Objective Lack of specific marker-sets prohibits definition and functional distinction of cellular subtypes in the intervertebral disc (IVD), such as those from the annulus fibrosus (AF) and the nucleus pulposus (NP). Design We recently generated immortalized cell lines from human NP and AF tissues; these comprise a set of functionally distinct clonal subtypes. Whole transcriptome analyses were performed of 12 phenotypically distinct clonal cell lines (4× NP-Responder, 4× NP-nonResponder, 2× AF-Sheet forming, and 2× AF-nonSheet forming). Data sets were filtered for membrane-associated marker genes and compared to literature. Results Comparison of our immortal cell lines to published primary NP, AF, and articular chondrocytes (AC) transcriptome datasets revealed preservation of AF and NP phenotypes. NP-specific membrane-associated genes were defined by comparison to AF cells in both the primary dataset (46 genes) and immortal cell-lines (161 genes). Definition of AF-specific membrane-associated genes yielded 125 primary AF cell and 92 immortal cell-line markers. Overlap between primary and immortal NP cells yielded high-confidence NP-specific marker genes for NP-R ( CLDN11, TMEFF2, CA12, ANXA2, CD44) and NP-nR (EFNA1, NETO2, SLC2A1). Overlap between AF and immortal AF subtypes yielded specific markers for AF-S ( COLEC12, LPAR1) and AF-nS ( CHIC1). Conclusions The current study provides a reference platform for preclinical evaluation of novel membrane-associated cell type-specific markers in the IVD. Future research will focus on their biological relevance for IVD function in development, homeostasis, and degenerate conditions.

中文翻译：

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以膜组为中心的方法为椎间盘中的细胞亚型定义了新的生物标记。

客观上缺乏特定的标记集，无法定义和区分椎间盘（IVD）中的细胞亚型，例如纤维环（AF）和髓核（NP）的亚型。设计我们最近从人的NP和AF组织生成了永生的细胞系。它们包括一组功能上不同的克隆亚型。对12个表型不同的克隆细胞系（4x NP-Responder，4x NP-nonResponder，2x AF-Sheet形成和2x AF-nonSheet形成）进行了整个转录组分析。过滤数据集的膜相关标记基因，并与文献进行比较。结果我们的永生细胞系与已发表的原发性NP，AF和关节软骨细胞（AC）转录组数据集的比较表明，AF和NP表型得以保留。通过与主要数据集（46个基因）和永生细胞系（161个基因）中的AF细胞进行比较，确定了与NP相关的膜相关基因。AF特定的膜相关基因的定义产生了125个原发性AF细胞和92个永生细胞系标记。初级和永生NP细胞之间的重叠产生了NP-R（CLDN11，TMEFF2，CA12，ANXA2，CD44）和NP-nR（EFNA1，NETO2，SLC2A1）的高可信度NP特异性标记基因。AF和永生性AF亚型之间的重叠产生了AF-S（COLEC12，LPAR1）和AF-nS（CHIC1）的特异性标记。结论本研究为IVD中新型膜相关细胞类型特异性标志物的临床前评估提供了参考平台。未来的研究将集中在IVD功能在发育，体内稳态和退化条件下的生物学相关性。