Carbonic anhydrase 12 precursor (EC 4.2.1.1) (Carbonate dehydratase XII) (Carbonic anhydrase XII) (CA-XII) (Tumor antigen HOM-RCC-3.1.3)

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Co-culturing nucleus pulposus mesenchymal stem cells with notochordal cell-rich nucleus pulposus explants attenuates tumor necrosis factor-α-induced senescence.

Cell therapy for the treatment of intervertebral disc degeneration (IDD) faces serious barriers since tissue-specific adult cells such as nucleus pulposus cells (NPCs) have limited proliferative ability and poor regenerative potential; in addition, it is difficult for exogenous adult stem cells to survive the harsh environment of the degenerated intervertebral disc. Endogenous repair by nucleus pulposus mesenchymal stem cells (NPMSCs) has recently shown promising regenerative potential for the treatment of IDD. Notochordal cells (NCs) and NC-conditioned medium (NCCM) have been proven to possess regenerative ability for the treatment of IDD, but this approach is limited by the isolation and passaging of NCs. Our previous study demonstrated that modified notochordal cell-rich nucleus pulposus (NC-rich NP) has potential for the repair of IDD. However, whether this can protect NPMSCs during IDD has not been evaluated. In the current study, tumor necrosis factor (TNF)-α was used to mimic the inflammatory environment of IDD. Human NPMSCs were cocultured with NC-rich NP explants from healthy rabbit lumbar spine with or without TNF-α. Cell proliferation and senescence were analyzed to investigate the effect of NC-rich NP explants on TNF-α-treated NPMSCs. The expression of mRNA encoding proteins related to matrix macromolecules (such as aggrecan, Sox-9, collagen Iα, and collagen IIα), markers related to the nucleus pulposus cell phenotype (including CA12, FOXF1, PAX1, and HIF-1α), and senescence markers (such as p16, p21, and p53), senescence-associated proinflammatory cytokines (IL-6), and extracellular proteases (MMP-13, ADAMTS-5) was assessed. The protein expression of CA12 and collagen II was also evaluated. After a 7-day treatment, the NC-rich NP explant was found to enhance cell proliferation, decrease cellular senescence, promote glycosaminoglycan (GAG), collagen II, and CA12 production, upregulate the expression of extracellular matrix (ECM)-related genes (collagen I, collagen II, SOX9, and ACAN), and enhance the expression of nucleus pulposus cell (NPC) markers (HIF-1α, FOXF1, PAX1, and CA12). Modified NC-rich NP explants can attenuate TNF-α-induced degeneration and senescence of NPMSCs in vitro. Our findings provide new insights into the therapeutic potential of NC-rich NP for the treatment of IDD.

MeSH Terms

  • Adult
  • Cell Proliferation
  • Coculture Techniques
  • Female
  • Humans
  • Male
  • Mesenchymal Stem Cells
  • Middle Aged
  • Notochord
  • Nucleus Pulposus
  • Tumor Necrosis Factor-alpha

Keywords

  • Intervertebral disc degeneration
  • Notochordal cell-rich nucleus pulposus explants
  • Nucleus pulposus mesenchymal stem cells
  • Senescence
  • TNF-α


Notochordal and nucleus pulposus marker expression is maintained by sub-populations of adult human nucleus pulposus cells through aging and degeneration.

The nucleus pulposus (NP) of the intervertebral disc (IVD) demonstrates substantial changes in cell and matrix composition with both ageing and degeneration. While recent transcriptomic profiling studies have helped define human NP cell phenotype, it remains unclear how expression of these markers is influenced by ageing or degeneration. Furthermore, cells of the NP are thought to derive from the notochord, although adult NP lacks identifiable notochordal (NC) cells. This study aimed to confirm expression of previously identified NP and NC marker genes in adult human NP cells from a range of ages and degenerate states. Importantly, using gene expression analysis (N = 60) and immunohistochemistry (N = 56) the study demonstrates expression of NP markers FoxF1, Pax-1, keratin-8/18, carbonic anhydrase-12, and NC markers brachyury, galectin-3 and CD24 in cells of the NP irrespective of age or degeneration. Our immunohistochemical data, combined with flow cytometry (N = 5) which identified a small number of CA12 Gal3 T CD24 cells, suggests the possible presence of a sub-population of cells with an NC-like phenotype in adult NP tissue. These findings suggest that the NP contains a heterogeneous population of cells, which may possess varied phenotypic and functional profiles and thus warrant further investigation to improve our understanding of IVD homeostasis and repair.

MeSH Terms

  • Adolescent
  • Adult
  • Aging
  • Biomarkers
  • Humans
  • Intervertebral Disc
  • Intervertebral Disc Degeneration
  • Middle Aged
  • Notochord
  • Nucleus Pulposus
  • Young Adult