Division of Orthopaedic Surgery, McGill University, Lady Davis Institute for Medical Research, Montreal, QC, Canada.
Spine (Phila Pa 1976). 2011 Jan 15;36(2):E131-8. doi: 10.1097/BRS.0b013e3181d52b9e.
the response of cells from the annulus fibrosus (AF) and nucleus pulposus (NP) to varying oxygen (O2) concentrations was examined when cultured in alginate.
to study the effect of O2 concentration on AF and NP cells.
AF and NP cells possess different metabolic profiles in situ. However, it is not clear whether this difference is maintained in in vitro culture conditions. AF and NP cells can respond differently in the different systems, which may differ from the in vivo environment in terms of nutrient supply and O2 levels. In vivo, O2 levels vary from 1% to 5% within the intervertebral disc, and there is evidence that disc cell metabolism can vary with O2 concentrations.
an alginate scaffold was seeded with bovine AF or NP cells and maintained in culture for up to 18 days under different O2 concentrations. The sulfated glycosaminoglycan (GAG) content in the culture medium and the expression of aggrecan, type I (COL1A2) and II (COL2A1) collagen genes were analyzed at day 9 and day 18.
in both NP and AF cells cultured either in normoxia (21% O2) or in hypoxia (5% and 1% O2), the GAG content of the culture medium increased with time, though the rate of increase was diminished in 5% O2. With a decrease in O2 levels, the expression of aggrecan mRNA increased in NP cells. There was little effect of O2 on aggrecan mRNA level in AF cells. However, there was a slight decrease with time. Interestingly, aggrecan mRNA levels did not reflect GAG release for either NP or AF cells. There was no effect with time or O2 levels on COL2A1 message in NP cells. The highest Aggrecan/COL2 message ratio for NP cells was with 1% O2, suggesting this to be the best condition for maintaining the NP phenotype. COL1A2 gene expression in NP and AF cells increased with time, but showed little change with O2 levels in NP cells. The highest COL2/COL1 ratio in NP cells was also observed with 1% O2. Finally, NP cells tended to remain localized in the alginate beads, whereas AF cells tended to migrate from the beads.
both NP and AF cells showed little change in GAG production with O2 levels ranging from 1% to 21%. Disc cell metabolism is not impaired at low O2 concentrations, which appear beneficial to matrix composition. Furthermore, low oxygen may promote a gelatinous NP matrix, whereas increased oxygen levels may promote a fibrous matrix.
当细胞在藻酸盐中培养时，研究了纤维环（AF）和髓核（NP）细胞对不同氧（O2）浓度的反应。
研究 O2 浓度对 AF 和 NP 细胞的影响。
AF 和 NP 细胞在原位具有不同的代谢特征。然而，目前尚不清楚这种差异是否在体外培养条件下得到维持。AF 和 NP 细胞在不同的系统中可能会有不同的反应，这可能与营养供应和 O2 水平方面的体内环境不同。在体内，椎间盘内的 O2 浓度从 1%到 5%不等，有证据表明椎间盘细胞的新陈代谢可以随 O2 浓度而变化。
将牛 AF 或 NP 细胞接种在藻酸盐支架上，并在不同的 O2 浓度下培养，最多可达 18 天。在第 9 天和第 18 天分析培养基中硫酸化糖胺聚糖（GAG）的含量以及聚集蛋白聚糖、I 型（COL1A2）和 II 型（COL2A1）胶原基因的表达。
无论是在常氧（21%O2）还是低氧（5%和 1%O2）条件下培养的 NP 和 AF 细胞，培养基中的 GAG 含量均随时间增加，但在 5%O2 中的增加速度减慢。随着 O2 水平的降低，NP 细胞中聚集蛋白聚糖 mRNA 的表达增加。O2 对 AF 细胞中聚集蛋白聚糖 mRNA 水平几乎没有影响。然而，随着时间的推移，其水平略有下降。有趣的是，NP 或 AF 细胞的 GAG 释放与 aggrecan mRNA 水平没有关系。NP 细胞中 COL2A1 基因的表达不受时间或 O2 水平的影响。NP 细胞中 aggrecan/COL2 基因表达的最高比值出现在 1%O2 时，这表明这是维持 NP 表型的最佳条件。NP 和 AF 细胞的 COL1A2 基因表达随时间增加，但 NP 细胞中的 O2 水平变化不大。NP 细胞中 COL2/COL1 的最高比值也出现在 1%O2 时。最后，NP 细胞倾向于在藻酸盐珠内局部化，而 AF 细胞则倾向于从珠内迁移。
O2 浓度在 1%至 21%范围内时，NP 和 AF 细胞的 GAG 产生均无明显变化。低 O2 浓度不会损害椎间盘细胞的新陈代谢，这似乎有利于基质成分。此外，低氧可能促进凝胶状 NP 基质的形成，而增加的氧水平可能促进纤维基质的形成。
