Hypoxic stress enhances extension and branching of dorsal root ganglion neuronal outgrowth

Junxuan Ma, Despina Stefanoska, Laura S. Stone, Maria Hildebrand, C.C. (René) van Donkelaar, Xuenong Zou, Valentina Basoli, Sibylle Grad, Mauro Alini, Marianna Peroglio (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

It has been shown that painful intervertebral discs (IVDs) were associated with a deeper innervation. However, the effect of the disc's degenerative microenvironment on neuronal outgrowth remains largely unknown. The focus of this study was to determine the influence of hypoxia on dorsal root ganglion (DRG) neurite outgrowth. Toward this aim, the DRG‐derived cell line ND7/23 was either directly subjected to 2% or 20% oxygen conditions or exposed to conditioned medium (CM) collected from IVDs cultured under 2% or 20% oxygen. Viability and outgrowth analysis were performed following 3 days of exposure. Results obtained with the cell line were further validated on cultures of rabbit spinal DRG explants and dissociated DRG neurons. Results showed that hypoxia significantly increased neurite outgrowth length in ND7/23 cells, which was also validated in DRG explant and primary cell culture, although hypoxia conditioned IVD did not significantly increase ND7/23 neurite outgrowth. While hypoxia dramatically decreased the outgrowth frequency in explant cultures, it significantly increased collateral sprouting of dissociated neurons. Importantly, the hypoxia‐induced decrease of outgrowth frequency at the explant level was not due to inhibition of outgrowth branching but rather to neuronal necrosis. In summary, hypoxia in DRG promoted neurite sprouting, while neuronal necrosis may reduce the density of neuronal outgrowth at the tissue level. These findings may help to explain the deeper neo‐innervation found in the painful disc tissue.
Original languageEnglish
Article numbere1090
Number of pages15
JournalSpine
Volume3
Issue number2
Early online date4 May 2020
DOIs
Publication statusPublished - 1 Jun 2020

Keywords

  • cell viability
  • dorsal root ganglion
  • hypoxia
  • low back pain
  • neuronal outgrowth

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