Objective The nucleus pulposus of the human intervertebral disc contains 2 cell types: notochordal (NC) and mature nucleus pulposus (MNP) cells. NC cell loss is associated with disc degeneration and this process may be initiated by mechanical stress and/or nutrient deprivation. This study aimed to investigate the functional responses of NC and MNP cells to hydrostatic pressures and glucose restriction. Design Bovine MNP and NC cells were cultured in 3-dimensional alginate beads under low (0.4-0.8 MPa) and high (1.6-2.4 MPa) dynamic pressure for 24 hours. Cells were cultured in either physiological (5.5 mM) glucose media or glucose-restriction (0.55 mM) media. Finally, the combined effect of glucose restriction and high pressure was examined. Results Cell viability and notochordal phenotypic markers were not significantly altered in response to pressure or glucose restriction. MNP cells responded to low pressure with an increase in glycosaminoglycan (GAG) production while high pressure significantly decreased ACAN gene expression compared with atmospheric controls. NC cells showed no response in matrix gene expression or GAG production with either loading regime. Glucose restriction decreased NC cell TIMP-1 expression but had no effect on MNP cells. The combination of glucose restriction and high pressure only affected MNP cell gene expression, with decreased ACAN, Col2α1, and ADAMTS-5 expression. Conclusion This study shows that NC cells are more resistant to acute mechanical stresses than MNP cells and provides a strong rationale for future studies to further our understanding the role of NC cells within the disc, and the effects of long-term exposure to physical stresses.

中文翻译：

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牛成熟髓核和脊索细胞对静水压力和葡萄糖限制的差异反应。

目的人椎间盘髓核包含两种细胞类型：脊索细胞（NC）和成熟髓核（MNP）细胞。NC细胞丢失与椎间盘退变有关，该过程可能是由于机械应力和/或营养缺乏引起的。这项研究旨在调查NC和MNP细胞对静水压力和葡萄糖限制的功能反应。设计牛MNP和NC细胞在低（0.4-0.8 MPa）和高（1.6-2.4 MPa）动态压力下在三维藻酸盐珠中培养24小时。在生理（5.5 mM）葡萄糖培养基或葡萄糖限制（0.55 mM）培养基中培养细胞。最后，检查了葡萄糖限制和高压的联合作用。结果在压力或葡萄糖限制下，细胞活力和脊索表型标记没有明显改变。与大气对照组相比，MNP细胞对低压作出反应，糖胺聚糖（GAG）产量增加​​，而高压显着降低ACAN基因表达。在两种加载方式下，NC细胞均未显示基质基因表达或GAG产生反应。葡萄糖限制降低了NC细胞TIMP-1表达，但对MNP细胞没有影响。葡萄糖限制和高压的组合仅影响MNP细胞基因表达，而ACAN，Col2α1和ADAMTS-5表达降低。