Compressive stress induces degeneration of cartilaginous endplate cells through the SOST/Wnt/beta-catenin pathway

doi:10.12307/2025.277

Abstract

Abstract: BACKGROUND: Many factors can cause disc degeneration, including aging, nutritional deficiency, and mechanical factors. The mechanical load is considered to be a very important factor, but its mechanism is still unclear.OBJECTIVE: To investigate the role of sclerostin (SOST) and Wnt/β-catenin signaling pathways in inducing degeneration of endplate cartilage.
METHODS: Cartilage endplate cells were extracted from 4-week-old male Sprague-Dawley rats. Compressive stress was applied to endplate chondrocytes in vitro using a mechanical loading apparatus, and the cell viability was determined by the cell counting kit-8 assay at 1, 3, 5, and 7 days after compression. Western blot, reverse transcription quantitative PCR, and cellular immunofluorescence techniques were employed to examine intracellular cartilage markers (Aggrecan and type II collagen) as well as calcification-related factors (Runx2 and osteocalcin). The expression of extracellular matrix degradation enzyme and genes related to the signaling pathway (SOST and β-catenin) was also analyzed.
RESULTS AND CONCLUSION: Under compressive stress, the cell activity of endplate chondrocytes increased with both the duration and intensity of stress. Furthermore, the expression levels of Aggrecan and type II collagen decreased in endplate cells under compressive stress, while those of calcification-related factors (Runx2 and osteocalcin) increased. Additionally, compressive stress promoted extracellular matrix degradation in endplate chondrocytes, leading to an increase in matrix metalloproteinase 3 and matrix metalloproteinase 13 expression. Abnormalities were observed in the Wnt/β-catenin signaling pathway within these cells under compressive stress, characterized by a decrease in specific inhibitory factor SOST expression accompanied by abnormal accumulation of β-catenin. To conclude, decreased SOST expression in endplate chondrocytes under compressive stress activates the Wnt/β-catenin signaling pathway, thereby promoting calcification, degeneration and extracellular matrix degradation in the cartilage endplate.

Key words: cartilage endplate, chondrocyte, SOST, Wnt/β-catenin, compressive stress, intervertebral disc degeneration

CLC Number:

Xiang Pan, Che Yanjun, Luo Zongping. Compressive stress induces degeneration of cartilaginous endplate cells through the SOST/Wnt/beta-catenin pathway[J]. Chinese Journal of Tissue Engineering Research, 2025, 29(5): 951-957.

Figures/Tables 6

2.1 压应力诱导软骨终板细胞活力降低 CCK-8结果显示，在受到10%形变压应力的作用下，软骨终板细胞在前几天的细胞活力与对照组相比没有明显差异。然而，在第5天时，压应力组的细胞活力开始出现轻微下降，并且在第7天时，与对照组相比，细胞活力的差异进一步增大(P < 0.01，图1A)。测试了在不同强度(0%，5%，10%，15%)下压应力对软骨终板细胞的影响，结果显示，随着压应力强度的增加，压应力组的细胞活性逐渐降低(P < 0.05或< 0.01，图1B)。这表明压应力程度对软骨终板细胞的生理功能产生了显著的影响。结果说明，压应力对软骨终板细胞的影响是与其形变程度和作用时间密切相关的，在较低程度的压应力下，细胞活力可能没有明显的改变，但随着压应力的增加，细胞活性逐渐下降。 2.2 压应力诱导软骨终板细胞退变 Western blot分析观察到在压应力组中，软骨终板细胞中聚集蛋白聚糖和Ⅱ型胶原的蛋白水平较对照组明显降低(P < 0.01)；RT-qPCR结果也显示，在压应力组中，软骨终板细胞中聚集蛋白聚糖和Ⅱ型胶原的基因表达水平显著下调(P < 0.05或< 0.01)。结果表明，压应力的作用对软骨终板细胞的软骨标记物的表达产生了抑制作用，见图2。 2.3 压应力诱导软骨终板细胞钙化利用Western blot和RT-qPCR技术检测了在压应力作用下软骨终板细胞中钙化相关因子(Runx2、骨钙素)的变化情况。Western blot分析发现在压应力组中，软骨终板细胞中Runx2和骨钙素的蛋白水平较对照组明显升高(P < 0.05或< 0.01)；RT-qPCR结果也显示，在压应力组中，软骨终板细胞中Runx2和骨钙素的基因表达水平显著上调(P < 0.01，图3)。结果提示，压应力的作用可以刺激软骨终板细胞中钙化相关因子的表达增加。 2.4 压应力促进软骨终板细胞外基质降解增加 Western blot分析发现在压应力组中，软骨终板细胞中基质金属蛋白酶3和基质金属蛋白酶13的蛋白水平较对照组明显升高(P < 0.01)；RT-qPCR结果也显示，在压应力组中，软骨终板细胞中两种基质金属蛋白酶的基因表达水平显著上调"

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