Korecki Casey L, Kuo Catherine K, Tuan Rocky S, Iatridis James C
Spine Bioengineering Lab, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05405, USA.
J Orthop Res. 2009 Jun;27(6):800-6. doi: 10.1002/jor.20814.
The maintenance of the intervertebral disc extracellular matrix is regulated by mechanical loading, nutrition, and the accumulation of matrix proteins and cytokines that are affected by both aging and degeneration. Evidence suggests that cellular aging may lead to alterations in the quantity and quality of extracellular matrix produced. The aims of this study were to examine the role of loading and maturation (a subset of aging), and the interaction between these two factors in intervertebral disc cell gene expression and biosynthesis in a controlled 3D culture environment. Cells were isolated from young (4-6 months) and mature (18-24 months) bovine caudal annulus fibrosus and nucleus pulposus tissue. Isolated cells were seeded into alginate and dynamically compressed for 7 days at either 0.1, 1, or 3 Hz or maintained as a free-swelling control. After 7 days, DNA and sulfated glycosaminoglycan contents were analyzed along with real time, quantitative reverse transcription-polymerase chain reaction analysis for collagen types I and II, aggrecan, and matrix metalloproteinase-3 gene expression. Results suggest that maturation plays an important role in intervertebral disc homeostasis and influences the cell response to mechanical loading. While isolated intervertebral disc cells responded to mechanical compression in 3D culture, the effect of loading frequency was minimal. Altered cellular phenotype and biosynthesis rates appear to be an attribute of the cell maturation process, potentially independent of changes in cellular microenvironment associated with lost nutrition and disc degeneration. Mature cells may have a decreased capacity to create or retain extracellular matrix components in response to mechanical loading compared to young cells.
椎间盘细胞外基质的维持受机械负荷、营养以及基质蛋白和细胞因子积累的调节，而这些又受到衰老和退变的影响。有证据表明，细胞衰老可能导致所产生的细胞外基质在数量和质量上发生改变。本研究的目的是在可控的三维培养环境中，研究负荷和成熟（衰老的一个子集）的作用，以及这两个因素之间的相互作用对椎间盘细胞基因表达和生物合成的影响。从年轻（4 - 6个月）和成熟（18 - 24个月）的牛尾纤维环和髓核组织中分离细胞。将分离的细胞接种到藻酸盐中，并在0.1、1或3 Hz下动态压缩7天，或作为自由膨胀对照进行培养。7天后，分析DNA和硫酸化糖胺聚糖含量，并对I型和II型胶原蛋白、聚集蛋白聚糖和基质金属蛋白酶-3基因表达进行实时定量逆转录-聚合酶链反应分析。结果表明，成熟在椎间盘稳态中起重要作用，并影响细胞对机械负荷的反应。虽然分离的椎间盘细胞在三维培养中对机械压缩有反应，但负荷频率的影响很小。细胞表型和生物合成率的改变似乎是细胞成熟过程的一个特征，可能独立于与营养缺失和椎间盘退变相关的细胞微环境变化。与年轻细胞相比，成熟细胞对机械负荷产生或保留细胞外基质成分的能力可能降低。
