。在髓核（NP）中检测到表达Ⅱ型胶原（Col2a1）细胞的短暂增加和Ⅱ型胶原蛋白的升高。穿刺后12周时，纤连蛋白（Fn1）表达上调50%，并观察到NP中有Ⅰ型胶原沉积。本研究首次使用损伤诱导模型来研究小鼠椎间盘退变。椎间盘退变涉及NP从脊索样向软骨样最终向纤维软骨样表型的短暂转变。这些退变变化与人类椎间盘退变有一些相似之处，表明该模型未来可能用于研究椎间盘退变的分子机制并剖析其途径。
