Division of Orthopaedic Surgery, McGill University, 1650 Cedar Avenue, Montreal, QC, Canada, H3G 1A4.
Arthritis Res Ther. 2011 Jul 25;13(4):R120. doi: 10.1186/ar3423.
Intervertebral disc (IVD) degeneration is associated with proteolytic degradation of the extracellular matrix, and its repair requires both the production of extracellular matrix and the downregulation of proteinase activity. These properties are associated with several growth factors. However, the use of growth factors in clinical practice is limited by their high cost. This cost can be circumvented using synthetic peptides, such as Link N, which can stimulate the synthesis of proteoglycan and collagen by IVD cells in vitro. The purpose of the present study was to evaluate the effect of Link N in vivo in a rabbit model of IVD degeneration.
New Zealand white rabbits received annular puncture in two lumbar discs. Two weeks after puncture, both punctured discs of each rabbit were injected with either Link N or saline. After 2 weeks, nine rabbits were euthanized and the annulus fibrosus (AF) and nucleus pulposus (NP) of Link N-injected and saline-injected IVDs were removed and used to prepare total RNA. Following reverse transcription, quantitative PCR was performed for aggrecan, COL2A1, COL1A1, ADAMTS-4, ADAMTS-5 and MMP-3. After 12 weeks, 19 rabbits were euthanized and the injected IVDs were removed for biochemical and histological analysis. Proteinase K digests were analyzed for DNA and sulfated glycosaminoglycan content. Disc height was monitored radiographically biweekly.
Following needle puncture, disc height decreased by about 25% over 2 weeks, and was partially restored by Link N injection. Puncture of the IVD resulted in a trend towards decreased proteoglycan content in both the NP and AF, and a trend towards partial restoration following Link N injection, although under the time course used this did not achieve statistical significance. Link N did not alter the DNA content of the discs. Link N injection led to a significant increase in aggrecan gene expression and a significant decrease in proteinase gene expression in both the NP and AF, when compared with saline alone.
When administered to the degenerate disc in vivo, Link N stimulated aggrecan gene expression and downregulated metalloproteinase expression, and there was a trend towards increased proteoglycan content of the disc, in both the NP and AF. These are features needed for any agent designed to stimulate disc repair. In principle, therefore, Link N supplementation could be an option for treating disc degeneration.
椎间盘（IVD）退变与细胞外基质的蛋白水解降解有关，其修复需要细胞外基质的产生和蛋白酶活性的下调。这些特性与几种生长因子有关。然而，生长因子在临床实践中的应用受到其高成本的限制。这种成本可以通过使用合成肽来规避，例如 Link N，它可以刺激 IVD 细胞在体外合成蛋白聚糖和胶原。本研究的目的是在兔 IVD 退变模型中评估 Link N 的体内作用。
新西兰白兔在两个腰椎间盘接受环形穿刺。穿刺后 2 周，每只兔子的两个穿刺椎间盘分别注射 Link N 或生理盐水。2 周后，处死 9 只兔子，取出 Link N 注射和生理盐水注射的 IVD 的纤维环（AF）和髓核（NP），并用于提取总 RNA。逆转录后，进行定量 PCR 检测聚集蛋白聚糖、COL2A1、COL1A1、ADAMTS-4、ADAMTS-5 和 MMP-3。12 周后，处死 19 只兔子，取出注射的 IVD 进行生化和组织学分析。蛋白酶 K 消化物用于分析 DNA 和硫酸化糖胺聚糖含量。每隔两周进行 X 射线监测椎间盘高度。
椎间盘穿刺后，2 周内椎间盘高度下降约 25%，Link N 注射后部分恢复。IVD 穿刺导致 NP 和 AF 中的蛋白聚糖含量呈下降趋势，Link N 注射后呈部分恢复趋势，但在所用时间过程中未达到统计学意义。Link N 不改变椎间盘的 DNA 含量。与单独使用生理盐水相比，Link N 注射可显著增加 NP 和 AF 中聚集蛋白聚糖基因的表达，并显著降低蛋白水解酶基因的表达。
在体内注入退变的椎间盘时，Link N 可刺激聚集蛋白聚糖基因的表达，下调金属蛋白酶的表达，并使 NP 和 AF 中椎间盘的蛋白聚糖含量呈上升趋势，这是任何刺激椎间盘修复的药物所必需的特征。因此，原则上，Link N 补充剂可能是治疗椎间盘退变的一种选择。
