Tissue Injury and Repair, School of Biomedicine, Faculty of Medical and Human Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, UK.
Arthritis Res Ther. 2010;12(1):R22. doi: 10.1186/ar2929. Epub 2010 Feb 11.
Nucleus pulposus (NP) cells have a phenotype similar to articular cartilage (AC) cells. However, the matrix of the NP is clearly different to that of AC suggesting that specific cell phenotypes exist. The aim of this study was to identify novel genes that could be used to distinguish bovine NP cells from AC and annulus fibrosus (AF) cells, and to further determine their expression in normal and degenerate human intervertebral disc (IVD) cells.
Microarrays were conducted on bovine AC, AF and NP cells, using Affymetrix Genechip(R) Bovine Genome Arrays. Differential expression levels for a number of genes were confirmed by quantitative real time polymerase chain reaction (qRT-PCR) on bovine, AC, AF and NP cells, as well as separated bovine NP and notochordal (NC) cells. Expression of these novel markers were further tested on normal human AC, AF and NP cells, and degenerate AF and NP cells.
Microarray comparisons between NP/AC&AF and NP/AC identified 34 NP-specific and 49 IVD-specific genes respectively that were differentially expressed > or =100 fold. A subset of these were verified by qRT-PCR and shown to be expressed in bovine NC cells. Eleven genes (SNAP25, KRT8, KRT18, KRT19, CDH2, IBSP, VCAN, TNMD, BASP1, FOXF1 & FBLN1) were also differentially expressed in normal human NP cells, although to a lesser degree. Four genes (SNAP25, KRT8, KRT18 and CDH2) were significantly decreased in degenerate human NP cells, while three genes (VCAN, TNMD and BASP1) were significantly increased in degenerate human AF cells. The IVD negative marker FBLN1 was significantly increased in both degenerate human NP and AF cells.
This study has identified a number of novel genes that characterise the bovine and human NP and IVD transcriptional profiles, and allows for discrimination between AC, AF and NP cells. Furthermore, the similarity in expression profiles of the separated NP and NC cell populations suggests that these two cell types may be derived from a common lineage. Although interspecies variation, together with changes with IVD degeneration were noted, use of this gene expression signature will benefit tissue engineering studies where defining the NP phenotype is paramount.
髓核（NP）细胞具有与关节软骨（AC）细胞相似的表型。然而，NP 的基质明显不同于 AC，这表明存在特定的细胞表型。本研究的目的是鉴定可用于区分牛 NP 细胞与 AC 和纤维环（AF）细胞的新基因，并进一步确定它们在正常和退变人椎间盘（IVD）细胞中的表达。
使用 Affymetrix Genechip（R）牛基因组芯片对牛 AC、AF 和 NP 细胞进行微阵列分析。通过定量实时聚合酶链反应（qRT-PCR）对牛、AC、AF 和 NP 细胞以及分离的牛 NP 和脊索（NC）细胞，对许多基因的差异表达水平进行了确认。进一步测试了这些新标记物在正常人和退变人 AC、AF 和 NP 细胞中的表达。
NP/AC&AF 和 NP/AC 之间的微阵列比较分别确定了 34 个 NP 特异性和 49 个 IVD 特异性基因，这些基因的差异表达 >或=100 倍。通过 qRT-PCR 验证了其中一部分，并证实其在牛 NC 细胞中表达。11 个基因（SNAP25、KRT8、KRT18、KRT19、CDH2、IBSP、VCAN、TNMD、BASP1、FOXF1 和 FBLN1）在正常人类 NP 细胞中也表现出差异表达，尽管程度较小。4 个基因（SNAP25、KRT8、KRT18 和 CDH2）在退变人 NP 细胞中显著减少，而 3 个基因（VCAN、TNMD 和 BASP1）在退变人 AF 细胞中显著增加。IVD 阴性标记物 FBLN1 在退变人 NP 和 AF 细胞中均显著增加。
本研究鉴定了一些新的基因，这些基因描述了牛和人 NP 和 IVD 的转录谱，并可区分 AC、AF 和 NP 细胞。此外，分离的 NP 和 NC 细胞群体的表达谱相似表明这两种细胞类型可能来自共同的谱系。尽管存在种间差异以及 IVD 退变的变化，但使用这种基因表达特征将有益于组织工程研究，在该研究中，定义 NP 表型至关重要。
