Effect of nutrient deprivation on the viability of intervertebral disc cells

Abstract

There is evidence that a fall in nutrient supply leads to disc degeneration but little understanding of the effects of nutrient deprivation on the physiology of disc cells which govern the composition of the disc. We examined the effects of changes in glucose and oxygen concentration and pH on the viability and metabolism of cells from bovine nucleus pulposus. Cells isolated from bovine discs and embedded in alginate beads were cultured under oxygen and glucose concentrations from zero to physiological levels and maintained at pH 7.4, pH 6.7, or pH 6.2 for up to 3 days. Interactions between nutrient concentrations were examined in relation to cell viability and lactic acid production. Cell viability was significantly reduced in the absence of glucose, with or without oxygen. Disc cells survived at 0% oxygen, provided that glucose was present, as seen previously. Cell viability decreased if the medium was acidic, more so when combined with low glucose concentrations. The rate of lactic acid production also fell as the pH became acidic and after 24 h or more at low glucose concentrations, but it did not appear to vary with oxygen concentration under the culture conditions used here. Glucose, rather than oxygen, appears to be the nutrient critical for maintaining disc cell viability. However, in an avascular tissue such as the disc, it is unlikely that glucose deprivation will occur alone; it will almost certainly correlate with a fall in oxygen concentration and pH. These results indicate that the combined nutrient and metabolite environment, rather than concentrations of any single nutrient, should be considered when studying cellular physiology in the disc.

Disc cell clusters in pathological human intervertebral discs are associated with increased stress protein immunostaining

“…In disc cells, activation of the stress sensing HSF-1 complex could be triggered by several mechanisms, which result in Hsp expression [21]. ECM degeneration may lead to an environmental trigger such as exposure of the disc cells, particularly in extruded or sequestrated states, to environmental conditions (including hydrostatic loading or oxygen tensions) different from those experienced by cells in intact discs [5,7]. Alternatively, a stress response could also be initiated by a proteotoxic stress: in this case, the presence of abnormal ECM components in the cytoplasm, such as incorrectly folded or denatured proteins.…”

Regulation of gene expression in intervertebral disc cells by low and high hydrostatic pressure

“…Disc degeneration is influenced by multiple factors like age [4], nutrition [2,17], mechanical factors [16] and genetics [19,18]. In the present study we focus on the influence of mechanical loading on intervertebral disc (IVD) cells as both overload as well as immobilisation are supposed to accelerate the disc degeneration.…”

“…Cells were harvested 24 h after the end of stimulation and changes in the expression of genes known to influence IVD matrix turnover (collagen-I, collagen-II, aggrecan, MMP1, MMP2, MMP3, MMP13) were analyzed by real-time RT-PCR. A Wilcoxon signed-rank test 1 and a Wilcoxon 2-sample test 2 were performed to detect differences between the stimulated and control samples 1 and differences between low and high hydrostatic pressure 2 . Multiple testing was considered by adjusting the p value appropriately.…”

Morphological changes in disc herniation in the lower cervical spine: an ultrastructural study

“…Moreover, rare glycogen deposits were seen in the control specimens presenting a low radiological degeneration grade in the aged control group. On the other hand, it is known that EP sclerosis causes a decrease in nutrient supply and, thus, advanced changes in the IVD [7,26,47]. Only half of the control discs, but nearly all of the herniated discs showed an in-growth of vascular vessels from the longitudinal ligament inwards the outer AF.…”